阅读说明：本技术 一种用于芳纶1414连续聚合的对苯二胺溶解系统及方法 (P-phenylenediamine dissolving system and method for continuous polymerization of aramid fibers 1414 ) 是由 崔晓静 孙潜 王昕玥 毛亚丽 汪健 于 2019-11-07 设计创作，主要内容包括：本发明公开了一种用于芳纶1414连续聚合的对苯二胺溶解系统及方法,属于人造纤维生产设备技术领域。通过对苯二胺储罐、溶剂储罐、静态混合器、混合罐、保温装置及氮封装置等设置,首先,在静态混合器中,将精馏后处于熔融态的对苯二胺与特定压力的溶剂预混合,产生细小微粒的预混料；其次,在混合罐中,将对苯二胺与溶剂再混合,促使对苯二胺在混合罐内快速溶解,形成浓度大于5%的对苯二胺溶液,同时有效避免对苯二胺被氧化,并保证聚合物质量和制备效率；本系统结构简单、方便及实用。(The invention discloses a p-phenylenediamine dissolving system and method for continuous polymerization of aramid fibers 1414, and belongs to the technical field of artificial fiber production equipment. Through the arrangement of a p-phenylenediamine storage tank, a solvent storage tank, a static mixer, a mixing tank, a heat preservation device, a nitrogen sealing device and the like, firstly, in the static mixer, the p-phenylenediamine which is in a molten state after rectification is premixed with a solvent with a specific pressure to generate a fine particle premix; secondly, in a mixing tank, the p-phenylenediamine and the solvent are mixed again to promote the p-phenylenediamine to be rapidly dissolved in the mixing tank to form a p-phenylenediamine solution with the concentration of more than 5 percent, and meanwhile, the p-phenylenediamine is effectively prevented from being oxidized, and the quality and the preparation efficiency of the polymer are ensured; the system has simple structure, convenience and practicability.)

1. A p-phenylenediamine dissolving system for continuous polymerization of aramid fiber 1414 is characterized by comprising a p-phenylenediamine storage tank (1) for storing the p-phenylenediamine which is in a molten state after rectification, a solvent storage tank (2) for storing an organic solvent, a static mixer (3) for premixing the p-phenylenediamine and the organic solvent, a mixing tank (4) for remixing the p-phenylenediamine and the organic solvent, a heat preservation device (6) for preserving the heat of the p-phenylenediamine and a nitrogen sealing device (5) for sealing the p-phenylenediamine with nitrogen,

the system is characterized in that the p-phenylenediamine storage tank (1) is connected with the static mixer (3) through a p-phenylenediamine delivery pipe (107), the solvent storage tank (2) is connected with the static mixer (3) through a solvent delivery pipe (207), and the static mixer (3) is connected with the mixing tank (4) through a mixing delivery pipe (307);

the heat preservation device (6) is connected with the p-phenylenediamine storage tank (1), the p-phenylenediamine delivery pipe (107), the static mixer (3) and the mixing delivery pipe (307);

and the nitrogen sealing device (5) is connected with the p-phenylenediamine storage tank (1), the solvent storage tank (2) and the mixing tank (4).

2. The p-phenylenediamine dissolving system for continuous polymerization of aramid fibers 1414 according to claim 1, wherein the nitrogen sealing device (5) comprises a nitrogen tank (501) and an exhaust tank (502), the nitrogen tank (501) and the exhaust tank (502) are both connected with the p-phenylenediamine storage tank (1), and a nitrogen passage for nitrogen sealing of p-phenylenediamine is formed among the nitrogen tank (501), the exhaust tank (502) and the p-phenylenediamine storage tank (1);

the nitrogen tank (501) and the waste gas tank (502) are both connected with the solvent storage tank (2), and a nitrogen passage sealed by organic solvent nitrogen is formed among the nitrogen tank (501), the waste gas tank (502) and the solvent storage tank (2);

the nitrogen tank (501) and the waste gas tank (502) are connected with the mixing tank (4), and a nitrogen passage for sealing mixed material nitrogen is formed among the nitrogen tank (501), the waste gas tank (502) and the mixing tank (4).

3. The p-phenylenediamine dissolving system for continuous polymerization of aramid fibers 1414 according to claim 2, wherein a nitrogen inlet on the p-phenylenediamine storage tank (1) is connected with the thermal insulation device (6), and a waste gas outlet on the p-phenylenediamine storage tank (1) is connected with the thermal insulation device (6).

4. The p-phenylenediamine dissolving system for the continuous polymerization of aramid fibers 1414 according to claim 1, wherein the static mixer (3) is provided with a p-phenylenediamine inlet (301) at the upper part, a solvent inlet (302) at the middle part, a premix outlet (303) at the lower part, and a mixing chamber (304) for premixing inside; the p-phenylenediamine inlet (301) is arranged above the mixing cavity (304), the premix outlet (303) is arranged below the mixing cavity (304), and the premix outlet (303) is connected with the mixing conveying pipe (307);

still be equipped with in static mixer (3) with solvent import (302) the organic solvent chamber of keeping in (305) intercommunication, organic solvent chamber of keeping in (305) one end and solvent import (302) intercommunication, the other end is equipped with nozzle (306), nozzle (306) and mixing chamber (304) intercommunication, solvent import (302), organic solvent chamber of keeping in (305) and nozzle (306) form organic solvent circulation passageway between the three.

5. The p-phenylenediamine dissolving system for continuous polymerization of aramid fibers 1414 according to claim 1, wherein a discharge pipe (407) is connected to the mixing tank (4), a circulation pipe (7) is connected to the discharge pipe (407), one end of the circulation pipe (7) is connected to the discharge pipe (407), the other end of the circulation pipe is connected to the mixing tank (4), and a material circulation path is formed among the mixing tank (4), the discharge pipe (407) and the circulation pipe (7).

6. A p-phenylenediamine dissolution system method for continuous polymerization of aramid 1414 according to any of claims 1-5, comprising the steps of:

A. storing the p-phenylenediamine in a molten state after rectification in a p-phenylenediamine storage tank (1), storing an organic solvent in a solvent storage tank (2), introducing nitrogen into the p-phenylenediamine storage tank (1), the solvent storage tank (2) and a mixing tank (4), and sealing;

B. conveying the molten p-phenylenediamine to a static mixer (3) through a p-phenylenediamine conveying pipe (107), and conveying the organic solvent to the static mixer (3) through a solvent conveying pipe (207); in a static mixer (3), p-phenylenediamine in a molten state is contacted and mixed with an organic solvent to form a premix; wherein the feeding flow of the p-phenylenediamine in a molten state is not more than one half of the feeding flow of the organic solvent, and the organic solvent enters the static mixer (3) under the pressure of more than 0.4 MPa;

C. b, conveying the premix obtained in the step B into a mixing tank (4) through a mixing conveying pipe (307), wherein the feeding flow of the premix is the sum of the feeding flow of molten p-phenylenediamine and the feeding flow of the organic solvent; controlling the temperature in the mixing tank (4) to be 50-90 ℃, the rotating speed of the stirring mechanism (401) to be 350-500 rpm and the micro-positive pressure to be 5-25 KPa, and dissolving the p-phenylenediamine to obtain a p-phenylenediamine solution.

7. The method for dissolving p-phenylenediamine for continuous polymerization of aramid fibers 1414 according to claim 6, wherein the static mixer (3) is dosed with the organic solvent before the p-phenylenediamine in a molten state is fed into the static mixer (3), and the organic solvent is fed into the mixing tank (4) through the mixing material feeding pipe (307) until the organic solvent covers the bottom of the mixing tank (4) and the stirring mechanism (401) in the mixing tank (4).

8. The method for dissolving p-phenylenediamine for continuous polymerization of aramid fibers 1414 according to claim 6, wherein in step a, the temperature of the p-phenylenediamine storage tank (1), the nitrogen inlet of the p-phenylenediamine storage tank (1), and the temperature of the waste gas outlet of the p-phenylenediamine storage tank (1) are all 150-180 ℃, and the micro-positive pressure is controlled to be 5-25 KPa; the temperature in the solvent storage tank (2) is 40-80 ℃, and the micro-positive pressure is controlled to be 5-25 KPa.

9. The p-phenylenediamine dissolution system method for continuous polymerization of aramid 1414 according to claim 6 or 8, wherein the p-phenylenediamine in a molten state is fed into a static mixer (3) at a flow rate of 500-3000 kg/h, and the organic solvent is fed into the static mixer (3) at a flow rate of 1000-6000 kg/h; the premix is fed into the mixing tank (4) at a flow rate of 1500-9000 kg/h.

10. The method for dissolving p-phenylenediamine for continuous polymerization of aramid 1414 according to claim 6, wherein in step B, the organic solvent is fed into a static mixer (3) at a pressure of 0.4-0.6 MPa.

Technical Field

The invention relates to a dissolving system and a method, in particular to a p-phenylenediamine dissolving system and a method for continuous polymerization of aramid fibers 1414, and belongs to the technical field of artificial fiber production equipment.

Background

Aramid 1414, also known as poly (p-phenylene terephthalamide) polymer (PPTA), is a high molecular polymer synthesized by low temperature solution polycondensation. DuPont, USA, utilized PPTA/H in 1965₂SO₄The liquid crystal behavior of the solution obtains the high-performance poly (p-phenylene terephthalamide) fiber by a dry jet wet spinning method. The fiber has high heat resistance, high tensile strength, high insulativity, chemical corrosion resistance, high compressibility and high bending strength, and stable thermal shrinkage and creep property, is used as a special fiber and a composite material, is applied to the fields of aerospace, aviation, traffic, communication and the like, and is particularly used for bulletproof finished products, civil engineering, composite materials, conveyor belts, friction sealing materials and the like.

The polymerization reaction to prepare poly (p-phenylene terephthalamide) is shown below:

at present, the preparation technology of aramid 1414 is a low-temperature polycondensation process, i.e., a monomer p-phenylenediamine (PPDA) participating in a polymerization reaction is dissolved in an organic solvent and undergoes a polycondensation reaction with terephthaloyl chloride (TPC), the organic solvent is used as a reaction medium, and the two reaction monomers react in the solvent system to generate a high-molecular polymer and are continuously precipitated in the solvent. Among them, one of the technical difficulties in this process is: how to dissolve the monomer p-phenylenediamine in an organic solvent.

P-phenylenediamine is a blocky crystal at normal temperature, has hard surface and compact texture, is very easy to oxidize when being contacted with air, and is easy to absorb moisture in the air; the solubility of p-phenylenediamine in organic solvents is extremely low and the dissolution rate is slow. In the conventional method of dissolving p-phenylenediamine in an organic solvent, the following problems are present:

directly adding p-phenylenediamine crystals into an organic solvent and dissolving the p-phenylenediamine crystals by stirring, but the p-phenylenediamine crystals are difficult to completely dissolve and reach the required concentration (more than 5 percent);

secondly, if the p-phenylenediamine crystal is crushed into powder, then the feeding and dissolving are carried out, but the oxidation speed of the p-phenylenediamine powder is higher, the water absorption is faster, and the quality of the aramid fiber 1414 product is seriously affected, such as: the oxidized p-phenylenediamine is black in color and is a colorant, the color of the aramid polymer is dark due to the fact that a very small amount of p-phenylenediamine is oxidized, and the aramid fiber prepared from the polymer is poor in color and cannot be used in many fields; for another example: the aramid fiber polymerization system has very high requirement on water, water molecules can make a high molecular polymer lose activity, the molecular weight of the polymer is low, the spinning requirement cannot be met, and the water in the polymerization system is generally required to be controlled below 50PPM, so that the water is very difficult to control by directly adopting crystal or powder feeding, and a very complicated sealed feeding system is required;

thirdly, the p-phenylenediamine crystal is crushed into powder, and the environment is seriously polluted in the feeding process;

fourthly, the p-phenylenediamine is crystalline at normal temperature, the melting point is 141 ℃, and the p-phenylenediamine in a molten state is added into the solvent for dissolving, so that the dissolving speed can be theoretically accelerated, but the implementation difficulty is great. Firstly, the oxidation rate of the p-phenylenediamine in a molten state can be increased rapidly, and the whole dissolving system can be damaged by trace air, so that the p-phenylenediamine is oxidized, and the color of the solution is abnormal; secondly, when the p-phenylenediamine in a molten state is added into a storage tank or a reaction tank which only contains a solvent, the p-phenylenediamine is contacted with the solvent with a low temperature, even in the air, the p-phenylenediamine in the molten state is cooled and solidified to be changed into the solid-state phenylenediamine, and finally the solid-state phenylenediamine cannot be effectively mixed and dissolved with the solvent, and if the temperature of a dissolving system is increased, the organic solvent is easy to have risks of evaporation, decomposition, combustion and the like at a high temperature.

Patent document CN105688706A entitled "apparatus and method for continuously dissolving p-phenylenediamine" was disclosed in 2016, 04/18.s, and discloses: the continuous dissolving device and the method of the p-phenylenediamine monomer in the continuous polymerization process of the resin for the para-aramid fiber, namely PPD continuous dissolution is used for replacing the common intermittent dissolution, so that all processes of PPTA polymerization are continuously operated, the stability of the molecular weight of the resin is further ensured, and the consistency of the color of the resin is realized. However, in the technical scheme, the p-phenylenediamine raw material is powder, which cannot effectively ensure the effective dissolution of the p-phenylenediamine.

Disclosure of Invention

The invention aims to solve the problems that the existing p-phenylenediamine dissolving system has long p-phenylenediamine dissolving time, p-phenylenediamine is easy to oxidize, and the evaporation is serious due to overhigh organic solvent temperature, and provides a p-phenylenediamine dissolving system and a method for continuous polymerization of aramid fibers 1414. In the technical scheme, a p-phenylenediamine storage tank, a solvent storage tank, a static mixer, a mixing tank, a heat preservation device, a nitrogen sealing device and the like are arranged, firstly, the p-phenylenediamine which is in a molten state after rectification is premixed with an organic solvent with certain pressure (in the static mixer, molten PPDA and a lower-temperature solvent are mixed to be cooled and solidified to generate fine particles and prevent large massive solidified bodies from being generated); secondly, the p-phenylenediamine (fine particles) and the organic solvent are mixed (in a mixing tank, the specific surface area of the p-phenylenediamine and the organic solvent is large, the p-phenylenediamine and the organic solvent are dissolved more completely), so that the p-phenylenediamine is quickly dissolved in the mixing tank to form a p-phenylenediamine solution with the concentration of more than 5 percent, meanwhile, the p-phenylenediamine is effectively prevented from being oxidized, and the quality and the preparation efficiency of the polymer are ensured; the system has simple structure, convenience and practicability.

In order to achieve the technical purpose, the following technical scheme is proposed:

a p-phenylenediamine dissolving system for continuous polymerization of aramid fibers 1414 comprises a p-phenylenediamine storage tank for storing the p-phenylenediamine which is in a molten state after rectification, a solvent storage tank for storing an organic solvent, a static mixer for premixing the p-phenylenediamine and the organic solvent, a mixing tank for remixing the p-phenylenediamine and the organic solvent, a heat preservation device for preserving the heat of the p-phenylenediamine and a nitrogen sealing device for preventing oxygen and water from contacting with the p-phenylenediamine and sealing the nitrogen sealing device,

the p-phenylenediamine storage tank is connected with the static mixer through a p-phenylenediamine delivery pipe, the solvent storage tank is connected with the static mixer through a solvent delivery pipe, and the static mixer is connected with the mixing tank through a mixing delivery pipe;

the heat preservation device is connected with the p-phenylenediamine storage tank, the p-phenylenediamine delivery pipe, the static mixer and the mixing delivery pipe to complete the heat preservation work of the p-phenylenediamine, so that the p-phenylenediamine is in a molten state and is finally completely dissolved; the heat preservation device is a heat preservation device in the prior mature technology;

the nitrogen sealing device is connected with the p-phenylenediamine storage tank, the solvent storage tank and the mixing tank, and nitrogen sealing is carried out on the p-phenylenediamine by using nitrogen so as to prevent the p-phenylenediamine from contacting oxygen and moisture.

Preferably, the nitrogen sealing device comprises a nitrogen tank and an exhaust gas tank, the nitrogen tank and the exhaust gas tank are both connected with the p-phenylenediamine storage tank, and a nitrogen passage for sealing p-phenylenediamine nitrogen is formed among the nitrogen tank, the exhaust gas tank and the p-phenylenediamine storage tank;

the nitrogen tank and the waste gas tank are connected with the solvent storage tank, and a nitrogen passage for sealing organic solvent nitrogen is formed among the nitrogen tank, the waste gas tank and the solvent storage tank, so that the influence on the p-phenylenediamine after oxygen and moisture brought by the organic solvent enter the static mixer is prevented, namely the p-phenylenediamine is indirectly sealed;

the nitrogen tank and the waste gas tank are connected with the mixing tank, and a nitrogen passage for sealing the mixed material by nitrogen is formed among the nitrogen tank, the waste gas tank and the mixing tank, namely indirectly sealing the p-phenylenediamine, preventing the p-phenylenediamine from contacting with oxygen and moisture, effectively improving the dissolution efficiency and quality of the p-phenylenediamine and providing stable and high-quality intermediate raw materials for continuous polymerization of aramid fibers 1414.

Preferably, a nitrogen inlet on the p-phenylenediamine storage tank is connected with the heat preservation device, and a waste gas outlet on the p-phenylenediamine storage tank is connected with the heat preservation device, so that the nitrogen inlet and the waste gas outlet are effectively prevented from blocking the conveying pipe due to crystals solidified after the molten p-phenylenediamine volatilizes.

Preferably, the upper part of the static mixer is provided with a p-phenylenediamine inlet, the middle part of the static mixer is provided with a solvent inlet, the lower part of the static mixer is provided with a premix outlet, and the static mixer is internally provided with a mixing cavity for premixing; the p-phenylenediamine inlet is arranged above the mixing cavity, the premix outlet is arranged below the mixing cavity, and the premix outlet is connected with the premix conveying pipe;

still be equipped with the organic solvent chamber of keeping in with solvent import intercommunication in the static mixer, organic solvent chamber one end of keeping in communicates with the solvent import, and the other end is equipped with the nozzle, and the nozzle communicates with the mixing chamber, forms organic solvent circulation passageway between solvent import, organic solvent chamber of keeping in and the nozzle three.

Preferably, be equipped with rabbling mechanism in the blending tank, the rabbling mechanism is among the current mature technique.

Preferably, the mixing tank is connected to the next process step through a discharge pipe.

Preferably, the discharge pipe is connected with a circulating pipe, one end of the circulating pipe is connected with the discharge pipe, the other end of the circulating pipe is connected with the mixing tank, and a material circulating passage is formed among the mixing tank, the discharge pipe and the circulating pipe.

On the p-phenylenediamine conveyer pipe, solvent conveyer pipe, discharging pipe, the conveyer pipe of being connected with the nitrogen gas jar and the conveyer pipe of being connected with the waste gas jar, can set up delivery pump, all kinds of valves and metering control mechanism etc. according to actual demand.

A p-phenylenediamine dissolving system method for continuous polymerization of aramid fibers 1414 specifically comprises the following steps:

A. storing the p-phenylenediamine in a molten state after rectification in a p-phenylenediamine storage tank, storing an organic solvent in a solvent storage tank, introducing nitrogen into the p-phenylenediamine storage tank, the solvent storage tank and a mixing tank, and performing nitrogen sealing protection to prevent the p-phenylenediamine and the organic solvent from contacting oxygen and moisture, thereby improving the quality of the raw materials;

the temperature in the p-phenylenediamine storage tank, the nitrogen inlet on the p-phenylenediamine storage tank and the waste gas outlet on the p-phenylenediamine storage tank are 150-180 ℃, and the micro-positive pressure is controlled to be 5-25 KPa; the temperature in the solvent storage tank is 40-80 ℃, and the micro-positive pressure is controlled to be 5-25 KPa;

B. conveying the molten p-phenylenediamine to a static mixer through a p-phenylenediamine conveying pipe, and conveying the organic solvent to the static mixer through a solvent conveying pipe; in a static mixer, molten p-phenylenediamine is contacted with an organic solvent to form fine and uniform granular premix, and the larger the specific surface area is, the easier the p-phenylenediamine and the organic solvent are dissolved in a mixing tank, namely, the preparation is made for the full dissolution in the mixing tank of the next process; wherein the feeding flow of the p-phenylenediamine in a molten state is not more than one half of the feeding flow of the organic solvent, and the organic solvent enters the static mixer under the pressure of more than 0.4 MPa;

preferably, the p-phenylenediamine in a molten state is conveyed into a static mixer at a flow rate of 500-3000 kg/h, and the organic solvent is conveyed into the static mixer at a flow rate of 1000-6000 kg/h; the higher the pressure is, the higher the injection speed of the organic solvent is, the better the mixing effect in the static mixer is, but in order to adapt to equipment and save cost, the organic solvent is preferably fed into the static mixer at the pressure of 0.4-0.6 MPa;

C. b, conveying the premix obtained in the step B into a mixing tank through a mixing conveying pipe, wherein the feed flow of the premix is the sum of the feed flow of molten p-phenylenediamine and the feed flow of the organic solvent; controlling the temperature in the mixing tank to be 50-90 ℃, the rotating speed of a stirring mechanism to be 350-500 rpm and the micro-positive pressure to be 5-25 KPa, dissolving p-phenylenediamine to obtain a p-phenylenediamine solution, and conveying the mixed material to the next procedure through a discharge pipe according to the requirement;

preferably, the premix is fed into the mixing tank at a flow rate of 1500 to 9000 kg/h.

Preferably, before the molten p-phenylenediamine is fed into the static mixer, the organic solvent is fed into the static mixer in a metered manner, and is conveyed into the mixing tank through the material mixing conveying pipe until the organic solvent covers the bottom of the mixing tank and a stirring mechanism in the mixing tank. After the organic solvent covers the stirring mechanism, the stirring mechanism can be started to stir, so that the stirring mechanism can stir materials, and the stirring mechanism can be prevented from being damaged; in addition, the pump on the discharge pipeline can be started after the organic solvent covers the bottom of the mixing tank, otherwise, the pump will be damaged. And according to the sequence of operation rules, after the bottom of the mixing tank is covered firstly, a certain liquid level exists in the mixing tank, the pump can be started to circulate, then the stirring mechanism is covered, and the stirring mechanism is started to stir the materials.

Preferably, a p-phenylenediamine solution with the concentration of more than or equal to 5 percent is obtained in the mixing tank, and particularly, the mixed solution with the p-phenylenediamine content of 5-10 percent is obtained.

Preferably, the organic solvent comprises NMP (N-methylpyrrolidone), DMAC (N, N-dimethylacetamide), HMPA (hexamethylphosphoramide) or tetramethylurea, and a cosolvent comprising CaCl₂(calcium chloride) or LiCl (lithium chloride).

By adopting the technical scheme, the beneficial effects brought are as follows:

1) in the invention, through the arrangement of a p-phenylenediamine storage tank, a solvent storage tank, a static mixer, a mixing tank, a heat preservation device, a nitrogen sealing device and the like, firstly, the p-phenylenediamine which is in a molten state after rectification is premixed with a solvent with certain pressure (in the static mixer, molten PPDA and a solvent with lower temperature are mixed to be cooled and solidified, so that fine particles are generated, and a large-block solidified body is prevented from being generated); secondly, the p-phenylenediamine (fine particles) and the solvent are mixed (in a mixing tank, the specific surface area of the p-phenylenediamine and the solvent is large, the p-phenylenediamine and the solvent are dissolved more completely), so that the p-phenylenediamine is quickly dissolved in the mixing tank to form a p-phenylenediamine solution with the concentration of more than 5%, meanwhile, the p-phenylenediamine is effectively prevented from being oxidized, and the quality and the preparation efficiency of the polymer are ensured; the system has simple structure, convenience and practicability;

2) in the invention, the arrangement of the heat preservation device ensures that the p-phenylenediamine is in a molten state, promotes the pre-mixing of the p-phenylenediamine in the static mixer and the re-mixing in the mixing tank, effectively improves the solubility of the p-phenylenediamine and plays an auxiliary role in the continuous polymerization of aramid fibers 1414;

3) in the invention, the nitrogen sealing device is arranged, and the p-phenylenediamine storage tank, the solvent storage tank and the mixing tank are sealed by using nitrogen, so that the p-phenylenediamine is prevented from being contacted with oxygen and moisture, the quality of raw materials is improved, and finally the stability, the efficiency and the quality of the aramid fiber 1414 production process are improved. The nitrogen sealing device comprises a nitrogen tank and an exhaust gas tank, wherein the nitrogen tank provides a source of nitrogen in the nitrogen sealing process, the exhaust gas tank collects exhaust gas discharged by nitrogen filling in the nitrogen sealing process, and the nitrogen tank and the exhaust gas tank are arranged to ensure the orderly, effective and stable operation of the nitrogen sealing process;

4) in the mixing tank, the stirring mechanism and the circulating pipe are arranged, so that on one hand, fine granular premix precipitation is effectively prevented, the p-phenylenediamine and the organic solvent are promoted to be uniformly mixed, the specific surface areas of the p-phenylenediamine and the organic solvent are increased, the contact probability of the p-phenylenediamine and the organic solvent is increased, and the p-phenylenediamine is completely dissolved; on the other hand, the dissolving speed is accelerated, and the p-phenylenediamine dissolving time is reduced, so that the industrial production efficiency is improved, the unit consumption level of raw material production is reduced, and the raw material cost is saved;

5) in the present invention, p-phenylenediamine can be rapidly formed into a higher dissolved concentration, i.e., greater than 5%, in an organic solvent. The method not only shows that the concentration of the p-phenylenediamine is higher in the same dissolving time and the same solvent amount, so that a polymerization reaction system can complete polymerization of more polymers, the solid content of the polymer after the reaction is completed is improved, more polymers can be obtained in unit production time, the production efficiency is improved, and the raw material cost is reduced.

This also means that less solvent can be used for dissolution per unit of production time, producing an equal mass of polymer. And the solvent after the polymerization reaction is recycled by polymer washing, washing liquid recovery, solvent rectification and the like. Namely, the reduction of the usage amount of the solvent also means the reduction of the washing cost, the recovery cost and the rectification cost; therefore, the invention not only can effectively improve the production efficiency and reduce the unit consumption level of raw materials, but also can greatly reduce other production costs;

6) in the invention, the contact between the p-phenylenediamine and air (oxygen and moisture) can be completely avoided by a completely sealed feeding mode of the p-phenylenediamine molten state, the oxidation and water absorption of the p-phenylenediamine can be effectively prevented, and the molecular weight stability and the color stability of a subsequent product polymer are further ensured;

7) in the invention, the organic solvent with lower temperature is adopted to dissolve the p-phenylenediamine, so that the volatilization amount of the organic solvent is reduced, the loss amount of the organic solvent is reduced, and potential safety hazards and even accidents caused by the high-temperature organic solvent are reduced;

8) in the invention, the p-phenylenediamine is in a molten state and stably and controllably enters a static mixer by controlling the temperature (150-180 ℃ and the melting point of the p-phenylenediamine is 140 ℃) and the micro-positive pressure (5-25 KPa) in a p-phenylenediamine storage tank, and the setting of the environment in the p-phenylenediamine storage tank is a preparation process for the p-phenylenediamine to enter the static mixer; through controlling the temperature (40-80 ℃) and the micro positive pressure (5-25 KPa) in the solvent storage tank, the organic solvent is stably and controllably fed into the static mixer, and the setting of the environment in the solvent storage tank provides a preparation process for feeding the organic solvent into the static mixer;

9) in the invention, the feeding flow of the p-phenylenediamine in a molten state is set to be not more than one half of the feeding flow of the organic solvent, and the organic solvent enters the static mixer under the pressure of more than 0.4 MPa, so that the PPDA in the molten state and the solvent with lower temperature are mixed to be cooled and solidified in the static mixer, fine particles are generated, massive solidified bodies are prevented from being generated, and a preparation process is provided for complete dissolution in the mixing tank;

10) in the invention, the temperature in the mixing tank is controlled to be 50-90 ℃, the rotating speed of the stirring mechanism is 350-500 rpm, and the micro-positive pressure is 5-25 KPa, so that the dissolving efficiency and quality of p-phenylenediamine are effectively improved, and finally, an effective pretreatment process is provided for continuous polymerization of aramid fibers 1414.

Drawings

FIG. 1 is a schematic flow diagram of a dissolution process of the present invention;

FIG. 2 is a schematic diagram of the structural logic connections of the present invention;

FIG. 3 is a cross-sectional view of a static mixer of the present invention;

the device comprises a p-phenylenediamine storage tank 1, a p-phenylenediamine storage tank 101, tank bottom valves I and 102, an inlet valve of a delivery pump I, a delivery pump I and 104, an outlet valve of the delivery pump I, a metering flowmeter 105 of the p-phenylenediamine, a self-control valve of the p-phenylenediamine delivery pipe 106, a p-phenylenediamine delivery pipe 107 and a p-phenylenediamine delivery pipe;

2. a solvent storage tank 201, kettle bottom valves II and 202, an inlet valve of a conveying pump II, 203, conveying pumps II and 204, outlet valves of the conveying pumps II and 205, solvent metering flow meters and 206, a solvent conveying pipe automatic control valve 207 and a solvent conveying pipe;

3. the device comprises a static mixer, a p-phenylenediamine inlet 301, a p-phenylenediamine inlet 302, a solvent inlet 303, a premix outlet 304, a mixing cavity 305, an organic solvent temporary storage cavity 306, a nozzle 307 and a mixing conveying pipe;

4. a mixing tank 401, a stirring mechanism 402, kettle bottom valves III, 403, an inlet valve of a delivery pump III, 404, delivery pumps III, 405, outlet valves of the delivery pumps III, 406, a discharge pipe valve 407 and a discharge pipe;

5. a nitrogen sealing device 501, a nitrogen tank 502 and an exhaust gas tank;

6. a heat preservation device;

7. circulation tube 701, circulation tube valve 702, sample.

Detailed Description

In the following, the technical solutions in the embodiments of the present invention are clearly and completely described, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.