Process for the preparation of polysulfone resin by stepwise polymerization

Abstract

The present application belongs to the field of polymer material production technology and, more particularly, relates to a process for producing polysulfone resin by staged polymerization. The present application provides a novel process for producing polysulfone resin by staged polymerization, in which a polymerization reaction is divided into two parts, namely a pre-polymerization reaction and a polymerization reaction after desalting. The pre-polymerization reaction uses two modes, namely excessive phenolic monomers and excessive halogenated monomers. The phenolic monomers and the halogenated monomers are desalted after the completion of a salt formation reaction in an initial stage of polymerization. At this time, the viscosity is low and the salt in the prepolymer can be easily separated, thereby solving the following problem:When producing polysulfone resin through a one-step synthesis process, after the polysulfone resin forms a high-molecular-weight polymer, the resin viscosity increases, and salts and small-molecule polymers trapped in the high-molecular-weight polymer cannot be effectively removed. This improves the quality of the polysulfone resin. At the same time, the polymerization system approaches a homogeneous phase after desalting, which significantly increases the reaction rate and allows controllable polymerization of ultrahigh-molecular-weight polymers without crosslinking and explosion.

Description

[0001] This application claims priority to Chinese Patent Application No. CN202311526518.4 filed with CNIPA (China National Intellectual Property Administration) on November 15, 2023, entitled “Method for producing polysulfone resin by stepwise polymerization,” the entire contents of which are incorporated into the present application by reference. TECHNICAL FIELD

[0002] The present application belongs to the field of production technology of polymer materials and, in particular, relates to a process for producing polysulfone resin by stepwise polymerization. STATE OF THE ART

[0003] The most advanced production process for polysulfone polymer materials currently is a one-step synthesis process in which the main raw materials, namely 4,4'-dichlorodiphenylsulfone (halogenated monomer), phenolic polymerized monomers, and alkali metal salts (such as potassium carbonate), are polymerized in a solvent. Commonly used solvents include dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and others. After the polymerization is complete, water, ethanol, or methanol is used as a precipitant. The polysulfone is separated from the polymer solution under the action of the precipitant. The separated polysulfone is purified, dried, granulated, and packaged to obtain polysulfone products.However, in the production of polysulfone resin by this one-step synthesis method, after the completion of polymerization, the polysulfone resin becomes a high-molecular-weight polymer, and the resin exhibits high viscosity. Salts and small-molecular-weight polymers trapped in the high-molecular-weight polymer cannot be effectively removed, which affects the product quality of the polysulfone resin. Because the polymerization system is heterogeneous, salts and small-molecular-weight polymers are present, which affects the frequency of intermolecular collisions during the stirring process of the polymerization reaction and impairs the reaction rate, thus preventing ultra-high-molecular-weight polysulfone products from being obtained by polymerization. CONTENT OF THE PRESENT INVENTION

[0004] Against this background, the object of the present application is to provide a process for producing polysulfone resin by stepwise polymerization. The present application uses a stepwise polymerization process for producing polysulfone resin that includes fewer salts and small-molecule polymers and exhibits a low product turbidity value. Furthermore, the stepwise polymerization process of the present application can produce ultrahigh-molecular-weight polysulfone products.

[0005] To achieve the above-mentioned object of the invention, the present application provides the following technical solution: The present application provides a process for producing polysulfone resin by stepwise polymerization, comprising the following steps: Mixing 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, wherein a molar ratio of the first halogenated monomer to the first phenolic monomer is 3.3 to 6:3, wherein the first halogenated monomer contains a sulfone group; Mixing a second halogenated monomer, a second phenolic monomer, a second alkali metal-containing substance and a second solvent to carry out a second prepolymerization reaction, to obtain a second prepolymer system, wherein a molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.3 to 6, wherein the second halogenated monomer contains a sulfone group; and Conducting a polymerization reaction of the first prepolymer system and the second prepolymer system after desalting them to obtain a polysulfone resin.

[0006] Preferably, the first halogenated monomer and the second halogenated monomer independently comprise 4,4'-dichlorodiphenyl sulfone and / or 4,4'-difluorodiphenyl sulfone. Preferably, the first phenolic monomer and the second phenolic monomer independently comprise one or more of bisphenol A, bisphenol S, and 4,4'-biphenol.

[0007] Preferably, the molar ratio of the first halogenated monomer to the first phenolic monomer is 3.8 to 5.3:3, with the molar ratio of the second halogenated monomer to the second phenolic monomer being 3:3.8 to 5.3.

[0008] Preferably, a molar ratio of a total amount of halogenated monomers to a total amount of phenolic monomers is 1 to 1.05:1 to 1.05, wherein the halogenated monomers include the first halogenated monomer and the second halogenated monomer, and wherein the phenolic monomers include the first phenolic monomer and the second phenolic monomer. Preferably, the first alkali metal-containing substance and the second alkali metal-containing substance independently comprise an alkali metal hydroxide and / or an alkali metal salt. Preferably, a molar ratio of the first alkali metal-containing substance to the first halogenated monomer and a molar ratio of the second alkali metal-containing substance to the second phenolic monomer independently of one another is 1.01 to 1.51:1.Preferably, the first prepolymerization reaction and the second prepolymerization reaction independently have a temperature of 180 °C to 200 °C and a duration of 2 to 3 hours.

[0009] Preferably, the polymerization reaction has a temperature of 220 °C to 250 °C and a duration of 2 to 8 hours.

[0010] Preferably, the polymerization reaction has a temperature of 230 °C to 250 °C and a duration of 4 to 8 hours.

[0011] The present invention further provides an apparatus for producing polysulfone resin by staged polymerization, comprising a first polymerization vessel, a second polymerization vessel connected in parallel to the first polymerization vessel, a filter device connected to a discharge port of the first polymerization vessel and the second polymerization vessel, and a third polymerization vessel connected to a discharge port of the filter device. Compared with the prior art, the present application has the following advantageous effects: The present application provides a novel process for producing polysulfone resin by stepwise polymerization, in which a polymerization reaction is divided into two parts, namely, a prepolymerization reaction (including the first prepolymerization reaction and the second prepolymerization reaction) and a polymerization reaction after desalting. Two modes, namely, excessive phenolic monomers and excessive halogenated monomers, are used in the prepolymerization reaction. By controlling the degree of excess of the phenolic monomers and the halogenated monomers, respectively, the increase in viscosity of a prepolymer system (including the first prepolymer system and the second prepolymer system) can be controlled.The phenolic monomers and the halogenated monomers complete a salt formation reaction in a prepolymerization step and then undergo desalting treatment; at this time, the viscosity is comparatively low. At a temperature of 200°C, the viscosity ranges from 5 to 20 mPa s, which can facilitate the separation of the salt in the prepolymer. After the desalting treatment in this step, the overall desalting effect is greatly improved, and the following problem is solved: in the production of polysulfone resin by the one-step synthesis method, after the polysulfone resin forms a high-molecular-weight polymer, the resin viscosity (i.e., ranging from 700 mPa s to 1200 mPa s) increases, and salts and small-molecule polymers trapped in the high-molecular-weight polymer cannot be effectively removed. This improves the quality of the polysulfone resin.

[0012] Furthermore, after desalting the prepolymer system of the present application (including the first prepolymer system and the second prepolymer system), the polymerization system approaches a homogeneous phase, with a high frequency of intermolecular collisions, which can significantly increase the reaction rate. At the same time, the temperature and time of the polymerization reaction are controlled, allowing controllable polymerization of ultrahigh molecular weight polymers without crosslinking and explosion. SHORT DESCRIPTION OF THE DRAWING

[0013] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings to be used in the embodiments are briefly presented below. Obviously, the drawings in the following description represent only some embodiments of the present application. Those skilled in the art can also obtain further drawings based on these drawings without inventive activity. Fig. 1 shows a simplified view of the apparatus for producing polysulfone resin by stepwise polymerization in Embodiment 1. DETAILED DESCRIPTION

[0014] The present application provides a process for producing polysulfone resin by segmented polymerization, comprising the following steps: Mixing 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, wherein a molar ratio of the first halogenated monomer to the first phenolic monomer is 3.3 to 6:3, wherein the first halogenated monomer contains a sulfone group; Mixing a second halogenated monomer, a second phenolic monomer, a second alkali metal-containing substance, and a second solvent to conduct a second prepolymerization reaction to obtain a second prepolymer system, wherein a molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.3 to 6, wherein the second halogenated monomer contains a sulfone group; and Conducting a polymerization reaction of the first prepolymer system and the second prepolymer system after desalting them to obtain a polysulfone resin.

[0015] Unless otherwise stated, materials and devices used in this application are commercially available products in the art.

[0016] In the present application, it is provided that the first halogenated monomer, the first phenolic monomer, the first alkali metal-containing substance and the first solvent are mixed and subjected to a first prepolymerization reaction to obtain the first prepolymer system, wherein the molar ratio of the first halogenated monomer to the first phenolic monomer is 3.3 to 6:3; and that the second halogenated monomer, the second phenolic monomer, the second alkali metal-containing substance and the second solvent are mixed and subjected to a second prepolymerization reaction to obtain the second prepolymer system, wherein the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.3 to 6.

[0017] In the present application, it is contemplated that the first halogenated monomer and the second halogenated monomer are preferably aromatic dihalosulfone monomers, preferably comprising 4,4'-dichlorodiphenylsulfone (DCPDS) and / or 4,4'-difluorodiphenylsulfone (DFDPS), wherein the first halogenated monomer and the second halogenated monomer are preferably 4,4'-difluorodiphenylsulfone.

[0018] In the present application, it is contemplated that the first phenolic monomer and the second phenolic monomer are preferably aromatic dihydroxy monomers, preferably comprising one or more of bisphenol A, bisphenol S and 4,4'-biphenol, wherein the first phenolic monomer and the second phenolic monomer are preferably 4,4'-biphenol.

[0019] In the present application, it is contemplated that 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. In the present application, the degree of excess of one of the monomers in the prepolymerization reaction (including the first prepolymerization reaction and the second prepolymerization reaction) is controlled, whereby the increase in viscosity of the prepolymer system (including the first prepolymer and the second prepolymer) can be controlled, which is advantageous for subsequent desalting.In the present application, it is contemplated that a molar ratio of a total amount of halogenated monomers to a total amount of phenolic monomers is preferably 1 to 1.05:1 to 1.05, more preferably 1 to 1.03:1, wherein the halogenated monomers include the first halogenated monomer and the second halogenated monomer, and wherein the phenolic monomers include the first phenolic monomer and the second phenolic monomer.

[0020] In the present application, it is provided that the first alkali metal-containing substance and the second alkali metal-containing substance independently of one another preferably comprise an alkali metal hydroxide and / or an alkali metal salt, wherein the alkali metal hydroxide preferably comprises sodium hydroxide and / or potassium hydroxide, and wherein the alkali metal salt preferably comprises one or more of sodium carbonate, potassium carbonate, potassium bicarbonate, sodium bicarbonate and sodium hydride.

[0021] In the present application, it is provided that a molar ratio of the first alkali metal-containing substance to the first halogenated monomer and a molar ratio of the second alkali metal-containing substance to the second phenolic monomer are independently of each other preferably 1.01 to 1.51:1, more preferably 1.1:1.

[0022] In the present application, it is contemplated that both the first solvent and the second solvent are preferably aprotic polar solvents, preferably comprising one or more of dimethyl sulfoxide (DMSO), dimethyl sulfone, diphenyl sulfone (DPS), diethyl sulfoxide, sulfolane, tetrahydrothiophene-1-monoxide, N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), and 1,3-dimethyl-2-imidazolinone (DMI).

[0023] In the present application, the first prepolymerization reaction and the second prepolymerization reaction independently of one another are carried out at a temperature that is preferably 180°C to 200°C, more preferably 190°C, and for a time that is preferably 2 to 3 hours. During the first prepolymerization reaction and the second prepolymerization reaction, hydroxyl end groups in the phenolic monomers react with alkali metal-containing substances (e.g., sodium carbonate) in an alkaline environment. The resulting alkali metal salt end groups of the phenolic monomers attack the halogen elements of the halogenated monomers at a high temperature to form preliminary backbone segments of the polymer, while the alkali metal and halogen elements form halogenated alkali metal salts that precipitate.

[0024] In the present application, the end groups of the prepolymer in the first prepolymer system are halogen elements, wherein the end groups of the prepolymer in the second prepolymer system are phenate end groups, wherein the viscosity of the first prepolymer system and the second prepolymer system is preferably 5 mPa s to 20 mPa s.

[0025] In the present application, after obtaining the first prepolymer and the second prepolymer, the first prepolymer system and the second prepolymer system are desalted and then polymerized to obtain the polysulfone resin.

[0026] In the present application, the desalting method is preferably hot filtration. The hot filtration temperature is preferably 160°C to 190°C. A hot filtration device is preferably a rod filter made of titanium metal. In the present application, hot filtration is used for desalting. Within the hot filtration temperature range described in the present application, the polymer obtained by the prepolymerization reaction has good solubility, and the halogenated alkali metal salt can be removed more thoroughly. In the present application, it is preferable to mix the first prepolymer and the second prepolymer before desalting. preferably further comprises adding an endcapping agent, wherein the endcapping agent preferably comprises a halogenated monomer and / or a phenolic monomer.The halogenated monomer is preferably of the same type as the first or second halogenated monomer, and the phenolic monomer is preferably of the same type as the first or second phenolic monomer, which will not be described repeatedly herein. The amount of endcapping agent used is preferably 1% of the total molar amount of the first halogenated monomer and the second halogenated monomer, or 2% of the total molar amount of the first phenolic monomer and the second phenolic monomer.

[0027] In the present application, it is provided that the polymerization reaction has a temperature which is preferably 220 °C to 250 °C, more preferably 230 °C to 250 °C and even more preferably 240 °C, and a time which is preferably 2 to 8 hours, more preferably 4 to 8 hours and even more preferably 6 hours.

[0028] In the present application, a polymer mixture is obtained after the polymerization reaction. After obtaining the polymer mixture, the present application preferably further comprises discharging and dispersing the resulting polymer mixture, crushing, washing, and drying, which are performed sequentially to obtain the polysulfone resin.

[0029] In the present application, no special requirements are imposed on the methods of discharging and dispersing and comminuting, and any method commonly used by those skilled in the art can be used. The reagent for discharging and dispersing is preferably water. The polysulfone resin is precipitated in the water during discharging and dispersing.

[0030] In the present application, the reagent for washing is preferably pure water, the mass ratio of water used for washing to material is preferably 8:1, the number of washing operations is preferably 8, and desalting can be carried out by washing.

[0031] In the present application, drying is carried out at a temperature preferably between 150 and 170°C, more preferably between 160°C, and preferably for 6 to 8 hours, more preferably for 7 hours. The present invention further provides an apparatus for producing polysulfone resin by staged polymerization, comprising a first polymerization vessel, a second polymerization vessel connected in parallel to the first polymerization vessel, a filter device connected to a discharge port of the first polymerization vessel and the second polymerization vessel, and a third polymerization vessel connected to a discharge port of the filter device. Fig.1 shows a simplified view of the apparatus for producing polysulfone resin by staged polymerization in embodiments of the present application. The apparatus includes a first polymerization vessel R1, a second polymerization vessel R2 connected in parallel to the first polymerization vessel R1, a filter device connected to a discharge port of the first polymerization vessel R1 and the second polymerization vessel R2, and a third polymerization vessel R3 connected to a discharge port of the filter device. The solution using the apparatus for producing polyethersulfone includes: after preliminary polymerization (i.e., a pre-polymerization reaction) is carried out in the polymerization vessels R1 and R2, respectively, desalting is carried out by the filter device; then, the filtered ordesalted product is subjected to a polymerization reaction in a reaction vessel R3 at a high temperature (from 220 °C to 250 °C) to obtain a polysulfone resin.

[0032] In order to further illustrate the present application, the process for producing polysulfone resin by stepwise polymerization according to the present application will be described in detail below with reference to the accompanying drawings and the working examples, which, however, should not be construed as limitations on the scope of the present application. Example 1

[0033] Using 4,4'-dichlorodiphenylsulfone and 4,4'-biphenol, the reaction proceeds according to a multi-stage polymerization: In an initial stage of the polymerization, the molar ratio of 4,4'-dichlorodiphenylsulfone to 4,4'-biphenol in the R1 polymerization vessel is 4:3: Add 11.486 kg of 4,4'-dichlorodiphenylsulfone, 5.61 kg of 4,4'-biphenol and 4.7 kg of sodium carbonate to the polymerization vessel R1, and Using sulfolane as a solvent, the added amount of which is 44.73 kg.

[0034] In the initial stage of polymerization, the molar ratio of 4,4'-dichlorodiphenylsulfone to 4,4'-biphenol in the polymerization vessel R2 is 3:4: Adding 8.615 kg of 4,4'-dichlorodiphenyl sulfone, 7.48 kg of 4,4'-biphenol and 4.7 kg of sodium carbonate to the polymerization vessel R2, and using sulfolane as a solvent, the added amount of which is 41.73 kg.

[0035] During the prepolymerization in polymerization vessels R1 and R2, a polymerization salt formation reaction is carried out at a temperature of 180 °C. After a three-hour polymerization, the reaction in the salt formation stage is completed. The preliminary polymerization products in polymerization vessels R1 and R2 are filtered or desalted through the filter device and then mixed in reaction vessel R3 to undergo high-temperature polymerization. 1% of 4,4'-dichlorodiphenyl sulfone (based on the total amount in polymerization vessels R1 and R2) is added to reaction vessel R3 for end-capping and is stirred and polymerized at a temperature of 220 °C for 5 hours. The entire polymerization process is carried out under the protection of inert gas (nitrogen).After the polymerization is completed, a finished polymer, i.e., polyphenylsulfone resin powder, is obtained by discharging and dispersing, crushing, washing (high-purity water with a mass ratio of water to material of 8:1 is used for the washing process, with the number of washing processes being 8) and drying.

[0036] The turbidity of the polysulfone product prepared in Example 1 is 1.1 and the low molecular weight polymer content is 40 ppm. Example 2

[0037] Using 4,4'-dichlorodiphenylsulfone and 4,4-dihydroxydiphenylsulfone, the reaction proceeds according to a multi-stage polymerization: In the initial stage of polymerization, the molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4-dihydroxydiphenyl sulfone in the polymerization vessel R1 is 4:3: adding 11.486 kg of 4,4'-dichlorodiphenyl sulfone, 7.5 kg of 4,4-dihydroxydiphenyl sulfone and 4.7 kg of sodium carbonate into the polymerization vessel R1, and using sulfolane as a solvent, the added amount of which is 50.388 kg.

[0038] In the initial stage of polymerization, the molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4-dihydroxydiphenyl sulfone in the polymerization vessel R2 is 3:4: adding 8.615 kg of 4,4'-dichlorodiphenyl sulfone, 10 kg of 4,4-dihydroxydiphenyl sulfone and 4.7 kg of sodium carbonate into the polymerization vessel R2, and using sulfolane as a solvent, the added amount of which is 49.275 kg.

[0039] During the prepolymerization in polymerization vessels R1 and R2, a polymerization salt formation reaction is carried out at a temperature of 180 °C. After a three-hour polymerization, the reaction in the salt formation stage is completed. The preliminary polymerization products in polymerization vessels R1 and R2 are filtered or desalted through the filter device and then mixed in reaction vessel R3 to undergo high-temperature polymerization. 2% of 4,4'-dihydroxydiphenyl sulfone (based on the total amount in polymerization vessels R1 and R2) is added to reaction vessel R3 for end-capping and is stirred and polymerized at a temperature of 220 °C for 5 hours. The entire polymerization process is carried out under the protection of inert gas (nitrogen).After the polymerization is completed, a finished polymer, i.e., polyphenylsulfone resin powder, is obtained by discharging and dispersing, crushing, washing (high-purity water with a mass ratio of water to material of 8:1 is used for the washing process, with the number of washing processes being 8) and drying.

[0040] The turbidity of the polysulfone product prepared in Example 2 is 1.5 and the low molecular weight polymer content is 50 ppm. Example 3

[0041] Using 4,4'-dichlorodiphenyl sulfone and 4,4-dihydroxydiphenyl sulfone, the reaction proceeds according to a multi-stage polymerization to produce an ultra-high molecular weight polymer, wherein the polymerization reaction is carried out at a solid content of 35%: In the initial stage of polymerization, the molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4-dihydroxydiphenyl sulfone in the polymerization vessel R1 is 4:3: adding 11.486 kg of 4,4'-dichlorodiphenyl sulfone, 7.504 kg of 4,4-dihydroxydiphenyl sulfone and 7.4 kg of sodium carbonate into the polymerization vessel R1, and using sulfolane as a solvent, the added amount of which is 31.2 kg.

[0042] In the initial stage of polymerization, the molar ratio of 4,4'-dichlorodiphenyl sulfone to 4,4'-dihydroxydiphenyl sulfone in the polymerization vessel R2 is 3:4: adding 8.615 kg of 4,4'-dichlorodiphenyl sulfone, 10.048 kg of 4,4-dihydroxydiphenyl sulfone and 7.4 kg of sodium carbonate into the polymerization vessel R2, and using sulfolane as a solvent, the added amount of which is 30.59 kg.

[0043] During the preliminary polymerization in polymerization vessels R1 and R2, a polymerization salt formation reaction is carried out at a temperature of 180°C, with a solid content of 35%. After three hours of polymerization, the reaction in the salt formation stage is completed. The preliminary polymerization products in polymerization vessels R1 and R2 are filtered or desalted through the filter device and then mixed in reaction vessel R3 to undergo high-temperature polymerization. In reaction vessel R3, stirring and polymerization take place at a temperature of 240°C for 6 hours, with the entire polymerization process being carried out under the protection of inert gas (nitrogen).After the polymerization is completed, a finished polymer, i.e., polyphenylsulfone resin powder, is obtained by discharging and dispersing, crushing, washing (high-purity water with a mass ratio of water to material of 8:1 is used for the washing process, with the number of washing processes being 8) and drying.

[0044] The weight average molecular weight of the polysulfone product prepared in Example 3 is 80 w. Comparison example 1

[0045] Using 4,4'-dichlorodiphenylsulfone and 4,4'-biphenol, the reaction proceeds according to the one-step synthesis procedure: The molar ratio of 4,4'-dichlorodiphenylsulfone to 4,4'-biphenol in the polymerization vessel is 1.03:1. Add 11.83 kg of 4,4'-dichlorodiphenylsulfone, 7.46 kg of 4,4'-biphenol, and 6.3 kg of sodium carbonate to the polymerization vessel, and use sulfolane as a solvent, the added amount of which is 14.5 kg. Conduct a polymerization salt formation reaction at a temperature of 180°C for 3 hours, then raise the temperature to 220°C, and stir the polymerization reaction for 5 hours. The entire polymerization process is carried out under the protection of inert gas (nitrogen). After the polymerization is completed, a finished polymer, i.e., polyphenylsulfone resin powder, is obtained by discharging and dispersing, crushing, washing (high-purity water with a mass ratio of water to material of 8:1 is used for the washing process, with the number of washing processes being 8) and drying.

[0046] The turbidity of the polysulfone product produced in Comparative Example 1 is 5, and the low-molecular-weight polymer content is 1000 ppm. From the data of the working examples and Comparative Example, it can be seen that the turbidity of the polysulfone resin produced by staged polymerization in the present application is significantly reduced, the low-molecular-weight polymer content is significantly reduced, and the quality of the polysulfone resin is significantly improved. At the same time, the present application further controls the solid content of the feed liquid, the temperature, and the polymerization reaction time during the polymerization process, thereby producing polysulfone products with an ultrahigh molecular weight (800,000.00).

[0047] Although the embodiments described above describe the present application in more detail, they represent only a part of the embodiments of the present application and not all embodiments. Based on the embodiments of the present application, further embodiments can be obtained without inventive step, which fall within the scope of protection of the present application. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] CH 202311526518.4

[0001]

Claims

[1] Process for the preparation of polysulfone resin by stepwise polymerization, characterized by that it includes the following steps: Mixing 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, wherein a molar ratio of the first halogenated monomer to the first phenolic monomer is 3.3 to 6:3, wherein the first halogenated monomer contains a sulfone group; Mixing a second halogenated monomer, a second phenolic monomer, a second alkali metal-containing substance and a second solvent to carry out a second prepolymerization reaction, to obtain a second prepolymer system, wherein a molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.3 to 6, wherein the second halogenated monomer contains a sulfone group; and Conducting a polymerization reaction of the first prepolymer system and the second prepolymer system after desalting them to obtain a polysulfone resin. [2] A process for producing polysulfone resin by stepwise polymerization according to claim 1, characterized by that the first halogenated monomer and the second halogenated monomer independently comprise 4,4'-dichlorodiphenyl sulfone and / or 4,4'-difluorodiphenyl sulfone. [3] A process for producing polysulfone resin by stepwise polymerization according to claim 1, characterized by that the first phenolic monomer and the second phenolic monomer independently comprise one or more of bisphenol A, bisphenol S and 4,4'-biphenol. [4] A process for producing polysulfone resin by stepwise polymerization according to claim 1, characterized by that the molar ratio of the first halogenated monomer to the first phenolic monomer is 3.8 to 5.3:3, wherein the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:3.8 to 5.

3. [5] A process for producing polysulfone resin by stepwise polymerization according to claim 4, characterized by that the molar ratio of the first halogenated monomer to the first phenolic monomer is 4:3, wherein the molar ratio of the second halogenated monomer to the second phenolic monomer is 3:

4. [6] A process for producing polysulfone resin by stepwise polymerization according to claim 1 or 4, characterized bythat a molar ratio of a total amount of halogenated monomers to a total amount of phenolic monomers is 1 to 1.05:1 to 1.05, wherein the halogenated monomers include the first halogenated monomer and the second halogenated monomer, and wherein the phenolic monomers include the first phenolic monomer and the second phenolic monomer. [7] A process for producing polysulfone resin by stepwise polymerization according to claim 1, characterized by that the first alkali metal-containing substance and the second alkali metal-containing substance independently comprise an alkali metal hydroxide and / or an alkali metal salt. [8] A process for producing polysulfone resin by stepwise polymerization according to claim 1 or 7, characterized bythat a molar ratio of the first alkali metal-containing substance to the first halogenated monomer and a molar ratio of the second alkali metal-containing substance to the second phenolic monomer are independently 1.01 to 1.51:

1. [9] A process for producing polysulfone resin by stepwise polymerization according to claim 1, characterized by that the first prepolymerization reaction and the second prepolymerization reaction independently have a temperature of 180 °C to 200 °C and a duration of 2 to 3 hours. [10] A process for producing polysulfone resin by stepwise polymerization according to claim 1, characterized by that it comprises adding an end-capping agent after desalting. [11] A process for producing polysulfone resin by stepwise polymerization according to claim 1, characterized bythat the polymerization reaction has a temperature of 220 °C to 250 °C and a duration of 2 to 8 hours. [12] A process for producing polysulfone resin by stepwise polymerization according to claim 11, characterized by that the polymerization reaction has a temperature of 230 °C to 250 °C and a duration of 4 to 8 hours. [13] A process for producing polysulfone resin by stepwise polymerization according to claim 1, characterized by that after the polymerization reaction, it further comprises discharging and dispersing, crushing, washing and drying the resulting polymer mixture, which are carried out in sequence, to obtain the polysulfone resin. [14] Apparatus for producing polysulfone resin by stepwise polymerization, characterized bythat it comprises a first polymerization vessel, a second polymerization vessel connected in parallel to the first polymerization vessel, a filter device connected to a discharge opening of the first polymerization vessel and the second polymerization vessel, and a third polymerization vessel connected to a discharge opening of the filter device.

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