Sulfone polymer and preparation method thereof

Abstract

The invention discloses a sulfone polymer and a preparation method thereof, and relates to the technical field of sulfone polymers. When the sulfone polymer is prepared, the thiourea inhibitor is used for inhibiting peroxide generated by decomposition of NMP under the alkaline high-temperature condition, and the problem that polymerization of the sulfone polymer is affected by peroxide, and consequently the color of the sulfone polymer is dark is solved; a methane chloride end-capping reagent is introduced in a microbubble form, so that the mass transfer effect is improved, the end-capping rate is increased, and the thermal stability of the sulfone polymer is improved.

Description

Technical Field

[0001] This invention relates to the field of sulfone polymer technology, and more specifically to sulfone polymers and their preparation methods. Background Technology

[0002] Sulfone polymers are a class of high-performance thermoplastic special engineering plastics whose main chain contains sulfone groups (-SO2-) and aromatic ring structural units. They mainly include polyethersulfone (PES), bisphenol A type polysulfone (PSU), and polyphenylene sulfone (PPSU). Due to their excellent high temperature resistance, mechanical strength, chemical stability and other properties, they are widely used in high-end fields such as medical devices, aerospace, and electronics.

[0003] Sulfone polymers are typically produced via a one-pot nucleophilic condensation polymerization of 4,4'-dichlorodiphenyl sulfone, bisphenol compounds, and an acid-binding agent. Commonly used solvents in this synthesis include sulfolane, N-methylpyrrolidone (NMP), dimethyl sulfoxide, and N,N-dimethylacetamide. In actual production, NMP is often used as the primary solvent for synthesizing sulfone polymers due to its advantages such as not requiring additional dehydrating agents and its fast reaction rate. However, NMP is prone to oxidation, which has consistently affected the color of sulfone polymer products. To address this, Chinese invention patent CN119661850A discloses a sulfone polymer with a narrow molecular weight distribution and low gel content, and its preparation method, which controls NMP oxidation through deoxygenation. Chinese invention patent CN119490657A discloses a method for preparing polysulfone with stable color and reduced yellowness, which involves adding a small amount of reducing compound to NMP to reduce the molar content of NMP peroxide to below 0.05%, thereby obtaining batch-stable polysulfone products. However, during the synthesis of sulfone polymers, NMP decomposes under high-temperature alkaline conditions, still producing peroxides. This patent only addresses the treatment of NMP in the early stages of polymerization and does not solve the problem of NMP decomposition and peroxide production during polymerization. Chinese invention patent CN117024735A discloses a method for preparing sulfone polymers with low nitrogen content, proposing that polar solvents easily decompose under high-temperature alkaline conditions to produce nitrogen-containing byproducts. Although this patent reduces the decomposition of polar solvents through stepwise feeding, it does not fundamentally solve the problem of polar solvent decomposition at high temperatures.

[0004] Therefore, it is urgent to find a method that can fundamentally solve the problem of NMP decomposing under high temperature and alkaline conditions to produce peroxides and affecting the color of sulfone polymers. Summary of the Invention

[0005] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art, provide sulfone polymers and their preparation methods, use thiourea inhibitors to inhibit the peroxides produced by the decomposition of NMP under alkaline high temperature conditions, solve the problem that peroxides affect the polymerization of sulfone polymers and thus cause their dark color, and use microbubbles to introduce chloromethane end-capping agent to increase mass transfer effect, increase end-capping rate, and thus improve the thermal stability of sulfone polymers.

[0006] NMP readily forms highly oxidizing NMP peroxides in air. In the synthesis of sulfone polymers, these peroxides oxidize the phenolic end groups to dark-colored quinones, resulting in a high yellow tint in the sulfone polymers. Simultaneously, under alkaline and high-temperature conditions, the carbon on NMP is activated, forming peroxides that further affect the color of sulfone polymer products (the principle is shown below). Therefore, controlling the formation of NMP peroxides under high-temperature alkaline conditions can effectively improve the color of sulfone polymer products.

[0007] .

[0008] To solve the above problems, the technical solution of the present invention is as follows: On one hand, this invention provides a method for preparing sulfone polymers, comprising mixing a bisphenol compound, 4,4'-dichlorodiphenyl sulfone, an acid-binding agent, an inhibitor, and N-methylpyrrolidone, heating under nitrogen protection to form a salt at a temperature of 180-200°C, while simultaneously refluxing to remove water, maintaining a constant temperature, and after polymerization is complete, diluting the reaction solution and cooling it to 140-160°C, then adding a capping agent to terminate the reaction, followed by filtration, water precipitation, crushing, washing with water, and drying to obtain the desired product. Sulfone polymers; wherein the inhibitor is thiourea, methylthiourea, dimethylthiourea, trimethylthiourea, tetramethylthiourea or phenylthiourea; the end-capping agent is chloromethane, which is introduced into the reaction in the form of microbubbles through a microbubble generator with a pore size of 2-20 μm; the molar ratio of bisphenol compound to 4,4'-dichlorodiphenyl sulfone, acid binder and inhibitor is 1:(0.95-1.05):(1.05-1.3):(0.008-0.05).

[0009] Preferably, the bisphenol compound is bisphenol A, bisphenol S, or 4,4'-biphenyl.

[0010] Preferably, the acid-binding agent is potassium carbonate.

[0011] Preferably, the molar ratio of the capping agent to the bisphenol compound is (0.02-0.08):1.

[0012] Preferably, the temperature is kept constant for 3-6 hours.

[0013] Preferably, before reflux and water separation, the solid-liquid ratio of the system is (0.95-1.1):1, and after water separation, the solid-liquid ratio of the system is (1.2-1.4):1. Here, the solid-liquid ratio refers to the ratio of the total mass of the bisphenol compound and 4,4'-dichlorodiphenyl sulfone to the mass of NMP.

[0014] On the other hand, the present invention provides sulfone polymers, which are prepared by the above-described method for preparing sulfone polymers.

[0015] Compared with the prior art, the present invention has the following advantages: This invention utilizes thiourea inhibitors to suppress peroxides, blocking the decomposition of NMP under high-temperature alkaline conditions. The sulfur atoms in the thiourea inhibitors donate electron pairs, breaking the O / O bonds of the peroxide, thus preventing the hydrolysis of NMP under these conditions. This solves the problems of NMP decomposition generating peroxides, oxidizing phenolic end groups to quinones, leading to unbalanced reaction ratios, long reaction times, and dark colors in sulfone polymers. Simultaneously, this invention uses microbubbles to introduce chloromethane end-capping agents, which creates disturbances in the system, intensifying liquid turbulence. Furthermore, the high gas content of microbubbles accelerates the liquid film renewal rate, increasing the dissolution rate of chloromethane in NMP and the liquid phase volumetric mass transfer coefficient. This further accelerates the mass transfer between chloromethane and phenolic end groups, improving the end-capping rate of sulfone polymers. Attached Figure Description

[0016] Figure 1 This is the infrared spectrum of the sulfone polymer prepared in Example 1 of this invention. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention.

[0018] Example 1 The preparation method of the sulfone polymer in this embodiment is as follows: In a 5L reactor equipped with a condenser, N2 protection, stirring, water separator, and temperature sensor, 456.58g of bisphenol A, 603.03g of 4,4'-dichlorodiphenyl sulfone, 317.88g of potassium carbonate, 4.567g of phenylthiourea, and 1059.62g of NMP are mixed and heated to 190°C. The system is then distilled to remove the mixed solvent of NMP and water. After about 245g of the mixed solvent has been separated, the water separation is stopped, and the polymerization is continued at 190°C for 5 hours until the polymerization is complete. NMP is then added to cool the system down to 140°C. 5.05g of chloromethane is introduced into the system using a microbubble generator with a pore size of 10μm for end capping. The polymer solution is then filtered, and the resulting filtrate is precipitated with water, broken up, and then boiled in deionized water at 100°C (2L / time) 5 times. Finally, the solution is dried in a forced-air oven at 140°C for 12 hours to obtain the sulfone polymer.

[0019] The infrared spectrum of the sulfone polymer prepared in this embodiment is as follows: Figure 1 As shown in the figure, 1583cm -1 The strong absorption peak observed at 1503.4 cm⁻¹ can be attributed to the absorption of the benzene ring. -1 and 1485.5cm -1 The two sharp, strong absorption peaks at 1233 cm⁻¹ are also related to the skeletal vibrations of the benzene ring; -1 The absorption peak at 1408.5 cm⁻¹ indicates the formation of an aryl ether (Ar-O-Ar). -1 The absorption peak at 1322.6 cm⁻¹ is attributed to the absorption of isopropylidene. -1 and 1147.2cm -1 The absorption peaks at these locations are attributed to the asymmetric and symmetric stretching vibrations of the sulfone group, respectively. This demonstrates that the sulfone polymer was successfully prepared in this embodiment.

[0020] Example 2 The preparation method of the sulfone polymer in this embodiment is as follows: In a 5L reactor equipped with a condenser, N2 protection, stirrer, water separator, and temperature sensor, 372.42g of 4,4-sulfone polymer was added. '-Bisphenol A, 545.6 g of 4,4'-dichlorodiphenyl sulfone, 290.24 g of potassium carbonate, 3.045 g of thiourea, and 966.34 g of NMP were mixed and heated to 190 °C. The system was then distilled to remove the NMP and water mixture. After about 201 g of the mixed solvent was separated, the water separation was stopped, and the polymerization was continued at 190 °C for 3 hours until the polymerization was complete. NMP was then added to cool the system down to 150 °C. 6.06 g of chloromethane was introduced into the system using a microbubble generator with a pore size of 5 μm for end capping. The polymer solution was then filtered, and the filtrate was precipitated with water, broken up, and boiled in 100 °C deionized water (2 L / time) 5 times. The solution was then dried in a forced-air oven at 140 °C for 12 hours to obtain the sulfone polymer.

[0021] Example 3 The preparation method of the sulfone polymer in this embodiment is as follows: In a 5L reactor equipped with a condenser, N2 protection, stirrer, water separator, and temperature sensor, 500.54g of bisphenol S, 574.32g of 4,4'-dichlorodiphenyl sulfone, 359.346g of potassium carbonate, 7.934g of tetramethylthiourea, and 977.14g of NMP are mixed and heated to 200°C. The system evaporates the mixed solvent of NMP and water; when approximately 210g of NMP is separated... After mixing the solvent, the water separation was stopped, and the polymerization was continued at 200℃ for 4.5 hours until the polymerization was completed. NMP was added to cool the temperature down to 160℃. 8.08g of chloromethane was introduced into the polymer using a microbubble generator with a pore size of 2μm to seal the ends. The polymer solution was then filtered, and the filtrate was precipitated with water, broken up, and boiled in 100℃ deionized water (2L / time) 5 times. The solution was then dried in a forced-air oven at 140℃ for 12 hours to obtain the sulfone polymer.

[0022] Example 4 The preparation method of the sulfone polymer in this embodiment is as follows: In a 5L reactor equipped with a condenser, N2 protection, stirring, water separator, and temperature sensor, 500.54g of bisphenol S, 585.81g of 4,4'-dichlorodiphenyl sulfone, 304.06g of potassium carbonate, 12.056g of trimethylthiourea, and 987.59g of NMP are mixed and heated to 190°C. The system is then distilled to remove the mixed solvent of NMP and water. After about 82g of the mixed solvent has been separated, the water separation is stopped, and the polymerization is continued at 190°C for 6 hours until the polymerization is complete. NMP is then added to cool the system down to 150°C. 4.04g of chloromethane is introduced into the system using a microbubble generator with a pore size of 15μm for end capping. The polymer solution is then filtered, and the resulting filtrate is precipitated with water, broken up, and then boiled in 100°C deionized water (2L / time) 5 times. Finally, the solution is dried in a forced-air oven at 140°C for 12 hours to obtain the sulfone polymer.

[0023] Example 5 The preparation method of the sulfone polymer in this embodiment is as follows: In a 5L reactor equipped with a condenser, N2 protection, stirrer, water separator, and temperature sensor, 372.42g of 4,4-sulfone polymer was added. '-Bisphenol A, 585.81 g of 4,4'-dichlorodiphenyl sulfone, 324.79 g of potassium carbonate, 1.667 g of dimethylthiourea, and 912.6 g of NMP were mixed and heated to 180 °C. The NMP and water mixed solvent was distilled off. After about 176 g of mixed solvent was separated, the water separation was stopped, and the polymerization was continued at 180 °C for 4 hours until the polymerization was completed. NMP was added to cool the mixture down to 140 °C. 2.02 g of chloromethane was introduced into the mixture to end-cap it using a microbubble generator with a pore size of 20 μm. The polymer solution was then filtered, and the filtrate was precipitated with water, broken up, and boiled in 100 °C deionized water (2 L / time) 5 times. The mixture was then dried in a forced-air oven at 140 °C for 12 hours to obtain the sulfone polymer.

[0024] Example 6 The preparation method of the sulfone polymer in this embodiment is as follows: In a 5L reactor equipped with a condenser, N2 protection, stirring, water separator, and temperature sensor, 456.58g of bisphenol A, 591.55g of 4,4'-dichlorodiphenyl sulfone, 331.7g of potassium carbonate, 3.786g of methylthiourea, and 1103.3g of NMP are mixed and heated to 190°C. The mixed solvent of NMP and water is distilled off. After about 265g of mixed solvent is separated, the water separation is stopped, and the polymerization is continued at 200°C for 4.3 hours until the polymerization is completed. NMP is then added to cool the system down to 160°C. 3.03g of chloromethane is introduced into the system using a microbubble generator with a pore size of 10μm for end capping. The polymer solution is then filtered, and the resulting filtrate is precipitated with water, broken up, and boiled in deionized water at 100°C (2L / time) 5 times. The solution is then dried in a forced-air oven at 140°C for 12 hours to obtain the sulfone polymer.

[0025] Comparative Example 1 The preparation method of the sulfone polymer in Comparative Example 1 is as follows: In a 5L reactor equipped with a condenser, N2 protection, stirring, water separator, and temperature sensor, 456.58g of bisphenol A, 603.03g of 4,4'-dichlorodiphenyl sulfone, 317.88g of potassium carbonate, and 1059.62g of NMP were mixed and heated to 190℃. The mixed solvent of NMP and water was distilled off. After about 245g of mixed solvent was separated, the water separation was stopped, and the polymerization was continued at 190℃ for 5 hours until the polymerization was completed. NMP was then added to cool the system down to 140℃. 5.05g of chloromethane was introduced into the system using a microbubble generator with a pore size of 10μm for end capping. The polymer solution was then filtered, and the filtrate was precipitated with water, broken up, and boiled in deionized water at 100℃ (2L / time) 5 times. The solution was then dried in a forced-air oven at 140℃ for 12 hours to obtain the sulfone polymer.

[0026] Comparative Example 2 The preparation method of the sulfone polymer in Comparative Example 2 is as follows: In a 5L reactor equipped with a condenser, N2 protection, stirrer, water separator, and temperature sensor, 456.58g of bisphenol A, 603.03g of 4,4'-dichlorodiphenyl sulfone, 317.88g of potassium carbonate, 4.567g of phenylthiourea, and 1059.62g of NMP were mixed and heated to 190℃. The mixed solvent of NMP and water was distilled off. When approximately 245g of NMP was separated... After mixing the solvent, the water separation was stopped, and the polymerization was continued at 190°C for 5 hours until the polymerization was completed. NMP was then added to cool the temperature down to 140°C. 5.05 g of chloromethane was introduced into the polymer using a microbubble generator with a pore size of 30 μm to seal the ends. The polymer solution was then filtered, and the filtrate was precipitated with water, broken up, and then boiled in 100°C deionized water (2 L / time) 5 times. Finally, it was dried in a forced-air oven at 140°C for 12 hours to obtain the sulfone polymer.

[0027] Comparative Example 3 The preparation method of the sulfone polymer in Comparative Example 3 is as follows: In a 5L reactor equipped with a condenser, N2 protection, stirring, water separator, and temperature sensor, 456.58g of bisphenol A, 603.03g of 4,4'-dichlorodiphenyl sulfone, 317.88g of potassium carbonate, and 1059.62g of NMP were mixed and heated to 190℃. The mixed solvent of NMP and water was distilled off. After about 245g of mixed solvent was separated, the water separation was stopped, and the polymerization was continued at 190℃ for 5 hours until the polymerization was completed. NMP was added to cool the system down to 140℃. 5.05g of chloromethane was introduced into the system using a microbubble generator with a pore size of 30μm for end capping. The polymer solution was then filtered, and the filtrate was precipitated with water, broken up, and boiled in deionized water at 100℃ (2L / time) 5 times. The solution was then dried in a forced-air oven at 140℃ for 12 hours to obtain the sulfone polymer.

[0028] Comparative Example 4 The preparation method of the sulfone polymer in Comparative Example 4 is as follows: In a 5L reactor equipped with a condenser, N2 protection, stirrer, water separator, and temperature sensor, 456.58g of bisphenol A, 603.03g of 4,4'-dichlorodiphenyl sulfone, 317.88g of potassium carbonate, 18.266g of phenylthiourea, and 1059.62g of NMP were mixed and heated to 190℃. The mixed solvent of NMP and water was distilled off. When approximately 245g of NMP was separated... After mixing the solvent, stop the water separation and continue the polymerization at 190°C for 5 hours until the polymerization is complete. Then add NMP to cool the temperature down to 140°C. Use a microbubble generator with a pore size of 10μm to introduce 5.05g of chloromethane for end capping. Then filter the polymerization liquid, add water to the filtrate to precipitate it, break it up, and boil it in 100°C deionized water (2L / time) 5 times. Then dry it in a forced-air oven at 140°C for 12 hours to obtain the sulfone polymer.

[0029] The end-capping rate and 5% thermogravimetric temperature of the sulfone polymers prepared in Examples 1-6 and Comparative Examples 1-4 were tested, and their yellowness index was tested by injection molding into color swatches. The test methods are as follows: the yellowness index was determined according to the "ASTM E313-10 Standard Implementation Procedure for Calculating Yellow and White Indices Based on Instrument-Measured Color Coordinates", with a sample thickness of 2 cm; the end-capping rate was determined by testing the change in phenolic hydroxyl content before and after end-capping of the sulfone polymer; the 5% thermogravimetric temperature was tested using TGA at a heating rate of 10℃ / min. The test results are shown in Table 1. Table 1. Test results of sulfone polymers and color plates prepared in Examples 1-6 and Comparative Examples 1-4.

[0030] As shown in Table 1, the sulfone polymers of Examples 1-6 of this invention have end-capping rates of over 85% and relatively high 5% thermogravimetric temperatures, resulting in low yellowness indices for their injection-molded color plates. It can also be seen that the sulfone polymer prepared in Comparative Example 3 has an end-capping rate of only 68.54%, a 5% thermogravimetric temperature of 513.2℃, and a yellowness index of 10.23 for its injection-molded color plate. In contrast, Comparative Example 2 introduced thiourea to inhibit NMP decomposition during the preparation of the sulfone polymer, which to some extent avoided the phenomenon of yellowing of the color plate product due to the generated peroxides. Furthermore, Comparative Example 1 used microbubbles with smaller pore sizes to introduce chloromethane during the preparation of the sulfone polymer, increasing the end-capping rate of the product from 68.54% to 85.39%, significantly improving mass transfer efficiency. Moreover, with the increase in end-capping rate, the yellowness index of the color plate product also improved. Although an inhibitor was added in Comparative Example 4, the amount added was excessive. While this increased the end-capping rate, it also led to an increase in the yellowness index of the sulfone polymer color chart. This is because adding too much inhibitor results in an excessive number of amino groups in the system that affect the phenolic hydroxyl groups, thus causing an imbalance in the reaction ratio, a deterioration in the product's color, and a decrease in product stability along with an increase in the yellowness index.

[0031] In summary, this invention introduces an inhibitor to suppress the decomposition of NMP and the generation of peroxides during the preparation of sulfone polymers. This addresses the problem of dark color caused by the byproducts of NMP decomposition under alkaline high-temperature conditions affecting the polymerization of sulfone polymers. Simultaneously, the introduction of chloromethane in the form of microbubbles intensifies liquid turbulence. The high gas content of the microbubbles accelerates the liquid film renewal rate, increases the dissolution rate of chloromethane in NMP, and increases the liquid phase volumetric mass transfer coefficient. This accelerates the mass transfer between chloromethane and phenolic end groups, improving the end-capping rate of the sulfone polymer and thus enhancing its thermal stability. Therefore, this invention, by introducing an inhibitor and introducing chloromethane in the form of microbubbles, achieves a synergistic effect, reducing the yellowness index of the prepared sulfone polymer and improving product quality.

Claims

1. A method for preparing sulfone polymers, characterized in that, Bisphenol compound, 4,4'-dichlorodiphenyl sulfone, acid-binding agent, inhibitor, and N-methylpyrrolidone are mixed and heated to form a salt under nitrogen protection at a temperature of 180-200℃. Simultaneously, water is removed by reflux and the mixture is kept at a constant temperature. After polymerization, the reaction solution is diluted and cooled to 140-160℃. A capping agent is then added to terminate the reaction. The mixture is then filtered, precipitated with water, crushed, washed with water, and dried to obtain a sulfone polymer. The inhibitor is thiourea, methylthiourea, dimethylthiourea, trimethylthiourea, tetramethylthiourea, or phenylthiourea. The capping agent is chloromethane, which is introduced into the reaction as microbubbles through a microbubble generator with a pore size of 2-20 μm. The molar ratio of bisphenol compound to 4,4'-dichlorodiphenyl sulfone, acid-binding agent, and inhibitor is 1:(0.95-1.05):(1.05-1.3):(0.008-0.05).

2. The method for preparing the sulfone polymer as described in claim 1, characterized in that, The bisphenol compound is bisphenol A, bisphenol S, or 4,4'-biphenyl.

3. The method for preparing sulfone polymers as described in claim 1, characterized in that, The acid-binding agent is potassium carbonate.

4. The method for preparing sulfone polymers as described in claim 1, characterized in that, The molar ratio of the capping agent to the bisphenol compound is (0.02-0.08):

1.

5. The method for preparing sulfone polymers as described in claim 1, characterized in that, Maintain constant temperature for 3-6 hours.

6. The method for preparing sulfone polymers as described in claim 1, characterized in that, Before the water separation, the solid-liquid ratio of the system was (0.95-1.1):

1. After the water separation, the solid-liquid ratio of the system was (1.2-1.4):

1.

7. A sulfone polymer, characterized in that, It is prepared by the method for preparing sulfone polymers as described in any one of claims 1-6.

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