Synthesis method of low-chlorine polyphenylene sulfide nitrile

Abstract

The invention relates to the technical field of high polymer materials, and discloses a synthesis method of low-chlorine polyphenylene sulfide nitrile, which comprises the following steps: carrying out pressurized prepolymerization reaction on a sodium sulfide solution and p-dichlorobenzene to obtain a first prepolymerization reaction product; carrying out copolymerization prepolymerization reaction on the first prepolymerization reaction product and 2, 6-dichlorobenzonitrile to obtain a second prepolymerization reaction product; carrying out heating polymerization reaction on the second prepolymerization reaction product and benzyl chloride to obtain a heating polymerization reaction product; and raising the temperature of the polymerization reaction product, and carrying out phase separation to obtain the low-chlorine polyphenylene sulfide nitrile. Under the condition of no auxiliary agent, the polymerization process of inert gas pressurization and phase separation is adopted, benzyl chloride is applied to adjust the end group, low-chlorine high-molecular-weight polyphenylene sulfide nitrile can be obtained in a short time, the production efficiency of synthesizing polyphenylene sulfide nitrile can be improved, the purification process of byproduct sodium chloride is shortened, auxiliary agent recovery is omitted, and the production cost is reduced. The engineering construction investment is reduced, and the production cost for manufacturing the polyphenylene sulfide nitrile is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, in particular to a method for synthesizing low-chlorine polyphenylene sulfide nitrile. Background Art

[0002] Polyphenylene sulfide (PPS) has the characteristics of excellent high temperature resistance, corrosion resistance, radiation resistance, self-flaming retardancy, balanced physical and mechanical properties, excellent dimensional stability and excellent electrical properties. The melting point of PPS is 285℃, the glass transition temperature is 92℃, and the heat deformation temperature after reinforcement is generally greater than 260℃. It can be used in the temperature range of 180-220℃. It is one of the best heat-resistant varieties of engineering plastics. The corrosion resistance of PPS is close to that of tetrafluoroethylene, and its chemical resistance is second only to polytetrafluoroethylene; currently only chloronaphthalene can dissolve PPS above 175℃. PPS has high strength and modulus, good rigidity, and the parts have a metallic texture. It is widely used as a structural polymer material. PPS itself has good flame retardancy, and the flame retardant grade of pure resin can reach V-0 / 5VA. At the same time, it can also be made into various functional films, coatings and composite materials, which have been successfully applied in the fields of electronics, military industry, aerospace, automobile transportation, etc.

[0003] Polyphenylene sulfide nitrile is a product obtained by introducing a cyano group into the molecular chain of polyphenylene sulfide (PPS for short). When preparing traditional polyphenylene sulfide, the reaction activity of p-dichlorobenzene is not high, and oligomers are easily precipitated from the solvent, resulting in a wide molecular weight distribution and the production of more oligomers. Polyphenylene sulfide can be improved by chemical modification to improve the synthesis activity and performance of polyphenylene sulfide. For example, the invention patents with publication numbers of US4894434A, JPH0267321A and CN102382304A use 2,6-dichlorobenzonitrile or 2,6-difluorobenzonitrile to react with sodium sulfide in a polar solvent to prepare polybenzonitrile sulfide. Although the reaction activity is high, due to the high cyano content and symmetrical molecular structure, it is easier to crystallize during the reaction, which has an adverse effect on the synthesis. In order to improve the solubility of the reaction product, the Chinese invention patent with publication number CN108384008A uses 4,4'-dichlorodiphenyl sulfone, 2,6-dichlorobenzonitrile and p-dichlorobenzene to react with sodium sulfide in a polar solvent to prepare cyano-containing polyphenylene sulfide sulfone. Although the introduction of sulfone groups improves the solubility, the introduction of sulfone groups reduces the chemical resistance of polyphenylene sulfide.

[0004] At present, in order to obtain high molecular weight polyphenylene sulfide nitrile in a short time, it is often necessary to add acetate additives, which increases the difficulty of purifying the byproduct sodium chloride salt, recovering the additives and NMP, and leads to an increase in the cost of manufacturing polyphenylene sulfide nitrile. In the prior art, Chinese invention patent CN115975195A discloses a polyphenylene sulfide nitrile and a production method thereof, wherein acetate is added during the preparation of polyphenylene sulfide nitrile, and the byproduct sodium chloride produced during the synthesis of acetate and polyphenylene sulfide nitrile enters the NMP solvent recovery system. After the NMP solvent is recovered, the solid residual sodium chloride and acetate mixture are difficult to separate and will be identified as hazardous waste; and filtered for multiple washings, a large amount of saline wastewater will be generated, and the saline wastewater needs to be concentrated and evaporated in industry, which has high energy consumption and will also produce a mixture of sodium chloride and acetate that is difficult to separate. At the same time, because the molar number of dichloroaromatic reaction monomers is excessive compared to sodium sulfide, the terminal residual chlorine of polyphenylene sulfide nitrile is high, and it is difficult to meet the industry's halogen content standard within 1000ppm.

[0005] Therefore, it is urgent to develop a synthesis method of low-chlorine polyphenylene sulfide nitrile to solve the above technical problems. Summary of the invention

[0006] The present invention aims to overcome the existing technical problems and provide a method for synthesizing low-chlorine polyphenylene sulfide nitrile by inert gas pressurization without auxiliary agent.

[0007] To achieve the above object, the present invention is implemented according to the following technical solutions:

[0008] A method for synthesizing low-chlorine polyphenylene sulfide nitrile comprises the following steps:

[0009] A sodium sulfide solution and p-dichlorobenzene are subjected to a pressurized prepolymerization reaction under an inert gas protective atmosphere of 0.1-1 MPa to obtain a first prepolymerization reaction product; the first prepolymerization reaction product is subjected to a copolymerization prepolymerization reaction with 2,6-dichlorobenzonitrile to obtain a second prepolymerization reaction product; the second prepolymerization reaction product is subjected to a temperature-raising polymerization reaction with benzyl chloride to obtain a temperature-raising polymerization reaction product; and a phase separation agent is added to the temperature-raising polymerization reaction product to perform phase separation to obtain low-chlorine polyphenylene sulfide nitrile.

[0010] Preferably, the preparation process of the sodium sulfide solution is as follows: sodium hydrosulfide and sodium hydroxide are reacted in a solvent, then NMP (N-methylpyrrolidone) is added, and part of the solvent is removed after heating to obtain a sodium sulfide solution.

[0011] Preferably, the molar ratio of sodium hydrosulfide, sodium hydroxide and NMP is 1:(1-1.1):(2-8); the solvent is water; the temperature of the reaction and solvent removal process is 200-220° C. and the time is 2-3.5 hours.

[0012] Further preferably, in the sodium sulfide solution, 2 to 3.5 mol of water remain per 1 mol of sodium sulfide; the residual water in the sodium sulfide solution includes crystal water and free water.

[0013] Further preferably, in the process of preparing the sodium sulfide solution, the temperature reaction is carried out in an inert gas atmosphere with a gas pressure of 0.1 MPa; specifically, the reactor is replaced with an inert gas, and after the replacement is completed, the raw materials for preparing the sodium sulfide solution are added at 0.1 MPa.

[0014] More preferably, sodium hydrosulfide and sodium hydroxide are prepared in the form of sodium hydrosulfide aqueous solution and sodium hydroxide aqueous solution.

[0015] More preferably, the concentration of the sodium hydrosulfide aqueous solution is 45-47 wt %, and the concentration of the sodium hydroxide aqueous solution is 40-50 wt %.

[0016] During the preparation of the sodium sulfide solution, the solvent is removed, and part of the NMP is distilled out during the removal process. Therefore, the NMP distilled out during the preparation of the sodium sulfide solution will be supplemented in the subsequent pressurized prepolymerization process.

[0017] Preferably, the ratio of the molar amount of sodium sulfide in the sodium sulfide solution to the sum of the molar amounts of p-dichlorobenzene and 2,6-dichlorobenzonitrile is 1:(1-1.03) (molar amount of sodium sulfide: sum of the molar amounts of p-dichlorobenzene and 2,6-dichlorobenzonitrile); the molar ratio of p-dichlorobenzene to 2,6-dichlorobenzonitrile is 1:(0.1-0.3); the molar ratio of sodium sulfide to benzyl chloride in the sodium sulfide solution is 1:(0.01-0.03).

[0018] Preferably, the pressurized prepolymerization reaction is carried out under an inert gas protective atmosphere; the pressure of the inert gas is 0.1-1 MPa.

[0019] Further preferably, the pressure of the inert gas is 0.3-0.5 MPa.

[0020] Preferably, the inert gas is any one of nitrogen, helium and argon.

[0021] Preferably, the reaction temperature of the pressurized prepolymerization reaction is 200-230° C., and the reaction time is 1-3 hours.

[0022] Specifically, the process of the pressurized prepolymerization reaction is as follows: in a high-pressure reactor, under an inert gas protective atmosphere of 0.1 to 1 MPa, p-dichlorobenzene is added to a sodium sulfide solution and mixed, and a prepolymerization reaction is carried out at a temperature of 200 to 230° C. to obtain a first prepolymerization reaction product.

[0023] Before the pressurized prepolymerization reaction, p-dichlorobenzene is heated and melted into a liquid to obtain a p-dichlorobenzene melt; the p-dichlorobenzene melt is added dropwise to the sodium sulfide solution in the high-pressure reactor; at this time, the NMP distilled out in the dehydration stage can also be replenished.

[0024] Preferably, the reaction temperature of the copolymerization prepolymerization reaction is 200-230° C., and the reaction time is 20-30 min.

[0025] Specifically, the copolymerization prepolymerization process is as follows: 2,6-dichlorobenzonitrile is pressed into the first prepolymerization product, and the copolymerization prepolymerization reaction is carried out at 200-230° C. to obtain a second prepolymerization product. When used, 2,6-dichlorobenzonitrile can be first dissolved in NMP, and then a mixture of 2,6-dichlorobenzonitrile and NMP is added to the reaction system for reaction.

[0026] Preferably, the reaction temperature of the temperature-raising polymerization reaction is 260-280° C., and the reaction time is 1-3 hours.

[0027] Specifically, the process of the temperature-raising polymerization reaction is as follows: benzyl chloride is pressed into the second prepolymerization reaction product, and the temperature-raising polymerization is carried out at 260-280° C. to obtain a temperature-raising polymerization reaction product.

[0028] Preferably, the phase separation process is: adding a phase separation agent to the heated polymerization reaction product, and then performing phase separation at a temperature of 250 to 260° C. for a phase separation time of 0.1 to 1 h; after the phase separation is completed, cooling and solid-liquid separation are performed to obtain low-chlorine polyphenylene sulfide nitrile.

[0029] Preferably, the phase separation agent is water, and the molar ratio of the phase separation agent to the sodium sulfide in the sodium sulfide solution is (2-6):1.

[0030] Specifically, the pressure prepolymerization reaction, copolymerization prepolymerization reaction, temperature-raising polymerization reaction, and phase separation are all carried out in the same high-pressure reactor under an inert gas protective atmosphere.

[0031] Preferably, the chlorine content of the low-chlorine polyphenylene sulfide nitrile prepared by the present invention is within 1000 ppm.

[0032] Working principle:

[0033] The present invention takes sodium hydrosulfide, sodium hydroxide and NMP and adds them to a solvent to heat up to obtain a sodium sulfide solution; in a high-pressure reactor, under an inert gas protection atmosphere of 0.1 to 1Mpa, p-dichlorobenzene is added to the sodium sulfide solution and mixed, and a prepolymerization reaction is carried out at a certain temperature to obtain a first prepolymerization reaction product; 2,6-dichlorobenzonitrile is pressed into the first prepolymerization reaction product, and a copolymerization prepolymerization reaction is carried out at a certain temperature to obtain a second prepolymerization reaction product. Benzyl chloride is pressed into the second prepolymerization reaction product, and the prepolymerization reaction product is subjected to temperature-raising polymerization at a certain temperature to obtain a temperature-raising polymerization reaction product; a phase separation agent is added to the temperature-raising polymerization reaction product, and then phase separation is carried out at a certain temperature to obtain polyphenylene sulfide nitrile. The present invention is based on adjusting the molecular weight with benzyl chloride, pressurizing polymerization, and adding a phase separation agent for phase separation. Under the condition of no auxiliary agent, a high molecular weight low-chlorine polyphenylene sulfide nitrile product can be prepared in a short time. The polyphenylene sulfide nitrile product of the present invention has the characteristics of large average particle size, low melt mass flow rate, and low chlorine content.

[0034] The method of the present invention is based on pressurized polymerization and phase separation polymerization with the addition of a phase separation agent. Inert gas pressurization can reduce the gasification of the reaction materials, so that the reaction materials undergo liquid phase polycondensation, and the time for the reaction materials to be converted into polyphenylene sulfide nitrile is shortened; after the phase separation agent is added, the reaction system is converted into two phases, namely, a polyphenylene sulfide nitrile concentrated phase and a polyphenylene sulfide nitrile NMP solution dilute phase. The polyphenylene sulfide nitrile concentrated phase can quickly grow into a high molecular weight polyphenylene sulfide nitrile, and a high molecular weight polyphenylene sulfide nitrile product can be prepared in a short time. The polyphenylene sulfide nitrile product has the characteristics of large average particle size and suitable molecular weight. At the same time, before polymerization at 260 to 280° C. (heating polymerization process), benzyl chloride is pressed into the reaction system. Benzyl chloride is a monofunctional reaction monomer, which can adjust the molecular weight of polyphenylene sulfide nitrile and the chlorine content of the molecular chain end group, and takes into account the good fluidity and low chlorine characteristics of polyphenylene sulfide nitrile.

[0035] The low-chlorine polyphenylene sulfide nitrile prepared by the invention has high molecular weight, excellent heat resistance and mechanical properties, can be used as special engineering plastics, and is widely used in multiple fields such as reinforced materials, composite materials, flame retardant materials, functional films, special fiber materials, etc.

[0036] Beneficial effects:

[0037] The invention adopts an inert gas pressurization and phase separation polymerization process under the condition of no auxiliary agent, and uses benzyl chloride to adjust the end group, so that low-chlorine high-molecular-weight polyphenylene sulfide nitrile can be obtained in a short time, the production efficiency of synthesizing polyphenylene sulfide nitrile can be improved, the by-product sodium chloride purification process can be shortened, the auxiliary agent recovery is omitted, the engineering construction investment is reduced, and the production cost of manufacturing polyphenylene sulfide nitrile is greatly reduced; the polyphenylene sulfide nitrile prepared by the method of the invention has a better average particle size and melt flow rate, can better adapt to the requirements of the post-processing process, and can improve the reliability and quality of product molding. DETAILED DESCRIPTION

[0038] The present invention is further described below with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0039] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0040] There is no particular limitation on the purity of all raw materials in the present invention, and the present invention preferably adopts the conventional purity used in the art.

[0041] The devices used in the present invention are not particularly limited and can be any of the commonly used devices in the art.

[0042] Example 1

[0043] A method for synthesizing low-chlorine polyphenylene sulfide nitrile comprises the following steps:

[0044] 1) First, 1.698 kg of 48 wt% sodium hydroxide aqueous solution and 2.206 kg of 47 wt% sodium hydrosulfide aqueous solution were added to a dehydration kettle, reacted at room temperature for 10 min to generate sodium sulfide, and then 6.000 kg of NMP was added. Under the protection of a nitrogen atmosphere, the temperature was gradually raised to 220° C. to remove water from the system. It took 3 hours to distill out 1.63 kg of water and 0.92 kg of NMP to obtain a sodium sulfide solution.

[0045] 2) 2.450 kg of p-dichlorobenzene was placed in a melting kettle, heated and melted into a liquid to obtain a p-dichlorobenzene melt; in a high-pressure reactor, the temperature of the sodium sulfide solution was lowered to 170°C, and then the p-dichlorobenzene melt was added dropwise to the high-pressure reactor over 0.1 h, and 0.92 kg of NMP distilled out in the dehydration stage was replenished.

[0046] 3) Fill the autoclave with 0.3MPa of nitrogen (based on the pressure gauge reading, when the pressure gauge reading is 0, it is expressed as atmospheric pressure), heat up to 220-230°C for prepolymerization reaction for 2h, then use a high-pressure pump to press in 0.319Kg of 2,6-dichlorobenzonitrile, 2,6-dichlorobenzonitrile is dissolved with 1.0Kg of NMP, and react for 20min (reaction temperature is 220-230°C); then press in 23.4g of benzyl chloride, heat up to 260-270°C for reaction for 2h, finally inject 800g of water into the autoclave, and phase separate and react at 250-255°C for 1h; cool the reaction system, and separate the solid and liquid to obtain polyphenylene sulfide nitrile powder and pellets.

[0047] Example 2

[0048] Compared with Example 1, the present embodiment is different in that: in step 3), 0.1 MPa of nitrogen is charged into the autoclave (based on the pressure gauge reading, when the pressure gauge reading is 0, it indicates atmospheric pressure).

[0049] Example 3

[0050] The difference between this embodiment and embodiment 1 is that in step 3), the amount of water injected is 700 g.

[0051] Comparative Example 1

[0052] Compared with Example 1, the difference between this comparative example and Example 1 is that: in step 3), the high-pressure reactor is replaced with nitrogen (the pressure gauge reading is 0), the temperature is raised to 220-230° C. for prepolymerization reaction for 2 hours, then the temperature is raised to 260-270° C. for reaction for 2 hours, and finally 800 g of water is injected into the high-pressure reactor, and the phase separation reaction is carried out at 250-255° C. for 1 hour; the reaction system is cooled, and the solid-liquid separation is performed to obtain polyphenylene sulfide nitrile powder and pellets.

[0053] Comparative Example 2

[0054] Compared with Example 1, the difference between this comparative example and Example 1 is that: in step 3), the high-pressure reactor is replaced with nitrogen (the pressure gauge reading is 0), the temperature is raised to 220-230°C for prepolymerization reaction for 2 hours, then the temperature is raised to 260-270°C for reaction for 2 hours, and finally the temperature is raised to 250-255°C for reaction for 1 hour; the reaction system is cooled, and the solid-liquid separation is performed to obtain polyphenylene sulfide nitrile powder and pellets.

[0055] Comparative Example 3

[0056] The difference between this comparative example and Example 1 is that in step 3), benzyl chloride is not pressed into the mixture.

[0057] Comparative Example 4

[0058] Compared with Example 1, the difference between this comparative example and Example 1 is that: in step 3), the temperature is raised to 220-230° C. for prepolymerization reaction for 2 hours, then the temperature is raised to 260-270° C. for reaction for 0.5 hours, and finally 800 g of water is injected into the high-pressure reactor, and the phase separation reaction is carried out at 250-255° C. for 0.3 hours; the reaction system is cooled, and the solid-liquid separation is performed to obtain polyphenylene sulfide nitrile powder and pellets.

[0059] The properties of the finished polyphenylene sulfide nitrile products obtained in Examples 1-3 and Comparative Examples 1-4 were tested.

[0060] 1. Based on GBT 15445.2-2006 "Presentation of particle size analysis results Part 2: Calculation of average particle size / diameter and moments from particle size distribution", the average particle size of polyphenylene sulfide nitrile finished products was tested.

[0061] 2. Based on GBT3682-2000 "Melt Mass Flow Rate", the melt mass flow rate of polyphenylene sulfide nitrile finished product at 315°C and 5kg was tested.

[0062] 3. High temperature GPC, using α-chloronaphthalene as solvent and testing temperature at 200°C, detects the weight average molecular weight and molecular weight distribution of polyphenylene sulfide nitrile.

[0063] 4. Based on BSEN 14582-2007 "Combustion characteristics and determination methods of halogen and sulfur content in closed systems", the chlorine content of polyphenylene sulfide nitrile is tested.

[0064] Test results:

[0065] The average particle size, melt mass flow rate, chlorine content and yield of the finished polyphenylene sulfide nitrile products of Examples 1-3 and Comparative Examples 1-4 are shown in Table 1.

[0066] Table 1

[0067]

[0068]

[0069] As can be seen from Table 1, compared with Comparative Example 1, the polyphenylene sulfide nitrile in Examples 1-3 has a larger average particle size and a lower melt flow rate, which indicates that inert gas pressurization during the polymerization of polyphenylene sulfide nitrile is conducive to obtaining a polyphenylene sulfide nitrile product with a higher molecular weight; compared with Comparative Example 2, the polyphenylene sulfide nitrile in Examples 1-3 has a larger average particle size and a lower melt flow rate, which indicates that adding water to polyphenylene sulfide nitrile after the polymerization is completed can promote the phase separation of polyphenylene sulfide nitrile and obtain high molecular weight polyphenylene sulfide nitrile in a short time; from Comparative Examples 1 and 2, the polyphenylene sulfide nitrile The average particle size and melt mass flow rate results of the product show that the effect of adding water during the phase separation process on the polyphenylene sulfide nitrile product is greater than the effect of inert gas pressurization during the polymerization process on the performance of the polyphenylene sulfide nitrile product; compared with Example 1, even if the reaction time is shortened, Example 3 can obtain high molecular weight polyphenylene sulfide nitrile by shortening the reaction time; compared with Examples 1 to 3 and Examples 1, 2, and 4, benzyl chloride can adjust the content of molecular chain chlorine in Example 3; compared with Example 1, benzyl chloride can adjust the molecular weight in Example 3 to obtain polyphenylene sulfide nitrile with better fluidity. In the process of preparing polyphenylene sulfide nitrile products, pressurized polymerization and adding water for phase separation work together to improve the average particle size and melt mass flow rate of the prepared polyphenylene sulfide nitrile product, and high molecular weight polyphenylene sulfide nitrile can be obtained in a short time.

[0070] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. All technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for synthesizing low-chlorine polyphenylene sulfide nitrile, characterized in that: The following steps are involved: A sodium sulfide solution and p-dichlorobenzene are subjected to a pressurized prepolymerization reaction under an inert gas protective atmosphere of 0.1-1 MPa to obtain a first prepolymerization reaction product; the first prepolymerization reaction product is subjected to a copolymerization prepolymerization reaction with 2,6-dichlorobenzonitrile to obtain a second prepolymerization reaction product; the second prepolymerization reaction product is subjected to a temperature-raising polymerization reaction with benzyl chloride to obtain a temperature-raising polymerization reaction product; and a phase separation agent is added to the temperature-raising polymerization reaction product to perform phase separation to obtain low-chlorine polyphenylene sulfide nitrile.

2. The method for synthesizing low-chlorine polyphenylene sulfide nitrile according to claim 1, characterized in that: The preparation process of sodium sulfide solution is as follows: sodium hydrosulfide and sodium hydroxide react in a solvent, then NMP is added, and part of the solvent is removed after heating to obtain a sodium sulfide solution.

3. The method for synthesizing low-chlorine polyphenylene sulfide nitrile according to claim 2, characterized in that: The molar ratio of sodium hydrosulfide, sodium hydroxide and NMP is 1:(1-1.1):(2-8); the solvent is water; the temperature of the reaction and solvent removal process is 200-220° C. and the time is 2-3.5 hours.

4. The method for synthesizing low-chlorine polyphenylene sulfide nitrile according to claim 1, characterized in that: The ratio of the molar amount of sodium sulfide in the sodium sulfide solution to the sum of the molar amounts of p-dichlorobenzene and 2,6-dichlorobenzonitrile is 1:(1-1.03); the molar ratio of p-dichlorobenzene to 2,6-dichlorobenzonitrile is 1:(0.1-0.3); and the molar ratio of sodium sulfide to benzyl chloride in the sodium sulfide solution is 1:(0.01-0.03).

5. The method for synthesizing low-chlorine polyphenylene sulfide nitrile according to claim 1, characterized in that: The inert gas is any one of nitrogen, helium and argon.

6. The method for synthesizing low-chlorine polyphenylene sulfide nitrile according to claim 1, characterized in that: The reaction temperature of the pressurized prepolymerization reaction is 200-230° C. and the reaction time is 1-3 hours.

7. The method for synthesizing low-chlorine polyphenylene sulfide nitrile according to claim 1, characterized in that: The reaction temperature of the copolymerization prepolymerization reaction is 200-230° C., and the reaction time is 20-30 minutes.

8. The method for synthesizing low-chlorine polyphenylene sulfide nitrile according to claim 1, characterized in that: The reaction temperature of the temperature-raising polymerization reaction is 260-280° C., and the reaction time is 1-3 hours.

9. The method for synthesizing low-chlorine polyphenylene sulfide nitrile according to claim 1, characterized in that: The phase separation process is as follows: adding a phase separation agent to the heated polymerization reaction product, and then performing phase separation at a temperature of 250-260° C. for a phase separation time of 0.1-1 h; cooling after the phase separation is completed, and performing solid-liquid separation to obtain low-chlorine polyphenylene sulfide nitrile.

10. The method for synthesizing low-chlorine polyphenylene sulfide nitrile according to claim 9, characterized in that: The phase separation agent is water, and the molar ratio of the phase separation agent to the sodium sulfide in the sodium sulfide solution is (2-6):1.

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