A low-ion-precipitation polyphenylene sulfide composite material, its preparation method and application

Abstract

This invention provides a low-ion-emission polyphenylene sulfide composite material, its preparation method, and its applications, belonging to the field of polymer composite material technology. By weight, it comprises 60-80 parts of modified PPS resin, 15-30 parts of low-ion reinforcing filler, 0.5-3 parts of ion scavenger, 0.3-1.5 parts of composite stabilizer, and 0.2-1 parts of processing aid. The ion scavenger is a compound of fluorosilicic acid or its derivatives and sodium silicate in a mass ratio of 3-5:1. The modified PPS resin is prepared using a two-stage polymerization process catalyzed by caprolactone and lithium acetate. A purification process involving the directional conversion of free ions through the fluorosilicic acid system reduces the sodium ion content of the resin to 80 ppm, significantly reducing the ion emission rate while maintaining the original excellent properties of the PPS material. It can be widely used in precision instruments, electronic packaging, and aerospace fields.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, specifically relating to a low-ion-emission polyphenylene sulfide composite material, its preparation method, and its application. Background Technology

[0002] Polyphenylene sulfide (PPS) is a semi-crystalline thermoplastic engineering plastic with an alternating benzene ring and sulfur atom main chain structure. It has excellent properties such as high temperature resistance, chemical corrosion resistance, flame retardancy, and good dimensional stability, and is widely used in the electronics, automotive and aerospace industries.

[0003] However, the industrial synthesis of PPS typically involves nucleophilic polymerization of sodium sulfide with p-dichlorobenzene in a polar solvent (such as N-methylpyrrolidone, NMP). This reaction inevitably produces a large amount of NaCl as a byproduct and introduces Na+ into the system. + Li + Residual metal ions. Traditional single-stage polymerization processes are carried out at high temperatures (usually above 220°C), and the rapid cross-linking of molecular chains easily leads to the embedding of salt byproducts such as NaCl in the resin matrix. Subsequent washing is difficult to completely remove them, resulting in the sodium ion content of PPS resin typically reaching 200~500ppm, and the lithium ion content can also reach more than 30ppm.

[0004] Existing post-treatment processes mostly use multi-stage water washing to remove residual ions from the resin, which usually requires more than 5 water washing operations. This not only consumes a lot of water and is cumbersome, but also has limited washing effect. Furthermore, there is a risk of secondary ion adsorption during the water washing process, making it difficult to reduce the ion content of the finished resin to a level that meets the requirements of high-cleanliness applications.

[0005] In the preparation of composite materials, the total metal ion content of conventional reinforcing fillers (such as ordinary glass fiber) can reach more than 180 ppm. The metal ions remaining on their surface will continue to be released into the environment during the use of the material, further aggravating the ion release problem of composite materials.

[0006] The aforementioned ion precipitation problem is particularly prominent in applications highly sensitive to ion cleanliness, such as structural components of new energy battery modules, high-voltage connectors, and automotive motor insulation frames. Excessive ion precipitation can not only trigger electrochemical corrosion but also lead to a decrease in circuit insulation performance and even affect battery safety and lifespan.

[0007] Therefore, there is a lack of complete technical solutions in the existing technology that can systematically solve the problems of high ion residue and large precipitation of PPS resin and its composite materials. There is an urgent need to develop a low-ion precipitation polyphenylene sulfide composite material and its matching preparation process. Summary of the Invention

[0008] The purpose of this invention is to overcome the defects of high ion residue and large precipitation in existing PPS materials and to fill the technological gap in the field of low ion precipitation of modified composite materials. It provides a low ion precipitation polyphenylene sulfide composite material and its preparation method. Through the synergistic effect of polymerization process optimization, directional purification and composite modification, the content of key ions in the material is reduced to below 50 ppm, significantly reducing the ion precipitation rate, while maintaining the original excellent performance of PPS materials.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a low-ion precipitation polyphenylene sulfide composite material, comprising the following components by weight: 60-80 parts of modified PPS resin, 15-30 parts of low-ion reinforcing filler, 0.5-3 parts of ion scavenger, 0.3-1.5 parts of composite stabilizer, and 0.2-1 parts of processing aid.

[0010] Preferably, the modified PPS resin has a sodium ion content ≤80ppm and a lithium ion content ≤10ppm; more preferably, the sodium ion content ≤30ppm.

[0011] Preferably, the low-ion reinforcing filler is plasma-treated glass fiber or carbon fiber with a total metal ion content ≤50ppm. Plasma treatment can clean residual ionic impurities on the fiber surface while activating functional groups on the fiber surface, improving the interfacial bonding with the PPS matrix, and controlling the amount of ion introduction at the filler end from the source.

[0012] Preferably, the ion scavenging agent is a compound of fluorosilicic acid or its derivatives and sodium silicate, with a mass ratio of 3 to 5:1. For example, it can be 3:1, 4:1, or 5:1, where fluorosilicic acid or its derivatives are mixed with free metal cations (such as Na+). + Li + Under specific pH conditions, sodium silicate can generate insoluble fluorosilicate crystals, thereby solidifying and locking free ions in the insoluble salt phase and inhibiting their migration and precipitation into the external environment of the matrix. The functions of sodium silicate are: firstly, to precisely adjust the pH of the system to a weakly acidic range of 2.5~3.5, providing the optimal acid-base environment for the precipitation reaction of fluorosilicic acid or its derivatives with metal cations, avoiding the hydrolysis and inactivation of fluorosilicate ions, and ensuring a sufficient and stable precipitation reaction; secondly, as a weakly alkaline additive, it buffers the acidity fluctuations of the system, preventing localized over-acidity that could lead to resin degradation, while also improving the dispersion stability of the slurry system and preventing solid particle agglomeration; thirdly, the trace amounts of sodium ions dissociated from it can preferentially participate in the fluorosilicate precipitation reaction, consuming free ions in the system, further reducing the residual ion content in the resin matrix, and enhancing the ion locking effect.

[0013] Preferably, fluorosilicic acid or its derivatives may be one or a combination of inorganic salts, organic amine / ammonium salts, or organofluorosilicic acid polymers.

[0014] Preferably, the composite stabilizer is a mixture of hindered phenolic antioxidants and phosphite-based auxiliary antioxidants in a mass ratio of 2:1. The hindered phenolic antioxidants provide protection against main chain breakage, while the phosphite-based antioxidants play an auxiliary role in processing stabilization. The synergistic use of the two can effectively inhibit the degradation of PPS molecular chains during high-temperature processing and long-term service, avoiding the release of internally encapsulated ions due to degradation, without introducing additional ionic impurities.

[0015] Processing aids can be commonly used lubricants, release agents, etc. in this field. They should be selected according to actual processing needs, and it is advisable not to introduce precipitable metal ions.

[0016] On the other hand, the present invention provides a method for preparing a low-ion precipitation polyphenylene sulfide composite material, comprising the following steps: S1. Preparation of modified PPS resin: This process is divided into three stages.

[0017] S11: In the first stage, sodium sulfide pentahydrate and N-methylpyrrolidone (NMP) are added to the reactor in a molar ratio of 1:3.0~3.5, for example, 1:3.0, 1:3.1, 1:3.2, 1:3.3, 1:3.4, or 1:3.5. Under nitrogen protection, the temperature is raised to 210~215℃ for dehydration. After the dehydration rate reaches 65~75%, the temperature is lowered to 130~135℃ and maintained at a constant temperature until the dehydration rate reaches 85~90%. Subsequently, NMP is added at 70~80℃ to compensate for evaporation losses. Then, p-dichlorobenzene (P-DCB) and catalyst A are added. The catalyst can be caprolactone. As a catalyst in the first stage, caprolactone can promote chain initiation under relatively mild temperature conditions, control the early molecular chain growth rate, avoid rapid cross-linking, and help reduce the embedding of by-product salts. The molar ratio of catalyst A to sodium sulfide pentahydrate is 0.15~0.25:1, for example, it can be 0.15:1, 0.16:1, 0.17:1, 0.18:1, 0.19:1, 0.20:1, 0.21:1, 0.22:1, 0.23:1, 0.24:1, or 0.25:1. The temperature is raised to 180~190℃, and the reaction is maintained at this temperature for 2~3 hours to complete the first stage of polymerization.

[0018] S12: In the second stage, the product from the first stage is heated to 225-235℃, and an NMP solution containing catalyst B is added. Catalyst B can be lithium acetate, and the molar ratio of lithium acetate to sodium sulfide pentahydrate is 0.15-0.25:1, for example, 0.15:1, 0.16:1, 0.17:1, 0.18:1, 0.19:1, 0.20:1, 0.21:1, 0.22:1, 0.23:1, 0.24:1, or 0.25:1. The reaction is carried out at a constant temperature for 3-4 hours to complete chain growth and molecular weight increase.

[0019] The two-stage heating polymerization strategy allows the polymerization system to proceed in an orderly manner. The molecular chains are uniformly initiated in the low-temperature stage and then grow in the high-temperature stage. This effectively avoids the problem of NaCl and other salt byproducts being trapped due to rapid cross-linking of molecular chains in traditional single-stage high-temperature polymerization, creating favorable conditions for the efficient removal of ions in the subsequent process.

[0020] S13: Cool the reaction system to below 100℃, and wash it with water once after discharge. The volume ratio of PPS slurry to deionized water is 1:5~10. Keep it at 30~40℃ and 100~300rpm for 5~15min, and filter to obtain filter cake A.

[0021] S2, Targeted Purification: Targeted purification is the key innovative process of this invention, used to directionally convert residual free ions in PPS resin into insoluble crystals, and achieve efficient removal through a simplified process.

[0022] S21: Mix filter cake A with water and beat it to prepare slurry A with a mass percentage of 15-25%.

[0023] S22: At 50-65℃ and a stirring rate of 300-500 rpm, add fluorosilicic acid aqueous solution and sodium silicate aqueous solution dropwise to slurry A. The amount of fluorosilicic acid aqueous solution is 1.7-3.9% of the dry weight of filter cake A, for example, 1.7%, 1.9%, 2.1%, 2.3%, 2.5%, 2.7%, 2.9%, 3.1%, 3.3%, 3.5%, 3.7%, or 3.9%. The amount of sodium silicate aqueous solution is 0.2-0.6% of the dry weight of filter cake A, for example, 0.2%, 0.3%, 0.4%, 0.5%, or 0.6%. Adjust the pH of the system to 2.5-3.5, and maintain the temperature for aging for 20-40 minutes to allow free Na+ to dissipate. + Li + Metal cations react with fluorosilicate ions to form insoluble sodium fluorosilicate crystals, achieving directional transformation and solidification of ions. The synergistic use of fluorosilicic acid and sodium silicate serves two purposes: firstly, fluorosilicate ions react with free cations to form an insoluble precipitate; secondly, pH is adjusted to maintain the system in a weakly acidic range conducive to precipitate formation and crystal growth, while aging at a controlled temperature ensures a complete and thorough reaction.

[0024] S23: Cool the system to room temperature at a cooling rate of 0.5~1.5℃ / min, stir at 100~200rpm for 15~30min, and then let it stand. Slow cooling is beneficial for the further aging and growth of fluorosilicate crystals, reducing fine particles and improving subsequent filtration efficiency.

[0025] S24: Filter cake B is obtained by pressure filtration at 0.2~0.5MPa, followed by secondary washing with clean water, wherein the volume ratio of filter cake B to clean water is 1:0.5~1. Finally, it is vacuum dried at 120~150℃ and vacuum degree of -0.09~-0.095MPa for 4~8h to obtain modified PPS resin with sodium ion content of 30~80ppm and lithium ion content ≤10ppm.

[0026] The simplified process of this invention, consisting of a single water washing step combined with directional conversion and a second water washing step, replaces the traditional multi-stage water washing process, reducing water consumption by more than 60%. Furthermore, because the directional conversion step solidifies ions into insoluble crystals which are discharged with the filter cake during pressure filtration, it avoids the secondary adsorption problems caused by changes in ion concentration gradients in traditional multiple water washing processes. Vacuum drying further removes residual moisture and trace solvents without introducing additional impurities.

[0027] S3, Composite Molding: Specifically, it includes: S31. Weigh the modified PPS resin, low-ion reinforcing filler, ion scavenger, composite stabilizer and processing aid according to the formula ratio. S32. Premix the modified PPS resin with the ion capture agent, composite stabilizer and processing aid in a high-speed mixer for 5-10 minutes at a speed of 800-1200 rpm and a temperature of 80-100℃. S33. Add low-ion reinforced filler and continue mixing for 3-5 minutes; S34. Add the above mixture to a twin-screw extruder for melt blending, then extrude and granulate. The temperatures of each section of the extruder are: Zone 1 260~270℃, Zone 2 280~290℃, Zone 3 290~300℃, Zone 4 285~295℃, and the die head temperature is 280~290℃. The screw speed is 300~400 rpm. S35. The obtained particles are injection molded or extruded to obtain a low-ion precipitation polyphenylene sulfide composite material.

[0028] The present invention also provides the application of the above-mentioned composite material in precision instruments, electronic packaging, optical device brackets, automotive precision structural parts, and aerospace functional components.

[0029] The preparation method provided by this invention introduces an ion trapping agent during the composite molding stage, which undergoes a secondary reaction with the residual trace free ions in the matrix under the high temperature conditions of melt processing to form a stable inorganic-organic composite structure. This locks the ions inside the material, constructs a long-term ion interception barrier inside the material, and further ensures the low ion release characteristics of the finished product during service.

[0030] Compared with the prior art, the present invention has the following beneficial effects: 1. Two-stage polymerization significantly reduces the intrinsic ion content of resin: The stepwise heating strategy effectively avoids the embedding of salt byproducts in high-temperature single-stage polymerization, reducing the sodium ion content of modified PPS resin to below 80 ppm, which is far lower than the 200~500 ppm level of existing single-stage polymerization processes, laying the raw material foundation for low ion precipitation.

[0031] 2. Targeted purification process for efficient removal of residual ions: The fluorosilicic acid-sodium silicate system is used to convert free ions into insoluble crystals. Combined with a simplified process of one-stage water washing + targeted conversion + two-stage water washing, it replaces the traditional multi-stage water washing, reducing water consumption by more than 60%. At the same time, it effectively avoids secondary adsorption of ions, and the purification efficiency is significantly better than that of traditional processes.

[0032] 3. Full-chain ion control achieves extremely low precipitation: Low-ion reinforced filler (works synergistically with ion capture agents in the composite molding stage to perform secondary curing of residual trace ions, constructing multiple ion interception defenses, so that the ion precipitation of the finished product after soaking in water at 70℃ for 24 hours is ≤5ppm, which is more than 95% lower than the control ratio).

[0033] 4. Simultaneous improvement of mechanical properties: The interfacial bonding force between the plasma-treated reinforcing fibers and the PPS matrix is ​​enhanced. Combined with reasonable extrusion process parameters, the tensile strength of the composite material can reach 125~132MPa and the flexural strength can reach 188~195MPa, which are about 20% and 18% higher than those of conventional processes, respectively.

[0034] 5. Composite stabilizers combine thermal stability and low ionic properties: The hindered phenol-phosphite composite stabilizer system effectively inhibits oxidative degradation during high-temperature processing and long-term use, prevents the release of internally encapsulated ions due to molecular chain breakage, and does not introduce additional metal ions into the system, thus balancing stability and cleanliness. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present application, the technical solutions in the specific embodiments of the present application will be clearly and completely described below. Unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0036] Example 1 This embodiment describes the preparation of modified PPS resin, and the specific steps are as follows: Raw materials were added to the reactor at a molar ratio of sodium sulfide pentahydrate to NMP of 1:3.2. Under nitrogen protection, the temperature was raised to 212℃ for dehydration. After the dehydration rate reached 70%, the temperature was lowered to 132℃ and kept constant until the dehydration rate reached 88%. NMP at 75℃ was added. P-DCB and caprolactone were added, with a molar ratio of caprolactone to sodium sulfide pentahydrate of 0.2:1. The reaction was carried out at 185℃ for 2.5 hours. The temperature was raised to 230℃, and lithium acetate NMP solution was added, with a molar ratio of lithium acetate to sodium sulfide pentahydrate of 0.2:1. The reaction was carried out at 185℃ for 3.5 hours. The temperature was lowered to below 100℃ and the material was discharged. The mixture was washed once with water at a volume ratio of PPS slurry to deionized water of 1:8, and stirred at 35℃ and 200 rpm for 10 minutes. The filtered product was filter cake A.

[0037] Filter cake A was mixed with water and pulped to prepare slurry A with a mass percentage of 20%. Under stirring at 60℃ and 400 rpm, a 25% (w / w) aqueous solution of fluorosilicic acid and a 12% (w / w) aqueous solution of sodium silicate were added dropwise to slurry A. The amount of fluorosilicic acid solution was 2.8% of the dry weight of filter cake A, and the amount of sodium silicate solution was 0.4% of the dry weight of filter cake A. The pH of the system was adjusted to 3.0, and the mixture was aged at this temperature for 30 min. The mixture was then cooled to room temperature at a rate of 1.0℃ / min, stirred at 150 rpm for 20 min, and allowed to stand. Filter cake B was obtained by pressure filtration at 0.3 MPa. Filter cake B was then washed twice with water, with a volume ratio of filter cake B to water of 1:0.8. Subsequently, the mixture was dried at 135℃ and a vacuum degree of -0.092 MPa for 6 h to obtain modified PPS resin. Testing showed that the sodium ion content was 45 ppm and the lithium ion content was 8 ppm.

[0038] Subsequently, 70 parts of modified PPS resin, 25 parts of plasma-treated low-ion glass fiber, 1.5 parts of ion scavenger, 0.8 parts of composite stabilizer, and 0.5 parts of processing aid were weighed according to weight. The ion scavenger was fluorosilicic acid and sodium silicate in a mass ratio of 4:1. The composite stabilizer was hindered phenols and phosphites in a molar ratio of 2:1.

[0039] PPS resin, ion trapping agent, composite stabilizer, and processing aid are premixed in a high-speed mixer at 1000 rpm and 90°C for 8 minutes. Glass fiber is then added and mixing continues for 4 minutes. The mixture is then placed in a twin-screw extruder with zone temperatures of 265 / 285 / 295 / 290 / 285°C and a screw speed of 350 rpm for extrusion granulation. The granules are then injection molded to obtain the finished product.

[0040] According to the test results, the tensile strength of the finished product in Example 1 was 125 MPa, the flexural strength was 188 MPa, and the ion precipitation after soaking in water at 70°C for 24 hours was 3.2 ppm.

[0041] Example 2 Based on Example 1, this embodiment changes the low-ion reinforcing filler to plasma-treated low-ion carbon fiber, with a dosage of 20 parts, and the dosage of ion scavenger is adjusted to 2.0 parts. The remaining formulation and process parameters are the same as in Example 1.

[0042] Testing revealed that the tensile strength of the product from Example 2 was 132 MPa, the flexural strength was 195 MPa, and the ion release after immersion in water at 70°C for 24 hours was 2.8 ppm. Carbon fiber has higher modulus and strength than glass fiber; therefore, Example 2 exhibits higher mechanical properties than Example 1 with the same addition amount, and the ion release is further reduced.

[0043] Example 3 This embodiment is based on Example 1, except that the ion capture agent is adjusted to a mass ratio of 2:1 of fluorosilicic acid and sodium silicate, with an addition amount of 1.5 parts. The rest of the formula and preparation process are completely consistent with Example 1.

[0044] Example 4 This embodiment is based on Example 1, except that the ion capture agent is adjusted to a mass ratio of 4:1 of fluorosilicate and sodium silicate, with an addition amount of 1.5 parts. The rest of the formulation and preparation process are completely consistent with Example 1.

[0045] Example 5 This embodiment is based on Example 1, except that the ion scavenger is adjusted to a mass ratio of 4:1 of fluorosilicate and sodium silicate, with an addition amount of 0.5 parts. The rest of the formulation and preparation process are completely consistent with Example 1.

[0046] Example 6 This embodiment is based on Example 1, but the ion scavenger is adjusted to a mass ratio of 4:1 of fluorosilicate and sodium silicate, with an addition amount of 3 parts. The rest of the formula and preparation process are completely consistent with Example 1.

[0047] Example 7 This embodiment is based on Example 1, except that the pH value of the mixed solution of slurry A and ion capture agent in the directional purification stage is adjusted to 4.0. The rest of the formula and preparation process are completely the same as in Example 1.

[0048] Example 8 This embodiment is based on Example 1, except that the pH value of the mixed solution of slurry A and ion capture agent in the directional purification stage is adjusted to 2.0. The rest of the formula and preparation process are completely the same as in Example 1.

[0049] Example 9 This embodiment is based on Example 1, except that the 25% fluorosilicic acid aqueous solution is replaced with a 15% sodium fluorosilicate solution, while the rest of the formulation and preparation process are completely consistent with Example 1.

[0050] Comparative Example 1 This comparative example demonstrates the preparation of conventional PPS resin. The specific steps include: adding raw materials to a reactor at a sodium sulfide pentahydrate to NMP molar ratio of 1:3.2; performing single-stage dehydration at 220°C under nitrogen protection until the dehydration rate reaches 88%; adding P-DCB and lithium acetate (catalyst to sodium sulfide pentahydrate molar ratio of 0.4:1); and reacting at a constant temperature of 230°C for 5 hours; after cooling, performing five water washes, each time with a PPS slurry to deionized water volume ratio of 1:10, stirring at 35°C for 20 minutes; filtering; and vacuum drying at 135°C for 6 hours to obtain conventional PPS resin. Testing revealed a sodium ion content of 280 ppm and a lithium ion content of 35 ppm.

[0051] Subsequently, 70 parts by weight of conventional PPS resin, 25 parts of ordinary glass fiber (total metal ion content 180ppm) without plasma treatment, 0.8 parts of hindered phenolic stabilizer (single type), and 0.5 parts of processing aid were weighed; the mixture was processed according to the same mixing and extrusion process parameters as in Example 1, and the finished product was obtained by injection molding.

[0052] The comparative sample product was tested and found to have a tensile strength of 110 MPa, a flexural strength of 165 MPa, and an ion leaching amount of 68 ppm after soaking in water at 70°C for 24 hours.

[0053] Table 1: Performance Comparison of Polyphenylene Sulfide Composite Materials Prepared in the Examples and Comparative Examples

[0054] As shown in Table 1, the synergistic effect of key technologies such as two-stage catalytic polymerization, directional purification, selection of low-ion fillers, and composite molding of ion scavengers in this invention not only significantly reduces the residual ion content of PPS resin, but also reduces the ion release of the composite material product by more than 95% compared with the comparative example, while improving mechanical properties by 18-20%. The overall performance is significantly better than that of products prepared by existing conventional processes.

[0055] Finally, it should be noted that the described embodiments are merely some, not all, of the embodiments of the present invention. Those skilled in the art will understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents; that is, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A low-ion precipitation polyphenylene sulfide composite material, characterized in that, By weight, it includes: The mixture contains 60-80 parts of modified PPS resin, 15-30 parts of low-ion reinforcing filler, 0.5-3 parts of ion scavenger, 0.3-1.5 parts of composite stabilizer, and 0.2-1 parts of processing aid. The ion scavenger is a compound of fluorosilicic acid or its derivatives and sodium silicate, with a mass ratio of 3 to 5:

1.

2. The low-ion precipitation polyphenylene sulfide composite material according to claim 1, characterized in that, The composite stabilizer is a mixture of hindered phenolic antioxidants and phosphite auxiliary antioxidants in a mass ratio of 2:

1.

3. The low-ion precipitation polyphenylene sulfide composite material according to claim 1, characterized in that, The low-ion reinforced filler is glass fiber or carbon fiber treated with plasma, and its total metal ion content is ≤50ppm.

4. A method for preparing a low-ion precipitation polyphenylene sulfide composite material as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Preparation of modified PPS resin: The raw materials are sodium sulfide pentahydrate and NMP. Catalyst A is added and the first stage of polymerization is completed at 180~190℃. Then, catalyst B is added and the second stage of polymerization is completed at 225~235℃. After discharge, filter cake A is obtained by washing and filtering with water once. S2. Targeted purification: Pulp filter cake A into slurry A with a mass percentage of 15-25%. Add ion scavenging agent to slurry A at 50-65℃, adjust the pH to 2.5-3.5, and keep it warm for 20-40 minutes. Cool to room temperature at a rate of 0.5-1.5℃ / min and let it stand. After pressure filtration, wash twice with water and vacuum dry to obtain modified PPS resin. S3. Composite molding: After premixing each component according to the formula ratio, the mixture is melt-blended and granulated by a twin-screw extruder, and then molded to obtain a low-ion precipitation polyphenylene sulfide composite material.

5. The preparation method according to claim 4, characterized in that, The molar ratio of sodium sulfide pentahydrate to NMP in S1 is 1:3.0~3.5; the dehydration temperature in the first stage is 210~215℃; the washing conditions for the first wash are: volume ratio of PPS slurry to deionized water 1:5~10, temperature 30~40℃, stirring speed 100~300rpm, and time 5~15min.

6. The preparation method according to claim 4, characterized in that, Catalyst A is caprolactone, with a molar ratio of caprolactone to sodium sulfide pentahydrate of 0.15~0.25:1; catalyst B is lithium acetate, with a molar ratio of lithium acetate to sodium sulfide pentahydrate of 0.15~0.25:

1.

7. The preparation method according to claim 4, characterized in that, The ion scavenger in S2 is a mixture of aqueous fluorosilicic acid solution and aqueous sodium silicate solution, wherein the amount of aqueous fluorosilicic acid solution is 1.7~3.9% of the dry basis mass of filter cake A, and the amount of aqueous sodium silicate solution is 0.2~0.6% of the dry basis mass of filter cake A.

8. The preparation method according to claim 4, characterized in that, The pressure of the filter press in S2 is 0.2~0.5MPa; the volume ratio of filter cake B to clean water in the secondary water washing is 1:0.5~1; the vacuum drying conditions are 120~150℃, vacuum degree -0.09~-0.095MPa, and drying time 4~8h.

9. The preparation method according to claim 4, characterized in that, In S3, premixing is carried out in a high-speed mixer at a speed of 800~1200 rpm and a temperature of 80~100℃. First, the modified PPS resin is premixed with the ion capture agent, composite stabilizer, and processing aid for 5~10 minutes, and then the low-ion reinforcing filler is added and the mixture is continued for 3~5 minutes. The temperatures of each section of the twin-screw extruder are as follows: Zone 1 260~270℃, Zone 2 280~290℃, Zone 3 290~300℃, Zone 4 285~295℃, and the die head 280~290℃. The screw speed is 300~400 rpm.

10. The application of a low-ion precipitated polyphenylene sulfide composite material as described in any one of claims 1 to 3.

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