Process for producing branched polyphenylene sulfide resin, branched polyphenylene sulfide resin, and use thereof

Abstract

The application provides a production process of branched polyphenylene sulfide resin, the branched polyphenylene sulfide resin and application thereof, and particularly relates to the technical field of high polymer material synthesis. The production process of the branched polyphenylene sulfide resin comprises the following steps: first, adding a strong base, a sulfur source and a solvent into a first reaction kettle and a second reaction kettle respectively, stirring and carrying out azeotropic dehydration; then, adding a branching agent into the first reaction kettle to carry out a prepolymerization reaction, so as to obtain a branched PPS prepolymer; no branching agent is added into the second reaction kettle to carry out a prepolymerization reaction, so as to obtain a linear PPS prepolymer; then, simultaneously discharging the branched PPS prepolymer and the linear PPS prepolymer into a third reaction kettle to carry out a first blending polymerization, and then, carrying out a second blending polymerization by increasing the temperature, so as to obtain the branched polyphenylene sulfide resin. The process significantly improves the uniformity of the branching degree distribution and inhibits burr generation; meanwhile, the stirring current is stable and has no mutation, no TCB residue is detected, and the purity of PDCB recovery and batch stability are ensured.

Description

Technical Field

[0001] This invention relates to the field of polymer material synthesis technology, and in particular to a production process for branched polyphenylene sulfide resin, the branched polyphenylene sulfide resin and its applications. Background Technology

[0002] Polyphenylene sulfide (PPS) is widely used in the automotive, electronics, and precision structural components industries due to its excellent heat resistance, chemical stability, and dimensional stability. Currently, the mainstream industrial process for preparing PPS involves synthesizing linear PPS through a stepwise polycondensation reaction using p-dichlorobenzene (PDCB) and alkali metal sulfides in organic amide solvents such as N-methyl-2-pyrrolidone. However, linear PPS has high molecular chain regularity and low melt elasticity, making it prone to penetrating into the mold's micro-gap during injection molding and solidifying to form burrs. This not only increases post-processing costs but also affects the product's appearance and assembly accuracy. To improve processing performance and suppress burrs, the industry commonly adopts a strategy of introducing branched structures: adding polyhalogenated aromatic compounds (such as 1,2,4-trichlorobenzene, TCB) as branching agents to the polymerization system. These branching agents, through their multifunctionality, induce three-dimensional topological reconstruction of the molecular chain, improving melt elasticity and melt strength, thereby enhancing the melt's ability to resist flow through mold gaps.

[0003] However, existing branched PPS synthesis technologies suffer from multiple process contradictions that are difficult to resolve in a coordinated manner: Firstly, if TCB and PDCB are fed simultaneously, the branching reaction will occur too early, resulting in uneven distribution of branching points and excessive local cross-linking. This will cause a sudden increase in stirring current and a sharp rise in system viscosity after phase separation, which may lead to safety risks such as explosive polymerization and reactor jamming during scale-up production.

[0004] Secondly, if TCB is added in a concentrated manner after the PDCB conversion rate is greater than 90%, although early branching runaway can be avoided, the instantaneous high concentration of the branching agent will cause local violent reactions, resulting in current spikes, extra-large lumps and excessive stirring load.

[0005] Third, none of the above methods can guarantee complete TCB conversion. Residual TCB enters the PDCB recovery system with the mother liquor, contaminating monomer purity and leading to fluctuations in molecular weight and performance discrepancies between batches of products. These defects collectively restrict the stable industrial production and consistent quality control of branched PPS, necessitating a novel synthetic route that can precisely control the branching structure while ensuring reaction stability and the cleanliness of the recovery system throughout the process.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a production process for branched polyphenylene sulfide resin, branched polyphenylene sulfide resin and its applications, in order to solve at least one of the above-mentioned technical problems in the prior art.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: The first aspect of this invention provides a production process for branched polyphenylene sulfide resin. A strong alkali, a sulfur source, and a solvent are added to a first reactor and a second reactor, respectively, and stirred to perform azeotropic dehydration. After dehydration, a branching agent is added to the first reactor to perform a prepolymerization reaction to obtain a branched PPS prepolymer. No branching agent is added to the second reactor, and a prepolymerization reaction is performed to obtain a linear PPS prepolymer. The branched PPS prepolymer and the linear PPS prepolymer are simultaneously discharged into a third reactor for a first blend polymerization, followed by a second blend polymerization at a higher temperature to obtain the branched polyphenylene sulfide resin.

[0009] Furthermore, the strong base includes at least one of NaOH, LiOH, KOH, RbOH, and CsOH, preferably NaOH.

[0010] Preferably, the sulfur source includes at least one of NaHS, Na2S, Rb2S, K2S, and Cs2S, with NaHS being the most preferred.

[0011] Preferably, the solvent includes at least one of N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), N-cyclohexyl-2-pyrrolidone (CHP), and hexamethylphosphoramide (HMAP), with NMP being the most preferred.

[0012] Preferably, the molar ratio of the strong alkali, the sulfur source and the solvent is (0.9~1.1):1:(3~5).

[0013] Furthermore, the azeotropic dehydration temperature is 180~210℃, and the time is 1~5h.

[0014] Preferably, the discharge rate of the branched PPS prepolymer is 0.3~0.7 kg / min.

[0015] Preferably, the discharge rate of the linear PPS prepolymer is 0.3~0.7 kg / min.

[0016] Preferably, the branching agent includes at least one of 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, 1,2,3,4-tetrachlorobenzene and 2,4,6-trichlorotoluene, and more preferably 1,2,4-trichlorobenzene and 1,3,5-trichlorobenzene.

[0017] Preferably, the molar amount of the branching agent is 0.005-0.06 times that of the sulfur source.

[0018] Preferably, the branching agent is added at a temperature of 160~180℃.

[0019] Furthermore, the temperature of the prepolymerization reaction is 230~240℃, and the time is 1~1.5h.

[0020] Preferably, the conversion rate of the sulfur source in the prepolymerization reaction is ≥90%.

[0021] Preferably, the temperature for the first blending polymerization is 230~240℃ and the time is 1~1.5h.

[0022] Preferably, the second blending polymerization is carried out at a temperature of 245~260℃ for 1.5~3h.

[0023] Furthermore, the production process also includes a phase separation process after the first blending polymerization.

[0024] Preferably, the phase separation process is as follows: water is added to the product after the first blending polymerization to separate the polymer-rich phase and the polymer-poor phase.

[0025] Furthermore, the production process also includes a post-processing step after the second blending polymerization.

[0026] Preferably, the post-processing includes filtering the material to obtain a filter cake, and then washing and drying the filter cake to obtain a branched polyphenylene sulfide resin.

[0027] Preferably, the drying temperature is 100~150℃ and the time is 2~4h.

[0028] A second aspect of the present invention provides a branched polyphenylene sulfide resin, which is produced using the production process described in the first aspect.

[0029] Furthermore, the branched polyphenylene sulfide resin is subjected to a temperature of 330°C and a shear rate of 2 seconds. -1 The shear viscosity at this point is 0.1 × 10⁻⁶. 5 ~5.0×10 5 Pa·s.

[0030] Furthermore, the branched polyphenylene sulfide resin has a non-Newtonian index of 1.8 to 3.5 and an angle of repose of 30° to 36°.

[0031] The third aspect of the present invention provides the application of the branched polyphenylene sulfide resin as an injection molding material.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects: The production process provided by this invention first generates branched PPS prepolymers in a first reactor, while a linear PPS prepolymer is simultaneously prepared in a second reactor, with the molecular weights and reactivity of the two prepolymers being matched. In a third reactor, the two types of chain segments are fully entangled and their end groups are in orderly contact, avoiding localized burst polymerization and sudden current increases caused by concentrated addition of the branching agent in a single-reactor system. Subsequently, a phase-separating agent is added and the temperature is raised for a two-stage polymerization, achieving both controllable extension of branching points and main chain growth in the polymer-rich phase. This process significantly improves the uniformity of branching distribution and suppresses burr formation; simultaneously, the stirring current is stable and without abrupt changes, and no TCB residues are detected, ensuring the purity and batch stability of PDCB recovery.

[0033] The branched polyphenylene sulfide resin provided by this invention has the characteristics of highly uniform branched structure and controllable molecular chain topology. Its non-Newtonian index reaches 1.8-3.5, which is significantly higher than that of linear PPS, indicating that the branching degree is high and the distribution is concentrated. At the same time, it has moderate shear viscosity and low angle of repose, and has both excellent melt elasticity and good powder flowability.

[0034] The application provided by this invention, given the advantages of the aforementioned branched polyphenylene sulfide resin, significantly suppresses burr formation. Under the same injection molding conditions, the burr length of the product is stably controlled at 45-59 μm, which is more than 60% lower than that of linear PPS under the same filler system, and far superior to existing branched PPS solutions, effectively reducing post-processing steps and trimming costs. Attached Figure Description

[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the production apparatus for branched polyphenylene sulfide resin provided by the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0038] In the following, the terms “comprising,” “having,” and their cognates, which may be used in various embodiments of the invention, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as excluding, firstly, the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations thereof.

[0039] The first aspect of this invention provides a production process for branched polyphenylene sulfide resin. A strong alkali, a sulfur source, and a solvent are added to a first reactor and a second reactor, respectively, and stirred to perform azeotropic dehydration. After dehydration, a branching agent is added to the first reactor to perform a prepolymerization reaction to obtain a branched PPS prepolymer. No branching agent is added to the second reactor, and a prepolymerization reaction is performed to obtain a linear PPS prepolymer. The branched PPS prepolymer and the linear PPS prepolymer are simultaneously discharged into a third reactor for a first blend polymerization, followed by a second blend polymerization at a higher temperature to obtain the branched polyphenylene sulfide resin.

[0040] The production process provided by this invention first generates branched PPS prepolymers in a first reactor, while a linear PPS prepolymer is simultaneously prepared in a second reactor, with the molecular weights and reactivity of the two prepolymers being matched. In a third reactor, the two types of chain segments are fully entangled and their end groups are in orderly contact, avoiding localized burst polymerization and sudden current increases caused by concentrated addition of the branching agent in a single-reactor system. Subsequently, a phase-separating agent is added and the temperature is raised for a two-stage polymerization, achieving both controllable extension of branching points and main chain growth in the polymer-rich phase. This process significantly improves the uniformity of branching distribution and suppresses burr formation; simultaneously, the stirring current is stable and without abrupt changes, and no TCB residues are detected, ensuring the purity and batch stability of PDCB recovery.

[0041] In a single reactor, the timing of adding the branching agent is difficult to control: adding it too early results in a chaotic distribution of branching points and localized over-branching; adding it too late (e.g., concentrated feeding when PDCB conversion is 90%) causes the branching reaction to erupt in the later stages, leading to a sudden increase in stirring current. This invention utilizes a dual-reactor prepolymerization and blending polymerization method to precisely confine branching points to the molecular chains of the product in reactor A, avoiding random spatial distribution. Two prepolymers are simultaneously and slowly fed into reactor C. By controlling the feeding rate, the two chain segments are ensured to fully contact and entangle. Water, a phase-separating agent, is then added to achieve phase separation, followed by a two-stage heating polymerization reaction, ensuring effective molecular chain growth. Furthermore, the degree of branching can be flexibly controlled by varying the amount of branching agent added in reactor A, avoiding over- or under-branching. Meanwhile, this process can effectively suppress the sudden increase in stirring current caused by the viscosity surge that is prone to occur in single-reactor reactions. The stirring current remains stable under this process, avoiding the risk of explosive polymerization. The process has strong scalability and is suitable for continuous industrial production, solving the core problem that branched PPS is difficult to produce on a large scale.

[0042] Furthermore, the strong base includes at least one of NaOH, LiOH, KOH, RbOH, and CsOH, preferably NaOH.

[0043] Preferably, the sulfur source includes at least one of NaHS, Na2S, Rb2S, K2S, and Cs2S, with NaHS being the most preferred.

[0044] Preferably, the solvent includes at least one of N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), N-cyclohexyl-2-pyrrolidone (CHP), and hexamethylphosphoramide (HMAP), with NMP being the most preferred.

[0045] Preferably, the molar ratio of the strong alkali, the sulfur source and the solvent is (0.9~1.1):1:(3~5).

[0046] Typically, but not limitingly, the molar ratio of the strong base, the sulfur source, and the solvent can be, for example, 0.9:1:3, 1:1:4, 1.1:1:5, or any ratio within the range of (0.9~1.1):1:(3~5).

[0047] Furthermore, the azeotropic dehydration temperature is 180~210℃, and the time is 1~5h.

[0048] Typically, but not limitingly, the azeotropic dehydration temperature can be, for example, 180°C, 190°C, 200°C, or 210°C, or any value within the range of 180°C to 210°C; the azeotropic dehydration time can be, for example, 1h, 2h, 3h, 4h, or 5h, or any value within the range of 1h to 5h.

[0049] Preferably, the discharge rate of the branched PPS prepolymer is 0.3~0.7 kg / min.

[0050] Preferably, the discharge rate of the linear PPS prepolymer is 0.3~0.7 kg / min.

[0051] Preferably, the branching agent includes at least one of 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, 1,2,3,4-tetrachlorobenzene and 2,4,6-trichlorotoluene, and more preferably 1,2,4-trichlorobenzene and 1,3,5-trichlorobenzene.

[0052] Preferably, the molar amount of the branching agent is 0.005-0.06 times that of the sulfur source.

[0053] Typically, but not limitingly, the molar ratio of the branching agent to the sulfur source can be, for example, 0.005:1, 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, or 0.06:1, or any multiple in the range of 0.005 to 0.06.

[0054] Preferably, the branching agent is added at a temperature of 160~180℃.

[0055] Typically, but not limitingly, the temperature at which the branching agent is added can be, for example, 160°C, 165°C, 170°C, 175°C, or 180°C, or any value within the range of 160°C to 180°C.

[0056] Furthermore, the temperature of the prepolymerization reaction is 230~240℃, and the time is 1~1.5h.

[0057] Typically, but not limitingly, the temperature of the prepolymerization reaction can be, for example, 230°C, 232°C, 235°C, 238°C, or 240°C, or any value within the range of 230°C to 240°C; the time of the prepolymerization reaction can be, for example, 1h, 1.1h, 1.2h, 1.3h, 1.4h, or 1.5h, or any value within the range of 1 to 1.5h.

[0058] Preferably, the conversion rate of the sulfur source in the prepolymerization reaction is ≥90%.

[0059] Preferably, the temperature for the first blending polymerization is 230~240℃ and the time is 1~1.5h.

[0060] Typically, but not limitingly, the temperature of the first blend polymerization can be, for example, 230°C, 232°C, 235°C, 238°C, or 240°C, or any value within the range of 230°C to 240°C; the time of the first blend polymerization can be, for example, 1h, 1.1h, 1.2h, 1.3h, 1.4h, or 1.5h, or any value within the range of 1h to 1.5h.

[0061] Preferably, the second blending polymerization is carried out at a temperature of 245~260℃ for 1.5~3h.

[0062] Typically, but not limitingly, the temperature of the second blend polymerization can be, for example, 245°C, 248°C, 250°C, 255°C, or 260°C, or any value within the range of 245°C to 260°C; the time of the second blend polymerization can be, for example, 1.5h, 2h, 2.5h, or 3h, or any value within the range of 1.5h to 3h.

[0063] Furthermore, the production process also includes a phase separation process after the first blending polymerization.

[0064] Preferably, the phase separation process is as follows: water is added to the product after the first blending polymerization to separate the polymer phase and the polymer-poor phase, thereby precipitating macromolecules while promoting the growth of small molecules, increasing the molecular weight of PPS while reducing the molecular weight distribution of the polymer.

[0065] Furthermore, the production process also includes a post-processing step after the second blending polymerization.

[0066] Preferably, the post-processing includes separating the material to obtain a filter cake, and then washing and drying the filter cake to obtain a branched polyphenylene sulfide resin.

[0067] Preferably, the drying temperature is 100~150℃ and the time is 2~4h.

[0068] Typically, but not limitingly, the drying temperature can be, for example, 100°C, 110°C, 120°C, 130°C, 140°C, or 150°C, or any value within the range of 100°C to 150°C; the drying time can be, for example, 2h, 2.5h, 3h, 3.5h, or 4h, or any value within the range of 2h to 4h.

[0069] In some embodiments of the present invention, the apparatus used is such as Figure 1 As shown, the production process of the branched polyphenylene sulfide resin includes: (1) Dehydration process: The required materials are added to polymerization reactors A and B through NaOH metering tanks, NaHS metering tanks, and NMP metering tanks, respectively, and then the temperature is raised to start azeotropic dehydration. During the process, the distilled water and NMP vapor enter the dehydration tower, are condensed into liquid by the condenser, and are collected in the distillate tank. The water content and sulfur loss in the distillate are measured by sampling, and dehydration is completed when the residual water in the system is about 1.1 mol / mol sulfur.

[0070] (2) Prepolymerization process: After dehydration, PDCB, water and NMP required for polymerization are added to polymerization reactor A and polymerization reactor B respectively through metering tank. A certain amount of branching agent is added to polymerization reactor A and the temperature is raised to carry out the prepolymerization reaction to obtain branched PPS prepolymer; no branching agent is added to polymerization reactor B and the prepolymerization reaction is carried out under the same conditions to obtain linear PPS prepolymer.

[0071] (3) Preheating process of polymerization reactor C: A certain amount of NMP solution is added to polymerization reactor C in advance, and the endpoint temperature of the prepolymerization reaction of polymerization reactor A and polymerization reactor B is preheated in preparation for subsequent blending polymerization.

[0072] (4) Blending polymerization process: After all the prepolymers from polymerization reactors A and B are discharged into polymerization reactor C, they are thoroughly mixed in reactor C for 5-10 minutes. Then, pure water preheated to a certain temperature is added to polymerization reactor C through a high-pressure pump to carry out phase separation. After the water is added, the temperature is raised to carry out the second stage of polymerization reaction, so as to increase the degree of branching and achieve the growth of molecular chains.

[0073] (5) Post-processing steps: After the polymerization reaction is completed, the polymer slurry is discharged, filtered through a screen, and the filter cake is washed to finally obtain the branched polyphenylene sulfide resin product.

[0074] In some embodiments of the present invention, the separated filter cake is washed three times with acetone, three times with water, then once with an aqueous solution containing 0.5% acetic acid, and further washed three times with water to obtain the washed polymer. Finally, it is dried at 120°C for 3 hours to obtain the final product.

[0075] A second aspect of the present invention provides a branched polyphenylene sulfide resin, which is produced using the production process described in the first aspect.

[0076] The branched polyphenylene sulfide resin provided by this invention features a highly uniform branched structure and controllable molecular chain topology. Its non-Newtonian index reaches 1.8-3.5, significantly higher than linear PPS, indicating a high degree of branching and concentrated distribution. Simultaneously, it exhibits moderate shear viscosity and a low angle of repose, combining excellent melt elasticity with good powder flowability. Furthermore, the branched polyphenylene sulfide resin, at 330°C and a shear rate of 2 seconds… -1 The shear viscosity at this point is 0.1 × 10⁻⁶. 5~5.0×10 5 Pa·s.

[0077] Furthermore, the branched polyphenylene sulfide resin has a non-Newtonian index of 1.8 to 3.5 and an angle of repose of 30° to 36°.

[0078] The third aspect of the present invention provides the application of the branched polyphenylene sulfide resin as an injection molding material.

[0079] The application provided by this invention, given the advantages of the aforementioned branched polyphenylene sulfide resin, significantly suppresses burr formation. Under the same injection molding conditions, the burr length of the product is stably controlled at 45-59 μm, which is more than 60% lower than that of linear PPS under the same filler system, and far superior to existing branched PPS solutions, effectively reducing post-processing steps and trimming costs.

[0080] The present invention is further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for illustrative purposes and should not be construed as limiting the invention in any way. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present invention were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0081] Example 1 This embodiment provides a branched polyphenylene sulfide resin, and the specific production process is as follows: 1. Dehydration: 4.91 kg (49.53 mol) of NMP, 1.94 kg (16.5 mol) of 47.58 wt% sodium hydrosulfide aqueous solution, and 1.378 kg (16.75 mol) of 48.62 wt% sodium hydroxide aqueous solution were sequentially added to two 30 L reactors, A and B. After purging the air from the reactors with nitrogen, the mixture was heated at a stirring speed of 23.8 rpm and a heating rate of 1.0 °C / min. Dehydration was complete when the temperature reached 200 °C and the residual water content in the system was approximately 1.1 mol / mol of sulfur. At this point, 2.27 kg of distillate was distilled off from each reactor. The calculated hydrogen sulfide loss during dehydration was 0.23 mol, therefore the actual effective sulfur source in the reactors was 16.27 mol, and the water / sulfur molar ratio of the system was 1.087.

[0082] 2. Prepolymerization: After the mixture in the reactor is cooled to 170°C, add 2.62 kg of PDCB, 2.13 kg of NMP, and 91.2 g of water to reactor A, along with 23.86 g of branching agent 1,2,4-trichlorobenzene. The molar ratio of PDCB to total sulfur is 1.095, the molar ratio of NMP to total sulfur is 4, the molar ratio of water to total sulfur is 1.4, and the molar ratio of branching agent to total sulfur is 0.008. Add the same amounts of PDCB, NMP, and H2O to reactor B. After the addition is complete, heat the polymerization feed mixture in both reactors to 238°C for prepolymerization. This yields branched PPS prepolymer and linear PPS polymer.

[0083] 3. Polymerization: The branched PPS prepolymer and linear PPS prepolymer were simultaneously and slowly fed into reactor C for the first blending. 0.81 kg of NMP was added to reactor C beforehand, resulting in a total NMP / total sulfur molar ratio of 4.25. The reactor was preheated to 238°C. After feeding, the mixture was thoroughly mixed in reactor C for 8 minutes. Then, 1.84 kg of water preheated to 80°C was added to the reactor using a high-pressure pump for phase separation, resulting in a total water / total sulfur molar ratio of 3.25. The mixture was then heated to 255°C at a rate of 0.5°C / min and reacted for 2 hours. The temperature was then lowered to 240°C at a rate of 2.0°C / min, and the reaction continued for 1 hour to obtain the second blended polymer. After the reaction, the mixture was rapidly cooled to 110°C. The resulting resin slurry was filtered through a 150-mesh sieve. The filter cake was washed sequentially with acetone, 0.5% acetic acid, and 85°C deionized water. Finally, it was dried at 120°C for 3 hours to obtain the branched polyphenylene sulfide resin. The obtained resin was tested, and the data are shown in Table 1.

[0084] Examples 2-5 The only difference between Examples 2-5 and Example 1 is the amount of branching agent added; all other process conditions, operating steps, and post-treatment methods are the same as in Example 1. The obtained resins were tested, and the data are shown in Table 1.

[0085] Comparative Example 1 This comparative example provides a polyphenylene sulfide resin, and the specific production process is as follows: 1. Dehydration: 9.82 kg (99.1 mol) of NMP, 3.88 kg (33 mol) of 47.58 wt% sodium hydrosulfide aqueous solution, and 2.76 kg (33.5 mol) of 48.62 wt% sodium hydroxide aqueous solution were sequentially added to reactor A. After purging the reactor with nitrogen, the mixture was heated at a stirring speed of 23.8 rpm and a heating rate of 1.0 °C / min. Dehydration was completed when the temperature reached 200 °C and the residual water content in the system was approximately 1.1 mol / mol of sulfur. At this point, 4.62 kg of distillate was distilled off. The calculated hydrogen sulfide loss during dehydration was 0.49 mol, therefore the actual effective sulfur source in the reactor was 32.51 mol, and the water / sulfur molar ratio of the system was 1.096.

[0086] 2. Prepolymerization: After the mixture in the reactor has cooled to 170°C, add 5.24 kg of PDCB, 5.14 kg of NMP, and 176 g of water to the reactor. The molar ratio of PDCB to total sulfur is 1.095, the molar ratio of NMP to total sulfur is 4.25, and the molar ratio of water to total sulfur is 1.4. No additional branching agent, 1,2,4-trichlorobenzene, is added. After the addition is complete, heat the polymerization reactor to 238°C to carry out the prepolymerization reaction.

[0087] 3. Polymerization: At the prepolymerization endpoint of 238℃, preheated water (1.083 kg) to 80℃ was added to the reactor using a high-pressure pump for phase separation. The molar ratio of total water to total sulfur in the system was 3.25. The temperature was then increased to 255℃ at a rate of 0.5℃ / min for 2 hours, followed by a decrease to 240℃ at a rate of 2.0℃ / min for another hour. After the reaction, the mixture was rapidly cooled to 110℃. The resulting resin slurry was filtered through a 150-mesh sieve. The filter cake was washed sequentially with acetone, 0.5% acetic acid, and deionized water at 85℃. Finally, it was dried at 120℃ for 3 hours to obtain polyphenylene sulfide resin. The obtained resin was tested, and the data are shown in Table 2.

[0088] Comparative Example 2 The same single-reactor polymerization process as Comparative Example 1 was used, except that during the prepolymerization feeding stage after dehydration, the branching agent 1,2,4-trichlorobenzene and PDCB were added together to the polymerization reactor at a ratio of TCB / S = 0.05. The resulting resin was tested, and the data are shown in Table 2.

[0089] Comparative Example 3 The same single-reactor polymerization process as Comparative Example 1 was used, except that after the prepolymerization reaction, the branching agent 1,2,4-trichlorobenzene and the phase separating agent water were added together into the polymerization reactor at a ratio of TCB / S = 0.05. The obtained resin was tested, and the data are shown in Table 2.

[0090] Test Example 1 The methods for determining and evaluating the physical properties and characteristics of the examples and comparative examples are as follows: (1) Shear viscosity (MV) test method: The shear viscosity of branched PPS was measured using a Netzsch RH2000 capillary rheometer. A specific die was used: 90° L=8mm, D=2.095mm. Approximately 25g of dry polymer was introduced into the apparatus, the temperature was set to 330℃, and after holding for 5 minutes, the viscosity was measured at a shear rate of 2 seconds. -1 The shear viscosity was measured below.

[0091] (2) Test method for non-Newtonian index (N): The non-Newtonian index of branched PPS was tested using a MARS60 rotational rheometer manufactured by HAAKE. The test conditions were: temperature 300℃, using a capillary mold with an aspect ratio L / D=40 (inner diameter 1mm, length 40mm), and collecting resin samples for 100~1000s. -1 The shear stress data at the shear rate are logarithmically taken and then linearly fitted. The slope of the resulting straight line is the non-Newtonian exponent, expressed by the formula SR = K•SS. N SR represents shear rate, unit: 1 / second; SS represents shear stress, unit: dynes / cm. 2 K represents a constant.

[0092] (3) Test method for angle of repose (θ): Generally, the flowability of powder can be evaluated by measuring the angle of repose. The angle of repose refers to the angle of inclination of the cone formed by the free fall of powder from a certain height. The test equipment we use is a powder tester manufactured by Hosokawa Micron Corporation. The test method is to use a funnel to gently drop the powder from a predetermined height onto a disc platform with a diameter of 80 mm, and use a protractor to measure the angle of inclination of the formed cone.

[0093] (4) Burr length: Each resin composition was injection molded under the following molding conditions using an injection molding machine to prepare molded articles for burr evaluation; the burr length at the burr-generating location of the molded article was measured using an image measuring instrument, and the burr length was analyzed. The shorter the burr length, the better the effect of suppressing burr generation.

[0094] The molding conditions are as follows: Molding machine: Lange LOG130S8 injection molding machine Barrel temperature: NH320-320-320-305-300 (°C) Mold temperature: 150℃ The obtained data is recorded as follows: Table 1

[0095] Table 2

[0096] Application examples In the following application example, 100 parts by weight of linear PPS resin, 10 parts by weight of branched PPS resin, and 80 parts by weight of inorganic filler glass fiber were mixed and stirred at high speed for 2 minutes to achieve uniform dispersion. The mixture was then fed into a twin-screw extruder with the barrel temperature set at 320°C for melt blending, extrusion granulation, and the resulting PPS resin composition granules were obtained. The burr length of the injection-molded products from the obtained granules was tested and evaluated using the test method of Test Example 1, and the relevant test results are listed in Table 3.

[0097] Table 3

[0098] As shown in the table above, in Comparative Application Example 1, the composition without branched PPS had a high burr length of up to 135 μm, indicating poor burr suppression. In Comparative Application Examples 2 and 3, adding 10 parts of branched PPS controlled the burr length to around 80-90 μm, with no significant suppression effect. In contrast, the branched PPS prepared in this invention, with only 10 parts added, can stably control the burr length between 40 and 60 μm, and the burr length in all application examples is below 60 μm, significantly superior to the branched PPS in existing patents. Therefore, the preparation method of this invention enables the branched PPS to achieve excellent burr suppression at low addition levels, significantly reducing modification costs while improving the stability of burr control, demonstrating its outstanding advantages in PPS modification applications.

[0099] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A production process for branched polyphenylene sulfide resin, characterized in that, A strong alkali, a sulfur source, and a solvent are added to the first and second reactors, respectively, and stirred to carry out azeotropic dehydration. After completion, a branching agent is added to the first reactor to carry out a prepolymerization reaction to obtain a branched PPS prepolymer. No branching agent is added to the second reactor to carry out a prepolymerization reaction to obtain a linear PPS prepolymer. The branched PPS prepolymer and the linear PPS prepolymer are simultaneously discharged into the third reactor for a first blend polymerization, and then heated to carry out a second blend polymerization to obtain a branched polyphenylene sulfide resin.

2. The production process according to claim 1, characterized in that, The strong base includes at least one of NaOH, LiOH, KOH, RbOH, and CsOH, preferably NaOH; Preferably, the sulfur source includes at least one of NaHS, Na2S, Rb2S, K2S, and Cs2S, with NaHS being the most preferred. Preferably, the solvent includes at least one of N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N-cyclohexyl-2-pyrrolidone, and hexamethylphosphoramide, and is more preferably N-methyl-2-pyrrolidone; Preferably, the molar ratio of the strong alkali, the sulfur source and the solvent is (0.9~1.1):1:(3~5).

3. The production process according to claim 1, characterized in that, The azeotropic dehydration is carried out at a temperature of 180~210℃ for 1~5 hours. Preferably, the discharge rate of the branched PPS prepolymer is 0.3~0.7 kg / min; Preferably, the discharge rate of the linear PPS prepolymer is 0.3~0.7 kg / min; Preferably, the branching agent includes at least one selected from 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, and 2,4,6-trichlorotoluene, and more preferably 1,2,4-trichlorobenzene and 1,3,5-trichlorobenzene; Preferably, the molar amount of the branching agent is 0.005-0.06 times that of the sulfur source; Preferably, the branching agent is added at a temperature of 160~180℃.

4. The production process according to claim 1, characterized in that, The prepolymerization reaction is carried out at a temperature of 230~240℃ for 1~1.5h. Preferably, the conversion rate of the sulfur source in the prepolymerization reaction is ≥90%; Preferably, the temperature for the first blend polymerization is 230~240℃, and the time is 1~1.5h; Preferably, the second blending polymerization is carried out at a temperature of 245~260℃ for 1.5~3h.

5. The production process according to any one of claims 1 to 4, characterized in that, It also includes the phase separation process after the first blending polymerization; Preferably, the phase separation process is as follows: water is added to the product after the first blending polymerization to separate the polymer-rich phase and the polymer-poor phase.

6. The production process according to any one of claims 1 to 4, characterized in that, It also includes a post-processing step after the second blending polymerization; Preferably, the post-processing includes filtering the material to obtain a filter cake, and then washing and drying the filter cake to obtain a branched polyphenylene sulfide resin. Preferably, the drying temperature is 100~150℃ and the time is 2~4h.

7. A branched polyphenylene sulfide resin, characterized in that, It is produced using the production process described in any one of claims 1 to 4.

8. The branched polyphenylene sulfide resin according to claim 7, characterized in that, At 330℃ and a shear rate of 2 seconds -1 The shear viscosity at this point is 0.1 × 10⁻⁶. 5 ~5.0×10 5 Pa·s.

9. The branched polyphenylene sulfide resin according to claim 7, characterized in that, The non-Newtonian exponent is 1.8 to 3.5, and the angle of repose is 30° to 36°.

10. The application of the branched polyphenylene sulfide resin according to any one of claims 7 to 9 as an injection molding material.

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