Method and system for preparing polyphenylene sulfide through continuous flow tubular reaction

Abstract

The invention discloses a system for preparing polyphenylene sulfide through continuous flow tubular reaction, and belongs to the technical field of high polymer materials, the system for preparing polyphenylene sulfide through continuous flow tubular reaction comprises a reaction kettle and a dehydration kettle, the top of the reaction kettle is communicated with a rectifying tower, the top of the reaction kettle is provided with a flow meter port, the reaction kettle is communicated with the dehydration kettle, and the rectification tower is communicated with the dehydration kettle. A water pump is arranged between the reaction kettle and the dehydration kettle, a cooling bypass pipe is communicated between the water pump and the dehydration kettle, the bottom of the dehydration kettle is communicated with a screw-type feeding pump, the other end of the screw-type feeding pump is communicated with a micro-channel reactor, the other end of the micro-channel reactor is communicated with a dynamic tubular reactor, and the dynamic tubular reactor is communicated with the dehydration kettle. A material receiving tank is arranged on the dynamic tubular reactor, and a back pressure valve is arranged at the top of the material receiving tank. The dynamic tubular reactor is arranged in the polyphenylene sulfide preparation process, so that heat in the preparation process can be dissipated in time, and the polyphenylene sulfide preparation efficiency is further ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a method and a system for preparing polyphenylene sulfide by continuous flow tubular reaction. Background Art

[0002] Polyphenylene sulfide (PPS) is a thermoplastic engineering plastic containing phenylthio groups on the main chain of the molecule. It is currently mostly used in electronics, electrical appliances, automobiles, aerospace and other fields. The production technology of PPS is gradually maturing in China. The mature production technology in the industry is mostly a batch reaction process, which is a highly exothermic polymerization reaction.

[0003] The practice in the laboratory environment is to slowly add one of the materials into the kettle, and the heat will be slowly and continuously removed. However, since the product of this reaction is a polymer, and film-grade polyphenylene sulfide resin also has certain requirements for molecular weight distribution and molecular weight, this method cannot be used for cooling in the actual production process. First, the reaction process temperature is high and the temperature is increased in stages. Secondly, the raw materials participating in the reaction need to be added at the same time, and then the temperature is rapidly increased under uniform conditions, and the temperature needs to be under controlled conditions. There are also requirements for the distribution range of the polymer molecular weight. If dripping or slow mixing is used, it will cause problems such as too wide molecular weight distribution, poor product performance and unstable quality. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the disadvantages of the prior art and provide a method and system for preparing polyphenylene sulfide by continuous flow tubular reaction.

[0005] The technical solution adopted to solve the above technical problems is:

[0006] A method and system for preparing polyphenylene sulfide by continuous flow tubular reaction, comprising a reactor and a dehydration kettle, wherein the top of the reactor is connected to a distillation tower, the top of the reactor is provided with a flow meter port, the reactor is connected to the dehydration kettle, a water pump is provided between the reactor and the dehydration kettle, a cooling bypass pipe is connected between the water pump and the dehydration kettle, a screw feed pump is connected to the bottom of the dehydration kettle, the other end of the screw feed pump is connected to a microchannel reactor, the other end of the microchannel reactor is connected to a dynamic tubular reactor, a receiving tank is installed on the dynamic tubular reactor, and a back pressure valve is provided on the top of the receiving tank.

[0007] Furthermore, cold oil is arranged in the cooling bypass pipe, and the normal temperature of the cold oil is 80-90°C.

[0008] Furthermore, the total capacity of the microchannel reactor is 560 ml.

[0009] Furthermore, the microchannel reactor is divided into a first-stage reactor and a second-stage reactor. The first-stage reactor is connected to a screw feed pump, the second-stage reactor is connected to the first-stage reactor, and the other end of the second-stage reactor is connected to a dynamic tubular reactor. The length of the first-stage reactor is 40 meters, and the length of the second-stage reactor is 160 meters.

[0010] Furthermore, the first stage reactor and the second stage reactor are respectively located in a first oil bath and a second oil bath, the temperature in the first oil bath is 230°C, and the temperature in the second oil bath is 265°C.

[0011] Furthermore, the first stage reactor includes a plurality of segmented reactors, and each segmented reactor is located in a separate first oil bath.

[0012] A method for using a continuous flow tubular reaction system to prepare polyphenylene sulfide comprises the following specific steps:

[0013] S1. First, sodium sulfide, sodium hydroxide and N-methylpyrrolidone are added into a reaction kettle, and the reaction kettle is heated to increase the temperature and dehydrate;

[0014] S2. When the temperature in the reactor rises to 202°C, take samples through the flow meter port, record the amount of water removed, and continue to increase the temperature and dehydrate;

[0015] S3. When the temperature in the reactor rises to 208-210°C, take samples through the flow meter port to detect the water content of the dewatered liquid. When the water content reaches below 2.0%, stop dehydration and press the material into the dehydration kettle;

[0016] S4, cool the material to between 130-150℃ by introducing cold oil through the cooling bypass pipe;

[0017] S5, after the dehydration kettle is cooled to 130-150°C, a mixed solution containing 3570g of p-dichlorobenzene and 3600g of N-methylpyrrolidone is added into the dehydration kettle, stirred for more than 30min, and kept warm at 130-150°C;

[0018] S6. Using a screw feed pump, the material is continuously fed into the microchannel reactor at a flow rate of 5.6 mL / min;

[0019] S7, the residence time of the material in the first stage reactor is 20 minutes, and the residence time of the material in the second stage reactor is 80 minutes;

[0020] S8, after the material flows out of the second stage reactor, it flows into the dynamic tubular reactor for cooling;

[0021] S9. After the material enters the receiving tank from the dynamic tubular reactor, the back pressure valve and the receiving tank are maintained at 0.5Mpa throughout the operation.

[0022] Through the above technical solution, the beneficial effects of the present invention are as follows:

[0023] (1) The present invention arranges a microchannel reactor and a dynamic tubular reactor after the dehydration kettle, so that the process of preparing polyphenylene sulfide can be carried out continuously. After passing through the microchannel reactor, the temperature of the material can be maintained at a temperature suitable for the reaction, which is more convenient for continuous preparation of polyphenylene sulfide. The dynamic tubular reactor also makes the preparation process more efficient and safe. The receiving tank and back pressure valve at the end of the system are also convenient for stably storing the prepared polyphenylene sulfide.

[0024] (2) The present invention provides a uniform and stable temperature environment by arranging oil baths in the first-stage reactor and the second-stage reactor. This is very necessary in the preparation process that requires precise temperature control. In addition, since the oil bath will not corrode most metal containers, it is a great advantage for experimental equipment that needs to be used for a long time, and it is also more convenient to prepare polyphenylene sulfide continuously for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0026] Figure numerals: 1. Reactor; 2. Dehydration kettle; 3. Distillation tower; 4. Flow meter port; 5. Water pump; 6. Cooling bypass pipe; 7. Screw feed pump; 8. Dynamic tubular reactor; 9. Receiving tank; 10. Back pressure valve; 11. First stage reactor; 12. Second stage reactor; 13. First oil bath; 14. Second oil bath. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] like Figure 1As shown, this embodiment provides a system for preparing polyphenylene sulfide by continuous flow tubular reaction, including a reactor 1 and a dehydration reactor 2. The top of the reactor 1 is connected to a distillation tower 3. The distillation tower 3 is a device for separating components in a mixture. The separation is performed based on the volatility difference between the components. The working principle of the distillation tower 3 is based on a cyclic process of partial vaporization and partial condensation. Through repeated gas-liquid contact, the light and heavy components in the mixture are separated. A flow meter port 4 is provided on the top of the reactor 1. The reactor 1 is connected to the dehydration reactor 2. A water pump 5 is provided between the reactor 1 and the dehydration reactor 2. The water pump 5 can extract the material in the reactor 1. A cooling bypass pipe 6 is connected between the water pump 5 and the dehydration reactor 2. The cooling bypass pipe 6 refers to a path that allows a fluid to bypass a part of the main cooling system. The purpose of this design is to reduce the time the fluid passes through the main cooler or completely avoid the main cooler in certain situations, such as the startup phase or specific working conditions, so as to quickly adjust the temperature of the system. Cold oil is arranged in the cooling bypass pipe 6. The normal temperature of the cold oil is 80-90°C. When the cold oil is overheated, it can be re-cooled to 80-90°C by the water in the washing water storage tank.

[0029] When the temperature in the reactor 1 reaches a specified value, it is necessary to detect the water content of the effluent. The most commonly used method is the Karl Fischer method, namely the KF method. The KF method is divided into the volumetric method and the coulometric method. Taking the volumetric method as an example, first accurately weigh a certain amount of the sample to be tested, and then place the sample in a titration bottle, add an appropriate amount of Karl Fischer reagent, and then use the Karl Fischer standard solution to titrate until a change in the color of the solution is observed or the potential indicator shows the end point. Finally, the water content in the sample is calculated based on the volume and concentration of the consumed standard solution, and the target ratio is less than 2%. The KF method is very suitable for measuring samples with low water content.

[0030] The bottom of the dehydration kettle 2 is connected to a screw feed pump 7. The screw feed pump 7, also known as a screw pump or a screw conveyor, is a commonly used positive displacement pump. It uses one or more screws to rotate in the pump body to convey fluids or dry bulk materials. The screw pump can provide a continuous and almost pulsation-free flow rate, which is suitable for applications that require stable conveying. The other end of the screw feed pump 7 is connected to a microchannel reactor. The total capacity of the microchannel reactor is 560ml. The other end of the microchannel reactor is connected to a dynamic tubular reactor 8. The microchannel reactor is divided into a first-stage reactor 11 and a second-stage reactor 12. The first-stage reactor 11 is connected to the screw feed pump 7, and the second-stage reactor 12 is connected to the first-stage reactor 11. The other end of the second-stage reactor 12 is connected to the dynamic tubular reactor 8. The length of the first-stage reactor 11 is 40 meters, and the length of the second-stage reactor 12 is 160 meters. The length of the second-stage reactor 12 is longer, so the material stays in the second-stage reactor 12 for a longer time, so most of the material can reach and remain at a temperature suitable for the reaction before entering the dynamic tubular reactor 8.

[0031] After the reactor 1 is cooled to 130-150°C, a mixed solution containing p-dichlorobenzene and N-methylpyrrolidone needs to be injected into the reactor 1. N-methylpyrrolidone is a polar aprotic solvent with excellent solubility and can dissolve a variety of organic and inorganic compounds. Therefore, it acts as a solvent in the mixed solution, while p-dichlorobenzene is used as a reactant. Since both N-methylpyrrolidone and p-dichlorobenzene are toxic to a certain extent, caution is required when adding and using them, and inhalation of their vapors or direct contact with the skin should be avoided.

[0032] The first-stage reactor 11 includes several segmented reactors, each of which is located in a separate first oil bath 13. The first-stage reactor 11 and the second-stage reactor 12 are respectively located in the first oil bath 13 and the second oil bath 14, providing a uniform and stable temperature environment, which is very necessary in the preparation process that requires precise temperature control. In addition, since the oil bath will not corrode most metal containers, it is a great advantage for experimental equipment that needs to be used for a long time, and it is also more convenient for the long-term continuous preparation of polyphenylene sulfide. The oil bath can reach a higher temperature than the water bath because the boiling point of oil is much higher than that of water, which means that the oil bath can be used in application scenarios that require high-temperature heating. The temperature in the first oil bath 13 is 230°C, and the temperature in the second oil bath 14 is 265°C. The first stage reactor 11 includes multiple segmented reactors, and the internal temperature of each first oil bath 13 is consistent. In general, the solution polymerization reaction for preparing polyphenylene sulfide is usually carried out between 175°C and 350°C. More specifically, the temperature range can be from 220°C to 225°C, or from 175°C to 250°C. In the present application, since the material needs to be cooled in the dynamic tubular reactor 8 after passing through the first stage reactor 11 and the second stage reactor 12, the temperature in the second oil bath needs to be slightly higher than the temperature for preparing polyphenylene sulfide.

[0033] A receiving tank 9 is installed on the dynamic tubular reactor 8. The dynamic tubular reactor 8 is also called a rotary cutting tubular reactor or a suspended tubular reactor. This type of reactor usually contains a special inner angle semi-axis or inner stirring shaft, which can generate a positive rotary cutting force. This structure can prevent the fluid from accumulating and clogging in the reactor. It is particularly suitable for treating viscous liquids or liquids containing suspended solids. They can reduce the back mixing phenomenon during the reaction process and provide better mass transfer and heat transfer performance than traditional kettle reactors. A back pressure valve 10 is provided on the top of the receiving tank 9. The back pressure valve 10 indicates 0.5Mpa. At the beginning, it needs to be replaced three times with nitrogen. In order to ensure the safety and purity of the pipeline or equipment, an inert gas, such as nitrogen, is used to replace the original gas or liquid. This replacement operation can reduce the risk of explosion or reaction and ensure the safety of subsequent operations. Then the back pressure valve 10 is adjusted to 0.5Mpa, and finally the feeding is started.

[0034] Before using nitrogen for replacement, it is necessary to close all valves connected to the receiving tank 9 to ensure that only the part to be replaced is isolated, and then perform the first replacement, open the nitrogen supply, and introduce nitrogen into the receiving tank 9 through the back pressure valve 10. Continue to introduce nitrogen for a period of time until the pressure in the receiving tank 9 is stable, then stop the gas supply, and then perform the second replacement, repeat the above steps, introduce nitrogen again, and finally perform the third nitrogen replacement to ensure that the gas or liquid inside the system has been completely replaced. After the last replacement, the exhaust gas at the outlet can be collected for analysis to ensure that it meets the safety standards.

[0035] Embodiment 1

[0036] A method for using a continuous flow tubular reaction system to prepare polyphenylene sulfide comprises the following specific steps:

[0037] S1, firstly, adding sodium sulfide, sodium hydroxide and N-methylpyrrolidone into the reaction kettle 1, and heating the reaction kettle 1 to increase the temperature and dehydrate it;

[0038] S2. When the temperature in the reactor 1 rises to 202°C, take a sample through the flow meter port 4, record the amount of water removed, and continue to increase the temperature and dehydrate;

[0039] S3, when the temperature in the reactor 1 rises to 208-210°C, sampling is performed through the flow meter port 4 to detect the water content of the dewatered liquid. When the water content reaches below 2.0%, dehydration is stopped and the material is pressed into the dehydration reactor 2;

[0040] S4, cooling the material to between 130-150°C by introducing cold oil through cooling bypass pipe 6;

[0041] S5, after the dehydration kettle 2 is cooled to 130-150°C, a mixed solution containing 3570g of p-dichlorobenzene and 3600g of N-methylpyrrolidone is added to the dehydration kettle 2, stirred for more than 30min, and kept warm at 130-150°C;

[0042] S6, using a screw feed pump 7, the material is continuously fed into the microchannel reactor at a flow rate of 5.6 mL / min;

[0043] S7, the residence time of the material in the first stage reactor 11 is 20 minutes, and the residence time of the material in the second stage reactor 12 is 80 minutes;

[0044] S8, after the material flows out of the second stage reactor 12, it flows into the dynamic tubular reactor 8 for cooling;

[0045] S9. After the material enters the receiving tank 9 from the dynamic tubular reactor 8, the back pressure valve 10 and the receiving tank 9 are kept at 0.5 MPa during the whole operation process.

[0046] Embodiment 2

[0047] A method for using a continuous flow tubular reaction system to prepare polyphenylene sulfide comprises the following specific steps:

[0048] S1, firstly, dichlorobenzene and sodium sulfide polyhydrate are added into the reaction kettle 1 as raw materials, alkali metal chloride is used as a catalyst, and N-methylpyrrolidone is used as a solvent, and the reaction kettle 1 is heated to increase the temperature and dehydrate;

[0049] S2. When the temperature in the reactor 1 rises to 202°C, take a sample through the flow meter port 4, record the amount of water removed, and continue to increase the temperature and dehydrate;

[0050] S3, when the temperature in the reactor 1 rises to 208-210°C, sampling is performed through the flow meter port 4 to detect the water content of the dewatered liquid. When the water content reaches below 2.0%, dehydration is stopped and the material is pressed into the dehydration reactor 2;

[0051] S4, cooling the material to between 130-150°C by introducing cold oil through cooling bypass pipe 6;

[0052] S5, after the dehydration kettle 2 is cooled to 130-150°C, a mixed solution containing 3570g of p-dichlorobenzene and 3600g of N-methylpyrrolidone is added to the dehydration kettle 2, stirred for more than 30min, and kept warm at 130-150°C;

[0053] S6, using a screw feed pump 7, the material is continuously fed into the microchannel reactor at a flow rate of 5.6 mL / min;

[0054] S7, the residence time of the material in the first stage reactor 11 is 20 minutes, and the residence time of the material in the second stage reactor 12 is 80 minutes;

[0055] S8, after the material flows out of the second stage reactor 12, it flows into the dynamic tubular reactor 8 for cooling;

[0056] S9. After the material enters the receiving tank 9 from the dynamic tubular reactor 8, the back pressure valve 10 and the receiving tank 9 are kept at 0.5 MPa during the whole operation process.

[0057] Embodiment 3

[0058] A method for using a continuous flow tubular reaction system to prepare polyphenylene sulfide comprises the following specific steps:

[0059] S1, firstly, adding sodium sulfide, sodium hydroxide and N-methylpyrrolidone into the reaction kettle 1, and heating the reaction kettle 1 to increase the temperature and dehydrate it;

[0060] S2. When the temperature in the reactor 1 rises to 202°C, take a sample through the flow meter port 4, record the amount of water removed, and continue to increase the temperature and dehydrate;

[0061] S3, when the temperature in the reactor 1 rises to 208-210°C, sampling is performed through the flow meter port 4 to detect the water content of the dewatered liquid. When the water content reaches below 2.0%, dehydration is stopped and the material is pressed into the dehydration reactor 2;

[0062] S4, cooling the material to between 140-170°C by introducing cooling oil through cooling bypass pipe 6;

[0063] S5, after the dehydration kettle 2 is cooled to 140-170°C, a mixed solution containing 3570g of p-dichlorobenzene and 3600g of N-methylpyrrolidone is added to the dehydration kettle 2, stirred for more than 30min, and kept warm at 130-150°C;

[0064] S6, using a screw feed pump 7, the material is continuously fed into the microchannel reactor at a flow rate of 5.6 mL / min;

[0065] S7, the residence time of the material in the first stage reactor 11 is 20 minutes, and the residence time of the material in the second stage reactor 12 is 80 minutes;

[0066] S8, after the material flows out of the second stage reactor 12, it flows into the dynamic tubular reactor 8 for cooling;

[0067] S9. After the material enters the receiving tank 9 from the dynamic tubular reactor 8, the back pressure valve 10 and the receiving tank 9 are kept at 0.5 MPa during the whole operation process.

[0068] Embodiment 4

[0069] A method for using a continuous flow tubular reaction system to prepare polyphenylene sulfide comprises the following specific steps:

[0070] S1, firstly, dichlorobenzene and sodium sulfide polyhydrate are added into the reaction kettle 1 as raw materials, alkali metal chloride is used as a catalyst, and N-methylpyrrolidone is used as a solvent, and the reaction kettle 1 is heated to increase the temperature and dehydrate;

[0071] S2. When the temperature in the reactor 1 rises to 202°C, take a sample through the flow meter port 4, record the amount of water removed, and continue to increase the temperature and dehydrate;

[0072] S3, when the temperature in the reactor 1 rises to 208-210°C, sampling is performed through the flow meter port 4 to detect the water content of the dewatered liquid. When the water content reaches below 2.0%, dehydration is stopped and the material is pressed into the dehydration reactor 2;

[0073] S4, cooling the material to between 140-170°C by introducing cooling oil through cooling bypass pipe 6;

[0074] S5, after the dehydration kettle 2 is cooled to 140-170°C, a mixed solution containing 3570g of p-dichlorobenzene and 3600g of N-methylpyrrolidone is added to the dehydration kettle 2, stirred for more than 30min, and kept warm at 130-150°C;

[0075] S6, using a screw feed pump 7, the material is continuously fed into the microchannel reactor at a flow rate of 5.6 mL / min;

[0076] S7, the residence time of the material in the first stage reactor 11 is 20 minutes, and the residence time of the material in the second stage reactor 12 is 80 minutes;

[0077] S8, after the material flows out of the second stage reactor 12, it flows into the dynamic tubular reactor 8 for cooling;

[0078] S9. After the material enters the receiving tank 9 from the dynamic tubular reactor 8, the back pressure valve 10 and the receiving tank 9 are kept at 0.5 MPa during the whole operation process.

[0079] Embodiment 5

[0080] A method for using a continuous flow tubular reaction system to prepare polyphenylene sulfide comprises the following specific steps:

[0081] S1, firstly, adding sodium sulfide, sodium hydroxide and N-methylpyrrolidone into the reaction kettle 1, and heating the reaction kettle 1 to increase the temperature and dehydrate it;

[0082] S2. When the temperature in the reactor 1 rises to 202°C, take a sample through the flow meter port 4, record the amount of water removed, and continue to increase the temperature and dehydrate;

[0083] S3, when the temperature in the reactor 1 rises to 208-210°C, sampling is performed through the flow meter port 4 to detect the water content of the dewatered liquid. When the water content reaches below 2.0%, dehydration is stopped and the material is pressed into the dehydration reactor 2;

[0084] S4, cooling the material to between 130-150°C by introducing cold oil through cooling bypass pipe 6;

[0085] S5, after the dehydration kettle 2 is cooled to 130-150°C, a mixed solution containing 4270g of p-dichlorobenzene and 4300g of N-methylpyrrolidone is added to the dehydration kettle 2, stirred for more than 30min, and kept warm at 130-150°C;

[0086] S6, using a screw feed pump 7, the material is continuously fed into the microchannel reactor at a flow rate of 5.6 mL / min;

[0087] S7, the residence time of the material in the first stage reactor 11 is 20 minutes, and the residence time of the material in the second stage reactor 12 is 80 minutes;

[0088] S8, after the material flows out of the second stage reactor 12, it flows into the dynamic tubular reactor 8 for cooling;

[0089] S9. After the material enters the receiving tank 9 from the dynamic tubular reactor 8, the back pressure valve 10 and the receiving tank 9 are kept at 0.5 MPa during the whole operation process.

[0090] Embodiment 6

[0091] A method for using a continuous flow tubular reaction system to prepare polyphenylene sulfide comprises the following specific steps:

[0092] S1, firstly, dichlorobenzene and sodium sulfide polyhydrate are added into the reaction kettle 1 as raw materials, alkali metal chloride is used as a catalyst, and N-methylpyrrolidone is used as a solvent, and the reaction kettle 1 is heated to increase the temperature and dehydrate;

[0093] S2. When the temperature in the reactor 1 rises to 202°C, take a sample through the flow meter port 4, record the amount of water removed, and continue to increase the temperature and dehydrate;

[0094] S3, when the temperature in the reactor 1 rises to 208-210°C, sampling is performed through the flow meter port 4 to detect the water content of the dewatered liquid. When the water content reaches below 2.0%, dehydration is stopped and the material is pressed into the dehydration reactor 2;

[0095] S4, cooling the material to between 130-150°C by introducing cold oil through cooling bypass pipe 6;

[0096] S5, after the dehydration kettle 2 is cooled to 130-150°C, a mixed solution containing 4270g of p-dichlorobenzene and 4300g of N-methylpyrrolidone is added to the dehydration kettle 2, stirred for more than 30min, and kept warm at 130-150°C;

[0097] S6, using a screw feed pump 7, the material is continuously fed into the microchannel reactor at a flow rate of 5.6 mL / min;

[0098] S7, the residence time of the material in the first stage reactor 11 is 20 minutes, and the residence time of the material in the second stage reactor 12 is 80 minutes;

[0099] S8, after the material flows out of the second stage reactor 12, it flows into the dynamic tubular reactor 8 for cooling;

[0100] S9. After the material enters the receiving tank 9 from the dynamic tubular reactor 8, the back pressure valve 10 and the receiving tank 9 are kept at 0.5 MPa during the whole operation process.

[0101] Embodiment 7

[0102] A method for using a continuous flow tubular reaction system to prepare polyphenylene sulfide comprises the following specific steps:

[0103] S1, firstly, adding sodium sulfide, sodium hydroxide and N-methylpyrrolidone into the reaction kettle 1, and heating the reaction kettle 1 to increase the temperature and dehydrate it;

[0104] S2. When the temperature in the reactor 1 rises to 202°C, take a sample through the flow meter port 4, record the amount of water removed, and continue to increase the temperature and dehydrate;

[0105] S3, when the temperature in the reactor 1 rises to 208-210°C, sampling is performed through the flow meter port 4 to detect the water content of the dewatered liquid. When the water content reaches below 2.0%, dehydration is stopped and the material is pressed into the dehydration reactor 2;

[0106] S4, cooling the material to between 140-170°C by introducing cooling oil through cooling bypass pipe 6;

[0107] S5, after the dehydration kettle 2 is cooled to 140-170°C, a mixed solution containing 4270g of p-dichlorobenzene and 4300g of N-methylpyrrolidone is added to the dehydration kettle 2, stirred for more than 30min, and kept warm at 130-150°C;

[0108] S6, using a screw feed pump 7, the material is continuously fed into the microchannel reactor at a flow rate of 5.6 mL / min;

[0109] S7, the residence time of the material in the first stage reactor 11 is 20 minutes, and the residence time of the material in the second stage reactor 12 is 80 minutes;

[0110] S8, after the material flows out of the second stage reactor 12, it flows into the dynamic tubular reactor 8 for cooling;

[0111] S9. After the material enters the receiving tank 9 from the dynamic tubular reactor 8, the back pressure valve 10 and the receiving tank 9 are kept at 0.5 MPa during the whole operation process.

[0112] Embodiment 8

[0113] A method for using a continuous flow tubular reaction system to prepare polyphenylene sulfide comprises the following specific steps:

[0114] S1, firstly, dichlorobenzene and sodium sulfide polyhydrate are added into the reaction kettle 1 as raw materials, alkali metal chloride is used as a catalyst, and N-methylpyrrolidone is used as a solvent, and the reaction kettle 1 is heated to increase the temperature and dehydrate;

[0115] S2. When the temperature in the reactor 1 rises to 202°C, take a sample through the flow meter port 4, record the amount of water removed, and continue to increase the temperature and dehydrate;

[0116] S3, when the temperature in the reactor 1 rises to 208-210°C, sampling is performed through the flow meter port 4 to detect the water content of the dewatered liquid. When the water content reaches below 2.0%, dehydration is stopped and the material is pressed into the dehydration reactor 2;

[0117] S4, cooling the material to between 140-170°C by introducing cooling oil through cooling bypass pipe 6;

[0118] S5, after the dehydration kettle 2 is cooled to 140-170°C, a mixed solution containing 4270g of p-dichlorobenzene and 4300g of N-methylpyrrolidone is added to the dehydration kettle 2, stirred for more than 30min, and kept warm at 130-150°C;

[0119] S6, using a screw feed pump 7, the material is continuously fed into the microchannel reactor at a flow rate of 5.6 mL / min;

[0120] S7, the residence time of the material in the first stage reactor 11 is 20 minutes, and the residence time of the material in the second stage reactor 12 is 80 minutes;

[0121] S8, after the material flows out of the second stage reactor 12, it flows into the dynamic tubular reactor 8 for cooling;

[0122] S9. After the material enters the receiving tank 9 from the dynamic tubular reactor 8, the back pressure valve 10 and the receiving tank 9 are kept at 0.5 MPa during the whole operation process.

[0123] Embodiment 9

[0124] A method for using a continuous flow tubular reaction system to prepare polyphenylene sulfide comprises the following specific steps:

[0125] S1, firstly, adding sodium sulfide, sodium hydroxide and N-methylpyrrolidone into the reaction kettle 1, and heating the reaction kettle 1 to increase the temperature and dehydrate it;

[0126] S2. When the temperature in the reactor 1 rises to 202°C, take a sample through the flow meter port 4, record the amount of water removed, and continue to increase the temperature and dehydrate;

[0127] S3, when the temperature in the reactor 1 rises to 208-210°C, sampling is performed through the flow meter port 4 to detect the water content of the dewatered liquid. When the water content reaches below 2.0%, dehydration is stopped and the material is pressed into the dehydration reactor 2;

[0128] S4, cooling the material to between 130-150°C by introducing cold oil through cooling bypass pipe 6;

[0129] S5, after the dehydration kettle 2 is cooled to 130-150°C, a mixed solution containing 3570g of p-dichlorobenzene and 3600g of N-methylpyrrolidone is added to the dehydration kettle 2, stirred for more than 30min, and kept warm at 120-130°C;

[0130] S6, using a screw feed pump 7, the material is continuously fed into the microchannel reactor at a flow rate of 5.6 mL / min;

[0131] S7, the residence time of the material in the first stage reactor 11 is 20 minutes, and the residence time of the material in the second stage reactor 12 is 80 minutes;

[0132] S8, after the material flows out of the second stage reactor 12, it flows into the dynamic tubular reactor 8 for cooling;

[0133] S9. After the material enters the receiving tank 9 from the dynamic tubular reactor 8, the back pressure valve 10 and the receiving tank 9 are kept at 0.5 MPa during the whole operation process.

[0134] Embodiment 10

[0135] A method for using a continuous flow tubular reaction system to prepare polyphenylene sulfide comprises the following specific steps:

[0136] S1, firstly, dichlorobenzene and sodium sulfide polyhydrate are added into the reaction kettle 1 as raw materials, alkali metal chloride is used as a catalyst, and N-methylpyrrolidone is used as a solvent, and the reaction kettle 1 is heated to increase the temperature and dehydrate;

[0137] S2. When the temperature in the reactor 1 rises to 202°C, take a sample through the flow meter port 4, record the amount of water removed, and continue to increase the temperature and dehydrate;

[0138] S3, when the temperature in the reactor 1 rises to 208-210°C, sampling is performed through the flow meter port 4 to detect the water content of the dewatered liquid. When the water content reaches below 2.0%, dehydration is stopped and the material is pressed into the dehydration reactor 2;

[0139] S4, cooling the material to between 130-150°C by introducing cold oil through cooling bypass pipe 6;

[0140] S5, after the dehydration kettle 2 is cooled to 130-150°C, a mixed solution containing 3570g of p-dichlorobenzene and 3600g of N-methylpyrrolidone is added to the dehydration kettle 2, stirred for more than 30min, and kept warm at 120-130°C;

[0141] S6, using a screw feed pump 7, the material is continuously fed into the microchannel reactor at a flow rate of 5.6 mL / min;

[0142] S7, the residence time of the material in the first stage reactor 11 is 20 minutes, and the residence time of the material in the second stage reactor 12 is 80 minutes;

[0143] S8, after the material flows out of the second stage reactor 12, it flows into the dynamic tubular reactor 8 for cooling;

[0144] S9. After the material enters the receiving tank 9 from the dynamic tubular reactor 8, the back pressure valve 10 and the receiving tank 9 are kept at 0.5 MPa during the whole operation process.

[0145] During the preparation of polyphenylene sulfide, sampling statistics need to be performed through the flow meter port every hour. The following table shows the statistical data of Example 1:

[0146]

[0147]

[0148] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention.

Claims

1. A system for preparing polyphenylene sulfide by continuous flow tubular reaction, comprising a reaction kettle (1) and a dehydration kettle (2), characterized in that: The top of the reactor (1) is connected to a distillation tower (3), the top of the reactor (1) is provided with a flow meter port (4), the reactor (1) is connected to a dehydration reactor (2), a water pump (5) is provided between the reactor (1) and the dehydration reactor (2), a cooling bypass pipe (6) is provided between the water pump (5) and the dehydration reactor (2), the bottom of the dehydration reactor (2) is connected to a screw feed pump (7), the other end of the screw feed pump (7) is connected to a microchannel reactor, the other end of the microchannel reactor is connected to a dynamic tubular reactor (8), a receiving tank (9) is installed on the dynamic tubular reactor (8), and a back pressure valve (10) is provided on the top of the receiving tank (9).

2. The system for preparing polyphenylene sulfide by continuous flow tubular reaction according to claim 1, characterized in that: The cooling bypass pipe (6) is provided with cold oil, and the normal temperature of the cold oil is 80-90°C.

3. The system for preparing polyphenylene sulfide by continuous flow tubular reaction according to claim 1, characterized in that: The total capacity of the microchannel reactor is 560 ml.

4. The system for preparing polyphenylene sulfide by continuous flow tubular reaction according to claim 3, characterized in that: The microchannel reactor is divided into a first-stage reactor (11) and a second-stage reactor (12). The first-stage reactor (11) is connected to a screw feed pump (7), and the second-stage reactor (12) is connected to the first-stage reactor (11). The other end of the second-stage reactor (12) is connected to a dynamic tubular reactor (8). The length of the first-stage reactor (11) is 40 meters, and the length of the second-stage reactor (12) is 160 meters.

5. The system for preparing polyphenylene sulfide by continuous flow tubular reaction according to claim 4, characterized in that: The first stage reactor (11) and the second stage reactor (12) are respectively located in a first oil bath (13) and a second oil bath (14). The temperature in the first oil bath (13) is 230°C, and the temperature in the second oil bath (14) is 265°C.

6. The system for preparing polyphenylene sulfide by continuous flow tubular reaction according to claim 4, characterized in that: The first stage reactor (11) comprises a plurality of segmented reactors, each of which is located in a separate first oil bath (13).

7. The system for preparing polyphenylene sulfide by continuous flow tubular reaction according to claim 1, characterized in that: The back pressure valve (10) indicates 0.5 MPa.

8. The method for using a continuous flow tubular reaction system for preparing polyphenylene sulfide according to any one of claims 1 to 7, characterized in that: The specific steps include: S1. First, sodium sulfide, sodium hydroxide and N-methylpyrrolidone are added into a reaction kettle (1), and the reaction kettle (1) is heated to increase the temperature and dehydrate; S2. When the temperature inside the reactor (1) rises to 202°C, take a sample through the flow meter port (4), record the amount of water removed, and continue to increase the temperature to remove water; S3, when the temperature in the reactor (1) rises to 208-210°C, sampling is performed through the flow meter port (4) to detect the water content of the dewatered liquid. When the water content reaches below 2.0%, dehydration is stopped and the material is pressed into the dehydration reactor (2); S4, cooling the material to between 130-150°C by introducing cooling oil through the cooling bypass pipe (6); S5, after the dehydration kettle (2) is cooled to 130-150°C, a mixed solution containing 3570g of p-dichlorobenzene and 3600g of N-methylpyrrolidone is added to the dehydration kettle (2), stirred for more than 30 minutes, and kept warm at 130-150°C; S6, using a screw feed pump (7), the material is continuously fed into the microchannel reactor at a flow rate of 5.6 mL / min; S7, the residence time of the material in the first stage reactor (11) is 20 minutes, and the residence time of the material in the second stage reactor (12) is 80 minutes; S8, after the material flows out of the second stage reactor (12), it flows into the dynamic tubular reactor (8) for cooling; S9. After the material enters the receiving tank (9) from the dynamic tubular reactor (8), the back pressure valve (10) and the receiving tank (9) are kept at 0.5 MPa throughout the operation.

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