Sulfone polymers and methods for making the same

Abstract

The application discloses a sulfone polymer and a preparation method thereof, and relates to the technical field of sulfone polymers.In the preparation of the sulfone polymer, a thiocyanate inhibitor is used to inhibit peroxide generated by the decomposition of NMP under the condition of alkaline high temperature, so that the problem that the peroxide influences the polymerization of the sulfone polymer and causes the color of the sulfone polymer to be deep is solved; and the monochloromethane end-capping agent is in the form of micro-bubbles and is introduced, the mass transfer effect is increased, the end-capping rate is increased, and the thermal stability of the sulfone polymer is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sulfone polymers, in particular to sulfone polymers and a preparation method thereof. BACKGROUND

[0002] Sulfone polymers are a kind of high-performance thermoplastic special engineering plastics with sulfone groups (-SO2-) and aromatic ring structure units in the main chain, mainly including polyether sulfone (PES), bisphenol A type polysulfone (PSU), polyphenylene sulfone (PPSU), etc. Due to their excellent high-temperature resistance, mechanical strength, chemical stability and other properties, they are widely used in medical devices, aerospace, electronics and other high-end fields.

[0003] Sulfone polymers are usually synthesized by one-pot nucleophilic polycondensation of 4,4'-dichlorodiphenyl sulfone, bisphenol compounds and acid binding agent. Commonly used solvents in the synthesis include sulfolane, N-methyl pyrrolidone (NMP), dimethyl sulfoxide, N,N-dimethylacetamide, etc. In actual production, NMP is often used as the main solvent for synthesizing sulfone polymers due to its characteristics such as not needing to add water-carrying agents and fast reaction rate. However, NMP is easily oxidized, which has been affecting the color of sulfone polymer products. In response to this, Chinese invention patent CN119661850A discloses a sulfone polymer with narrow molecular weight distribution and low gel content and a preparation method thereof, which controls the oxidation of NMP by removing oxygen. Chinese invention patent CN119490657A discloses a preparation method of color-stable and yellow-reduced polysulfone, which reduces the molar content of NMP peroxide to below 0.05% by adding a small amount of reducing compound to NMP, thereby obtaining batch-stable polysulfone products. However, during the synthesis of sulfone polymers, NMP will decompose under high-temperature alkaline conditions, and peroxides will still be produced. This patent only involves the treatment of NMP in the early stage of polymerization and does not solve the problem of peroxide production caused by the decomposition of NMP in the polymerization process. Chinese invention patent CN117024735A discloses a preparation method of a sulfone polymer with low nitrogen content, which proposes that polar solvents are easily decomposed under high-temperature alkaline conditions to produce nitrogen-containing byproducts. Although this patent reduces the decomposition of polar solvents by stepwise feeding, it does not fundamentally solve the problem of decomposition of polar solvents at high temperatures.

[0004] Therefore, in view of the problem of the decomposition of NMP under high-temperature alkaline conditions to produce peroxides and affect the color of sulfone polymers, it is urgent to find a method that can fundamentally solve the above problems. SUMMARY

[0005] The technical problem solved by the present application is to overcome the shortcomings of the prior art, provide a sulfone polymer and a preparation method thereof, use thiourea inhibitors to inhibit the peroxide generated by the decomposition of N-methylpyrrolidone (NMP) under alkaline high-temperature conditions, solve the problem that the peroxide affects the polymerization of the sulfone polymer and thus causes the color of the sulfone polymer to be deep, and pass the end-capping agent chloromethane in the form of microbubbles to increase the mass transfer effect and increase the end-capping rate, thereby improving the thermal stability of the sulfone polymer.

[0006] NMP is extremely easy to produce NMP peroxide with strong oxidizing property in air, which can oxidize the phenolic end group to quinone in the synthesis of the sulfone polymer, causing the sulfone polymer to have a high yellow index; meanwhile, under alkaline high-temperature conditions, the carbon on the NMP is activated to form peroxide, thereby affecting the product color of the sulfone polymer (principle shown below). Therefore, controlling the generation of peroxide of NMP under high-temperature alkaline conditions can effectively improve the color of the sulfone polymer product.

[0007] .

[0008] To solve the above problems, the technical scheme of the present application is as follows:

[0009] In one aspect, the present application provides a preparation method of a sulfone polymer, which comprises mixing a bisphenol compound, 4,4'-dichlorodiphenyl sulfone, an acid-binding agent, an inhibitor and N-methylpyrrolidone, heating to form a salt under nitrogen protection, the heating temperature being 180-200 DEG C, refluxing water at the same time, constant temperature preservation, diluting the reaction liquid and cooling to 140-160 DEG C after the polymerization is completed, then adding an end-capping agent to terminate the reaction, and then sequentially performing filtration, water addition and precipitation, crushing, water washing and drying to obtain the sulfone polymer; wherein the inhibitor is thiourea, methylthiourea, dimethylthiourea, trimethylthiourea, tetramethylthiourea or phenylthiourea; the end-capping agent is chloromethane, which is passed into the reaction in the form of microbubbles through a microbubble generator, the pore size of the microbubble generator being 2-20 μm; the molar ratio of the bisphenol compound to 4,4'-dichlorodiphenyl sulfone, the acid-binding agent and the inhibitor is 1:(0.95-1.05):(1.05-1.3):(0.008-0.05).

[0010] Preferably, the bisphenol compound is bisphenol A, bisphenol S or 4,4'-diphenol.

[0011] Preferably, the acid-binding agent is potassium carbonate.

[0012] Preferably, the molar ratio of the end-capping agent to the bisphenol compound is (0.02-0.08):1.

[0013] Preferably, the constant temperature preservation is performed for 3-6 h.

[0014] Preferably, before refluxing, the solid-liquid ratio of the system is (0.95-1.1):1, and after the water is drained, the solid-liquid ratio of the system is (1.2-1.4):1. The solid-liquid ratio refers to the mass ratio of the total mass of the bisphenol compound and 4,4'-dichlorodiphenyl sulfone to the mass of NMP.

[0015] In another aspect, the present application provides a sulfone polymer prepared by the above-mentioned method for preparing a sulfone polymer.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] The thiocyanate inhibitor used in the present application can inhibit the decomposition of NMP under high-temperature alkaline conditions, and the sulfur atom in the thiocyanate inhibitor provides an electron pair to break the O-O bond of the peroxide, thereby blocking the hydrolysis of NMP under high-temperature alkaline conditions, and solving the problems of the oxidation of phenolic end groups to quinone due to the decomposition of NMP to generate peroxide, the imbalance of reaction ratio, long reaction time, and dark color of the sulfone polymer. At the same time, the present application uses micro-bubbles of methyl chloride blocking agent, which can produce a certain disturbance effect on the system, intensify the turbulence of the liquid, and further increase the gas holdup of the micro-bubbles, accelerate the liquid film renewal rate, accelerate the dissolution rate of methyl chloride in NMP, and increase the liquid phase volumetric mass transfer coefficient, thereby accelerating the mass transfer effect of methyl chloride and phenolic end groups and improving the blocking rate of the sulfone polymer. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the infrared spectrum of the sulfone polymer prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions of the present application will be described in detail below in combination with the embodiments of the present application.

[0020] Example 1

[0021] The preparation method of the sulfone polymer of the present example is as follows: 456.58 g of bisphenol A, 603.03 g of 4,4'-dichlorodiphenyl sulfone, 317.88 g of potassium carbonate, 4.567 g of phenylthiourea, and 1059.62 g of NMP are mixed in a 5 L reaction kettle equipped with a condenser, N2 protection, stirring, a water separator, and a temperature sensor, and the system is heated to 190°C, and the mixed solvent of NMP and water is evaporated; when about 245 g of the mixed solvent is separated, the water separation is stopped, and the polymerization is continued, from 190°C to the completion of polymerization for 5 h, NMP is added to reduce the temperature to 140°C; 5.05 g of methyl chloride is introduced into the system using a micro-bubble generator with a pore size of 10 μm for end-capping, and then the polymerization solution is filtered, the obtained filtrate is precipitated with water, broken, and boiled in 100°C deionized water (2 L / time) for 5 times, and dried in a blast drying oven at 140°C for 12 h, to obtain the sulfone polymer.

[0022] The infrared spectrum of the sulfone polymer prepared in the present example is shown in Figure 1 , in which the strong absorption peak observed at 1583 cm -1 is attributed to the absorption of benzene ring, and the two sharp and strong absorption peaks at 1503.4 cm -1 and 1485.5 cm -1 are also related to the skeleton vibration of benzene ring; the absorption peak at 1233 cm -1 indicates the formation of aryl ether (Ar-O-Ar), the absorption peak at 1408.5 cm -1 is attributed to the absorption of isopropylidene; the absorption peaks at 1322.6 cm -1 and 1147.2 cm -1 are respectively attributed to the asymmetric and symmetric stretching vibration of sulfone group. It is proved that the sulfone polymer is successfully prepared in the present example.

[0023] Example 2

[0024] The preparation method of the sulfone polymer of the present example is as follows: 456.58 g of bisphenol A, 603.03 g of 4,4'-dichlorodiphenyl sulfone, 317.88 g of potassium carbonate, 4.567 g of phenylthiourea, and 1059.62 g of NMP are mixed in a 5 L reaction kettle equipped with a condenser, N2 protection, stirring, a water separator, and a temperature sensor, and the system is heated to 190°C, and the mixed solvent of NMP and water is evaporated; when about 245 g of the mixed solvent is separated, the water separation is stopped, and the polymerization is continued, from 190°C to the completion of polymerization for 5 h, NMP is added to reduce the temperature to 140°C; 5.05 g of methyl chloride is introduced into the system using a micro-bubble generator with a pore size of 10 μm for end-capping, and then the polymerization solution is filtered, the obtained filtrate is precipitated with water, broken, and boiled in 100°C deionized water (2 L / time) for 5 times, and dried in a blast drying oven at 140°C for 12 h, to obtain the sulfone polymer.

[0025] Example 3

[0026] The preparation method of the sulfone polymer of this example is as follows: 500.54 g of bisphenol S, 574.32 g of 4,4'-dichlorodiphenyl sulfone, 359.346 g of potassium carbonate, 7.934 g of tetramethyl thiourea, and 977.14 g of NMP are mixed in a 5L reaction kettle equipped with a condenser, N2protection, stirring, a water separator, and a temperature sensor, and the system is heated to 200°C to evaporate the mixed solvent of NMP and water; when about 210 g of the mixed solvent is separated, the water separation is stopped, and the polymerization is continued for 4.5 h from 200°C to completion, NMP is added to reduce the temperature to 160°C; 8.08 g of methyl chloride is introduced for end-capping using a micro-bubble generator with a pore size of 2 μm, then the polymerization liquid is filtered, the obtained filtrate is precipitated with water, broken, and boiled in 100°C deionized water (2L / time) for 5 times, and dried in a 140°C air oven for 12 h to obtain the sulfone polymer.

[0027] Example 4

[0028] The preparation method of the sulfone polymer of this example is as follows: 500.54 g of bisphenol S, 574.32 g of 4,4'-dichlorodiphenyl sulfone, 359.346 g of potassium carbonate, 7.934 g of tetramethyl thiourea, and 977.14 g of NMP are mixed in a 5L reaction kettle equipped with a condenser, N2protection, stirring, a water separator, and a temperature sensor, and the system is heated to 200°C to evaporate the mixed solvent of NMP and water; when about 210 g of the mixed solvent is separated, the water separation is stopped, and the polymerization is continued for 4.5 h from 200°C to completion, NMP is added to reduce the temperature to 160°C; 8.08 g of methyl chloride is introduced for end-capping using a micro-bubble generator with a pore size of 2 μm, then the polymerization liquid is filtered, the obtained filtrate is precipitated with water, broken, and boiled in 100°C deionized water (2L / time) for 5 times, and dried in a 140°C air oven for 12 h to obtain the sulfone polymer.

[0029] Example 5

[0030] The preparation method of the sulfone polymer of the present example is as follows: 372.42 g of 4,4'-diphenol, 585.81 g of 4,4'-dichlorodiphenyl sulfone, 324.79 g of potassium carbonate, 1.667 g of dimethyl thiourea and 912.6 g of NMP are mixed in a 5L reaction kettle equipped with a condenser, N2 protection, stirring, water separator and temperature sensor, and the system is heated to 180°C to evaporate the mixed solvent of NMP and water; when about 176 g of the mixed solvent is separated, the water separation is stopped, and the polymerization is continued for 4 h from 180°C to completion, NMP is added to reduce the temperature to 140°C; 2.02 g of methyl chloride is introduced into the system using a micro-bubble generator with a pore size of 20 μm for end-capping, then the polymerization solution is filtered, the obtained filtrate is precipitated with water, broken, boiled in 2 L of deionized water at 100°C for 5 times, and dried in a blast drying oven at 140°C for 12 h to obtain the sulfone polymer.

[0031] Example 6

[0032] The preparation method of the sulfone polymer of the present example is as follows: 372.42 g of 4,4'-diphenol, 585.81 g of 4,4'-dichlorodiphenyl sulfone, 324.79 g of potassium carbonate, 1.667 g of dimethyl thiourea and 912.6 g of NMP are mixed in a 5L reaction kettle equipped with a condenser, N2 protection, stirring, water separator and temperature sensor, and the system is heated to 180°C to evaporate the mixed solvent of NMP and water; when about 176 g of the mixed solvent is separated, the water separation is stopped, and the polymerization is continued for 4 h from 180°C to completion, NMP is added to reduce the temperature to 140°C; 2.02 g of methyl chloride is introduced into the system using a micro-bubble generator with a pore size of 20 μm for end-capping, then the polymerization solution is filtered, the obtained filtrate is precipitated with water, broken, boiled in 2 L of deionized water at 100°C for 5 times, and dried in a blast drying oven at 140°C for 12 h to obtain the sulfone polymer.

[0033] Comparative Example 1

[0034] The preparation method of the sulfone polymer of the present example is as follows: 372.42 g of 4,4'-diphenol, 585.81 g of 4,4'-dichlorodiphenyl sulfone, 324.79 g of potassium carbonate, 1.667 g of dimethyl thiourea and 912.6 g of NMP are mixed in a 5L reaction kettle equipped with a condenser, N2 protection, stirring, water separator and temperature sensor, and the system is heated to 180°C to evaporate the mixed solvent of NMP and water; when about 176 g of the mixed solvent is separated, the water separation is stopped, and the polymerization is continued for 4 h from 180°C to completion, NMP is added to reduce the temperature to 140°C; 2.02 g of methyl chloride is introduced into the system using a micro-bubble generator with a pore size of 20 μm for end-capping, then the polymerization solution is filtered, the obtained filtrate is precipitated with water, broken, boiled in 2 L of deionized water at 100°C for 5 times, and dried in a blast drying oven at 140°C for 12 h to obtain the sulfone polymer.

[0035] Comparative Example 2

[0036] 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.

[0037] Comparative Example 3

[0038] 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.

[0039] Comparative Example 4

[0040] The preparation method of the sulfone polymer of Comparative Example 4 is as follows: 456.58 g of bisphenol A, 603.03 g of 4,4'-dichlorodiphenyl sulfone, 317.88 g of potassium carbonate, 18.266 g of phenylthiourea and 1059.62 g of NMP are mixed in a 5L reaction kettle equipped with a condenser, N2protection, stirring, water separator, temperature sensor, and the system is heated to 190°C to evaporate the mixed solvent of NMP and water; when about 245 g of the mixed solvent is separated, the water separation is stopped, and the polymerization is continued, from 190°C to the completion of polymerization for 5h, NMP is added to reduce the temperature to 140°C; a microbubble generator with a pore size of 10μm is used to introduce 5.05 g of methyl chloride to terminate, then the polymerization liquid is filtered, the obtained filtrate is precipitated with water, broken, and then boiled in 100°C deionized water (2L / time) for 5 times, and dried in a 140°C air oven for 12h to obtain the sulfone polymer.

[0041] The termination rate, 5% thermal weight loss temperature of the sulfone polymers prepared in Examples 1-6 and Comparative Examples 1-4 are tested, and the yellowness index of the color plate molded by the sulfone polymers is tested, and the test method is as follows: the yellowness index is tested according to ASTM E313-10 Standard Practice for Calculation of Yellow and White Index from Instrumentally Measured Color Coordinates, and the sample thickness is 2cm; the termination rate is determined by testing the change of phenolic hydroxyl content before and after the termination of the sulfone polymer; the 5% thermal weight loss temperature is tested by TGA, and the heating rate is 10°C / min. The test results are shown in Table 1:

[0042] Table 1 Test results of sulfone polymers and color plates prepared in Examples 1-6 and Comparative Examples 1-4

[0043]

[0044] As shown in Table 1, the end-capping rate of the sulfone polymers of Examples 1-6 is more than 85%, and the 5% thermal weight loss temperature is high, and the yellowness index of the color plates formed by injection molding is at a low level. It can also be seen that the end-capping rate of the sulfone polymer prepared in Comparative Example 3 is only 68.54%, the 5% thermal weight loss temperature is 513.2℃, and the yellowness index of the color plate formed by injection molding is 10.23; compared with Comparative Example 3, in Comparative Example 2, the thiourea substance is introduced to inhibit the decomposition of NMP, which can avoid the phenomenon that the generated peroxide makes the color plate product yellow to a certain extent; in addition, in Comparative Example 1, the monochloromethane is introduced in the form of micro-bubbles with a smaller pore size, which increases the end-capping rate of the product from 68.54% to 85.39%, greatly improves the mass transfer efficiency, and with the increase of the end-capping rate, the yellowness index of the color plate product is also improved. In Comparative Example 4, although the inhibitor is added, the amount of the inhibitor is too much, although the end-capping rate is increased, but the yellowness index of the sulfone polymer color plate is also increased. This is because the addition of too much inhibitor will make the system contain too much amino group which affects the phenolic hydroxyl group, thereby causing the reaction ratio to be unbalanced, the color of the product to be poor, the yellowness index to be increased, and the stability of the product to be reduced.

[0045] In summary, in the preparation of the sulfone polymer, the inhibitor is introduced to inhibit the decomposition of NMP to generate peroxide, which solves the problem that the by-products generated by the decomposition of NMP under high temperature and alkaline conditions affect the polymerization of the sulfone polymer and cause the color to be deep; at the same time, the monochloromethane is introduced in the form of micro-bubbles, which can intensify the turbulence of the liquid, and the micro-bubbles have a high gas content, which can accelerate the liquid film renewal rate, accelerate the dissolution rate of monochloromethane in NMP, increase the liquid phase volumetric mass transfer coefficient, thereby accelerating the mass transfer effect of monochloromethane and phenolic end groups, improving the end-capping rate of the sulfone polymer, and further improving the thermal stability of the sulfone polymer. Therefore, by introducing the inhibitor and introducing the monochloromethane in the form of micro-bubbles, the yellowness index of the prepared sulfone polymer is reduced, and the quality of the product is improved.

Claims

1. Process for the preparation of sulfone polymers, characterized in that, The bisphenol compound, 4,4'-dichlorodiphenyl sulfone, acid-binding agent, inhibitor and N-methyl pyrrolidone are mixed, and the salt is formed under the protection of nitrogen, the heating temperature is 180-200 DEG C, and the water is refluxed at the same time, the constant temperature is kept, after the polymerization is completed, the reaction liquid is diluted and cooled to 140-160 DEG C, then the end-capping agent is added to terminate the reaction, and the filtration, water separation, crushing, water washing and drying are sequentially carried out, and the sulfone polymer is obtained; wherein the inhibitor is thiourea, methyl thiourea, dimethyl thiourea, trimethyl thiourea, tetramethyl thiourea or phenyl thiourea; the end-capping agent is methyl chloride, and the micro-bubbles are introduced into the reaction through a micro-bubble generator, the pore size of the micro-bubble generator is 2-20 μm; the molar ratio of the bisphenol compound, 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 a sulfone polymer according to claim 1, characterized by, The bisphenol compound is bisphenol A, bisphenol S or 4,4'-diphenylol.

3. The method of claim 1, wherein the sulfone polymer is prepared by the reaction of a sulfone monomer and a sulfone oligomer. 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 end-capping agent and the bisphenol compound is (0.02-0.08):

1.

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

6. The method for preparing sulfone polymers as described in claim 1, characterized in that, Before the water is refluxed, the solid-liquid ratio of the system is (0.95-1.1):1, and after the water is refluxed, the solid-liquid ratio of the system is (1.2-1.4):

1.

7. Sulfonyl polymer, characterized in that, The sulfone polymer is prepared by the preparation method of any one of claims 1-6.

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