A method for synthesizing a polyether sulfone resin

Abstract

The application discloses a method for synthesizing polyether sulfone resin, and specifically comprises the following steps: adding solvent cyclobutane sulfone into a reactor provided with a nitrogen gas pipe, a gas distributor, mechanical stirring and a water separation condensing device, starting stirring, and adding monomer 4,4'-dichlorodiphenyl sulfone, bisphenol S and a salifying agent; after nitrogen replacement, the nitrogen flow is adjusted, and the temperature is raised to 210-240 DEG C; the gas distributor is used for distributing nitrogen, the system is continuously bubbled by nitrogen flow for dehydration, and the reaction is carried out for 3-5 hours; the nitrogen is turned off, the polymerized mucus is poured into water for precipitation, and the polyether sulfone resin is obtained through the steps of crushing, washing and drying. The application uses high-purity nitrogen flow for dehydration, thus avoiding the addition of flammable and toxic organic water-carrying agents, improving operation safety, not polluting products, and being simple in operation and short in reaction period.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high molecular compound synthesis, and particularly relates to a method for synthesizing polyether sulfone resin. BACKGROUND

[0002] Polyether sulfone resin (PES) is a kind of special engineering plastic with excellent comprehensive performance, and has good thermal stability, physical and mechanical properties, chemical inertness and biocompatibility, etc. It is widely used in the fields of aerospace, electronic appliances, automobiles, military industry, coatings, etc., and has an important position in the fields of water treatment membrane and medical dialysis membrane, etc.

[0003] At present, there are two reaction routes for synthesizing polyether sulfone resin, i.e. electrophilic substitution and nucleophilic substitution. Although the electrophilic substitution route has mild reaction conditions, molecular chain branching and crosslinking often occur in the polymerization process, which seriously affects the quality of polyether sulfone, and therefore the electrophilic substitution process route is gradually eliminated in industry. The nucleophilic substitution route can be divided into high-temperature melting desalination method and solution desalination method. The high-temperature melting desalination method has harsh polymerization conditions, requires high equipment, and has more difficult post-treatment and purification operation. The solution desalination method has relatively suitable synthesis conditions, and the prepared polyether sulfone resin has better quality, and therefore the solution desalination method is basically used for preparing polyether sulfone resin in industry.

[0004] The solution desalination polymerization process is as follows: in an aprotic polar solvent (sulfolane, N-methylpyrrolidine, dimethyl sulfoxide, etc.), bisphenol S is first reacted with a salt-forming agent (potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, etc.) to generate bisphenol salt and water, and the generated bisphenol salt is polymerized with 4,4'-dichlorodiphenyl sulfone at high temperature. The by-product water generated in the system will hinder the forward reaction, and how to remove the water in the system is the key to preparing polyether sulfone. In the prior art, toluene, chlorobenzene, xylene or trimethylbenzene, etc. are added to the solvent system as water-carrying agents, and the water generated in the reaction is carried out of the reaction system by azeotropic dehydration with the water-carrying agent. It is found in actual operation that this process has the following technical defects: (1) toluene, chlorobenzene and xylene, etc. are flammable and toxic, and long-term contact will cause irreversible damage to the human body. A large amount of such organic dehydration agent needs to be added in the reaction process, which not only increases the operation risk, but also pollutes the product to some extent and affects the product quality; (2) the water-carrying agent needs to be evaporated after dehydration, but the boiling point of such organic water-carrying agent is relatively high and it has good compatibility with the reaction solvent, and a large amount of water-carrying agent is found to be still remained in the operation process, and a variety of solvents need to be separated and recovered in the post-treatment, which is complex and high in cost; (3) the polymerization reaction rate is slow, and the polymerization time is more than 10 hours in the patents CN1176970A, CN1231302A and CN1268526A, and the reaction cycle is long and the cost is high.

[0005] Chinese patents CN201410531141.6, CN201410531099.8 disclose a method for improving the reaction rate by using organic amine salt, organic acid salt, etc. as phase transfer catalyst, but the thermal stability of such phase transfer catalyst is poor, and the residual amount may decompose during the later resin high-temperature processing, affecting the use performance of the material.

[0006] Chinese patent CN20211019272.4 uses N, N-dimethylacetamide with relatively low boiling point as a solvent, and the reaction temperature is near the boiling point of the solvent. The system water is brought out by evaporating part of the solvent, avoiding the addition of volatile, flammable and toxic organic water-carrying agents. However, in actual operation, it is found that this process has certain technical defects: (1) To remove the system water, 35%-60% of the total amount of solvent needs to be evaporated during the dehydration stage, and the amount of solvent used is large; (2) Although the addition of ionic liquid as a phase transfer catalyst in the system can improve the reaction rate, the overall reaction rate is still relatively slow, and the polymerization time is more than 14h, and the reaction period is long; (3) The ionic liquid is expensive, and it is not easy to recover when mixed with carbonate and chloride salt in aqueous solution.

[0007] Therefore, it is urgent to find a safe, pollution-free, simple operation, short reaction period and low production cost process for preparing polyether sulfone resin. SUMMARY

[0008] In order to overcome the defects of the prior art, the purpose of the present application is to provide a method for synthesizing polyether sulfone resin. The present application uses sulfolane as a solvent and utilizes high-speed nitrogen flow for dehydration to synthesize polyether sulfone resin.

[0009] The basic principle is to use a gas distributor to achieve uniform dispersion of nitrogen flow in the reaction system. A large amount of nitrogen gas rising in the system will carry low-boiling water, and under the action of stirring, the surface is quickly updated to create a larger diffusion interface, successfully removing the byproduct water generated during the reaction to achieve efficient dehydration.

[0010] In order to achieve the above purpose, the following technical scheme is proposed:

[0011] A method for synthesizing polyether sulfone resin, comprising the following steps:

[0012] 1) Add the solvent sulfolane into a reactor with a nitrogen gas pipe, a gas distributor, mechanical stirring and a water separation condensing device, start stirring, and sequentially add the monomer 4, 4'-dichlorodiphenyl sulfone, bisphenol S and a salt-forming agent;

[0013] 2) After nitrogen replacement, adjust the nitrogen flow and heat to 210-240℃, the gas distributor distributes the nitrogen, and the dehydration is carried out by continuous bubbling of nitrogen in the system, and the reaction is carried out for 3-5 hours;

[0014] 3) Close the nitrogen, introduce the polymerized mucilage into water to precipitate, and obtain the polyether sulfone resin after the steps of crushing, washing, drying, etc.

[0015] Further, the salt forming agent in step 1) is one of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, and barium carbonate.

[0016] Further, the salt forming agent in step 1) is pretreated by crushing, sieving, and drying, and has a particle size of 15-40 μm.

[0017] Further, the molar ratio of bisphenol S, 4,4'-dichlorodiphenyl sulfone, and the salt forming agent in step 1) is 1:1.004-1.01:1.05-1.15.

[0018] Further, the gas distributor is a tubular gas distributor or a loop gas distributor.

[0019] Further, the oxygen content in the nitrogen in step 2) is less than 200 ppm, preferably less than 50 ppm, and the nitrogen flow rate is 0.5-2 L / min.

[0020] The present application has the following beneficial effects:

[0021] Currently, there is no report on the use of nitrogen to achieve efficient dehydration in the synthesis of polyether sulfone, and the method described in the present application is innovative. The present application can obtain high molecular weight polyether sulfone resin while reducing the reaction time to 3-5 hours, which can significantly shorten the reaction period. In addition, the addition of toxic and flammable water-carrying agents is avoided, which improves the product quality and operation safety. At the same time, the separation and recovery of the water-carrying agent step is omitted, which simplifies the operation process and reduces the production cost. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The infrared spectrum of the polyether sulfone resin prepared in Example 1 of the present application is shown in the following figure:

[0023] Figure 2 The GPC spectrum of the polyether sulfone resin prepared in Example 1 of the present application is shown in the following figure:

[0024] Figure 3 The GPC spectrum of the polyether sulfone resin prepared in Example 2 of the present application is shown in the following figure:

[0025] Figure 4 The GPC spectrum of the polyether sulfone resin prepared in Example 3 of the present application is shown in the following figure:

[0026] Figure 5 The GPC spectrum of the polyether sulfone resin prepared in Example 4 of the present application is shown in the following figure:

[0027] Figure 6 The GPC spectrum of the polyether sulfone resin prepared in Example 5 of the present application is shown in the following figure:

[0028] Figure 7 GPC trace of polyethersulfone resin prepared for Inventive Example 6;

[0029] Figure 8 GPC trace of polyethersulfone resin prepared for Inventive Example 7;

[0030] Figure 9 GPC trace of polyethersulfone resin prepared for Inventive Example 8;

[0031] Figure 10 GPC trace of polyethersulfone resin prepared for Comparative Example 1. DETAILED DESCRIPTION

[0032] The application will be further explained with reference to the following examples, which do not limit the application in any form.

[0033] The test conditions for molecular weight and molecular weight distribution index in the following examples of the application are as follows:

[0034] Instrument: Waters 1515 Gel Permeation Chromatograph

[0035] Sample preparation: The sample to be tested was dissolved in chromatographic grade N,N-dimethylacetamide solvent to prepare a 4 mg / mL solution, which was filtered using an organic filter head with a pore size of 0.45 μm.

[0036] Injection volume: 100 μL

[0037] Eluent: LiBr was dissolved in chromatographic grade N,N-dimethylacetamide solvent to prepare a 3 mg / mL solution, which was filtered using an organic filter head with a pore size of 0.45 μm.

[0038] Eluent flow rate: 1 mL / min

[0039] Column temperature: 80°C

[0040] Example 1

[0041] Into a 10L reactor equipped with nitrogen inlet, loop gas distributor, mechanical stirring and water separator condenser, 5000.0g of sulfolane was added, and stirring was started. Then 1152.5g of 4, 4'-dichlorodiphenyl sulfone, 1000.0g of bisphenol S and 635.0g of potassium carbonate were added in sequence and mixed well. The potassium carbonate was pretreated by crushing, sieving and drying to obtain a particle size of 15-40μm. The nitrogen was replaced for three times, and the nitrogen flow was adjusted to 2L / min with an oxygen content of 50ppm. The temperature was raised to 220℃, and the nitrogen was distributed by the loop gas distributor. The generated water was carried out by the continuous nitrogen bubbling, and then condensed and entered the water separator. The system was changed from turbid heterogeneous solution to clear homogeneous solution, and the viscosity increased continuously. The reaction was carried out for about 4h, and the mechanical stirring torque was basically unchanged. The polymerization viscous liquid was obtained by stopping the reaction. The nitrogen was turned off, and the polymerization viscous liquid was poured into deionized water to precipitate and crush. The polymerization viscous liquid was washed in 90-95℃ water for 6 times, and then dried to obtain the polyether sulfone resin.

[0042] The weight average molecular weight Mw of the polyether sulfone resin was 80724, the number average molecular weight Mn was 25220, and the molecular weight distribution index PDI was 3.20, which were measured by GPC. The infrared spectrum was shown in Figure 1 ; the GPC spectrum was shown in Figure 2 ; and the NMR spectrum was shown in Figure 1 . In the NMR spectrum, the anti-symmetrical stretching vibration absorption peak of sulfone group O=S=O appeared at 1319.91cm -1 and 1296.16cm -1 , the symmetrical stretching vibration absorption peak of sulfone group O=S=O appeared at 1145.72cm -1 , which indicated that the sulfone group existed in the structure. The anti-symmetrical stretching vibration absorption peak of aromatic ether C-O-C appeared at 1234.44cm -1 , and the symmetrical stretching vibration absorption peak of aromatic ether C-O-C appeared at 1010.7cm -1 , which indicated that the aromatic ether bond existed. There were no characteristic absorption peaks of branched chains at 763cm -1 , 1055cm -1 , 1442cm -1 and 1463cm -1 , which indicated that the self-made resin was a linear polyether sulfone resin without branching.

[0043] Example 2

[0044] In Example 1, the loop gas distributor was replaced by a tubular gas distributor, and other conditions were the same as those in Example 1. The weight average molecular weight Mw of the polyether sulfone resin was 72462, the number average molecular weight Mn was 21249, and the molecular weight distribution index PDI was 3.41, which were measured by GPC. The GPC spectrum was shown in Figure 3From the results of Example 1 and Example 2, it can be seen that the polyether sulfone prepared in Example 1 has a relatively higher molecular weight at the same time, because compared with the tubular gas distributor, the loop gas distributor has more gas distribution points, which is more conducive to the removal of water from the system, and the reaction rate is faster.

[0045] Example 3

[0046] In Example 1, the nitrogen flow rate is reduced from 2 L / min to 1 L / min, and the other conditions remain the same as in Example 1. The GPC measured that the weight average molecular weight Mw of the prepared polyether sulfone resin is 62593, the number average molecular weight Mn is 16472, and the molecular weight distribution index PDI is 3.80, and the GPC spectrum is shown in Figure 4 .

[0047] Example 4

[0048] In Example 1, the nitrogen flow rate is reduced from 2 L / min to 0.5 L / min, and the other conditions remain the same as in Example 1. The GPC measured that the weight average molecular weight Mw of the prepared polyether sulfone resin is 41763, the number average molecular weight Mn is 10658, and the molecular weight distribution index PDI is 3.91, and the GPC spectrum is shown in Figure 5 From the results of Example 1, Example 3 and Example 4, it can be seen that at the same time, the greater the nitrogen flow rate, the greater the number average molecular weight and the weight average molecular weight of the prepared polyether sulfone, and increasing the nitrogen flow rate can increase the water removal rate and thus increase the reaction rate.

[0049] Example 5

[0050] In Example 1, the reaction temperature is reduced from 220℃ to 210℃, and the other conditions remain the same as in Example 1. The GPC measured that the weight average molecular weight Mw of the prepared polyether sulfone resin is 61995, the number average molecular weight Mn is 17365, and the molecular weight distribution index PDI is 3.57, and the GPC spectrum is shown in Figure 6 .

[0051] Example 6

[0052] In Example 1, the reaction temperature is increased from 220℃ to 230℃, and the other conditions remain the same as in Example 1. The GPC measured that the weight average molecular weight Mw of the prepared polyether sulfone resin is 70462, the number average molecular weight Mn is 21033, and the molecular weight distribution index PDI is 3.35, and the GPC spectrum is shown in Figure 7 .

[0053] Example 7

[0054] The reaction temperature was increased from 220 °C to 240 °C in Example 1, and other conditions were consistent with Example 1. The prepared polyether sulfone resin had a weight average molecular weight Mw = 31314, a number average molecular weight Mn = 10001, and a molecular weight distribution index PDI = 3.13, and the GPC spectrum was as shown in Figure 8 From the results of Example 1, Example 5, Example 6, and Example 7, it can be seen that under the same time, with the increase of temperature, the molecular weight of the prepared polyether sulfone shows a trend of first increasing and then decreasing, and the molecular weight and molecular weight distribution are optimal when the reaction temperature is 220 °C. When the reaction temperature is 240 °C, the molecular weight of the prepared polyether sulfone is significantly smaller, because the solvent sulfolane starts to decompose when the temperature exceeds 220 °C, and the decomposition rate increases with the increase of temperature, and the decomposition of the solvent hinders the further progress of the polymerization reaction.

[0055] Example 8

[0056] In Example 1, the salt forming agent potassium carbonate was replaced with sodium carbonate, and the molar ratio of the salt forming agent was kept consistent, and other conditions were consistent with Example 1. The prepared polyether sulfone resin had a weight average molecular weight Mw = 52733, a number average molecular weight Mn = 13350, and a molecular weight distribution index PDI = 3.95, and the GPC spectrum was as shown in Figure 9 From Example 1 and Example 8, it can be seen that compared with sodium carbonate as a salt forming agent, the molecular weight and molecular weight distribution of the polyether sulfone prepared by potassium carbonate as a salt forming agent are more optimal under the same polymerization time.

[0057] Comparative Example 1

[0058] 5000.0 g of sulfolane and 500 g of xylene were added into a 10 L reactor with a nitrogen tube, mechanical stirring, and a water separator condenser, and the stirring was started. Then 1152.5 g of monomer 4,4'-dichlorodiphenyl sulfone, 1000.0 g of bisphenol S, and 635.0 g of potassium carbonate were sequentially added and mixed uniformly. The system was replaced with nitrogen three times to ensure that the residual air in the system was exhausted. The temperature was increased to 200 °C for reflux dehydration. During the process, a large amount of white solid was precipitated, and the system had poor fluidity. At the same time, the water generated during the reaction was removed with xylene, and then condensed into the lower layer of the water separator. After refluxing for 4 h, no water was generated, and the xylene in the system was discharged and the temperature was increased to 220 °C for 5 h. The polyether sulfone polymerization liquid was obtained. The polymerization liquid was poured into deionized water to precipitate and crush, and then dried to obtain the polyether sulfone resin.

[0059] The prepared polyether sulfone resin had a weight average molecular weight Mw = 65198, a number average molecular weight Mn = 15611, and a molecular weight distribution index PDI = 4.18, and the GPC spectrum was as shown in Figure 10It can be seen from Example 1 and Comparative Example 1 that, under the same reaction conditions, the dehydration operation with nitrogen flow is simpler, the reaction rate is faster, the polymerization cycle is shorter, and the molecular weight and molecular weight distribution index of the prepared polyether sulfone are more optimal, compared with xylene reflux dehydration.

[0060] Table 1 Experimental conditions and results of Examples 1-8 and Comparative Example 1

[0061]

[0062]

Claims

1. A process for the synthesis of a polyether sulfone resin, characterized in that Comprising the following steps: 1) adding solvent sulfolane into a reactor with nitrogen conduit, gas distributor, mechanical stirring and water separation condenser, starting stirring, sequentially adding monomers 4,4'-dichlorodiphenyl sulfone, bisphenol S and salt forming agent; After nitrogen replacement, adjusting nitrogen flow and heating to 210~240℃, nitrogen is distributed by gas distributor, and the system is continuously bubbled by nitrogen flow for dehydration, and the reaction is carried out for 3~5 hours; Turning off the nitrogen, pouring the polymer slurry into water for precipitation, and after the steps of crushing, washing and drying, the polyether sulfone resin is obtained; The gas distributor is a tubular gas distributor or a loop gas distributor. The oxygen content in the nitrogen in step 2) is less than 200 ppm, and the nitrogen flow is 0.5~2 L / min.

2. The method of claim 1, wherein The salt forming agent in step 1) is one of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate and barium carbonate.

3. The method of claim 1, wherein The salt forming agent in step 1) is pretreated by crushing, sieving and drying, and the particle size is 15~40 μm.

4. The method of claim 1, wherein The molar ratio of bisphenol S, 4,4'-dichlorodiphenyl sulfone and salt forming agent in step 1) is 1:1.004~1.01:1.05~1.15.

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