A method for preparing polysulfone resin by segmented polymerization

Abstract

This invention belongs to the field of polymer material preparation technology, specifically relating to a method for preparing polysulfone resins via segmented polymerization. This invention provides a novel segmented polymerization method for polysulfone resins, dividing the polymerization reaction into two parts: a prepolymerization reaction and a post-desalting polymerization reaction. The prepolymerization reaction employs either an excess of phenolic monomers or an excess of halogenated monomers. After the initial salt-forming reaction of the phenolic and halogenated monomers, desalting is performed. At this point, the viscosity is low, making it easier to separate the salts from the prepolymer. This solves the problem in one-step synthesis methods of polysulfone resins where the resin viscosity increases after the formation of the polymer, making it difficult to effectively remove salts and small polymer molecules trapped within the polymer. This improves the quality of the polysulfone resin. Simultaneously, after salt removal, the polymerization system approaches homogeneity, significantly increasing the reaction rate and enabling controlled polymerization of ultra-high molecular weight polymers without cross-linking or explosive polymerization.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer material preparation, and in particular relates to a method for preparing polysulfone resin by segmented polymerization. Background Art

[0002] At present, the most advanced production process of polysulfone polymer materials is a one-step synthesis method, in which the main raw materials 4,4'-dichlorodiphenyl sulfone (halogenated monomer), phenolic polymerization monomer and alkali metal salt (such as potassium carbonate) are polymerized in a solvent. Common solvents include dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, etc. After the polymerization, water, ethanol or methanol is used as a precipitant. Under the action of the precipitant, polysulfone is separated from the polymer solution. The separated polysulfone is purified, dried, granulated and packaged to obtain polysulfone products. However, this one-step synthesis method is used to prepare polysulfone resins. After the polymerization, the polysulfone resins are high molecular polymers with high resin viscosity. It is impossible to effectively remove the salts and small molecular polymers contained in the high molecular polymers, which affects the product quality of the polysulfone resins. Moreover, because there are salt substances in the polymerization system, the polymerization system is heterogeneous, which will affect the frequency of intermolecular collisions and the reaction rate during the polymerization reaction stirring process, and it is impossible to polymerize to obtain ultra-high molecular weight polysulfone products. Summary of the invention

[0003] In view of this, the object of the present invention is to provide a method for preparing polysulfone resin by segmented polymerization. The present invention adopts the segmented polymerization method to prepare polysulfone resin, which contains less salts and small molecular polymers and has a low product haze value; and the segmented polymerization method of the present invention can obtain ultra-high molecular weight polysulfone products.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing a polysulfone resin by staged polymerization, comprising the following steps:

[0006] Mixing a first halogenated monomer, a first phenolic monomer, a first alkali metal-containing substance and a first solvent for a first prepolymerization reaction to obtain a first prepolymer system; the molar ratio of the first halogenated monomer to the first phenolic monomer is 3.3 to 6:3;

[0007] A second halogenated monomer, a second phenolic monomer, a second alkali metal-containing substance and a second solvent are mixed to perform a second prepolymerization reaction to obtain a second prepolymer system; the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.3-6;

[0008] The first prepolymer system and the second prepolymer system are desalted and then subjected to polymerization reaction to obtain the polysulfone resin.

[0009] Preferably, the first halogenated monomer and the second halogenated monomer independently include 4,4'-dichlorodiphenyl sulfone and / or 4,4'-difluorodiphenyl sulfone.

[0010] Preferably, the first phenolic monomer and the second phenolic monomer independently include one or more of bisphenol A, bisphenol S and 4,4′-biphenol.

[0011] Preferably, the molar ratio of the first halogenated monomer to the first phenolic monomer is 3.8-5.3:3, and the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.8-5.3.

[0012] Preferably, the molar ratio of the total amount of halogenated monomers to the total amount of phenolic monomers is 1-1.05:1-1.05, the halogenated monomers include a first halogenated monomer and a second halogenated monomer, and the phenolic monomers include a first phenolic monomer and a second phenolic monomer.

[0013] Preferably, the first alkali metal-containing substance and the second alkali metal-containing substance independently comprise alkali metal hydroxides and / or alkali metal salts.

[0014] Preferably, the molar ratio of the first alkali metal-containing substance to the first halogenated monomer and the molar ratio of the second alkali metal-containing substance to the second phenolic monomer are independently 1.01-1.51:1.

[0015] Preferably, the temperature of the first prepolymerization reaction and the second prepolymerization reaction are independently 180-200° C., and the time is independently 2-3 hours.

[0016] Preferably, the polymerization reaction temperature is 220-250° C. and the time is 2-8 hours.

[0017] Preferably, the polymerization reaction temperature is 230-250° C. and the time is 4-8 hours.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The invention provides a novel segmented polymerization method for polysulfone resins. The polymerization reaction is divided into two parts: a prepolymerization reaction (including a first prepolymerization reaction and a second prepolymerization reaction) and a polymerization reaction after desalting. The prepolymerization reaction adopts two modes of excess phenolic monomers and excess halogenated monomers. The degree of excess phenolic monomers and excess halogenated monomers can be controlled to control the increase of viscosity of a prepolymer system (including a first prepolymer system and a second prepolymer system). The phenolic monomers and the halogenated monomers complete a salt-forming reaction in the prepolymerization stage, and then desalting treatment is performed. At this time, the viscosity is relatively low. Under the temperature of 200 DEG C, the viscosity range is 5 to 20 mPa·s, and the salt in the prepolymer can be separated more easily. After the desalting treatment is performed at this stage, the overall desalting effect is greatly improved, and the problem that the polysulfone resin is prepared by a one-step synthesis method, after the polysulfone resin forms a high molecular polymer, the resin viscosity becomes large (700 to 1200 mPa·s), and the salt and small molecular polymer contained in the high molecular polymer cannot be effectively removed is solved, and the product quality of the polysulfone resin is improved.

[0020] Furthermore, after the salts are removed from the prepolymer system of the present invention (including the first prepolymer system and the second prepolymer system), the polymerization system approaches a homogeneous phase, the frequency of intermolecular collisions is high, the reaction rate can be greatly improved, and the temperature and time of the polymerization reaction can be controlled at the same time, so that the controllable polymerization of ultra-high molecular weight polymers can be achieved without the occurrence of cross-linking explosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 This is a schematic diagram of the apparatus for preparing polysulfone resin by staged polymerization in Example 1. DETAILED DESCRIPTION

[0023] The present invention provides a method for preparing a polysulfone resin by staged polymerization, comprising the following steps:

[0024] Mixing a first halogenated monomer, a first phenolic monomer, a first alkali metal-containing substance and a first solvent for a first prepolymerization reaction to obtain a first prepolymer system; the molar ratio of the first halogenated monomer to the first phenolic monomer is 3.3 to 6:3;

[0025] A second halogenated monomer, a second phenolic monomer, a second alkali metal-containing substance and a second solvent are mixed to perform a second prepolymerization reaction to obtain a second prepolymer system; the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.3-6;

[0026] The first prepolymer system and the second prepolymer system are desalted and then subjected to polymerization reaction to obtain the polysulfone resin.

[0027] In the present invention, unless otherwise specified, the materials and equipment used are commercially available products in the art.

[0028] The present invention mixes a first halogenated monomer, a first phenolic monomer, a first alkali metal-containing substance and a first solvent to carry out a first prepolymerization reaction to obtain a first prepolymer system; the molar ratio of the first halogenated monomer to the first phenolic monomer is 3.3 to 6:3;

[0029] A second halogenated monomer, a second phenolic monomer, a second alkali metal-containing substance and a second solvent are mixed to carry out a second prepolymerization reaction to obtain a second prepolymer system; the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.3-6.

[0030] In the present invention, the first halogenated monomer and the second halogenated monomer are preferably aromatic dihalogen sulfone monomers, and the aromatic dihalogen sulfone monomers preferably include 4,4′-dichlorodiphenyl sulfone (DCPDS) and / or 4,4′-difluorodiphenyl sulfone (DFDPS), and the first halogenated monomer and the second halogenated monomer are preferably 4,4′-dichlorodiphenyl sulfone.

[0031] In the present invention, the first phenolic monomer and the second phenolic monomer are preferably aromatic dihydroxy monomers, the aromatic dihydroxy monomers preferably include one or more of bisphenol A, bisphenol S and 4,4′-biphenol, and the first halogenated monomer and the second halogenated monomer are preferably 4,4′-biphenol.

[0032] In the present invention, the molar ratio of the first halogenated monomer to the first phenolic monomer is preferably 3.8 to 5.3:3, more preferably 4:3, and the molar ratio of the second halogenated monomer to the second phenolic monomer is preferably 3:3.8 to 5.3, more preferably 3:4. The present invention controls the degree of excess of one of the monomers in the prepolymerization reaction (including the first prepolymerization reaction and the second prepolymerization reaction), which can control the increase in viscosity of the prepolymer system (including the first prepolymer and the second prepolymer), which is beneficial to the subsequent desalination.

[0033] In the present invention, the molar ratio of the total amount of halogenated monomers to the total amount of phenolic monomers is preferably 1-1.05:1-1.05, more preferably 1-1.03:1, the halogenated monomers include a first halogenated monomer and a second halogenated monomer, and the phenolic monomers include a first phenolic monomer and a second phenolic monomer.

[0034] In the present invention, the first alkali metal-containing substance and the second alkali metal-containing substance are independently preferably alkali metal hydroxides and / or alkali metal salts, the alkali metal hydroxides preferably include sodium hydroxide and / or potassium hydroxide, and the alkali metal salts preferably include one or more of sodium carbonate, potassium carbonate, potassium bicarbonate, sodium bicarbonate and sodium hydride.

[0035] In the present invention, the molar ratio of the first alkali metal-containing substance to the first halogenated monomer and the molar ratio of the second alkali metal-containing substance to the second phenolic monomer are independently preferably 1.01-1.51:1, more preferably 1.1:1.

[0036] In the present invention, the first solvent and the second solvent are preferably both aprotic polar solvents, and the aprotic polar solvent preferably includes one or more of dimethyl sulfoxide (DMSO), dimethyl sulfone, diphenyl sulfone (DPS), diethyl sulfoxide, cyclopentane, tetrahydrothiophene-1-monoxide, N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and 1,3-dimethyl-2-imidazolidinone (DMI).

[0037] In the present invention, the temperature of the first prepolymerization reaction and the second prepolymerization reaction is independently preferably 180-200°C, more preferably 190°C, and the time is independently preferably 2-3h. During the first prepolymerization reaction and the second prepolymerization reaction, the hydroxyl end groups in the phenolic monomer react with the alkali metal-containing substance (such as sodium carbonate) in an alkaline environment, and the alkali metal salt end groups of the generated phenolic monomer attack the halogen elements of the halogenated monomer at high temperature to form a preliminary polymer base segment, and the alkali metal and the halogen elements form a halogenated alkali metal salt that falls off.

[0038] In the present invention, the terminal groups of the prepolymers in the first prepolymer system are halogen elements, and the terminal groups of the prepolymers in the second prepolymer system are phenolate terminal groups; the viscosities of the first prepolymer system and the second prepolymer system are preferably 5 to 20 mPa·s.

[0039] After obtaining the first prepolymer and the second prepolymer, the present invention desalts the first prepolymer system and the second prepolymer system and then performs a polymerization reaction to obtain the polysulfone resin.

[0040] In the present invention, the desalination method is preferably hot filtration, the temperature of the hot filtration is preferably 160-190°C, and the hot filtration device is preferably a metal titanium rod filter. The present invention uses hot filtration for desalination. Within the temperature range of the hot filtration described in the present invention, the polymer obtained by the prepolymerization reaction has good solubility and can more thoroughly remove the halogenated alkali metal salt.

[0041] In the present invention, the first prepolymer and the second prepolymer are preferably mixed and then desalted. After the desalting, a capping agent is preferably added. The capping agent preferably includes a halogenated monomer and / or a phenolic monomer. The halogenated monomer is preferably of the same type as the first halogenated monomer or the second halogenated monomer. The phenolic monomer is preferably of the same type as the first phenolic monomer or the second phenolic monomer. Details are not repeated here. The amount of the capping agent is preferably 1% of the total amount of the first halogenated monomer and the second halogenated monomer.

[0042] In the present invention, the polymerization reaction temperature is preferably 220-250° C., more preferably 230-250° C., and more preferably 240° C., and the polymerization reaction time is preferably 2-8 h, more preferably 4-8 h, and more preferably 6 h.

[0043] The present invention obtains a polymer mixture after the polymerization reaction. After obtaining the polymer mixture, the present invention preferably further comprises discharging, dispersing, crushing, washing and drying the polymer mixture in sequence to obtain the polysulfone resin.

[0044] The present invention has no special requirements for the method of dispersing and pulverizing the material, and the method commonly used by those skilled in the art can be adopted. The reagent used for dispersing the material is preferably water, and the polysulfone resin is precipitated in the water during the dispersing process.

[0045] In the present invention, the washing reagent is preferably pure water, the water-to-material mass ratio of the washing is preferably 8:1, the number of washing times is preferably 8 times, and the washing can remove salt.

[0046] In the present invention, the drying temperature is preferably 150-170° C., more preferably 160° C., and the drying time is preferably 6-8 h, more preferably 7 h.

[0047] Figure 1The schematic diagram of the device for preparing polysulfone resin by staged polymerization in the embodiment of the present invention comprises a first polymerization kettle R1, a second polymerization kettle R2 connected in parallel with the first polymerization kettle R1, a filtering device connected to the discharge ports of the first polymerization kettle R1 and the second polymerization kettle R2, and a third polymerization kettle R3 connected to the discharge port of the filtering device. The scheme of preparing polyethersulfone resin by using the device comprises: after preliminary polymerization (prepolymerization reaction) in the polymerization kettles R1 and R2, desalting by the filtering device, and then the filtered and desalted product is subjected to high temperature (220-250°C) polymerization reaction in the reactor R3 to obtain polysulfone resin.

[0048] In order to further illustrate the present invention, the method for preparing polysulfone resin by staged polymerization of the present invention is described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0049] Example 1

[0050] Using 4,4'-dichlorodiphenyl sulfone and 4,4'-biphenyl diphenol, the reaction is carried out according to multi-stage polymerization:

[0051] The molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4'-biphenol in the polymerization reactor R1 is 4:3: 11.486 kg of 4,4'-dichlorodiphenyl sulfone, 5.61 kg of 4,4'-biphenol and 4.7 kg of sodium carbonate are added to the polymerization reactor R1, and cyclopentane is used as the solvent, and the added amount is 44.73 kg;

[0052] The molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4'-biphenyl diphenol in the polymerization reactor R2 in the initial stage polymerization is 3:4: 8.615 kg of 4,4'-dichlorodiphenyl sulfone, 7.48 kg of 4,4'-biphenyl diphenol and 4.7 kg of sodium carbonate are added to the polymerization reactor R2, and cyclopentane is used as the solvent, and the added amount is 41.73 kg;

[0053] The preliminary polymerization in the R1 and R2 polymerization kettles was carried out at 180°C for the polymerization salt-forming reaction, and the reaction in the salt-forming stage was completed after polymerization for 3 hours. The preliminary polymerization products in the R1 and R2 polymerization kettles were filtered and desalted through a filtering device, and then mixed in the R3 reactor for high-temperature polymerization reaction. 1% of the substance amount of 4,4'-dichlorodiphenyl sulfone (based on the total amount in the R1 polymerization kettle and the R1 polymerization kettle) was added to the R3 reactor for end-capping, and the polymerization was stirred at a temperature of 220°C for 5 hours. The entire polymerization process was carried out under the protection of inert gas (nitrogen). After the polymerization was completed, the finished polymer polyphenylsulfone resin powder was obtained by dispersing, crushing, washing (using ultrapure water in the washing process at a water-to-material mass ratio of 8:1 for 8 times) and drying.

[0054] The polysulfone product obtained in Example 1 had a haze of 1.1 and a content of small molecule polymers of 40 ppm.

[0055] Example 2

[0056] Using 4,4'-dichlorodiphenyl sulfone and 4,4-dihydroxydiphenyl sulfone, the reaction is carried out according to multi-stage polymerization:

[0057] The molar ratio of 4,4'-dichlorodiphenyl sulfone and 4,4-dihydroxydiphenyl sulfone in the polymerization reactor R1 is 4:3: 11.486 kg of 4,4'-dichlorodiphenyl sulfone, 7.5 kg of 4,4-dihydroxydiphenyl sulfone and 4.7 kg of sodium carbonate are added to the polymerization reactor R1, and cyclopentane is used as the solvent, and the added amount is 50.388 kg;

[0058] The molar ratio of 4,4'-dichlorodiphenyl sulfone and 4,4-dihydroxydiphenyl sulfone in the polymerization reactor R2 in the initial stage polymerization is 3:4: 8.615 kg of 4,4'-dichlorodiphenyl sulfone, 10 kg of 4,4-dihydroxydiphenyl sulfone and 4.7 kg of sodium carbonate are added to the polymerization reactor R2, and cyclopentane is used as the solvent, and the added amount is 49.275 kg;

[0059] The preliminary polymerization in the R1 and R2 polymerization kettles was carried out at 180°C for the polymerization salt-forming reaction, and the reaction in the salt-forming stage was completed after polymerization for 3 hours. The preliminary polymerization products in the R1 and R2 polymerization kettles were filtered and desalted by a filtering device, and then mixed in the R3 reactor for high-temperature polymerization reaction. 2% of the substance amount of 4,4-dihydroxydiphenyl sulfone (based on the total amount in the R1 polymerization kettle and the R1 polymerization kettle) was added to the R3 reactor for end-capping, and the polymerization was stirred at a temperature of 220°C for 5 hours. The entire polymerization process was carried out under the protection of inert gas (nitrogen). After the polymerization was completed, the finished polymer polyphenylsulfone resin powder was obtained by dispersing, crushing, washing (using ultrapure water in the washing process according to the water-to-material mass ratio of 8:1 for 8 times) and drying.

[0060] The haze of the polysulfone product obtained in Example 2 was 1.5, and the content of small molecular polymers was 50 ppm.

[0061] Example 3

[0062] Using 4,4'-dichlorodiphenyl sulfone and 4,4-dihydroxydiphenyl sulfone, a multi-stage polymerization reaction was carried out to prepare an ultra-high molecular weight polymer, and the polymerization reaction was carried out at a solid content of 35%:

[0063] The molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4-dihydroxydiphenyl sulfone in the polymerization reactor R1 is 4:3: 11.486 kg of 4,4'-dichlorodiphenyl sulfone, 7.504 kg of 4,4-dihydroxydiphenyl sulfone and 7.4 kg of sodium carbonate are added to the polymerization reactor R1, and 31.2 kg of cyclopentane is used as the solvent;

[0064] The molar ratio of 4,4'-dichlorodiphenyl sulfone and 4,4'-dihydroxydiphenyl sulfone in the polymerization reactor R2 in the initial stage polymerization is 3:4: 8.615 kg of 4,4'-dichlorodiphenyl sulfone, 10.048 kg of 4,4-dihydroxydiphenyl sulfone and 7.4 kg of sodium carbonate are added into the polymerization reactor R2, and cyclopentane is used as the solvent, and the added amount is 30.59 kg;

[0065] The initial polymerization in the R1 and R2 polymerization kettles was carried out at 180°C to form a salt, with a solid content of 35%. The salt-forming stage was completed after 3 hours of polymerization. The initial polymerization products in the R1 and R2 polymerization kettles were filtered and desalted by a filtration device, and then mixed in the R3 reactor for high-temperature polymerization. The R3 reactor was stirred and polymerized at a temperature of 240°C for 6 hours. The entire polymerization process was carried out under the protection of inert gas (nitrogen). After the polymerization was completed, the finished polymer polyphenylsulfone resin powder was obtained by discharging, dispersing, crushing, washing (using ultrapure water in the washing process at a water-to-material mass ratio of 8:1 for 8 times) and drying.

[0066] The weight average molecular weight of the polysulfone product obtained in Example 3 is 80w.

[0067] Comparative Example 1

[0068] 4,4'-Dichlorodiphenyl sulfone and 4,4'-biphenyl diphenol were used to carry out the polymerization reaction in a one-step process:

[0069] The molar ratio of 4,4'-dichlorodiphenyl sulfone and 4,4'-biphenol in the polymerization kettle is 1.03:1: 11.83kg of 4,4'-dichlorodiphenyl sulfone, 7.46kg of 4,4'-biphenol and 6.3kg of sodium carbonate are added to the polymerization kettle, and cyclopentane is used as the solvent, and the addition amount is 14.5kg; the polymerization salt reaction is carried out at 180℃ for 3h, and then the temperature is raised to 220℃ and stirred for polymerization reaction for 5h. The whole polymerization process is carried out under the protection of inert gas (nitrogen). After the polymerization is completed, the finished polymer polyphenylsulfone resin powder is obtained by discharging, dispersing, crushing, washing (using ultrapure water in the washing process according to the water-to-material mass ratio of 8:1 for 8 times) and drying.

[0070] The polysulfone product prepared in Comparative Example 1 had a haze of 5 and a content of small molecule polymers of 1000 ppm.

[0071] It can be seen from the data of the embodiments and comparative examples that the haze of the polysulfone resin product obtained by staged polymerization of the present invention is significantly reduced, the content of small molecular polymers is significantly reduced, and the product quality of the polysulfone resin is significantly improved. At the same time, the present invention further controls the solid content of the feed liquid during the polymerization process, the temperature and time of the polymerization reaction, and obtains a polysulfone product with an ultra-high molecular weight (800,000).

[0072] Although the above-mentioned embodiments have made a detailed description of the present invention, they are only some embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on the embodiments of the present invention without creative work, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing polysulfone resin by staged polymerization, characterized in that: The following steps are involved: Mixing a first halogenated monomer, a first phenolic monomer, a first alkali metal-containing substance and a first solvent for a first prepolymerization reaction to obtain a first prepolymer system; the molar ratio of the first halogenated monomer to the first phenolic monomer is 3.3 to 6:3; A second halogenated monomer, a second phenolic monomer, a second alkali metal-containing substance and a second solvent are mixed to perform a second prepolymerization reaction to obtain a second prepolymer system; the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.3-6; Desalting the first prepolymer system and the second prepolymer system and subjecting them to polymerization reaction to obtain the polysulfone resin; The first halogenated monomer and the second halogenated monomer independently include 4,4′-dichlorodiphenyl sulfone and / or 4,4′-difluorodiphenyl sulfone; The first phenolic monomer and the second phenolic monomer independently include one or more of bisphenol A, bisphenol S and 4,4′-biphenyl diphenol; The molar ratio of the first alkali metal-containing substance to the first halogenated monomer and the molar ratio of the second alkali metal-containing substance to the second phenolic monomer are independently 1.01 to 1.51:1; The temperature of the first prepolymerization reaction and the second prepolymerization reaction are independently 180-200° C., and the time is independently 2-3 hours; The molar ratio of the total amount of halogenated monomers to the total amount of phenolic monomers is 1-1.05:1-1.05, the halogenated monomers include a first halogenated monomer and a second halogenated monomer, and the phenolic monomers include a first phenolic monomer and a second phenolic monomer.

2. The method for preparing polysulfone resin by staged polymerization according to claim 1, characterized in that: The molar ratio of the first halogenated monomer to the first phenolic monomer is 3.8-5.3:3, and the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.8-5.

3.

3. The method for preparing polysulfone resin by staged polymerization according to claim 1, characterized in that: The first alkali metal-containing material and the second alkali metal-containing material independently include alkali metal hydroxides and / or alkali metal salts.

4. The method for preparing polysulfone resin by staged polymerization according to claim 1, characterized in that: The polymerization reaction temperature is 220-250° C. and the reaction time is 2-8 hours.

5. The method for preparing polysulfone resin by staged polymerization according to claim 4, characterized in that: The polymerization reaction temperature is 230-250° C. and the reaction time is 4-8 hours.

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