JPH0329883B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for producing aromatic polyamide fibers, and more specifically, after producing a liquid crystal prepolymer dope (prepolymer) of fully aromatic polyamide in advance, a molecular orientation polymerization method using a polymerization accelerator is performed. The present invention relates to a method for producing aromatic polyamide fibers having high strength and high abrasion resistance and having a single structure and no crystal bonding layer. Conventional technology Recently, there has been a demand for the development of new materials that are extremely lightweight and strong in the aircraft and spaceflight industries, and high-strength, high-elasticity glass fibers made of ceramics, graphite, boron, etc. have been developed and used. However, the reality is that such substances are quite expensive and inconvenient to handle, so they cannot be widely applied. However, it has been discovered that aromatic polyamide fibers have high abrasion resistance, high strength, and high elasticity as a new material, and active development is being carried out in this field. It is often used as a raw material for manufacturing plastic materials, and resin compositions reinforced with glass fiber are already widely used as building materials. However, as a result of research, it has been found that the conventionally used materials have many problems, and kwolek is used as a fiber development technology to compensate for these shortcomings.
Publication No. 1810426 of the Federal Republic of Germany states:
For example, wet-erosion spinning using a dope of carboxyl aromatic polyamide, which is optically anisotropic,
A technique has been introduced which claims to add exceptional strength to fibers and can increase tensile strength and elasticity by heating fibers under tension. This creates an aromatic polyamide dope,
When spun to produce fibers or films, especially short fibers with a pulp-like substance structure in addition to the above-mentioned characteristics, such pulp-like short fibers can be used as electrical insulators, heat-insulating materials, and durable materials. It is highly expected to be used as an abrasive agent to replace asbestos. As described above, aromatic polyamide fibers, especially pulp-like short fibers, have been studied and developed by various methods due to their many advantages, and the following are conventional techniques related to this. That is, conventional techniques related to polymerization and spinning of polyamide fibers are disclosed in U.S. Pat.
This technology is introduced in the issue, but after dissolving an inorganic salt and an aromatic diamine in an amide solvent, aromatic diacid chloride is polymerized at low temperature to form a crumb form, such as an acid crumb form. Wash the polymer with water, separate the polymerization solvent and inorganic salt, dry it, and then dissolve it in 98% or more sulfuric acid or about 20% by weight of a sulfuric acid solvent such as chlorosulfuric acid or fluorosulfuric acid to make a liquid crystal dope. ,
This technique produces aromatic polyamide fibers and films by passing this dope through an orifice, spinning it with water, neutralizing it, washing it with water, drying it, and mechanically treating it. However, when using such a method, the process is complicated, as it must go through, for example, a polymerization process, a washing process, dope production using sulfuric acid, spinning, and a mechanical treatment process. The disadvantage is that the cost is high, and the use of sulfuric acid may corrode the manufacturing equipment and is dangerous, so it is not suitable.Also, the physical properties of the fiber deteriorate due to the polymer decomposition reaction in the dope, and it is produced as a by-product. In addition to the difficulty in processing calcium sulfate (CaSO ₄ ), the residual sulfuric acid in the fibers causes the color of the fibers to darken over time.
It was undesirable. In addition, fiber products manufactured by this method have weak compressive strength due to the kink band phenomenon of the fiber itself, which is much lower than the original theoretical strength of aromatic polyamide fiber, and the fiber itself has crystal defects. Since a layer (crystal defect layer) is formed, chemical resistance is also considerably inferior. Another method is disclosed in Japanese Patent Publication No. 59-47694, in which a low molecular weight aromatic polyamide obtained by interfacial polymerization is dissolved in an amide solvent, and this solution is stirred in a precipitant to produce pulp-like particles. However, since this polymer is precipitated in water or alcohol and stirred, the intrinsic viscosity remains at a level of about 2 to 3.5, which deteriorates the physical properties and makes it almost impossible to produce high-performance polyamide short fibers. It was hot. Also, a recent technology, U.S. Patent No. 4511623
In this issue, a tertiary amine such as pyridine is used during the polymerization process of aromatic polyamide to rapidly increase the reaction rate, and a mechanical shear force (160 sec ^-1 above) and have a high degree of orientation and high degree of polymerization,
A method for producing high-strength polyamide pulp-like short fibers with an intrinsic viscosity of 5 to 7 has been introduced.
When producing pulpy short fibers using this method, it is also necessary to simultaneously add an amide solvent and a large amount of tertiary amine during the polymerization process, so the amount of terephthaloyl chloride that is finally added is Due to the rapid increase in viscosity during polymerization, the polymerization is terminated within 10 seconds, making process control very difficult and making continuous production impossible. Note that U.S. Patent Nos. 3,672,143 and 3,817,941 introduce technologies similar to the present invention.
That is, the polymer solution is doped before the polymerization is completed (this dope is an in situ
Spinning in a precipitant as a polymer dope),
Alternatively, fibers can be obtained through a simple manufacturing process by extrusion injection, but due to the use of water as a precipitant during polymerization, the effect of increasing the molecular weight cannot be obtained, and the intrinsic viscosity cannot be increased. It has been impossible to obtain fibers with excellent physical properties. On the other hand, the conventional method for producing aromatic polyamide fibers is to dope high molecular weight PPTA with concentrated sulfuric acid to a concentration of about 20% by weight after polymerization and washing, and then spin the fiber in water through an air gap. Because it is manufactured by applying the principle that molecular chains are oriented by stretching when high molecular weight polymers are spun using a high concentration (20%) solution, even if the molecular chains of aromatic polyamide Although it is hard and forms liquid crystal, the viscosity at 80℃ is
It becomes more than 1000 poise, and complete orientation of the molecular chains does not occur. Therefore, if we take a closer look at the microstructure of the aromatic polyamide fiber finally produced, we can see that crystal defects are formed in units of 250 nm, as shown in the attached Figure 6 a and b, and in the spun form it is a pleated sheet. Structure (radially arranged pleated sheet structure)
It has a skin-core structure, consisting of a core part with a strong structure and a skin part with a dense and well-oriented structure. (Journal of Polymer-science:
Polymer Physics Edition Vol.21, 1955−1969
(1983)) Due to the pleated sheet structure of the core portion in such a skin-core dual structure, the strength of the fiber is considerably lower than the theoretical strength. In addition, J.Polym.Sci.Polym.Phys.ED21, 1757
(1983) states that when spinning with sulfuric acid dope, the polymer chain ends are
Like NH ₃ ⁺ HSO ₄ ⁺ , it has ionic properties, so these clusters form and a crystal defect layer is formed in this part, which becomes a weak part, and at this time, stress When subjected to such damage, kink bands are formed, the strength is reduced, and chemical resistance also deteriorates as corrosion by chemical chemicals begins in this area. Therefore, the above-mentioned paper also reveals the fact that the strength can be further increased by preventing the molecular chain terminal distribution from forming in the form of groups, but this was not possible with conventional methods. On the other hand, in the case of polyethylene (PE),
Existing PE fibers have a strength of less than 5 g/d, but when the molecular chain structure is expanded using a special spinning method called gel spinning, the strength increases to more than 20 g/d, so even if they are the same compound, The present inventors focused on the fact that the physical properties of aromatic polyamides vary greatly depending on their crystal structure, and as a result of long-term research in order to dramatically improve the physical properties of aromatic polyamides, they arrived at the present invention. Problems to be Solved by the Invention Therefore, the purpose of the present invention is to solve the conventional problems, namely, economic disadvantages due to long steps, difficulty in process control due to rapid increase in degree of polymerization, and low degree of polymerization. To provide a method for producing aromatic polyamide fibers having high strength and high degree of orientation, in which fibers are produced by separating the polymerization process of a prepolymer and the molecular orientation process, and the final polymerization and molecular chain orientation are performed simultaneously. be. Another object of the present invention is to provide a manufacturing method that allows for easy process control, low manufacturing costs, and continuous production of aromatic polyamide fibers that can be obtained directly at the same time as polymerization. Means for Solving the Problems The present invention will be described in detail below. The present invention provides an aromatic solvent to a solvent (first composition) selected from the group consisting of an amide solvent, an amide solvent in which an inorganic salt is dissolved, and an amide solvent containing a small amount of tertiary amine and in which an inorganic salt is dissolved. The following general formula () whose intrinsic viscosity is 1.0 to 4.0 before complete polymerization of a mixed solution prepared by adding equimolar amounts of group diamine and aromatic diacid chloride at a low temperature of 40°C or less
After producing an optically anisotropic liquid crystal prepolymer dope that is a copolymer or homopolymer having repeating units of -40℃ in a mixed solvent or a polymerization-promoting precipitation solvent (second composition) containing a small amount of inorganic salt.
This is a method for producing aromatic polyamide fibers, characterized in that the fibers are obtained by spinning at a low temperature of 1 to 4 at a spinning draw ratio of 1 to 4, and continuously winding the fibers. In addition, the present invention uses an optically anisotropic liquid crystal prepolymer dope having repeating units of the following general formula () or () produced by the same method as above as a polymerization-promoting precipitation solvent (second composition). Aromatic polyamide fibers in the form of pulp-like short fibers, characterized in that they are obtained continuously by extrusion injection or contact with a liquid crystal prepolymer dope and applying a shear rate of at least 20 sec ^-1 with a polymerization-promoting precipitation solvent. This is the manufacturing method. However, R ₁ , R ₂ , R ₃ are

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【formula】 (X is H, Cl, Br, l)

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[Formula] R ₁ and R ₂ are the same or different, and R ₁
and R ₂ are present in approximately equimolar amounts. According to the manufacturing method of the present invention, the microstructure of the final molded fiber has a completely expanded molecular chain structure due to sufficient molecular orientation polymerization, and the chain ends are distributed evenly (randomly) in the axial direction of the fiber. ) is formed, there are no defects and crystal defect layers that follow the pleated sheet structure in the axial direction of the fiber, and the intrinsic viscosity is 3.0.
In this manner, aromatic polyamide fibers having a single structure having a strength of 15 g/d or more can be obtained. The present invention will be explained in more detail below. The optically anisotropic liquid crystal prepolymer dope featured in the present invention consists of an amide solvent, an amide solvent in which an inorganic salt is dissolved, and an amide solvent containing a small amount of tertiary amine and an inorganic salt dissolved therein. During the polymerization reaction by adding a mixed solution of aromatic diamine and aromatic diacid chloride in a solvent selected from the group consisting of solvents (first composition), gelation occurs after stirring opalescence. Refers to a polymer solution formed at a previous point in time that has copolymer or homopolymer properties. For example, the polymerization method for the liquid crystal prepolymer dope (polymerization solution or in situ polymer dope) includes an amide solvent, an amide solvent in which an inorganic salt (metal halide salt) is dissolved, and a small amount of tertiary amine. After dissolving the aromatic diamine in a solvent (first composition) selected from the group consisting of amide solvents in which inorganic salts are dissolved, the aromatic diamine is cooled at a low temperature under a nitrogen stream, and the aromatic diacid chloride is dissolved at a temperature below 40°C. It can be obtained by polymerization using a solution polymerization method in which the reaction is carried out at low temperatures, but at this time, the monomer and solvent contain a minimum amount of impurities so that the polymerization reaction proceeds quantitatively. A liquid crystal prepolymer dope with a suitable molecular weight that can be supplied to the liquid crystal prepolymer dope is obtained. For example, in the polymerization solvent used as the first composition in the present invention, an amide-based and urea-based organic solvent alone, a mixture of these with an inorganic salt, or a mixture of these with an inorganic salt and a small amount of a tertiary solvent are used. Amide-based and urea-based organic solvents containing grade amines are used, and the amide-based or urea-based substances used in this case include, for example, N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAC). , hexamethylphosphoramide (HMPA), N,N-dimethylformamide (DMF), N,N-dimethylsulfoxide (DMSO), N,N,N',N'-tetramethylurea (TMU), etc. In addition, N-methylpiperidone, N-methylcaprolactam, N-methylpiperidone, N-methylcaprolactam,
-acetylpyrrolidine, N-ethylpyrrolidine,
Examples include dimethylpropionamide, dimethylisobutyramide, and dimethylpropyl urea. In addition, when adding a tertiary amine to the mixed solvent of the first composition in order to adjust the reaction rate, it is desirable to use 0.01 to 2% by weight of the mixed solvent. pyridine,
It can be selected from quinoline, triethylamine, t-butylamine, picoline, pyridine, pyrazine, and quinoxaline. If the amount of amine used in the mixed solvent is less than 0.01% by weight, the effect of adding the tertiary amine will be lost, which is undesirable.On the other hand, if more than 2% by weight is added, it will be difficult to adjust the reaction rate. Because it is difficult and the process control is not easy, the third
It is preferable to add a class amine. On the other hand, the inorganic salts used to increase the solubility of polymers are preferably metal halides; examples include lithium chloride (LiCl), calcium chloride (CaCl ₂ ), potassium chloride (KCl), and potassium bromide (KBr). ), lithium bromide (LiBr), etc. are mainly used, but it is better to use them by adding 0.5 to 15% by weight (weight of salt/capacity of amide solvent) to the polymerization solvent. In this way, an amide solvent alone, an amide solvent with an inorganic salt dissolved therein, or an amide solvent with an inorganic salt dissolved and a small amount of tertiary amine (primary amide solvent) can be used.
When an aromatic diamine, such as p-phenylene diamine, and an aromatic diacid chloride, such as terephthaloyl chloride, are added to the composition (composition) at a low temperature, stirred, and allowed to react to some extent, the state is before the reaction is completed. The polymer in the optically anisotropic liquid crystal prepolymer dope is obtained with poly(p-phenylene terephthalamide) having the following structural formula (). At this time, after the dope is completely polymerized,
It is distinguished from a dope in which the polymer is separated and dissolved in a sulfuric acid solvent (isolated polymer dope). Here, it is sufficient that the liquid crystal prepolymer dope has a polymer content of 4 to 20% by weight.
If it is more than 20% by weight, it is not suitable for use as a dope, that is, the reaction rate will increase rapidly, making process control difficult;
In the following cases, there is a disadvantage that the intrinsic viscosity of the final polymer decreases rapidly, resulting in a loss in terms of cost, so it is preferable to adjust the content within the above range. More preferably, it is 5 to 15% by weight. In addition, the intrinsic viscosity of the liquid crystal prepolymer is 1.0 to 4.0.
However, in terms of process control, it is more desirable to have an intrinsic viscosity of 1.5 to 3.5. In the unlikely event that the polymer content or intrinsic viscosity is high, it will be difficult to use it as a dope, and it will be difficult to spin or extrude it even through the nozzle or die of the present invention. is good. Meanwhile, the liquid crystal prepolymer dope obtained as described above is transferred to a cylindrical container that can control the temperature and has a cap attached, and is passed through a cap of a certain size so that the water content is less than 5000 ppm, and the liquid crystal prepolymer dope is The polymerization promoting precipitant (second composition) made with a tertiary amine solvent is spun, and the reaction is caused by a molecular orientation polymerization method. When removed, the molecular blending degree of the polymer increases, and when this is washed and dried,
The aromatic polyamide fiber required by the present invention can be obtained. On the other hand, the polymerization conditions of the present invention are such that all monomers and solvents used in the polymerization have a minimum amount of impurities (moisture).
It is desirable that the weight is determined under equivalence conditions, and the tertiary amine or the mixed solvent of the tertiary amine and the amide solvent is preferably maintained at a low temperature. On the other hand, the ratio (L/D) of the capillary length to the diameter of the spinneret where the liquid crystal prepolymer dope is spun and the diameter of the spinneret at the spinning nozzle is not absolute, but the size of the spinneret is 50μ to 10,000μ. is appropriate, and the best L/D is 0.5 to 10. However, as the size of the nozzle becomes smaller, the amide solvent penetrates into the inside of the discharged polymer relatively easily, and the intrinsic viscosity (ηinh or IV), the degree of molecular orientation of the polymer can be easily increased, the winding speed can be adjusted to improve the degree of molecular orientation of the polymer to some extent, and the precipitation time in the tertiary amine solvent can be increased to a certain extent. Although it is good, it is uneconomical in terms of time, so it is appropriate to adjust the precipitation time to within 0.1 to 1000 seconds. At this time, the ejection velocity (the average velocity of the polymer in the spinning nozzle capillary, expressed as 'JV' and calculated from the bulk of the polymer passing through the orifice and the cross-sectional area of the orifice) is preferably between 1 m/min and 300 m/min. , 50m/min to 100m/min is most appropriate;
The spinning draw ratio is the ratio of the fiber speed at which the tertiary amine solvent is released to the ejection speed, and the spinning draw ratio at this time may be from 1 to 4. According to the present invention, the temperature during spinning is usually carried out at a low temperature of 50°C or lower, and the lower the spinning temperature, the more the molecular orientation effect increases. It is best to carry out the test in a temperature range. If carried out at a temperature below -40℃, the molecular orientation effect will further increase, but it will be uneconomical due to the increased cost associated with maintaining the temperature.On the other hand, if carried out at a temperature above 50℃, the effect will be higher The molecular orientation effect is unnecessarily reduced and is not compatible with the present invention. More preferably, it is carried out at a temperature in the range of 0°C to 25°C, most preferably at room temperature. When the fibers obtained by the above method are heat-treated, various physical properties are improved. That is, when the fibers are heat-treated under tension, the modulus increases and the elongation rate decreases. At this time, the modulus is 30 to 80. %
degree increases, and the elongation rate decreases by about 30 to 40%. On the other hand, when it is desired to obtain pulp-like short fibers by a known method before drying the fibers obtained by the above-mentioned method, the fibers are transported through a feed roll with a grinder, and then mechanically processed by chopping and chopping. After carrying out the grinding process, pulpy staple fibers according to the invention are obtained. In the present invention, the optically anisotropic liquid crystal prepolymer dope produced by the same method as described above is extruded or brought into contact with a polymerization-promoting precipitation solvent, and the polymerization-promoting precipitation solvent causes a shear of at least 20 sec ^-1 . When speed is applied, pulp-like short fibers are directly produced, and an example of the process for producing the aromatic polyamide pulp-like short fibers according to the present invention will be described in detail below with reference to the accompanying drawings. That is, FIG. 1 is a process schematic diagram showing a first specific example of the present invention, in which a reaction tank 1 having a size that can accommodate the above-mentioned liquid crystal prepolymer dope at a certain level is shown.
A gear pump 4 attached to a transfer line 3 is operated to transfer the liquid crystal prepolymer dope placed in the reaction tank 1 into a storage tank 2 in which the liquid crystal prepolymer dope and a polymerization promoting precipitant are stored separately. At the same time, the polymerization-promoting precipitant stored in the storage tank 2 is also supplied to the nozzle jet device 7 along the transfer line 6 through the circulation pump 5. Then, following the transfer line 3, the liquid crystal prepolymer dope is introduced into the nozzle jet device 7 through the small holes of the nozzle jet device 7 at a shear rate of at least 20 sec ^-1 into the polymerization promoting precipitate. Polymerization occurs within the injection tube 8 by contacting the agent while being extruded and injected. Here, a transfer line 6 through which the polymerization promoting precipitant is transferred.
The flow rate must be within a range that allows the liquid crystal prepolymer dope introduced into the nozzle jet 7 to be sufficiently oriented, so the flow rate ratio is between 1:50 and 1:5.
A ratio of 0.1 is sufficient, but more preferably a ratio of 1:15 to 1:0.2 will result in considerably superior process control and various physical properties of the pulp-like short fibers.
The length and diameter of the pulp-like short fibers produced can also be adjusted by adjusting the flow rate ratio as described above. On the other hand, the diameter of the transfer line 3 for transferring the liquid crystal prepolymer dope can be selected from 1/16'', 1/8'', 1/4'', and 1/2''. The extrusion speed of the combined dope may be 5 m/min or more. In particular, as shown in FIG. 2 of the accompanying drawings, the diameter of the same nozzle jet 7 is preferably 0.006 to 1 mm, more preferably 0.01 to 1 mm.
It is better to use a nozzle with a diameter of 0.7 mm. Here, limiting the diameter of the nozzle and the number of nozzles determines the size and degree of orientation of the short pulp fibers, but the speed in the transfer lines 3 and 6 mostly controls the flow rate. Although it is best for the nozzle to be circular, the present invention does not limit the nozzle to a circular shape as described above. On the other hand, the length of the ejection tube 8 needs to be long enough to ensure sufficient time for the liquid crystal prepolymer dope and the polymerization promoting precipitant to come into contact with each other and for the reaction to be completed. The liquid crystal prepolymer dope and the polymerization-promoting precipitant thus extruded and injected by the nozzle jet device are brought into sufficient contact with each other in the ejection pipe 8 by the molecular orientation polymerization method, and the aromatic polyamide pulp-like short fibers are directly released from the recovery tank 9. is obtained. On the other hand, FIG. 3 is a process schematic diagram showing a second specific example of the present invention, in which the temperature of the liquid crystal prepolymer dope introduced into the reaction tank 21 is increased to 30° C. by the circulation of the coolant supplied through the inlet 22. Maintained at low temperatures below. At this time, the refrigerant whose cooling effect has been completed is discharged from the outlet 2.
It is discharged to the outside through 3. 2 to 20 through the inlet 24 of the reaction tank 21
When a nitrogen pressure of Kg/cm ² is applied, the liquid crystal prepolymer dope placed inside the reaction tank 21 has a diameter of 1/2.
8", and is passed through a stainless steel discharge pipe 25 and supplied to a stirrer 26. A stainless steel pipe smaller than the diameter of the discharge pipe 25 is attached to the end of the discharge pipe 25, or a diameter of 1/2" smaller than this is attached to the end of the discharge pipe 25. It is sufficient to use a nozzle 27 or a nozzle 27 with a diameter of 8" or less. The liquid crystal prepolymer dope put into the polymerization-promoting precipitant 28, which is the second composition placed in the stirrer 26, is subjected to shearing force while being stirred by the operation of the motor 29. At this time, the distance between the blades 30 and the nozzle 27 is preferably maintained within at least 2.54 mm, and the reason for this is to position the nozzle 27 close to the blades 30 to increase the shearing force. In addition, since stirring is performed at a minimum shear rate of about 20 sec ^-1 , sufficient intramolecular orientation occurs. The highly oriented final polymer polymerized while being stirred in this process is mixed with a polymerization-promoting precipitant and supplied to the filtration device 32 along the transfer pipe 31, where the final polymer is filtered through the dividing plate 33 and processed into the final product. The polymerization-promoting precipitant separated from the polymer and recovered is re-supplied into the stirrer 26 through the circulation pipe 34.
At this time, the pump 35 is operated within a range that can prevent backflow of the polymerization-promoting precipitant. The final polymer thus obtained is washed,
When dried, aromatic polyamide pulp-like short fibers with an intrinsic viscosity of 3.0 or more are obtained. Note that FIG. 4 is a drawing showing a third specific example of the present invention, in which an amide solvent or a small amount of tertiary amine is At the same time, a solution obtained by completely dissolving an inorganic salt and an aromatic diamine in an amide solvent containing supplied. When the two solutions supplied into the mixer 43 are mixed to obtain the same liquid crystal prepolymer dope as in the first specific example, this liquid crystal prepolymer dope is immediately degassed by the vacuum pump 44. The speed of the solution is controlled by a gear pump 45 and the solution is transferred to a jetting machine 46 having a jetting port attached thereto. The liquid crystal prepolymer dope supplied by the jetter 46 as described above is passed from the side of the jetter 46 to the supply pipe 47.
contacted with a polymerization-promoting precipitant supplied through the
As shown in FIG. 5, the liquid crystal prepolymer dope introduced through the polymer inlet 48 and the polymerization-promoting precipitant, which is supplied separately from the liquid crystal prepolymer dope and forming an angle 49, are simultaneously introduced. Since they are injected, they are merged at the merging jet port 50. At this time, the liquid crystal prepolymer dope
0, and is contacted at low temperature with a tertiary amine alone, a mixed solvent of a tertiary amine and an organic amide solvent, or a mixed solvent of these and an inorganic salt, and the shearing force is 20 sec ^-1 or more as in the first embodiment of the present invention. They are squirted together. Here, there is no particular restriction on the pattern of the merging spout 50, but a circular shape is most suitable, and the circular spout is preferably 50μ to 500μ, and the L/D (ratio of the length to the orifice diameter) of the spout should be in the range of 1 to 10. On the other hand, the contact angle 49 between the liquid crystal prepolymer dope and the tertiary amine solvent is preferably between 20° and 80°, but if the contact angle is smaller than 20°, the alignment effect increases but the pulverizing effect decreases. On the other hand, if the angle is larger than 80°, the crushing effect will increase, but the orientation effect will decrease, which is not good. More preferably, the angle is between 40° and 50°. The jetting speed of the polymerization-promoting precipitant is preferably 1 mm/min to 300 m/min, and the length of the merging jet port 50 is most preferably such that the polymerization-promoting precipitant and the liquid crystal prepolymer dope are in sufficient contact with each other. The polymerization-promoting precipitant and liquid crystal prepolymer dope that have passed through the confluence spout 50 are separated into solid and liquid by a filter conveyor 51 as shown in FIG. The pulp-like short fibers are collected in a collection tank 54. At this time, the polymerization-promoting precipitant, which has been combined with the liquid crystal prepolymer dope and has an increased degree of orientation, is recovered by the pump 55 after the reaction is completed, and is again transferred to the polymerization-promoting precipitant storage tank 57 through the recovery line 56. Meanwhile, in the above step, the polymerization-promoting precipitant of the second composition significantly improves the degree of polymerization of the liquid crystal prepolymer, and simultaneously forms hydrogen bonds between amide bonds in the polymer upon completion of polymerization. It has the advantage of improving molecular orientation growth. For example, in the polymerization-promoting precipitant used in the embodiments of the present invention, a tertiary amine solvent may be used alone, or a mixed solvent of a tertiary amine solvent and an amide solvent may be used. It is preferable to use amide solvent, and the amount of amide solvent added is 10 to
90% by volume is appropriate. For example, a tertiary amine solvent may be used alone, or an amide solvent (NMP, DMAC, CMF, HMPA,
A mixed solvent of TMU, DMSO) or a small amount of inorganic salt added to these may be used. Examples of tertiary amines used at this time include pyridine, t-butylamine, quinoline, picoline, quiniclidine, triethylamine, dimethylethylamine, pyrazine, quinoxaline, and pyrimidine, among which a high intrinsic viscosity and good degree of orientation are obtained. It is preferable to select and use effective pyridine. In addition, amide solvents such as N-methylpyrrolidine (NMP), hexamethylphosphoramide (HMPA), N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), , N,N',N'-tetramethylurea (TMU), etc. can be used, and inorganic salts such as lithium chloride (LiCl), calcium chloride (CaCl ₂ ), potassium chloride (KCl), or potassium bromide (KBr) can be used. can be used. Here, the inorganic salt is 0.1
It suffices if it is dissolved to about 10% by weight. Further, the temperature at which the polymerization-promoting precipitant of the second composition and the liquid crystal prepolymer dope are brought into contact is usually a low temperature of 50°C or lower, but preferably in the temperature range of -40°C to 50°C. . For example, the lower the temperature, the higher the degree of molecular orientation, but if it is carried out at temperatures below -40°C, additional equipment is required to maintain the low temperature, which increases costs and is uneconomical; on the other hand, above 50°C When carried out at high temperatures, it is not effective due to the unnecessary reduction in the molecular orientation effect due to high temperatures. The temperature is preferably -10°C to 40°C, more preferably 0°C to 25°C. In addition, various physical properties of the pulp-like short fibers produced by the above method are improved by heat treatment. In other words, when the pulp-like short fibers are heat-treated, the crystallinity increases, resulting in an increase in modulus and a decrease in elongation. The crystallinity at this time increases by 20 to 30%, and at the same time the modulus increases to 30 to 30%.
It has the effect of increasing the growth rate by 300% and decreasing the elongation rate by 30 to 200%. Furthermore, evaluation of the physical properties of the fibers produced according to the present invention can generally be easily determined using the following relational expression for intrinsic viscosity (IV). IV=In(μrel)/C In the formula, C is the concentration of the polymer solution (0.5 in 100ml of solvent).
g of polymers or fibers), and μrel indicates the relative viscosity, which is the flow time ratio between the solution and the solvent measured with a capillary viscometer at a temperature of 30°C. Sulfuric acid (95-98% H ₂ SO ₄ )
It is. Effects of the Invention Therefore, the present invention is significantly different from conventional methods in the following points. That is, 1. During the polymerization process, before the polymerization is completed, the liquid crystal prepolymer dope (the aromatic diacid chloride as the final monomer is added and the state from after stirring opalescence to just before gelation) is converted into a tertiary polymer. Extrusion injection at a shear rate of 20 sec ^-1 or more with a mixed solvent of amine or tertiary amine and an amide solvent, or a mixed solvent with a small amount of inorganic salt added thereto, or spinning at a spinning elongation rate of 1 to 4. However, aromatic polyamide fibers with high strength and high degree of orientation can be obtained by a molecular orientation polymerization method that promotes polymerization and simultaneously causes molecular orientation. 2 The polymerization process of the liquid crystal prepolymer dope, the formation of a highly polymerized polymer, and the molecular orientation process are separated, and in particular, the polymerization process in the polymerization solvent is separated from the polymerization process of the liquid crystal prepolymer dope until the final product fiber is obtained. Since various conditions such as the coalesced content, polymerization temperature, and temperature of the polymerization solvent can be changed, the intrinsic viscosity of the liquid crystal prepolymer can be maintained at 1.0 to 4.0 for up to 30 minutes, making process control easy. 3. Because a tertiary amine or a mixed solvent of tertiary amine and an organic amide solvent is used as the polymerization-promoting precipitant, fibers with an increased intrinsic viscosity of 3.0 or more can be obtained due to the polymerization-promoting action of the solvent, and the polymerization by the polymerization-promoting precipitant is Since promotion and molecular chain orientation are possible, it is easy to produce fibers with extended molecular chains and a high degree of orientation. 4 After separating the polymer from the polymer solution and washing with water,
To produce fibers directly in the polymerization process without the need for the accompanying steps of producing sulfuric acid dope and spinning,
The process is simple and manufacturing costs can be reduced, and unlike conventional fibers, the color does not change over time due to residual sulfuric acid. 5 Appropriately change the spinning draw ratio or extrusion pressure, the length of the transfer line, the diameter of the nozzle, etc., and adjust the size (length, diameter, and thickness) of the final fiber to be produced.
And the shape and molecular weight can be easily adjusted. 6. The polymerization-promoting precipitant has the advantage that it can be reused continuously within a range where the content of impurities does not have a large effect on improving the degree of polymerization. On the other hand, due to such differences in the manufacturing process, the textile products obtained from the present invention are considerably superior to conventional textile products.
As a result of confirming the pleated sheet structure of conventional fibers as shown in the figure through a polarizing microscope,
From the photograph as shown in Figure 9a of the accompanying drawings,
Transverse bands of about 500 to 600 nm were found in the direction perpendicular to the fiber axis, and defects were present in the direction of the fiber axis. For these reasons, as a result of observing the surface of the short fibers of conventional fibers using an electron microscope (SEM), crystal defect layers were observed as shown in Figures 8a and 11a.
Amide fibers with such crystal defect layers are not only significantly inferior in terms of strength and elastic modulus, but also weak in terms of compressive strength, so they can be used not only as substitute materials for asbestos and glass fibers, but also for plastics, rubber, etc. is subject to various limitations in its use as a reinforcing material. In addition, as mentioned above, the molecular chains cannot be perfectly oriented and there are crystal nodes, so sulfuric acid, chlorosulfuric acid,
It is easily dissolved in strong acids such as fluorosulfuric acid, and is easily hydrolyzed by alkalis, etc., so there are many restrictions on its usage. In addition, Figure 10a is a photograph taken after etching the conventional fiber with NaOH or HCl, and it shows that a layer with a thickness of about 20 Å has separated in the core part, and the crystal defect layer is spaced at a constant interval in the fiber axis direction. You can see that it exists. In other words, conventionally H ₂ SO ₄ −PPD−T (approximately 20
%) Since it is spun with dope and has a viscosity of over 1000 poise, the fiber itself has a double structure as a result of insufficient orientation during spinning, and as a result, it is unable to exhibit sufficient physical properties. The disadvantage is that the compressive strength is weak due to the presence of a crystal defect layer due to the pleated sheet structure in the center of the fiber, and therefore it is not only easily soluble in strong acids such as sulfuric acid, but also
Acid and alkali hydrolysis also occurred. On the other hand, the aromatic polyamide fiber (PPD-T) according to the present invention is easily oriented in a relatively low molecular state, crystal defects are uniformly distributed, and the molecular chain structure is perfect as shown in Figure 7. As a result of observation using an electron microscope (SEM) as shown in Fig. 8b and Fig. 11b (TEM),
No crystal defect layer was present, and as a result of observation with a polarizing microscope, as shown in FIG. 9b, no weak portion was observed in the direction perpendicular to the fiber axis. In addition, as shown in Figure 10b, the aromatic polyamide fiber according to the present invention was photographed after being etched, and the result showed that it did not have a skin-core structure (double structure) as in the past, but a single structure. It is found that the chain end distribution is different from that of conventional fibers.
It showed a single structure similar to a skin structure with a diameter of only 0.1 μm, and no crystal defect layer was found in the fiber axis direction. Thus, it can be seen that the almost completely expanded aromatic polyamide fiber exhibits significantly superior physical properties in terms of strength, elasticity, and compressive strength compared to existing products. A comparison of PPD-T according to the present invention with conventional products in terms of physical properties is as shown in the table below, and it can be seen from this table that even with a low molecular weight, it exhibits excellent physical properties.

[Table] Examples The present invention will be explained below based on Examples and Comparative Examples. Example 1 A 4-necked flask with a volume _of
Pour 200ml of NMP1 into the flask and heat to 100°C.
27.0g of inorganic salt (CaCl ₂ ) at elevated temperature to
After completely dissolving 24.5 g of PPD in the above solution, and cooling the solution using a cooling water bath (ice bath) to lower the temperature, add 45.95 g of TPC and stir well. The stirring speed (rpm) at this time was 3000 times/min, and the reaction was carried out for 15 minutes to prepare a prepolymer solution. The polymerized dope thus obtained is introduced into a cylinder having a cap having a diameter of 0.7 mm and an L/D of 0.5, and is passed through pyridine (Py) while being spun. The winding speed at this time is 20 m/min. This is then washed with water and dried to obtain polyamide fibers. The intrinsic viscosity at this time is 5.0,
D/E/T/Mi is 3/7/21/476. Example 2 Polymerization times are varied using reaction solvents and inorganic salts and polymerization-promoting precipitants as shown in Table 1 below. All other conditions were the same as in Example 1 above. The measurement results of intrinsic viscosity and D/E/T/Mi for this are shown in Table 1 below.

[Table] Example 3 As shown in Table 2 below, reaction solvents and inorganic salts were used, and pyridine was used as a polymerization-promoting precipitant.
was used, and the other conditions were the same as in Example 1. Intrinsic viscosity and D/E/T/Mi for this
The values of are shown in Table 2 below.

[Table] Example 4 The same procedure as in Example 1 was carried out except that the polymerization solvent and polymerization-promoting precipitant shown in Table 3 were used, and the L/D and spinning draw ratio were adjusted. The results are shown in Table 3 below.

[Table] Example 5 In a 4-necked flask with a volume of 1 from which water was removed,
After adding and dissolving 150ml of NMP and 50ml of DMAC,
Add 5.4 g of CaCl ₂ and 4.9 g of PPD and dissolve completely.
Add 9.19 g of TPC to the solution dissolved as above and polymerize with stirring. At this time, the reaction is carried out while cooling with cold water so that the temperature of the solution does not exceed 40°C. After stirring the solution for about 20 minutes, the diameter becomes 0.6 mm.
The amide fiber is obtained by spinning it on pyridine through a spinneret with an L/D of 0.8, winding it, washing it with water, and drying it. The winding speed at this time was 40 m/min, the intrinsic viscosity (IV) was 4.9, and D/E/T/Mi=3/12/
It is 21/450. Example 6 The same procedure as in Example 5 was carried out except that the reaction solvent shown in Table 4 was used and the conditions of the spinning draw ratio and L/D were changed. The results are shown in Table 4 below.

[Table] Example 7 The reaction solvent, L/D, spinning draw ratio, and polymerization-promoting precipitant were changed as shown in Table 5 below, and the other conditions were the same as in Example 5 above. The results are shown in Table 5 below.

【table】

[Table] Example 8 After dissolving 5.4 g of CaCl ₂ in 200 ml of DMAC,
Add 4.9g of PPD, stir for about 5 minutes, and then
Add 9.9g of TPC and polymerize. At this time, after stirring for about 10 minutes while cooling the polymerization solution with cooling water so that the temperature does not exceed 10°C, it is spun into pyridine through a spinneret with a diameter of 0.7 mm and an L/D of 2. Wind it up at a speed of 1 minute, wash it with water, and then dry it to obtain the fiber. At this time, the intrinsic viscosity (IV) is 4.9, and D/
E/T/Mi is 31/1.5/22/450. Example 9 After dissolving 13.82 g of LiC in 200 ml of NMP,
Add 4.1g of PPD and dissolve while stirring. Here
7.66 g of TPC is added and polymerized with stirring, and the polymerization reaction is carried out while cooling with cooling water so that the temperature of the polymerization solution does not exceed 40°C. After reacting the polymerization solution for about 20 minutes, the diameter becomes
After putting it into a cylinder with a cap of 0.5 mm and L/D of 0.5, it is spun into pyridine, wound at a speed of 30 m/min, washed with water, and dried to obtain fibers. At this time, the intrinsic viscosity (IV) is 4.3, and D/
E/T/Mi is 5/11/19/450. Example 10 All the conditions were the same as in Example 9 except that the reaction solvent, L/D, spinning draw ratio, and composition of the polymerization-promoting precipitant were changed as shown in Table 6 below. The results are shown in Table 6 below. Comparative Example 1 Data comparing the intrinsic viscosity of the final product in Example 10 and the intrinsic viscosity when the polymerization solution was spun into water are shown in Table 7 below. Example 11 In a solution of 5.4 g of CaCl ₂ dissolved in 200 ml of NMP,
After dissolving 2.16 g of PPD and 5.05 g of 3,4'-diaminodiphenyl ether, 9.19 g of TPC was added and polymerized at low temperature. The reaction was carried out for about 10 minutes, and the next prepolymer solution was prepared with a diameter of 0.3 mm, L/ Spinning into a pyridine solvent through a nozzle with D of 5 and winding at a speed of 50 m/min,
After washing with water and drying, fibers are obtained. At this time, the intrinsic viscosity (IV) is 5.6.

[Table] Table 7 Number of experiments Pyridine/amide solvent Water 1 4.3 1.7 2 4.8 1.8 3 5.1 2.3 4 4.9 2.1 5 5.7 2.7 6 4.9 2.2 7 5.2 2.4 8 5.1 2.3 Example 12 In a mixed solvent of 100 ml of NMP and 100 ml of HMPA
Add 5.4g of CaCl ₂ and 4.90g of PPD and dissolve them.
Add 9.19 g of TPC and stir while cooling. After stirring the solution for about 30 minutes, it was spun into a mixed solvent of pyridine/HMPA (80 parts by weight/220 parts by weight) through a spinneret under the same conditions as in Example 11 and wound up, washed with water, and dried. , fibers are obtained. The intrinsic viscosity (IV) at this time is 4.6, and T/
E/Mi/Den is 7/10/400/3. Example 13 This example relates to the first embodiment of the present invention in which polyamide pulp-like short fibers are directly obtained by extrusion injection, and the reaction tank is sufficiently purified with N ₂ to completely remove moisture. Here as an amide solvent
Add 250ml of NMP, raise the temperature to 80℃,
10.0 g of calcium chloride (CaCl ₂ ) as a metal halide salt is added and stirred for 30 minutes to dissolve. Add 10.38 g of PPD to the amide polymerization solvent in which the inorganic salt has been dissolved as described above, dissolve while stirring for 10 minutes, add 19.55 g of terephthaloyl chloride (TPC) at a low temperature of 30°C or less, and heat it vigorously. Stir. Stirring is stopped about 8 minutes after the addition, and the obtained liquid crystal prepolymer dope is sent to a nozzle jet device through a 1/8 inch transfer pipe under pressure using a gear pump in a polymerization vessel. At this time, the diameter of the nozzles was 0.3 mm, the number of nozzles was 15, and the gear pump was operated at a pressure of 3 kg/cm ² . Immediately after the liquid crystal prepolymer dope starts to be extruded by the nozzle jet device, the pyridine (water content is 1000 ppm or less) in the polymerization accelerating precipitant storage tank is transferred to 1/4 by applying a pressure of 0.3 kg/cm ² with a transfer pump. Pressure into the nozzle jet through the inch transfer line. The liquid crystal prepolymer dope and pyridine, brought into contact with each other at a temperature of 20 DEG C. by a nozzle jet device, are forced out under pressure through a jet tube 4 m long and 1/4 inch in diameter. The compressed short pulp particles and pyridine are filtered by a filtration device, the filtrate pyridine is circulated, and the pulp particles are dried in a vacuum drying device at a temperature of 110°C for 5 hours. . At this time, the intrinsic viscosity (I.
V.) is 4.03. Example 14 All the steps in this example were carried out in the same manner as in Example 13, and when the intrinsic viscosity (IV) of the liquid crystal prepolymer was changed, the intrinsic viscosity (I.
V.) changes are shown in Table 8 below.

[Table] Example 15 In this example, a mixed solvent of pyridine and amide-based substances shown in Table 9 below was used as the polymerization-promoting precipitant, and the transfer pressure of the polymerization-promoting precipitant was 0.5 Kg/cm ²
The conditions were the same as in Example 13 except that the conditions were the same as in Example 13, and the intrinsic viscosity (IV) of the liquid crystal prepolymer and the final pulp-like staple fiber (IV) are shown in Table 9 below.

[Table] Example 16 This example was carried out in the same manner as in Example 13 except that a tertiary amine similar to that shown in Table 10 below was used alone as a polymerization-promoting precipitant. At this time, the intrinsic viscosity (IV) of all liquid crystal prepolymers is the same as 2.71.

[Table] Example 17 In this example, all the conditions were carried out in the same manner as in Example 13, and the speed of the gear pump for extruding the liquid crystal prepolymer dope and the speed of the circulation pump for extruding and transferring the polymerization-promoting precipitant were Make the changes as shown in Table 11 below,
The intrinsic viscosity (IV) of the liquid crystal prepolymer was changed. In this regard, the intrinsic viscosity of short pulp fibers (I.
V.) The changes are shown in Table 11 below. At this time, the diameter of the nozzle used was 0.5 mm.

[Table] Example 18 In this example, all the conditions were the same as in Example 13, and the gear pump pressure was set at 5 Kg/cm ² , the circulation pump pressure was fixed at 0.7 Kg/cm 2 , and the liquid crystal preliminary weight was set at 5 kg/cm ² . Table 12 below shows the results of measuring the intrinsic viscosity (IV) of the final pulp-like short fibers when changing the diameter and number of nozzles while changing the combined intrinsic viscosity (IV). Example 19 In this example, all the conditions were the same as in Example 13, and the length of the ejection tube was changed as shown in Table 13 while changing the intrinsic viscosity (IV) of the liquid crystal prepolymer. Intrinsic viscosity of final pulp-like short fibers (I.
V.) changes are shown in Table 13 below. At this time, the diameter and number of nozzles are 0.5mm and 15, and the pressure of the liquid crystal prepolymer solution dope is 5Kg/cm ²
The flow pressure of pyridine is 0.7Kg/ ^cm2 . Example 20 In this example, all the conditions were the same as in Example 13, except that a mixture of NMP and HMPA was used instead of NMP, a solution of DMAC alone or mixed with HMPA was used, and a mixture of NMP and HMPA was used. For the mixed solution, 10.0 g of CaCl ₂ was used as an inorganic salt as in Example 13, and for the mixed solution of DMAC alone or HMPA, 10.0 g of LiCl was used to separate the liquid crystal prepolymer and final pulp-like short fibers. The changes in intrinsic viscosity (IV) are shown in Table 14 below. At this time, the nozzle conditions, liquid crystal prepolymer dope, and pyridine flow pressure were the same as in Example 19.

【table】

【table】

[Table] Example 21 In this example, all the conditions were the same as in Example 13, and the aromatic diamine and aromatic diacid chloride used during polymerization of the liquid crystal prepolymer dope were as shown in Table 15 below. Table 15 below shows the results of measuring the intrinsic viscosity (IV) of the liquid crystal prepolymer and final pulp-like staple fibers by replacing them with similar substances. At this time, the diameter and number of nozzles were 0.7 mm and 15 nozzles, and the pressure of the liquid crystal prepolymer dope and the flow pressure of pyridine were 4 Kg/cm ² and 0.5 Kg/cm ² . In particular, when using 3,4-diaminodiphenyl ether as a monomer, 25 mol% of p-phenylenediamine, 50 mol% of terephthaloyl chloride, and 25 mol% of 3,4-diaminodiphenyl ether are added. Use as monomer.

【table】

[Table] Example 22 In this example, all the conditions were the same as in Example 13 above, and when an amide solvent to which a small amount of tertiary amine, ie, a small amount of pyridine, was added as the polymerization solvent, the polymerization The composition of the solvent, the inorganic salt and the intrinsic viscosity (IV) changes of the final pulp-like short fibers are shown in Table 16 below.
It was shown to.

[Table] Comparative Example 2 In this example, the final pulp according to the change in the intrinsic viscosity (IV) of the liquid crystal prepolymer obtained by feeding the liquid crystal prepolymer solution dope into a nozzle jet device using water as a precipitant as in the prior art. The results of changes in intrinsic viscosity (IV) of short fibers are shown in Table 17 below. Table 17 IV of Prepolymer IV of Final Pulp-like Short Fibers 2.1 2.13 2.37 2.29 3.04 3.16 3.65 3.83 3.97 3.95 Example 23 (Comparative Example 3) This example is a second embodiment of the present invention relating to the direct production of pulp-like short fibers. This is an example according to the example, in which a liquid crystal prepolymer dope was prepared in the same manner as in Example 13, and each composition contained 240 ml of NMP, 7.2 g of CaCl ₂ ,
After producing a liquid crystal prepolymer dope using 6.53g of PPD and 12.26g of TPC, it was transferred to a dope storage tank maintained at a low temperature by a refrigerant, and polymerized through a 1/8 inch stainless steel tube at a nitrogen pressure of 3Kg/ ^cm2. Pyridine, an accelerated precipitant, is stirred at 0° C. while being squeezed out. At this time, the diameter of the stirrer blade is 6.5cm, and the width is 1.2cm.
cm, the stirring speed was 1500 rpm, the distance between the lowest end of the discharge tube and the highest end of the blade was approximately 1.0 mm, and the pressure was stirred in water to see the effect of pyridine.
The results of measuring the intrinsic viscosity (IV) after extruding and stirring the NaHCO ₃ containing solution, washing the final polymer with water, and drying it under vacuum at a temperature of 110°C for 6 hours are shown in Table 18 below. At this time, water was used as the precipitation solvent, and the results of measuring the IV of the final polymer were also shown for comparison. Table 18 Precipitating solvent IV Water 2.36 6% NaHCO ₃ 2.37 Pyridine 5.62 Example 24 (Comparative Example 4) In this example, all conditions were the same as in Example 23, and after adding TPC, polymerization time and size of release tube were The following table shows the form, stirring speed during extrusion, and precipitant.
The results of measuring the intrinsic viscosity (IV) of the final pulp-like short fibers are shown in Table 19 below. The results of measuring the intrinsic viscosity (IV) are also shown for comparison.

[Table] Example 25 (Comparative Example 5) In this example, all the conditions were the same as in Example 23, and as shown in Table 20 below, after adding TPC, the polymerization time, stirring speed, and polymerization-promoting precipitant were changed to amide. The results of measuring the intrinsic viscosity (IV) of the final pulp-like short fibers using a mixture of solvent and pyridine are shown in Table 20 below. The results of measuring (IV) are also shown for comparison.

【table】

[Table] Example 26 (Comparative Example 6) In this example, all conditions were the same as in Example 23 except that DMAC was used as the amide solvent and LiCl was used instead of CaCl ₂ . At this time, after TPC was added, the results of measuring the intrinsic viscosity (IV) of the final pulp-like short fibers when the polymerization time, the diameter and shape of the discharge tube, and the polymerization-promoting precipitant were the same as shown in Table 21 below are shown below. Table 21 shows a comparison of the intrinsic viscosity (IV) values of the final pulp-like short fibers when water or ethanol was used as the precipitation solvent. At this time, the stirring speed is 3000 rpm.

【table】

[Table] Example 27 In this example, all the conditions were the same as in Example 23, and the composition of the polymerization solvent and inorganic salts were used as shown in Table 22 below, and the intrinsic viscosity (I .
The results of measuring V.) are shown in Table 22 below.

[Table] Example 28 This example is the third embodiment of the present invention for the direct production of pulp-like short fibers, and the liquid crystal prepolymer dope was prepared in the same manner as in Example 13 above, and was placed at the lower end of the mixing tank. Open the pump valve to supply the injection machine, add pyridine from the pyridine storage tank, and inject it simultaneously with the liquid crystal polymer. The temperature at this time was -60℃, and the diameter of the injection port was
0.3 mm, length is 3 m, jet speed is 1 m/min, and jet speed of pyridine is 30 m/min. The final pulp-like short fibers obtained here have an intrinsic viscosity (IV) of 6.5. Example 29 This example was carried out under the conditions shown in Table 23 below, and all other conditions were the same as in Example 28 above, and the intrinsic viscosity (IV) of the final pulp-like short fibers was
The results of the measurements are shown in Table 23 below.

[Table] Example 30 In this example, all conditions were carried out in the same manner as in Example 28 above, and the intrinsic viscosity (IV) and jetting speed (m/min) of the liquid crystal prepolymer were changed as shown in Table 24 below. The results of measuring the intrinsic viscosity (IV) of the final pulp-like short fibers are shown in Table 24 below.

[Table] Example 31 This example was carried out under the same conditions as in Example 28 above, and the final pulp-like short fibers obtained according to the content ratio of the pulp-like short fibers to the polymer solvent in the composition of the liquid crystal prepolymer dope were The results of measuring the intrinsic viscosity (IV) of the fibers are shown in Table 25 below.

[Table] Comparative Example 7 In this comparative example, all conditions were carried out in the same manner as in Example 28, and the intrinsic viscosity (IV) of the liquid crystal prepolymer and the final pulp shape when a solvent other than a tertiary amine-based solvent was used. The results of measuring the intrinsic viscosity (IV) of the short fibers are shown in Table 26 below.

[Table] le

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a manufacturing process according to a first embodiment of the present invention, FIG. 2 is an enlarged sectional view of the nozzle jet device of FIG. 1, and FIG. 3 is a schematic diagram of a manufacturing process according to a second embodiment of the present invention. 4 is a schematic diagram of the manufacturing process according to the third embodiment of the present invention, FIG. 5 is an enlarged sectional view of the injection device of FIG. 4, and FIG. 6a is an aromatic polyamide fiber manufactured by a conventional method. FIG. 6b is an enlarged schematic diagram of the pleated sheet structure of the core portion of the aromatic polyamide fiber produced by the conventional method.
The figure is a schematic cutaway perspective view showing the structure of the aromatic polyamide fiber according to the present invention, and FIG. ), 8th
Figure b is an electron micrograph showing the fiber shape of the aromatic polyamide fiber according to the present invention (it can be seen that there is no crystal defect layer), and Figure 9a is a drawing showing the fiber shape of the conventional aromatic polyamide fiber. (Skin-core structure and crystal defect layer can be seen at the same time); FIG. 9b is a polarized light micrograph instead of a drawing showing the fiber shape of the aromatic polyamide fiber (ppD-T) according to the present invention. (It can be seen that there is no skin-core part and crystal defect layer), No. 10a
The figure is a replacement for a conventional drawing showing the fiber shape after etching aromatic polyamide fiber with NaOH.
SEM photograph (representing a state selectively eroded by a crystal defect layer); FIG. 10b is a SEM photograph (representing a state selectively eroded by a crystal defect layer); FIG.
Photograph (showing that there is no crystal defect layer),
Figure 11a is a TEM photograph showing the fiber shape of a conventional aromatic polyamide fiber (it can be seen that crystal defect layers are regularly present in the direction perpendicular to the fiber axis), and Figure 11b is a photograph of the fiber according to the present invention. A TEM photograph (instead of a drawing) showing the fiber shape of an aromatic polyamide fiber (it can be seen that the crystal defect layer does not exist regularly in the direction perpendicular to the fiber axis). The symbols in the drawings mean the following: ,1,2
1,41...Reaction tank, 2,42,57...Storage tank, 3,6,31...Transfer line, 4,5,35,4
4, 45, 55... pump, 7, 27... nozzle jet, 8... jet pipe, 9, 53... collection tank,
22... Inlet, 23... Outlet, 24... Inlet, 25... Discharge pipe, 26... Stirrer, 28...
Solvent, 29...Motor, 30...Blade, 32...
Filtration device, 33...Divided sieve, 34...Circulation tube, 43...Mixer, 46...Blower, 47...
... Supply line, 48 ... Inlet, 49 ... Contact angle, 50 ... Merging spout, 51 ... Filter conveyor, 52 ... Cutting roller, 53 ... Scrubber, 54 ... Recovery tank, 56 ... Recovery line.

Claims (1)

[Scope of Claims] 1. A solvent selected from the group consisting of an amide solvent, an amide solvent in which an inorganic salt is dissolved, and an amide solvent containing a small amount of tertiary amine and in which an inorganic salt is dissolved. An optically anisotropic liquid crystal prepolymer dope is produced before complete polymerization at low temperature of a mixed solution obtained by adding aromatic diamine and aromatic diacid chloride in equimolar amounts to A method for producing an aromatic polyamide filament, which comprises transferring the filament to a polymerization accelerating precipitant (second composition), spinning the filament at a spinning draw ratio of 1 to 4, and winding the filament directly. 2. The method according to item 1 above, characterized in that when a tertiary amine is used in the first composition, it is mixed in an amount of 0.01 to 2% by weight based on the polymerization solvent. 3. The method according to item 2 above, wherein the tertiary amine is at least one selected from pyridine, quinoline, triethylamine, t-butylamine, picoline, pyrimidine, pyrazine, and quinoxaline. 4. The method according to item 3 above, wherein the tertiary amine is selected from pyridine. 5. In item 1 above, the polymerization-promoting precipitant of the second composition is a tertiary amine alone, a mixed solvent of a tertiary amine and an amide solvent, or a mixture of these with a small amount of inorganic salt. How to do it. 6. The method according to item 5, wherein the tertiary amine is at least one selected from pyridine, quinoline, triethylamine, t-butylamine, picoline, pyrimidine, pyrazine, and quinoxaline. 7. The method according to item 6 above, wherein the tertiary amine is selected from pyridine. 8. The method according to item 5 or 6, characterized in that the tertiary amine contains at least an equivalent amount of hydrochloric acid produced during the polymerization reaction from the mixed solution with the amide system. 9. The method according to item 5 above, characterized in that the amide solvent is added and mixed with the tertiary amine in an amount of 10 to 90% by volume. 10 In the above item 9, the amide solvent is N-
2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAC), hexamethylphosphoramide (HMPA), N,N-dimethylformamide (DMF), N,N-dimethylsulfoxide (DMSO), N,N, N',N'-tetramethylurea (TMU), N-methylpiperidone, N-methylcaprolactam, N-acetylpyrrolidine, N
- A method characterized in that at least one of ethylpyrrolidine, dimethylpropionamide, dimethylisobutyramide, and dimethylpropylurea is selected. 11. The method according to item 5 above, characterized in that 0.01 to 10% by weight of an inorganic salt is added to and mixed with the polymerization-promoting precipitation solvent. 12. The method according to item 11 above, wherein the inorganic salt is selected from at least one of potassium chloride, calcium chloride, lithium chloride, potassium bromide, and lithium bromide. 13 In the above item 1, the temperature conditions when the liquid crystal prepolymer dope is spun into a polymerization-promoting precipitant or extruded and injected together with a polymerization-promoting precipitant are -40°C to
A method characterized by a temperature of 50°C. 14 In the above item 13, the temperature is -10℃ to
A method characterized by heating at 40℃. 15 In the above item 13, the temperature is between 0°C and 25°C.
A method characterized in that the temperature is reduced to ℃. 16. The method according to item 1, wherein the polymerization-promoting precipitant is contacted with the liquid crystal prepolymer dope spun through the spinneret for at least 0.1 seconds to 1000 seconds. 17 Aromatic diamine in a solvent (first composition) selected from the group consisting of an amide solvent, an amide solvent in which an inorganic salt is dissolved, and an amide solvent containing a small amount of tertiary amine and in which an inorganic salt is dissolved. An optically anisotropic liquid crystal prepolymer dope is produced before complete polymerization at low temperature of a mixed solution obtained by adding equimolar amounts of and aromatic diacid chloride. , production of aromatic polyamide fibers in the form of short pulp-like fibers, characterized in that the fibers are extruded or brought into contact with a polymerization-promoting precipitant (second composition) and a shear rate of at least 20 sec ^-1 is applied by the polymerization-promoting precipitant (second composition). Method. 18 In the above item 17, a third composition is added to the first composition.
When using grade amine, 0.01
or 2% by weight. 19. The method according to item 18, wherein the tertiary amine is at least one selected from pyridine, quinoline, triethylamine, t-butylamine, picoline, pyrimidine, pyrazine, and quinoxaline. 20. The method according to item 19, wherein the tertiary amine is selected from pyridine. 21 In item 17 above, the polymerization-promoting precipitant of the second composition is a tertiary amine alone, a mixed solvent of a tertiary amine and an amide solvent, or a solvent in which a small amount of an inorganic salt is mixed with these. How to do it. 22. The method according to item 21, wherein the tertiary amine is at least one selected from pyridine, quinoline, triethylamine, t-butylamine, picoline, pyrimidine, pyrazine, and quinoxaline. 23. The method according to item 22 above, wherein the tertiary amine is selected from pyridine. 24 In the above paragraph 21 or 22, the third
A method characterized in that the mixed solution of the class amine and the amide system contains at least an equivalent amount of hydrochloric acid produced during the polymerization reaction. 25. The method according to item 21 above, characterized in that the amide solvent is added to and mixed with the tertiary amine in an amount of 10 to 90% by volume. 26 In the above item 25, the amide solvent is N
-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAC), hexamethylphosphoramide (HMPA), N,N-dimethylformamide (DMF), N,N-dimethylsulfoxide (DMSO), N,N , N', N'-tetramethylurea (TMU), N-methylpiperidone, N-methylcaprolactam, N-acetylpyrrolidine, N
- A method characterized in that at least one of ethylpyrrolidine, dimethylpropionamide, dimethylisobutyramide, and dimethylpropylurea is selected. 27. The method according to item 21 above, characterized in that 0.01 to 10% by weight of an inorganic salt is added to and mixed with the polymerization-promoting precipitation solvent. 28. The method according to item 27, wherein the inorganic salt is selected from at least one of potassium chloride, calcium chloride, lithium chloride, potassium bromide, and lithium bromide. 29. The method according to item 17, characterized in that the temperature condition when the liquid crystal prepolymer dope is spun into a polymerization-promoting precipitant or extruded and injected together with a polymerization-promoting precipitant is -40°C to 50°C. . 30 In the above item 29, the temperature is -10℃ to
A method characterized by heating at 40℃. 31 In the above item 29, the temperature is set between 0°C and 25°C.
A method characterized in that the temperature is reduced to ℃. 32. The method according to item 17, characterized in that the liquid crystal prepolymer dope is extruded at a speed of 5 m/min or more. 33. The method of claim 17, wherein the liquid crystal prepolymer dope is introduced into the polymerization-promoting precipitant while being subjected to a shear force of at least 20 sec ^-1 . 34 Item 17 is characterized in that the liquid crystal prepolymer dope is prepared separately from the polymerization-promoting precipitant, and the liquid crystal prepolymer dope and the polymerization-promoting precipitant are simultaneously contacted and merged while forming an angle of 20° to 80° with each other. How to do it.