A process for the preparation of polyether sulfone by nucleophilic substitution

Abstract

The application discloses a method for preparing polyether sulfone by a nucleophilic substitution reaction, and discloses the following steps: taking dimethyl sulfone as a solvent, canceling a double-phenol S / potassium carbonate salification mode, and replacing the double-phenol S / potassium carbonate salification mode with cheap sodium hydroxide / potassium hydroxide, so that the cost is reduced; the whole polymerization process does not emit carbon dioxide; the reaction temperature is increased, the molecular activity is strong, the reaction time is shortened, and the polymerization efficiency is improved; the product is porous after ethanol washing, water can enter the inside of the particles during water washing, salt is washed out, and the salt content in the finished product resin is reduced; no solvent hydrolysis phenomenon occurs in the polymerization process, no N-methyl-4-hydroxyaminobutyric acid is generated, and the product has high purity; the polymerization is a full solid-state feeding process, and no solvent needs to be supplemented, so that the method is a simple and efficient polymerization method and can be applied to industrial production.

Description

Technical Field

[0001] This invention discloses a method for synthesizing polyethersulfone, which uses dimethyl sulfone as a solvent and produces polyethersulfone by reacting a monomer, 4,4′-dichlorodiphenyl sulfone, with sodium hydroxide to form a salt. This is a novel method for preparing polyethersulfone and belongs to the field of polymer synthesis technology. Background Technology

[0002] Existing methods for synthesizing polyethersulfone mainly involve nucleophilic synthesis: using 4,4′-dihydroxydiphenyl sulfone (bisphenol S) or 4,4′-dichlorodiphenyl sulfone (DCDPS) as monomers, N-methylpyrrolidone or sulfolane as solvents, and potassium carbonate as a salt-forming agent, the synthesis is carried out at 190-200℃ for 4-5 hours. The principle is that bisphenol S first reacts with potassium carbonate to form a potassium phenolate salt solution of bisphenol S and carbon dioxide. As the temperature rises, the water and carbon dioxide evaporate and are discharged from the system. The potassium phenolate salt of bisphenol S continues to react with DCDPS to form a polymer and potassium chloride. After the reaction, the polymerization liquid is poured into water to break it up, then washed 3-5 times with pure water and dried. Because N-methylpyrrolidone has a low boiling point, the synthesis temperature can only be below 200℃, resulting in low activity of the bisphenol S potassium salt monomer, a long polymerization time, and slow water removal. This makes it difficult to remove N-methylpyrrolidone, which hydrolyzes to N-methyl-4-hydroxyaminobutyric acid under alkaline conditions, from the system. While sulfolane has a high boiling point, meeting the synthesis requirements, it also hydrolyzes at high temperatures, producing harmful impurities that are difficult to remove. Furthermore, during the drainage process, N-methylpyrrolidone and sulfolane solvent are discharged along with the water, causing an imbalance in the solvent-reactant / product / solvent ratio, necessitating mid-process solvent replenishment and complicating the operation. Post-reaction treatment using water precipitation from the resin results in salts being trapped inside the resin, making them difficult to remove.

[0003] Polyether sulfone (PES) can be prepared mainly through two methods: nucleophilic polymerization and electrophilic polymerization. Nucleophilic polymerization is more widely used, but byproducts are difficult to separate, the solvent is easily hydrolyzed, and the purity is not high. Electrophilic polymerization requires Lewis acids as catalysts, and the reaction and separation conditions are relatively harsh. Therefore, developing a novel method for preparing PES is of great significance. Summary of the Invention

[0004] This invention discloses a method for preparing polyethersulfone via nucleophilic substitution reaction. It utilizes sodium hydroxide / potassium hydroxide instead of potassium carbonate as the salt-forming agent and dimethyl sulfone instead of N,methylpyrrolidone as the solvent to prepare polyethersulfone through nucleophilic substitution reaction. This method solves the problems of long reaction time, complex operation, easy hydrolysis of the solvent N-methylpyrrolidone in the presence of alkali, and difficulty in removing salt residues in existing polyethersulfone synthesis methods.

[0005] The present invention discloses a method for preparing polyethersulfone via nucleophilic substitution reaction, which mainly uses 4,4′-dichlorodiphenyl sulfone as a monomer, sodium / potassium hydroxide as a salt-forming agent, and dimethyl sulfone as a polymerization solvent, and reacts at 180-240°C for 1-4 hours. The main steps include:

[0006] 1) In a closed reactor connected to a condenser, nitrogen gas is continuously introduced, and 4,4′-dichlorodiphenyl sulfone, a salt-forming agent, and a solvent are added. The mass of the dimethyl sulfone solvent added is 0.5-3 times the sum of the masses of 4,4′-dichlorodiphenyl sulfone and the salt-forming agent. The mixture is heated to 180-240℃ and stirred for 1-4 hours.

[0007] 2) After the reaction is complete, cool and crush the mixture, wash it 3-10 times with 0-100% ethanol / deionized water (V / V) at 0-100℃, and dry it to obtain a sponge-like porous polyethersulfone.

[0008] The salt-forming agent is sodium hydroxide, potassium hydroxide, or a mixture of both, with a molar ratio of 0-1:1.

[0009] The volume content of the ethanol / deionized aqueous solution is 0-100%, the washing temperature is 0-100℃, and the number of washing cycles is 3-10.

[0010] The molar ratio of the salt-forming agent to the monomer is 2-2.5:1.

[0011] The advantages of this invention are as follows: it eliminates the bisphenol S / potassium carbonate salt formation method and replaces it with inexpensive sodium hydroxide / potassium hydroxide, reducing costs; the entire polymerization process is free of carbon dioxide emissions; the increased reaction temperature leads to stronger molecular activity, shortening the reaction time and improving polymerization efficiency; the product is porous after ethanol washing, allowing water to penetrate the particles during water washing and remove the salt, reducing the salt content in the finished resin; there is no solvent hydrolysis during polymerization, resulting in no N-methyl-4-hydroxyaminobutyric acid (NABA) produced, leading to high product purity; the polymerization is entirely solid-state feeding, requiring no solvent replenishment, making it a simple and efficient polymerization method applicable to industrial production. Implementation

[0012] The present invention is further illustrated by the following embodiments, which are not intended to limit the invention in any way. Any modifications or alterations made to the present invention that are easily implemented by those skilled in the art without departing from the technical solutions of the present invention shall fall within the scope of the claims of the present invention. Example 1

[0013] 1. Nitrogen gas is continuously introduced into a 1000ml sealed four-necked flask connected to a condenser and a stirrer. 436g of dimethyl sulfone, 287.16g of 4,4′-dichlorodiphenyl sulfone, 40g of sodium hydroxide, and 58g of potassium hydroxide are then added.

[0014] 2. The flask containing the added material was heated to 230℃ and stirred for 3 hours. The material in the flask was then poured out, cooled, and crushed. It was washed 8 times with 50% ethanol / deionized water solution (V / V) at 60℃ and dried to obtain a sponge-like porous polyethersulfone. GPC analysis showed that the Mw was 145300 and the ash content was 0.05w. Example 2

[0015] 1. Nitrogen gas is continuously introduced into a 100L reactor connected to a condenser, and 43.6 kg of dimethyl sulfone, 28.716 kg of 4,4′-dichlorodiphenyl sulfone, and 11.6 kg of potassium hydroxide are added.

[0016] 2. Heat the material in the reactor to 220℃ and stir for 3 hours. Open the discharge valve to discharge the material from the reactor. Cool, crush, and wash 6 times with 50% ethanol / deionized water solution (V / V) at 60℃. After drying, the polyethersulfone product is obtained. GPC testing showed that the Mw was 16030 and the ash content was 0.11w. Example 3

[0017] 1. Nitrogen gas is continuously introduced into a 500L reactor connected to a condenser, and 174.4 kg of dimethyl sulfone, 114.86 kg of 4,4′-dichlorodiphenyl sulfone, and 46.4 kg of potassium hydroxide are added.

[0018] 2. Heat the material in the reactor to 225℃ and stir for 3 hours. Open the discharge valve to discharge the material from the reactor. Cool, crush, and wash 8 times with 45% ethanol / deionized water solution (V / V) at 60℃. After drying, the polyethersulfone product is obtained. GPC testing showed that the Mw was 166502 and the ash content was 0.09w. Example 4

[0019] 1. Nitrogen gas is continuously introduced into a 1000L reactor connected to a condenser, and 444.7-2.4 kg of dimethyl sulfone, 369.4 kg of 4,4′-dichlorodiphenyl sulfone, and 81.6 kg of sodium hydroxide are added.

[0020] 2. Heat the material in the reactor to 230℃ and stir for 3 hours. Open the discharge valve to discharge the material from the reactor. Cool, crush, and wash 8 times with 60% ethanol / deionized water solution (V / V) at 65℃. After drying, the polyethersulfone product is obtained. GPC testing showed that the Mw was 170687 and the ash content was 0.08w. Example 5

[0021] 1. Nitrogen is continuously introduced into a 1000L reactor connected to a condenser, and 453.44 kg of dimethyl sulfone, 298.65 kg of 4,4′-dichlorodiphenyl sulfone, 41.6 kg of sodium hydroxide, and 60.32 kg of potassium hydroxide are added.

[0022] 2. Heat the material in the reactor to 230℃ and stir for 2 hours. Open the discharge valve to discharge the material from the reactor. Cool, crush, and wash 9 times with 80% ethanol / deionized water solution (V / V) at 70℃. After drying, the polyethersulfone product is obtained. GPC testing showed that the Mw was 152584 and the ash content was 0.15w.

[0023] The following comparative examples further demonstrate the positive effects of the present invention:

[0024] Compare with Example 1

[0025] 1. In a 1000ml sealed four-necked flask connected to a condenser and a stirrer, nitrogen gas is continuously introduced, and 350ml of N-methylpyrrolidone, 287.16g of 4,4′-dichlorodiphenyl sulfone, 250.27g of bisphenol S, and 145g of potassium carbonate are added.

[0026] 2. The flask containing the added material was heated to 200℃ and stirred for 4 hours. The material in the flask was then poured out, cooled, crushed, washed 5 times with deionized water, and dried to obtain white granular polyethersulfone. GPC analysis showed that the Mw was 125632 and the ash content was 1.71w.

[0027] Table 1.

[0028]

[0029] Conclusion: Through the analysis of Examples 1-5 of the present invention and Comparative Example 1, the weight-average molecular weight of the obtained polyethersulfone was greater than that of the control example, and the ash content of the obtained polyethersulfone was much lower than that of the control example.

Claims

1. A method for preparing polyethersulfone via nucleophilic substitution reaction, using 4,4′-dichlorodiphenyl sulfone as a monomer, sodium hydroxide and / or potassium hydroxide as salt-forming agents, and dimethyl sulfone as a polymerization solvent, specifically comprising the following steps: 1) In a closed reactor connected to a condenser, nitrogen gas is continuously introduced, and 4,4′-dichlorodiphenyl sulfone, a salt-forming agent, and a solvent are added. The mass of the dimethyl sulfone solvent added is 0.5-3 times the sum of the masses of 4,4′-dichlorodiphenyl sulfone and the salt-forming agent. The mixture is heated to 220-240℃ and stirred for 1-4 hours. 2) After the reaction is complete, cool and crush the material, wash it 3-10 times with ethanol / deionized water solution, and dry it to obtain a sponge-like porous polyethersulfone. The salt-forming agent is sodium hydroxide, potassium hydroxide, or a mixture of the two in a 1:1 molar ratio; The ethanol / deionized aqueous solution has a volume content of 45%-80% (V / V), the washing temperature is 60℃-70℃, and the number of washing cycles is 3-10. The molar ratio of the salt-forming agent to the monomer is 2-2.5:1.

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