Method and apparatus for producing modified meta-aramid fiber by continuous polymerization-dry / wet spinning

Abstract

A method and an apparatus for producing modified meta-aramid fibers by continuous polymerization-dry-wet spinning, the method comprising the steps of: (1) preparing a DMAc mixed solution of meta-phenylenediamine and copolymer diamine monomers using a solubilizing agent; (2) mixing an isophthaloyl chloride melt with the DMAc mixed solution of meta-phenylenediamine and copolymer diamine monomers, pre-condensation polymerization, and condensation polymerization to obtain a modified meta-aramid resin solution; and (3) adding an auxiliary to the modified meta-aramid resin solution, filtering, degassing, and dry-wet spinning the modified meta-aramid resin solution. and (3) obtaining modified meta-aramid fiber by subjecting the pre-polymerization system of the continuous polymerization-dry-wet spinning device to a micro-mixer and a micro-reactor connected in sequence, the micro-channel of the micro-reactor is designed in a heart shape, and the condensation polymerization system is a combination of multi-stage micro-screws, which comprehensively solves the problems in the production process of meta-aramid fiber, and the obtained product has a complete structure, excellent performance, is stable and controllable, and can realize continuous and efficient production.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials, relates to the manufacturing technology of resins and fibers, and particularly relates to a manufacturing method and apparatus for aramid fiber products by continuous polymerization-dry and wet spinning technology.

Background Art

[0002] The unique chemical structure of polyarylamide endows it with excellent properties such as high modulus, high strength, high temperature resistance, and insulation. Since its emergence in the 1960s and 1970s, it has attracted a large number of domestic and foreign scientific researchers to conduct development research. Now it has become one of the important materials in the high-tech field and is widely applied in advanced fields such as electronics, national defense, aerospace, military, and emergency rescue, as well as high-end civilian fields such as rail transit, construction, high-temperature transmission, filtration, and sports supplies. Heterocyclic rings such as imidazole, oxazole, and thiazole have excellent thermal stability and good polarity. Introducing it into the polymer main chain can not only improve heat resistance and mechanical properties, but also improve the solubility and processability of the polymer due to the presence of heteroatoms. Russia was the first to develop heterocyclic aramids such as Armos and SVM. Their modulus and strength are much higher than those of para- or meta-aramids and can even rival high-performance carbon fiber T800H. Therefore, the development and research of heterocyclic aramids have received general attention in the high-performance materials industry and have become a major research focus. The research technology of heterocyclic ring modification of para-aramid has already entered the mature stage and is monopolized by foreign patents and markets. However, the research on meta-aramid modification is still in the budding development stage and has relatively large room for breakthrough.

[0003] Currently, China is facing the following difficulties in meta-aramid spinning technology.

[0004] 1) Meta-aramid resin produced by conventional kettle batch polymerization has low molecular weight, wide molecular weight distribution, low solid content of the spinning solution, and problems with lot stability.

[0005] The manufacturing method of meta-aramid resin commonly used in China is solution polymerization at low temperature, and the equipment is a kettle reactor. On the one hand, although the heat dissipation rate of the meta-aramid polymerization system is high, since the kettle reactor only exchanges heat through an external jacket, the heat of the reaction system cannot be quickly removed, the low temperature of the reaction system and the temperature uniformity of the entire reaction system cannot be guaranteed, the reaction synchronization is very poor, there are many side reactions, and it is difficult to control the polymer molecular weight and its distribution. On the other hand, the viscosity of the meta-aramid polymerization system is relatively high, and the materials cannot be uniformly mixed in the stirring mode of the kettle polymerizer. Especially in the later stage of the reaction, the viscosity of the polymerization system increases, the mixing difficulty of the materials becomes even higher, the local monomer concentration becomes too high or too low, which causes local explosion or the local degree of polymerization is too low, the reaction is not sufficient, and the obtained meta-aramid resin has a low molecular weight, a wide molecular weight distribution, and poor spinnability of the resin solution.

[0006] 2) The performance of the fibers obtained by wet spinning cannot meet the application requirements in the high-end field.

[0007] The mature commercial production processes of meta-aramid fibers mainly include wet spinning and dry spinning. The wet spinning technology has relatively low difficulty, a large production volume per single spinneret, and low production costs, but the performance of the produced fibers is average. The fibers produced by dry spinning have excellent comprehensive performance, but the technology has high difficulty, high requirements for process control and equipment, and high production costs. Dry-wet spinning combines the characteristics of wet spinning and dry spinning. Compared with wet spinning, dry-wet spinning has higher requirements for the spinning dope and process control, and it is necessary to improve the spinning dope, spinning equipment and process.

[0008] 3) Continuous and efficient production has not been achieved, and there are problems such as the neutralization of the meta-aramid resin solution, low filtration efficiency, clogging of the spinneret by the inorganic salts contained therein, wool yarn, yarn breakage phenomenon, and poor performance of the obtained fibers.

Summary of the Invention

Problems to be Solved by the Invention

[0009] The technical problem to be solved by the present invention is how to improve the overall equipment and process to produce modified meta-aramid fibers with a complete structure and excellent performance, and overcome the deficiencies and drawbacks mentioned in the above background technology. The present invention provides a method and apparatus for producing modified meta-aramid fibers by continuous polymerization-dry-wet spinning.

Means for Solving the Problem

[0010] The technical solution proposed by the present invention is as follows.

[0011] A method for producing modified meta-aramid fibers by continuous polymerization-dry-wet spinning, comprising: Step (1) of preparing a mixed solution of meta-phenylenediamine and copolymer diamine monomers; Step (2) of mixing isophthaloyl chloride with the mixed solution of meta-phenylenediamine and copolymer diamine monomers, performing a preliminary condensation polymerization reaction to obtain a prepolymer, and subjecting the prepolymer to condensation polymerization to obtain a modified meta-aramid resin solution; Step (3) of adding an auxiliary agent to the modified meta-aramid resin solution, filtering, degassing, and obtaining modified meta-aramid fibers by dry-wet spinning.

[0012] The key to producing high-molecular-weight meta-aramid resin by low-temperature solution condensation polymerization lies in the following three points, namely, (1) strictly controlling the raw material purity, metering accuracy, and system moisture content to ensure equimolar amounts of acid chloride and diamine of the reaction monomers; (2) efficiently exchanging heat in the system, accurately controlling the reaction temperature, and avoiding side reactions; (3) efficiently moving substances in the system to ensure uniform mixing of materials.

[0013] With respect to the above important features, the present invention has been improved from the following three directions, namely, 1) improving the spinnability of the meta-aramid spinning dope by introducing a copolymerized diamine monomer or adding an auxiliary agent, 2) using a continuous polymerization apparatus combining a microchannel reactor and a multi-stage micro screw to produce a high molecular weight and high solid content meta-aramid resin spinning dope, assisting heat dissipation and mass transfer in the reaction system, and 3) manufacturing high-performance meta-aramid fibers using dry-wet spinning with corresponding parameters based on the performance of the aforementioned spinning dope.

[0014] Preferably, the preparation of the mixed solution of the meta-phenylenediamine and the copolymerized diamine monomer in step (1) is to first dissolve the solubilizer in the solvent, remove water with a drying system, and then dissolve the copolymerized diamine monomer and meta-phenylenediamine in the solvent containing the solubilizer.

[0015] In general meta-aramid resin polymerization, since the chlorinated salt obtained from hydrochloric acid, which is its neutralization by-product, can function as a solubilizer, no solubilizer is particularly added. Adding a solubilizer here is advantageous for dissolving the copolymerized diamine monomer and the polymer, and is also advantageous for obtaining a high molecular weight polymer.

[0016] Preferably, the solvent of the mixed solution of the meta-phenylenediamine and the copolymerized diamine monomer in step (1) is DMAc.

[0017] Preferably, the solubilizer in step (1) is an alkali metal or alkaline earth metal inorganic chloride, and the content of the solubilizer is 0.1% - 10% of the solvent mass of the copolymerized diamine monomer solution, and more preferably 0.2% - 5%.

[0018] Preferably, the alkali metal or alkaline earth metal inorganic chloride is LiCl.

[0019] LiCl has a better solubilizing effect than chlorinated salts such as calcium chloride and sodium chloride in solubilizing aramid, has a relatively small molecular weight, requires less amount of solubilizing agent, and has a low desalination pressure.

[0020] Preferably, the copolymerized diamine monomer is at least one of 6,4'-diamino-2'-trifluoromethyl-2-phenylbenzimidazole, 2-(4-aminophenyl)-5-aminophenylbenzimidazole, 5-amino-2-(4-aminophenyl)benzoxazole, 5-amino-2-(4-aminophenyl)benzothiazole, 2,6-diaminobenzothiazole, 2,6-diaminopyridine, 2-(4-aminophenyl)-5-aminopyridine, 2,5-bis(4-aminophenyl)pyridine, o-chloro-p-phenylenediamine, and p-phenylenediamine, and its content (mol) is 0.1% - 10%, more preferably 1% - 5%.

[0021] The selected copolymerized diamine monomer is soluble in DMAc, its molecular structure is rigid and thermally stable, contains polar groups, increases the viscosity of the spinning dope without affecting the stability of the system, improves the spinnability, and does not reduce or enhances fiber mechanics, heat resistance, etc.

[0022] Preferably, the mixing in step (2) occurs in a micromixer. Isophthaloyl chloride is in a molten state at a temperature of 45 - 60°C, more preferably 50 - 60°C, before being introduced into the micromixer. The DMAc mixed solution of meta-phenylenediamine and the copolymerized diamine monomer is in a solution state at a temperature of -20 - 10°C before being introduced into the micromixer. The temperature of the micromixer is controlled to -20 - 60°C, more preferably -20 - 10°C. The preliminary condensation polymerization reaction occurs in a microreactor, and the temperature of the microreactor is controlled to 10 - 60°C, more preferably 10 - 30°C.

[0023] Microchannel reactors are generally used for reactions with relatively low viscosities. Since the solution of the present invention has a relatively high viscosity, a heart-shaped microreactor is selected. The heart-shaped microchannel improves the heat exchange area in the reactor, and the heart-shaped design contributes to the mixing of the solution in the reactor, avoiding clogging of the microchannel, and enhancing the heat exchange efficiency, mass transfer effect, and product quality.

[0024] The condensation polymerization in step (2) occurs in a multi-stage micro-screw device, and the temperature of the multi-stage micro-screw device is controlled at 20 to 70 °C, more preferably 30 to 60 °C.

[0025] Preferably, the microreactor includes any one of a heart shape, a circular shape, a triangular shape, a linear shape, and a spiral shape, and more preferably, it is a heart shape.

[0026] The microreactor has an extremely large heat exchange area and mixing efficiency, can achieve rapid heat exchange, solve the problem that the initial reaction temperature of the preliminary condensation polymerization is too high, and can realize accurate control of the temperature in the preliminary condensation polymerization process, thereby preventing high-temperature oxidation and yellowing of the resin due to local overheating and the generation of by-products. The microreactor may be in a heart shape, a circular shape, an elliptical shape, etc., and a heart-shaped microreactor is preferably selected.

[0027] The heart-shaped microchannel reactor (Figure 2), due to its structural design of the heart-shaped microchannel, extremely enhances the heat exchange area and mixing efficiency, can achieve sufficient mixing in the material pipe, and by avoiding local overheating, improves the molecular weight and its distribution of the resin, and enhances the spinnability of the spinning dope and the performance of the obtained fibers.

[0028] Due to the special structural design of the heart-shaped microreactor, the materials can be sufficiently mixed within the heart-shaped region, further polymerization can occur, and they can not only be transported through the pipe to the rear end, but also some materials can pass through the side-end pipe and remix and react with new materials again, thereby improving the molecular weight and its distribution of the resin, and enhancing the spinnability of the spinning dope and the properties of the obtained fibers, especially the mechanical properties and heat resistance.

[0029] Preferably, the inherent viscosity of the obtained modified meta-aramid resin is ≧1.8 dl / g.

[0030] Preferably, an organic auxiliary agent capable of forming a hydrogen bond with an amide group is added to the modified meta-aramid resin solution in step (3) before filtration.

[0031] Preferably, the organic auxiliary agent includes at least one of low molecular weight alcohol-based, acid-based or high heat-resistant organosilicon-based. The low molecular weight alcohol-based and acid-based include at least one of trifluoroacetamide, trifluoroethanol, trifluoroacetic acid, hexafluoroisopropanol, ethylene glycol, glycerin, sorbic acid, and salicylic acid. The usage amount is 0.01% - 3 wt% of the usage amount of the modified meta-aramid resin solution, more preferably 0.05% - 1 wt%. The organosilicon-based includes at least one of polyether-modified polysiloxane, fluorine or polysiloxane containing an alkoxy group or a hydroxyl group. The usage amount is 0.1% - 10 wt% of the aramid resin, more preferably 0.1% - 2 wt%.

[0032] The organic auxiliary agent reduces the surface tension of the resin solution, improves its apparent viscosity, thereby enhancing its spinnability, and also improves its surface activity, contributing to the subsequent dry-wet spinning step.

[0033] Preferably, the wet-dry spinning process in step (3) involves passing the spinning dope through a spinneret, passing through a first air layer, and then entering a first coagulation bath to obtain primary fibers. After drafting the primary fibers, they are subjected to a second coagulation bath, water washing, drying, dry heat drawing, heat setting, and winding / cutting to obtain modified meta-aramid fibers.

[0034] Preferably, the hole diameter of the spinneret is 0.06 - 0.25 mm. On the premise of ensuring the spinnability of the spinning dope, it is beneficial to alleviate the swelling effect of the orifice of the dope and obtain fibers with better performance. The height of the air layer through which the spinning dope passes is 2 - 80 mm, more preferably 5 - 60 mm. The spinning dope forms a yarn in the air layer, and some solvents volatilize from the yarn. At the same time, due to the drafting of the first roll, the yarn obtains a certain pre-orientation in the air layer, obtains sufficient strength, and is beneficial for the smooth progress of the subsequent process. The drafting speed of the pre-orientation is 2 - 5 times the spinning speed of the dope, more preferably 2.5 - 4 times. Drafting directly affects the microstructure of the fiber and further affects the performance of the fiber. The drafting rate of the present invention is determined based on the characteristics of the spinning dope obtained from the modified meta-aramid resin solution of the present invention.

[0035] Preferably, the first coagulation bath and the second coagulation bath are aqueous DMAc solutions. The DMAc concentration is 20 - 45 wt%, more preferably 25 - 40 wt%. The temperature is 20 - 50 °C, more preferably 25 - 40 °C. By not additionally adding other auxiliaries or inorganic salts to this coagulation bath, the solvent recovery cost is reduced and the economy of fiber production is enhanced.

[0036] The DMAc concentration in the second coagulation bath is 15 - 40 wt%, and the temperature is 30 - 60 °C. Due to the relatively low-temperature second coagulation bath, the diffusion and precipitation of the solvent in the yarn are more gentle, the fiber structure is more complete, the plasticizing drawing ratio is 1.1 - 4, and the plasticizing drawing further diffuses the solvent in the fiber outward to obtain a higher degree of orientation.

[0037] The dry heat stretching adopts a pipe or slit form, the temperature is 280 - 350°C, more preferably 290 - 330°C, the stretching ratio is 1.1 - 3, more preferably 1.5 - 2.5. If the stretching ratio is too high, the fibers are likely to be torn, resulting in yarn breakage and fuzz. If the stretching ratio is too low, the fibers cannot obtain a sufficiently high crystallinity and orientation degree, and the comprehensive performance is relatively low.

[0038] The heat setting adopts a pipe or slit form, the temperature is 280 - 350°C, more preferably 290 - 330°C.

[0039] Preferably, the breaking strength of the modified meta-aramid fiber obtained by the continuous polymerization-dry and wet spinning is ≥6.0 cN / dtex, the elongation at break is 25 - 50%, and the initial modulus is ≥90 cN / dtex.

[0040] Based on the same technical concept, the present invention further provides a manufacturing apparatus for modified meta-aramid fibers by continuous polymerization-dry and wet spinning, mainly including a raw material storage device, a prepolymerization system, a condensation polymerization system, a post-treatment system, a spinning system, a coagulation and water washing system, a drying system, a heat treatment system, a winding / cutting system, and a heat exchange system. The prepolymerization system, the condensation polymerization system, and the post-treatment system are connected in sequence. The heat exchange system is connected to the prepolymerization system and the condensation polymerization system respectively to control the temperatures of the prepolymerization system and the condensation polymerization system. The prepolymerization system includes a micromixer and a microreactor connected in sequence. The condensation polymerization system includes a multi-stage micro-screw device, a microreactor, and a multi-edge micro-screw device connection.

[0041] Preferably, the raw material storage device includes an isophthaloyl chloride raw material storage tank, a meta-phenylenediamine and copolymer diamine monomer raw material storage tank, a solvent storage tank, and a solvent raw material storage tank containing a solubilizing agent. The isophthaloyl chloride raw material storage tank and the meta-phenylenediamine and copolymer diamine monomer raw material storage tank are each connected to a micromixer via a constant flow pump and a transfer pipe.

[0042] Preferably, a solvent dehydration device is further connected between the meta-phenylenediamine and copolymer diamine monomer raw material storage tank and the solvent raw material storage tank containing a solubilizing agent. The isophthaloyl chloride raw material storage tank, the meta-phenylenediamine and copolymer diamine monomer raw material storage tank, the constant flow pump, and the transfer pipe are all equipped with heat preservation jackets.

[0043] The heat exchange system includes a refrigeration cycle device and a heating cycle device. The refrigeration cycle device includes a refrigeration medium storage tank containing a refrigeration medium, a heat exchange medium transfer pump, a rotor flow meter, and a medium transfer pipe. A heat exchange medium transfer pump and a rotor flow meter are connected between the refrigeration medium storage tank and the micromixer. The medium transfer pipe connects the refrigeration medium storage tank, the micromixer, and the microreactor to form a cycle circuit. The heating cycle device includes a heating medium storage tank containing a heating medium, a heat exchange medium transfer pump, a rotor flow meter, and a medium transfer pipe. A heat exchange medium transfer pump and a rotor flow meter are connected between the heating medium storage tank and the multi-stage micro screw device. The medium transfer pipe connects the heating medium storage tank and the multi-stage micro screw device to form a cycle circuit.

[0044] The multi-stage micro-screw device includes, but is not limited to, a single-stage micro-screw machine, a two-stage micro-screw machine, a three-stage micro-screw machine, and a four-stage micro-screw machine that are sequentially connected. A heat preservation jacket is installed on each of the single-stage micro-screw machine to the four-stage micro-screw machine. The heat medium in the heating cycle device is introduced into the heat preservation jacket. The screw diameters of the single-stage micro-screw machine to the four-stage micro-screw machine gradually increase, the aspect ratio of the screw gradually decreases, the screw rotation speed gradually decreases, and the jacket temperature gradually increases. The screw diameters of the single-stage micro-screw machine to the four-stage micro-screw machine are 15 mm to 40 mm, the aspect ratio of the screw is 30 to 80, the screw rotation speed is 100 to 420 rpm, and the jacket temperature is 30 to 60 °C. The screws of the single-stage micro-screw machine to the four-stage micro-screw machine include one or more of single screw, double screw, triple screw, or quad screw.

Effect of the Invention

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0046] 1) In the process of obtaining a modified meta-aramid resin solution by continuous polymerization, the present invention improves the spinnability of the meta-aramid spinning dope by introducing a copolymer diamine monomer or adding an auxiliary agent, manufactures a meta-aramid resin spinning dope with high molecular weight and high solid content, supports the heat dissipation and mass transfer of the reaction system, and manufactures high-performance meta-aramid fibers using dry-wet spinning of corresponding parameters based on the performance of the aforementioned spinning dope.

[0047] 2) Dry-wet spinning has higher requirements for the spinning dope than wet spinning. By introducing a third copolymer monomer containing polar groups in the polymer main chain and adding an organic auxiliary that can form hydrogen bonds with amide groups, the spinnability of the spinning solution is improved, and other functional fillers or auxiliaries can be added according to the usage requirements. The third copolymer monomer containing polar groups can improve the intermolecular force and the surface wettability of meta-aramid. The organic auxiliary can form hydrogen bonds with the meta-aramid molecular chain, reduce the surface tension of the system, improve the apparent viscosity, and enhance the spinnability of the resin dope. Here, low molecular weight alcohol-based and carboxylic acid-based auxiliaries contain groups such as -F, -OH, -COOH, etc., and can improve the spinnability of the resin dope by forming hydrogen bonds with the amide groups in the meta-aramid molecular main chain. Moreover, they can be easily removed during the coagulation and water washing processes and do not affect the structure and performance of the final fiber product. The high heat-resistant organosilicon-based auxiliary can form hydrogen bonds with the amide groups in the meta-aramid molecular main chain through groups such as -O-, -F, -OR, -OH, etc., improve the spinnability of the resin dope, function as an oiling agent during the fiber spinning process, reduce hairiness, improve the product appearance, and since polysiloxane has excellent properties such as high heat resistance, it does not affect the performance of the fiber product.

[0048] 3) By directly spinning the resin dope obtained by continuous polymerization without neutralization, the neutralization and filtration desalination processes are avoided, the production efficiency is increased, and problems such as hairiness or yarn breakage caused by clogging of the spinneret due to inorganic salts and defects such as holes caused by precipitation of salts are avoided, enhancing the internal structure, appearance, and various properties of the fiber product.

[0049] 4) By using a microreactor for prepolymerization, the heat transfer problem is solved and the occurrence of side reactions is avoided. The microreactor has an excellent heat transfer effect, can effectively transfer the heat released from the polymerization initial reaction system, ensure accurate control of the system temperature, prevent the generation of by-products due to local overheating of the system, ensure that the polydispersity of the resin molecules of the product is low, and the intrinsic viscosity is stable and controllable.

[0050] 5) By performing condensation polymerization using a multi-stage screw, the mass transfer problem is solved, and a resin stock solution with high molecular weight and high solid content (high viscosity) is obtained. The low-viscosity polymer exiting the microreactor enters a multi-stage micro-screw device, which is mainly used to solve the mass transfer problem after the viscosity of the polymerization system rapidly increases, and the viscosity of the polymer in the multi-stage micro-screw device increases rapidly.

[0051] 6) By combining a multi-stage micro-screw device and a pre-polymerization microreactor, the continuous stability of the reaction device is ensured, and by adjusting the rotational speed of the multi-stage micro-screw device at different stages and the residence time of the materials, the mass transfer requirements in the condensation polymerization stage of the aramid polymerization process are completed, and different requirements can be satisfied simultaneously. Moreover, compared with the conventional reaction kettle, the continuous micro-reaction device has no amplification effect and is suitable for large-scale continuous industrial production.

[0052] 7) By using dry-wet spinning, the advantages of dry spinning and wet spinning are combined to achieve both high performance and high spinning efficiency of aramid fibers. By controlling the process, the dry-wet spinning of meta-aramid is successfully realized, and meta-aramid fibers with excellent performance are obtained.

Brief Description of the Drawings

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following briefly introduces the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings based on these drawings without creative efforts.

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0054] To facilitate the understanding of the present invention, the following will be combined with the specification drawings and better embodiments to describe the present invention more comprehensively and in detail. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0055] Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used in this specification are only used to specifically describe the purpose of the embodiments and are not intended to limit the protection scope of the present invention.

[0056] Unless otherwise specified, various raw materials, reagents, instruments, and equipment used in the present invention can all be obtained by purchasing in the market or by manufacturing by conventional methods.

[0057] Example 1: The examples of the present invention are all carried out in a production apparatus for modified meta-aramid fibers by continuous polymerization-dry-wet spinning. Referring to FIG. 1, the apparatus includes the following systems.

[0058] (1) Raw material storage device: It includes isophthaloyl chloride raw material storage tank 1, meta-phenylenediamine and copolymer diamine monomer raw material storage tank 2, solvent storage tank 3, solvent raw material storage tank 4 containing solubilizer, and dehydration device 5. The above raw material storage device and solvent raw material storage tank 4 containing solubilizer are connected to dehydration device 5. Dehydration device 5 and solvent storage tank 3 are connected to meta-phenylenediamine and copolymer diamine monomer raw material storage tank 2. Isophthaloyl chloride raw material storage tank 1 is connected to constant flow pump 7 and solvent storage tank 3 via three-way valve 6. Constant flow pump 7 is connected to micromixer 9. Meta-phenylenediamine and copolymer diamine monomer raw material storage tank 2 is also connected to micromixer 9 via a constant flow pump. Heat preservation jackets 8 for controlling the temperature of the raw materials before they enter the micromixer are installed on isophthaloyl chloride raw material storage tank 1, meta-phenylenediamine and copolymer diamine monomer raw material storage tank 2, constant flow pump 7 and the transfer piping.

[0059] (2) Prepolymerization system: It includes micromixer 9, microreactor 10 and metering pump, transport pipe member valve, instruments (pressure gauge, thermometer). Micromixer 9 is connected to microreactor 10. The microreactor is the heart-shaped microchannel reactor shown in Figure 2. The microreactor is designed in a heart shape, and a plurality of heart-shaped microreactors are connected by microchannels. The microchannels connect the tip and the recess of the heart shape respectively.

[0060] (3) Condensation polymerization system: It is a multi-stage micro-screw device 11, and multi-stage micro-screw device 11 is connected to microreactor 10.

[0061] (4) Post-treatment system: It includes auxiliary agent addition and mixer 12, filter 13, degassing kettle 14 and spinning solution storage tank 15. (5) Spinning system: It includes metering pump 16, spinning filter 17, spinning assembly 18. The spinning assembly includes a spinneret and a spinneret, etc. (6) Coagulation and washing system: including a coagulation bath 19, a first coagulation bath 20, a second coagulation bath 21, and a washing system 22. The washing system 22 includes a washing machine, a washing liquid storage tank, a draft roll, etc. (7) Drying system 24: including a dryer and a draft roll (8) Heat treatment system: including a dry heat stretching device 25, a heat setting device 26, a nitrogen gas system, and a draft roll (9) Winding / cutting system 27: including a winder / cutter Among the above-mentioned coagulation and washing system, drying system 24, heat treatment system devices, and winding / cutting system 27, the devices are respectively connected via a tractor 23. (10) Heat exchange system: It includes a refrigerant storage tank 28, a heating medium storage tank 29, a heat exchange medium transfer pump 30, and a heat exchange medium storage tank and a rotor flow meter. A heat exchange medium transfer pump 30 and a rotor flow meter are connected between the refrigerant storage tank 28 and the micromixer 9. The medium transfer pipe connects the refrigerant storage tank 28, the micromixer 9 and the microreactor 10 to form a cycle circuit. A heat exchange medium transfer pump 30 and a rotor flow meter are connected between the heating medium storage tank 29 and the multi-stage micro screw device 11. The medium transfer pipe connects the heating medium storage tank 29 and the multi-stage micro screw device 11 to form a cycle circuit. The multi-stage micro screw device 11 includes a single-stage micro screw machine, a two-stage micro screw machine, a three-stage micro screw machine and a four-stage micro screw machine connected in sequence. A heat preservation jacket is installed on each of the single-stage micro screw machine to the four-stage micro screw machine. The heat medium in the heating cycle device is introduced into the heat preservation jacket. The screw diameters of the single-stage micro screw machine to the four-stage micro screw machine gradually increase, the aspect ratio of the screw gradually decreases, the screw rotation speed gradually decreases, and the jacket temperature gradually increases. The screw diameters of the single-stage micro screw machine to the four-stage micro screw machine are 15 mm to 40 mm, the aspect ratio of the screw is 30 to 80, the screw rotation speed is 100 to 420 rpm, and the jacket temperature is 30 to 60 °C. The screws of the single-stage micro screw machine to the four-stage micro screw machine may be single screw, double screw, triple screw or quad screw.

[0062] The manufacturing process of Example 1 is specifically as follows.

[0063] As shown in the flow chart of Fig. 1, a DMAc mixed solution of meta-phenylenediamine containing 10 wt% solid content of LiCl (2%) and 6,4'-diamino-2'-trifluoromethyl-2-phenylbenzimidazole (the molar ratio of the two is 98:2) was prepared and maintained at -20°C. At the same time, isophthaloyl chloride was melted and maintained at 55°C. After the mixed solution and the isophthaloyl chloride cartridge were metered according to equimolar amounts by a constant flow pump, they were mixed in a micromixer 9 and then transported to a heart-shaped microreactor 10. The temperatures of the micromixer 9 and the microreactor 10 were controlled at -20 to 10°C and 10 to 30°C respectively. The prepolymer flowing out of the microreactor 10 entered from a single-stage micro-screw machine into a four-stage micro-screw machine for condensation polymerization. Here, the single-stage micro-screw machine has a screw diameter of 15 mm, an aspect ratio of 80, a rotation speed of 420 rpm, and a jacket temperature of 30°C. The two-stage micro-screw machine has a screw diameter of 20 mm, an aspect ratio of 60, a rotation speed of 300 rpm, and a jacket temperature of 40°C. The three-stage micro-screw machine has a screw diameter of 30 mm, an aspect ratio of 40, a rotation speed of 220 rpm, and a jacket temperature of 50°C. The four-stage micro-screw machine has a screw diameter of 40 mm, an aspect ratio of 30, a rotation speed of 100 rpm, and a jacket temperature of 60°C. The screws from the single-stage micro-screw machine to the four-stage micro-screw machine are all quad screws. After the polymer flowing out of the multi-stage micro-screw device 11 entered the treatment system, 1 wt% trifluoroethanol was added. After filtration and defoaming, a spinning dope was obtained. The spinning dope was spun, washed with water, dried, dry heat stretched, heat set, wound or cut to obtain modified meta-aramid fibers.Here, the hole diameter of the spinneret is 0.12 mm, the height of the air layer is 40 mm, the drafting speed for pre-orientation is 3.5 times the spinning speed of the spinning solution, the DMAc concentration in the first coagulation bath is 25 wt%, the temperature is 40 °C, the DMAc concentration in the second coagulation bath is 20 wt%, the temperature is 55 °C, the plasticizing draw ratio is 3.0, the dry heat drawing temperature is 310 °C, the drawing ratio is 2.0, and the heat setting temperature is 320 °C.

[0064] Example 2: The reaction apparatus is the same as that in Example 1. The hole diameter of the spinneret in Example 1 is adjusted to 0.1 mm, the air layer is adjusted to 20 mm, the speed of the first drafting roll is adjusted to 3.0 times the speed of the spinning solution, the DMAc concentration in the first coagulation bath is adjusted to 35%, the temperature is adjusted to 40 °C, the DMAc concentration in the second coagulation bath is adjusted to 25%, the temperature is adjusted to 45 °C, the plasticizing draw ratio is adjusted to 2.5, and the other processes and process parameters are the same as those in Example 1.

[0065] Example 3: The reaction apparatus is the same as that in Example 1. The height of the air layer in Example 1 is adjusted to 10 mm, the speed of the first drafting roll is adjusted to 2.0 times the speed of the spinning solution, the temperature of the first coagulation bath is adjusted to 35 °C, the second coagulation bath is adjusted to 45 °C, the plasticizing draw ratio is adjusted to 2.8, and the other processes and process parameters are the same as those in Example 1.

[0066] Example 4: The reaction apparatus is the same as that in Example 1. The height of the air layer in Example 1 is adjusted to 60 mm, the speed of the first drafting roll is adjusted to 4.0 times the speed of the spinning solution, the DMAc concentration in the first coagulation bath is adjusted to 30%, the temperature is adjusted to 25 °C, the DMAc concentration in the second coagulation bath is adjusted to 25%, the temperature is adjusted to 35 °C, the plasticizing draw ratio is adjusted to 3.2, and the other processes and process parameters are the same as those in Example 1.

[0067] Example 5: The reaction apparatus is the same as that in Example 1. The dry heat drawing temperature in Example 1 was adjusted to 300 °C, the magnification was adjusted to 1.8, the heat setting temperature was adjusted to 310 °C, and the other processes and process parameters were the same as those in Example 1.

[0068] Example 6: The reaction apparatus is the same as that in Example 1. The dry heat drawing temperature in Example 1 was adjusted to 320 °C, the magnification was adjusted to 2.4, the heat setting temperature was adjusted to 330 °C, and the other processes and process parameters were the same as those in Example 1.

[0069] Example 7: The reaction apparatus is the same as that in Example 1. The copolymerized diamine monomer in Example 1 was changed to 2-(4-aminophenyl)-5-aminophenylbenzimidazole, the molar ratio of meta-phenylenediamine to the copolymerized diamine monomer was set to 95:5, the amount of LiCl used was adjusted to 4%, the auxiliary agent was adjusted to 0.05% glycerin, and without changing other processes and parameters, modified meta-aramid fibers were obtained.

[0070] Figure 3 is the infrared spectrum of the modified meta-aramid resin containing the copolymerized diamine monomer of Example 7.

[0071] Example 8: The reaction apparatus is the same as that in Example 1. The copolymerized diamine monomer in Example 1 was changed to 5-amino-2-(4-aminophenyl)benzoxazole, the molar ratio of meta-phenylenediamine to the copolymerized diamine monomer was set to 97:3, the auxiliary agent was adjusted to 1.5% polyether-modified polysiloxane, the amount of LiCl used was adjusted to 3%, and without changing other processes and parameters, modified meta-aramid fibers were obtained.

[0072] Example 9: The reaction apparatus was the same as that in Example 1. The copolymerized diamine monomer in Example 1 was changed to 5-amino-2-(4-aminophenyl)benzothiazole, the molar ratio of meta-phenylenediamine to the copolymerized diamine monomer was set to 96:4, the amount of LiCl used was adjusted to 4%, and without changing other processes and parameters, modified meta-aramid fibers were obtained.

[0073] Example 10: The reaction apparatus was the same as that in Example 1. The copolymerized diamine monomer in Example 1 was changed to 2,6-diaminobenzothiazole, the auxiliary agent was adjusted to 0.3% sorbic acid, and without changing other processes and parameters, modified meta-aramid fibers were obtained.

[0074] Example 11: The reaction apparatus was the same as that in Example 1. The copolymerized diamine monomer in Example 1 was changed to 2,6-diaminopyridine, the auxiliary agent was adjusted to 0.1% salicylic acid, and without changing other processes and parameters, modified meta-aramid fibers were obtained.

[0075] Example 12: The reaction apparatus was the same as that in Example 1. The copolymerized diamine monomer in Example 1 was changed to 2-(4-aminophenyl)-5-aminopyridine, the auxiliary agent was adjusted to 0.2% trifluoroacetamide, and without changing other processes and parameters, modified meta-aramid fibers were obtained.

[0076] Example 13: The reaction apparatus was the same as that in Example 1. The copolymerized diamine monomer in Example 1 was changed to 2,5-bis(4-aminophenyl)pyridine, the auxiliary agent was adjusted to 2% hydroxyl-containing polysiloxane, and without changing other processes and parameters, modified meta-aramid fibers were obtained.

[0077] Example 14: The reaction apparatus was the same as that in Example 1. The copolymerized diamine monomer in Example 1 was changed to o-chloro-p-phenylenediamine, the molar ratio of meta-phenylenediamine to the copolymerized diamine monomer was 95:5, the amount of LiCl used was adjusted to 1%, the auxiliary agent was adjusted to 0.2% trifluoroacetic acid, and other processes and parameters were not changed, and modified meta-aramid fibers were obtained.

[0078] Example 15: The reaction apparatus was the same as that in Example 1. The copolymerized diamine monomer in Example 1 was changed to p-phenylenediamine, the auxiliary agent was adjusted to 0.8% fluorine-containing siloxane, and other processes and parameters were not changed, and modified meta-aramid fibers were obtained.

[0079] Comparative Example 1: Pure meta-aramid, batch polymerization - wet spinning Meta-aramid was produced using conventional kettle batch polymerization. The inherent viscosity of the resin was 1.84, the molecular weight distribution was 1.49, the viscosity at 50 °C was 28000 cp, and meta-aramid fibers were obtained using wet spinning.

[0080] Comparative Example 2: Pure meta-aramid, batch polymerization - dry-wet spinning The polymerization method was the same as that in Comparative Example 1. The viscosity at 50 °C was 80000 cp, and spinning was performed using dry-wet spinning, and the "paste plate" phenomenon occurred.

[0081] Comparative Example 3: Pure meta-aramid, continuous polymerization - wet spinning Meta-aramid resin was produced using continuous polymerization. The inherent viscosity of the resin was 1.82, the molecular weight distribution was 1.39, the viscosity at 50 °C was 36000 cp, and meta-aramid fibers were obtained using wet spinning.

[0082] Comparative Example 4: Pure meta-aramid, continuous polymerization - dry-wet spinning The polymerization method was the same as that in Comparative Example 3. The viscosity at 50 °C was 76000 cp, and spinning was performed using dry-wet spinning. The spinnability of the spinning dope was general, and yarn breakage and fuzz occurred.

[0083] Comparative Example 5: Pure meta-aramid, continuous polymerization - additive addition - dry-wet spinning 0.5 wt% of ethylene glycol was added to the meta-aramid resin solution of Comparative Example 4. The viscosity at 50 °C was 82,000 cp. Dry-wet spinning was used to obtain meta-aramid fibers. The spinnability of the spinning dope was somewhat improved compared to Comparative Example 4, and the occurrence frequency of fluff and yarn breakage decreased.

[0084] Comparative Example 6: Modified meta-aramid, continuous polymerization - dry-wet spinning A modified meta-aramid resin with a copolymer diamine monomer o-chloro-p-phenylenediamine content of 2% (mole fraction) was produced using continuous polymerization. The inherent viscosity of the resin was 2.08, the molecular weight distribution was 1.41, the viscosity at 50 °C was 70,000 cp. Dry-wet spinning was used to obtain meta-aramid fibers. The spinnability of the spinning dope was somewhat improved compared to Comparative Example 4, and the occurrence frequency of fluff and yarn breakage decreased.

[0085] Table 1 Performance comparison between examples and comparative examples JPEG0007690610000001.jpg215170

Explanation of symbols

[0086] 1. Isophthaloyl chloride raw material storage tank, 2. Meta-phenylenediamine and copolymer diamine monomer raw material storage tank, 3. Solvent storage tank, 4. Solvent raw material storage tank containing solubilizer, 5. Dehydration device, 6. Three-way valve, 7. Constant flow pump, 8. Heat preservation jacket, 9. Micro mixer, 10. Micro reactor, 11. Multi-stage micro screw device, 12. Auxiliary agent addition and mixer, 13. Filter, 14. Defoaming kettle, 15. Spinning solution storage tank, 16. Metering pump, 17. Spinning filter, 18. Spinning assembly, 19. Coagulation bath, 20. First coagulation bath, 21. Second coagulation bath, 22. Water washing system, 23. Tractor, 24. Drying system, 25. Dry heat stretching device, 26. Heat setting device, 27. Winding / cutting system, 28. Refrigerant storage tank, 29. Heating medium storage tank, 30. Heat exchange medium transfer pump.

Claims

Claim 1 A method for producing a modified meta-aramid fiber by continuous polymerization-dry and wet spinning, comprising: Step (1) of preparing a mixed solution of meta-phenylenediamine and a copolymer diamine monomer; Step (2) of mixing isophthaloyl chloride with the mixed solution of meta-phenylenediamine and the copolymer diamine monomer, performing a preliminary condensation polymerization reaction to obtain a prepolymer, and subjecting the prepolymer to condensation polymerization to obtain a modified meta-aramid resin solution; Step (3) of adding an auxiliary agent to the modified meta-aramid resin solution, filtering, defoaming, and obtaining the modified meta-aramid fiber by dry and wet spinning; In step (1), the preparation of the mixed solution of meta-phenylenediamine and the copolymer diamine monomer is to first dissolve a solubilizer in a solvent, remove water with a drying system, and then dissolve the copolymer diamine monomer and meta-phenylenediamine in the solvent containing the solubilizer; The solvent of the mixed solution of meta-phenylenediamine and the copolymer diamine monomer in step (1) is DMAc; The solubilizer in step (1) is LiCl, and the content of the solubilizer is 0.1% to 10% of the mass of the solvent of the copolymer diamine monomer mixed solution; The copolymer diamine monomer includes at least one of 6,4'-diamino-2'-trifluoromethyl-2-phenylbenzimidazole, 2-(4-aminophenyl)-5-aminophenylbenzimidazole, 5-amino-2-(4-aminophenyl)benzoxazole, 5-amino-2-(4-aminophenyl)benzothiazole, 2,6-diaminobenzothiazole, 2,6-diaminopyridine, 2-(4-aminophenyl)-5-aminopyridine, 2,5-bis(4-aminophenyl)pyridine, o-chloro-p-phenylenediamine, and p-phenylenediamine, and its molar content is 0.1% to 10% of isophthaloyl chloride; In step (3), an organic auxiliary agent capable of forming a hydrogen bond with an amide group is added to the modified meta-aramid resin solution before filtration. The organic auxiliary agent contains at least one of low-molecular-weight alcohol-based, acid-based, or high heat-resistant organosilicon-based substances. The low-molecular-weight alcohol-based and acid-based substances contain at least one of trifluoroacetamide, trifluoroethanol, trifluoroacetic acid, hexafluoroisopropanol, ethylene glycol, glycerin, sorbic acid, and salicylic acid. The usage amount is 0.01% to 3 wt% of the usage amount of the modified meta-aramid resin solution. The organosilicon-based substance contains at least one of polyether-modified polysiloxane, fluorine, or polysiloxane containing an alkoxy group or a hydroxyl group. The usage amount is 0.1% to 10 wt% of the usage amount of the modified meta-aramid resin solution. A method for manufacturing modified meta-aramid fibers by continuous polymerization-dry and wet spinning, characterized by the above.

2. The mixing in step (2) occurs in a micromixer. Isophthaloyl chloride is in a molten state at a temperature of 45°C to 60°C before being introduced into the micromixer. The mixed solution of meta-phenylenediamine and copolymer diamine monomer is in a solution state at a temperature of -20°C to 10°C before being introduced into the micromixer. The temperature of the micromixer is controlled at -20°C to 60°C. The preliminary condensation polymerization reaction occurs in a microreactor, and the temperature of the microreactor is controlled at 10°C to 60°C. The condensation polymerization occurs in a multi-stage micro-screw device, and the temperature of the multi-stage micro-screw device is controlled at 20°C to 70°C. A method for manufacturing modified meta-aramid fibers by continuous polymerization-dry and wet spinning according to claim 1, characterized by the above.

3. The microreactor includes any one of a heart shape, a circle, a triangle, a straight line shape, and a spiral shape. A method for manufacturing modified meta-aramid fibers by continuous polymerization-dry and wet spinning according to claim 2, characterized by the above.

4. The inherent viscosity of the modified meta-aramid resin is ≧ 1.8 dl / g. A method for manufacturing modified meta-aramid fibers by continuous polymerization-dry and wet spinning according to claim 1, characterized by the above.

5. The process of the wet-dry spinning in step (3) includes passing the spinning dope through a spinneret, passing through an air layer, entering a first coagulation bath to obtain primary fibers, subjecting the primary fibers to break draft and then entering a second coagulation bath, followed by water washing, drying, dry heat drawing, heat setting and winding / cutting to obtain modified meta-aramid fibers. The method for manufacturing modified meta-aramid fibers by continuous polymerization-wet-dry spinning according to claim 1 is characterized by this.

6. The hole diameter of the spinneret is 0.06 to 0.25 mm, the height through which the spinning dope passes through the air layer is 2 to 80 mm, and the draft speed of the break draft is 2 to 5 times the spinning speed of the dope. The method for manufacturing modified meta-aramid fibers by continuous polymerization-wet-dry spinning according to claim 5 is characterized by this.

7. The first coagulation bath and the second coagulation bath are aqueous DMAc solutions. The DMAc concentration of the first coagulation bath is 20 to 45 wt%, the temperature is 20 to 50 °C, the DMAc concentration in the second coagulation bath is 15 to 40 wt%, the temperature is 30 to 60 °C, the plasticizing draw ratio is 1.1 to 4, the temperature of the dry heat drawing is 280 to 350 °C, the draw ratio is 1.1 to 3, and the heat setting temperature is 280 to 350 °C. The method for manufacturing modified meta-aramid fibers by continuous polymerization-wet-dry spinning according to claim 5 is characterized by this.

8. The breaking strength of the meta-aramid fibers obtained by the manufacturing by continuous polymerization-wet-dry spinning is ≥ 6.0 cN / dtex, the elongation at break is 25 to 50%, and the initial modulus is ≥ 90 cN / dtex. The method for manufacturing modified meta-aramid fibers by continuous polymerization-wet-dry spinning according to any one of claims 1 to 7 is characterized by this.

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