Method for preparing polysulfone through polymerization in different temperature sections

Abstract

The invention discloses a method for preparing polysulfone through polymerization in different temperature sections, and relates to the technical field of high polymer materials. The method for preparing polysulfone through polymerization in different temperature sections comprises the following steps: mixing raw materials, controlling the temperature of the mixture to be 140-150 DEG C, and reacting for 2-4 hours to prepare a bisphenol salt reaction material; controlling the temperature of the bisphenol salt reaction material to be 150-155 DEG C, and reacting for 3-5 hours to prepare an oligomer reaction material; controlling the temperature of the oligomer reaction material to be 160-200 DEG C, and performing high polymerization reaction for 4-8 hours to obtain a high molecular weight polymerization reaction material; wherein in the polymerization reaction process, the viscosity of a reaction material is controlled not to exceed 10000 cp by adding a solvent. The reaction section is divided into three specific reaction sections, and the viscosity of the three reaction sections is controlled within a specific range, so that cyclization side reaction caused by a high-temperature system is inhibited, and the content of cyclic oligomer is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material preparation, and particularly relates to a method for preparing polysulfone by polymerization in temperature segments. Background Art

[0002] Bisphenol A type polysulfone resin has excellent mechanical properties, thermal stability and chemical stability, and is thus widely used in fields such as electronics and electrical appliances, aerospace, automobiles and medical devices. At present, the main industrial production process of polysulfone resin is the one-step synthesis method. The raw materials for preparation include bisphenol monomers, 4,4'-dichlorodiphenyl sulfone, alkaline catalysts and solvents. After high-temperature polymerization, it is solidified and precipitated in water, methanol or ethanol to obtain crude polysulfone, and then the crude polysulfone is crushed, washed, dried, granulated and packaged.

[0003] In the above one-step synthesis method, cyclic oligomer by-products with a degree of polymerization less than 5 are easily generated. Among them, the cyclic oligomers are mainly cyclic dimers, cyclic trimers and cyclic tetramers. In the polycondensation reaction of polysulfone, the generated polymer is mainly a linear polymer, and there are significant differences in physical properties such as solubility and rigidity between the cyclic oligomer by-products and the main chain of the linear polymer. Moreover, too high a content of cyclic oligomers also causes the polysulfone product to be opaque, affecting the quality of downstream polysulfone products. For example, during the preparation and casting of the polysulfone membrane casting solution, crystallization precipitation is likely to occur, resulting in an uneven microstructure on the membrane surface, affecting the transparency and optical properties of the membrane, and making it perform poorly in some optical applications; and the cyclic oligomer by-products also easily cause uneven pore size distribution of the membrane, reducing the filtration efficiency and selectivity of the membrane. Summary of the Invention

[0004] The main object of the present invention is to provide a method for preparing polysulfone by polymerization in temperature segments, aiming to solve the problem that the existing polysulfone products contain a high content of cyclic oligomers.

[0005] To achieve the above object, the present invention provides a method for preparing polysulfone by polymerization in temperature segments, including the following steps:

[0006] S10. Mix bisphenol A, 4,4'-dichlorodiphenyl sulfone, an alkaline catalyst and a solvent to obtain a mixed material;

[0007] S20. Control the temperature of the mixed material obtained in step S10 to be 140 - 150 °C, and carry out a salt-forming reaction for 2 - 4 h to obtain a bisphenolate reaction material;

[0008] S30. Control the temperature of the bisphenolate reaction material obtained in step S20 to be 150 - 155 °C, and carry out a low-polymerization reaction for 3 - 5 h to obtain an oligomer reaction material;

[0009] S40. Control the temperature of the oligomer reaction material obtained in step S30 to be 160 - 200 °C, and conduct high polymerization reaction for 4 - 8 h to obtain a high molecular weight polymerization reaction material;

[0010] S50. Post-treat the high molecular weight polymerization reaction material obtained in step S40 to obtain a polysulfone product;

[0011] Wherein, in step S30 and step S40, the viscosity of the reaction material is controlled not to exceed 10000 cp by adding a solvent.

[0012] Optionally, in step S30, control the viscosity of the reaction material not to exceed 6500 cp;

[0013] In step S40, control the viscosity of the reaction material not to exceed 7000 cp.

[0014] Optionally, in step S30 and step S40, the solvent used to adjust the viscosity of the reaction material is added to the reaction material at a rate of 1 - 3 kg / min.

[0015] Preferably, the solvent used to adjust the viscosity of the reaction material is added to the reaction material at a rate of 2 kg / min.

[0016] Optionally, in step S30 and step S40, the solvent used to adjust the viscosity of the reaction material is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, sulfolane, and N-methylpyrrolidone.

[0017] Optionally, in step S50, the post-treatment includes filtering, curing, pulverizing, washing, and drying the reaction material.

[0018] Optionally, in step S50, the solvent for washing is selected from at least one of N,N-dimethylacetamide, N-methylpyrrolidone, sulfolane, ethanol, and isopropanol.

[0019] Optionally, in step S50, the solvent for washing is a mixture of N,N-dimethylacetamide and ethanol, or

[0020] the solvent for washing is a mixture of N,N-dimethylacetamide and cyclohexane;

[0021] Wherein, the content of N,N-dimethylacetamide in the mixed solvent is 50 - 70 v%.

[0022] Preferably, the content of N,N-dimethylacetamide in the mixed solvent is 60 v%.

[0023] Optionally, in the step S10, the molar ratio of bisphenol A, 4,4'-dichlorodiphenyl sulfone, the basic catalyst and the solvent is (1.01 - 1.05):1:(1.2 - 1.4):(3.5 - 4.5).

[0024] Preferably, the molar ratio of bisphenol A, 4,4'-dichlorodiphenyl sulfone, the basic catalyst and the solvent is 1.03:1.0:1.3:4.3.

[0025] Optionally, in the steps S20 to S40, the reaction is carried out under the conditions of a nitrogen atmosphere and stirring.

[0026] In the technical solution of the present invention, through the control of temperature, the reaction stage is divided into a salt-forming reaction stage, an oligomer synthesis stage and a high molecular weight synthesis stage. In the salt-forming reaction stage, the bisphenol monomer undergoes a salt-forming reaction with the basic catalyst to generate a bisphenolate reaction material; in the oligomer synthesis stage, the reaction between the bisphenolate and 4,4'-dichlorodiphenyl sulfone is promoted to carry out a low-degree polymerization reaction, while reducing the generation of cyclic oligomers; in the high molecular weight synthesis reaction stage, the oligomers undergo a high molecular chain polymerization reaction to generate a high molecular weight polymerization material. This application divides the reaction stage into three specific reaction stages, and the temperatures of the three reaction stages are controlled within a specific temperature range to inhibit the cyclization side reaction caused by the same high-temperature system and reduce the content of cyclic oligomers such as cyclic dimers, cyclic trimers and cyclic tetramers.

[0027] Since as the reaction proceeds, the viscosities of the reaction materials corresponding to the oligomer synthesis stage and the high molecular weight synthesis stage gradually increase. Although the high viscosity can inhibit the occurrence of cyclic polymerization side reactions, it will also affect the polymerization of molecules. Therefore, on the basis of dividing the temperature sections, this application further controls the viscosities of the reaction materials corresponding to each reaction stage within a specific range, so as to further inhibit the occurrence of cyclic polymerization side reactions while ensuring relatively stable polymerization between molecules. The polysulfone product prepared contains a low content of cyclic oligomers such as cyclic dimers, cyclic trimers and cyclic tetramers, and the polysulfone product is transparent, ensuring the quality of downstream polysulfone products. Description of the Drawings

[0028] Figure 1 It is the gel chromatogram of the polysulfone product prepared in Example 1 of the present invention.

[0029] The realization, functional characteristics and advantages of the object of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed Embodiments

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0031] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0032] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and / or" appearing throughout the text includes three parallel scenarios. Taking "A and / or B" as an example, it includes scenario A, scenario B, or the scenario where A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] The present invention provides a method for preparing polysulfone by polymerization in different temperature segments, which includes the following steps:

[0034] S10: Mix bisphenol A, 4,4'-dichlorodiphenyl sulfone, a basic catalyst, and a solvent to obtain a mixed material.

[0035] S20: Control the temperature of the mixed material obtained in step S10 to be 140 - 150 °C, and carry out a salt-forming reaction for 2 - 4 h to obtain a bisphenolate reaction material.

[0036] S30: Control the temperature of the bisphenolate reaction material obtained in step S20 to be 150 - 155 °C, and carry out a low-polymerization reaction for 3 - 5 h to obtain an oligomer reaction material.

[0037] S40: Control the temperature of the oligomer reaction material obtained in step S30 to be 160 - 200 °C, and carry out a high-polymerization reaction for 4 - 8 h to obtain a high-molecular-weight polymerization reaction material.

[0038] S50: Post-treat the high-molecular-weight polymerization reaction material obtained in step S40 to obtain a polysulfone product.

[0039] Among them, in the steps S30 and S40, the viscosity of the reaction materials is controlled not to exceed 10,000 cp by adding a solvent.

[0040] It should be noted that in step S10, the basic catalyst is sodium carbonate or potassium carbonate; the solvent is N,N-dimethylacetamide (DMAC). In the steps S20 to S40, the reaction is carried out under a nitrogen atmosphere and stirring.

[0041] In the technical solution of the present application, the reaction section is divided into three specific reaction sections, and the temperatures of the three reaction sections are controlled within a specific temperature range to inhibit the cyclization side reaction caused by the same high-temperature system and reduce the content of cyclic oligomers such as cyclic dimers, cyclic trimers, and cyclic tetramers. Moreover, the viscosity of the reaction materials corresponding to each reaction section is further controlled to further inhibit the occurrence of cyclic polymerization side reactions while ensuring stable polymerization between molecules. The prepared polysulfone product contains a low content of cyclic oligomers such as cyclic dimers, cyclic trimers, and cyclic tetramers.

[0042] Furthermore, in step S30, the viscosity of the reaction materials is controlled not to exceed 6,500 cp; in step S40, the viscosity of the reaction materials is controlled not to exceed 7,000 cp.

[0043] Furthermore, in the steps S30 and S40, the solvent used to adjust the viscosity of the reaction materials is added to the reaction materials at a rate of 1 to 3 kg / min; the solvent for adjusting the viscosity of the reaction materials is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and sulfolane. Adding the solvent to the reaction materials at a specific rate does not affect the reaction of the materials in the reaction system and can effectively adjust the viscosity of the reaction system.

[0044] Furthermore, in step S50, the post-treatment includes filtering, curing, pulverizing, washing, and drying the polysulfone reaction material; among them, the solvent for washing is selected from one or more mixtures of N,N-dimethylacetamide, sulfolane, ethanol, and isopropanol, and the washing time is 1 to 3 h.

[0045] Specifically, in step S50, the solvent for washing is a mixture of N,N-dimethylacetamide and ethanol, or the solvent for washing is a mixture of N,N-dimethylacetamide and cyclohexane; among them, the content of N,N-dimethylacetamide in the mixed solvent is 50 to 70 v%. Washing the pulverized material with a mixed solvent to further remove residual cyclic oligomers and other by-products. It can be understood that "v%" refers to volume percentage.

[0046] Further, the molar ratio of bisphenol A, 4,4'-dichlorodiphenyl sulfone, the basic catalyst and the solvent is (1.01 - 1.05):1:(1.2 - 1.4):(3.5 - 4.5). The amount of bisphenol A used is slightly in excess relative to the amount of 4,4'-dichlorodiphenyl sulfone, which can improve the content of cyclic oligomers in the polysulfone product. The reason may be that slightly excessive bisphenol A makes the two ends of some molecular chains in the reaction system both bisphenol alkali metal salts. In this way, the formation of rings by molecular chains can be reduced to a certain extent, and the bisphenol alkali metal salt has nucleophilic properties and has the opportunity to break the formed cyclic molecular weight.

[0047] The technical solutions of the present invention will be further described in detail below with reference to specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0048] Example 1

[0049] A method for preparing polysulfone by polymerization in temperature segments includes the following steps:

[0050] S10: Add 103 mol of bisphenol A, 100 mol of 4,4'-dichlorodiphenyl sulfone, and 130 mol of potassium carbonate into 40 L of N,N-dimethylacetamide. Under the conditions of a nitrogen atmosphere and stirring (150 r / min), heat up to 80 °C to obtain a mixed material.

[0051] S20: Under the conditions of a nitrogen atmosphere and stirring (100 r / min), heat up the mixed material to 145 °C. The bisphenol A and potassium carbonate undergo a salt formation reaction for 3 h to obtain a bisphenol salt reaction material.

[0052] S30: Under the conditions of a nitrogen atmosphere and stirring (100 r / min), heat up the bisphenol salt reaction material to 155 °C. The bisphenol salt and 4,4'-dichlorodiphenyl sulfone undergo a low-degree polymerization reaction for 4 h to obtain an oligomer reaction material.

[0053] S40: Under the conditions of a nitrogen atmosphere and stirring (100 r / min), heat up the oligomer reaction material to 185 °C. The oligomers undergo a high-molecular polymerization reaction for 5 h to obtain a high-molecular weight polymerization reaction material.

[0054] S50: Dilute the high-molecular weight polymerization reaction material with N,N-dimethylacetamide. The amount of N,N-dimethylacetamide used is 1.5 wt% of the high-molecular weight polymerization reaction material to obtain a dilution solution. Filter the dilution solution to remove salts, add the filtered filtrate into water for curing, and crush, wash, dry, and granulate the obtained crude polysulfone to obtain a polysulfone product.

[0055] Among them, in step S30, when the viscosity of the reaction material reaches 6000 cp, N,N-dimethylacetamide is added to the reaction material at a rate of 2.0 kg / min to reduce the viscosity of the reaction material to 5600 cp;

[0056] In step S40, when the viscosity of the reaction material reaches 6500 cp, N,N-dimethylacetamide is added to the reaction material at a rate of 2.0 kg / min to reduce the viscosity of the reaction material to 6100 cp;

[0057] In step S50, the crushed material is washed with N,N-dimethylacetamide. When washing, the crushed material is added to N,N-dimethylacetamide (the mass ratio of the crushed material to N,N-dimethylacetamide is 1:1), and stirring and washing are carried out at a stirring rate of 100 r / min for 2 times, with each washing duration being 1 h.

[0058] Examples 2 - 3

[0059] Examples 2 - 3 are based on Example 1, and the difference is that: in step S30, the upper limit of the viscosity of the reaction material has changed, and the others are the same as Example 1.

[0060] Example 2: In step S30, when the viscosity of the reaction material reaches 6150 cp, N,N-dimethylacetamide is added to the reaction material at a rate of 2.0 kg / min to reduce the viscosity of the reaction material to 5600 cp.

[0061] Example 3: In step S30, when the viscosity of the reaction material reaches 6300 cp, N,N-dimethylacetamide is added to the reaction material at a rate of 2.0 kg / min to reduce the viscosity of the reaction material to 5600 cp.

[0062] Examples 4 - 5

[0063] Examples 4 - 5 are based on Example 2, and the difference is that: in step S40, the upper limit of the viscosity of the reaction material has changed, and the others are the same as Example 2.

[0064] Example 4: In step S40, when the viscosity of the reaction material reaches 6650 cp, N,N-dimethylacetamide is added to the reaction material at a rate of 2.0 kg / min to reduce the viscosity of the reaction material to 6100 cp.

[0065] Example 5: In step S40, when the viscosity of the reaction material reaches 6800 cp, N,N-dimethylacetamide is added to the reaction material at a rate of 2.0 kg / min to reduce the viscosity of the reaction material to 6100 cp.

[0066] Examples 6 - 7

[0067] Examples 6 to 7 are based on Example 4, and the difference is that in step S50, when washing, a mixed solvent is used to replace N,N-dimethylacetamide, and the amount of the mixed solvent used is the same as that of N,N-dimethylacetamide, and the others are the same as in Example 4.

[0068] Example 6: In step S50, the washing solvent is a mixed solution of N,N-dimethylacetamide and ethanol, and the volume ratio of N,N-dimethylacetamide to ethanol is 3:2.

[0069] Example 7: In step S50, the washing solvent is a mixed solution of N,N-dimethylacetamide and cyclohexane, and the volume ratio of N,N-dimethylacetamide to cyclohexane is 3:2.

[0070] Comparative Example 1

[0071] This comparative example is based on Example 1, and the difference is that step S30 is not included, and the others are the same as in Example 1.

[0072] Comparative Example 2

[0073] This comparative example is based on Example 1, and the difference is that in step S50, the crushed material is washed with water, and the amount of water used is the same as the mass of N,N-dimethylacetamide, and the others are the same as in Example 1.

[0074] Performance Test

[0075] 1. After testing, the main component of the polysulfone products prepared in Examples 1 to 7 and Comparative Examples 1 to 2 is polysulfone resin.

[0076] 2. Referring to the test method of "Determination of Molecular Weight Distribution of Solution Polymers by Gel Permeation Chromatography" SH / T1759-2007, the molecular weight distribution of the polysulfone product prepared in Example 1 was tested using a gel permeation chromatograph (GPC), and the gel chromatogram is as Figure 1 shown.

[0077] 3. The content of cyclic oligomers in the polysulfone products prepared in Examples 1 to 7 and Comparative Examples 1 to 2 was detected. Among them, the cyclic oligomers include cyclic dimers, cyclic trimers and cyclic tetramers, and the detection results are shown in Table 1 below.

[0078] Table 1 Content of Cyclic Oligomers

[0079]

[0080] As can be seen from the test results in Table 1, the content of cyclic oligomers in the polysulfone products prepared in Examples 1-7 of the present application is relatively low, which can ensure the quality of downstream polysulfone products. Examples 1-5 investigated the influence of the viscosity of the reaction materials on the content of cyclic oligomers during the low-polymerization reaction and the high-molecular polymerization reaction. Since the viscosity of the reaction materials gradually increases as the reaction proceeds, although high viscosity can inhibit the occurrence of cyclic polymerization side reactions, excessively high viscosity will affect the polymerization of molecules and the polymerization of molecules is hindered. Therefore, it is necessary to control the viscosity within a specific range to ensure the polymerization between molecules while effectively inhibiting the occurrence of cyclic polymerization side reactions.

[0081] Examples 6-7 investigated the influence brought about by washing the crushed materials with different solvents. Washing the crushed materials with a specific mixed solvent can further remove the residual cyclic oligomers and other by-products.

[0082] In Comparative Example 1, since the polysulfone product was prepared by using the existing two reaction stages of the salt-forming reaction stage and the polymerization stage, the content of cyclic oligomers in the prepared polysulfone product is relatively high, indicating that the present application divides the reaction stage into three specific reaction temperature stages: the salt-forming reaction stage, the oligomer synthesis stage, and the high-molecular weight synthesis stage, which can relatively stably inhibit the cyclization side reaction caused by the same high-temperature system. In Comparative Example 2, the existing water was used as the washing solvent, and the residual cyclic oligomers and other by-products could not be removed well.

[0083] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the patent protection scope of the present invention.

Claims

1. A method for preparing polysulfone by temperature-stage polymerization, characterized in that: The following steps are involved: S10, mixing bisphenol A, 4,4'-dichlorodiphenyl sulfone, an alkaline catalyst and a solvent to prepare a mixture; S20, controlling the temperature of the mixture obtained in step S10 to 140-150° C., and performing a salt-forming reaction for 2-4 hours to obtain a bisphenolate reaction material; S30, controlling the temperature of the bisphenolate reaction material obtained in step S20 to 150-155° C., and carrying out the oligomerization reaction for 3-5 hours to obtain an oligomer reaction material; S40, controlling the temperature of the oligomer reaction material obtained in step S30 to 160-200° C., and performing a high polymerization reaction for 4-8 hours to obtain a high molecular weight polymerization reaction material; S50, post-treating the high molecular weight polymerization reaction material obtained in step S40 to obtain a polysulfone product; Wherein, in the step S30 and the step S40, the viscosity of the reaction material is controlled not to exceed 10000 cp by adding a solvent.

2. The method for preparing polysulfone by temperature-stage polymerization according to claim 1, characterized in that: In the step S30, the viscosity of the reaction material is controlled not to exceed 6500cp; In the step S40, the viscosity of the reaction material is controlled not to exceed 7000 cp.

3. The method for preparing polysulfone by temperature-stage polymerization according to claim 1, characterized in that: In the step S30 and the step S40, the solvent for adjusting the viscosity of the reaction material is added to the reaction material at a rate of 1 to 3 kg / min.

4. The method for preparing polysulfone by temperature-stage polymerization according to claim 1, characterized in that: In the step S30 and the step S40, the solvent used to adjust the viscosity of the reaction material is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, sulfolane and N-methylpyrrolidone.

5. The method for preparing polysulfone by temperature-stage polymerization according to claim 1, characterized in that: In the step S50, the post-processing includes filtering, solidifying, crushing, washing and drying the reaction material.

6. The method for preparing polysulfone by temperature-stage polymerization according to claim 5, characterized in that: In the step S50, the solvent used for washing is selected from at least one of N,N-dimethylacetamide, N-methylpyrrolidone, sulfolane, ethanol and isopropanol.

7. The method for preparing polysulfone by temperature-stage polymerization according to claim 6, characterized in that: In step S50, the washing solvent is a mixture of N,N-dimethylacetamide and ethanol, or The solvent used for washing is a mixture of N,N-dimethylacetamide and cyclohexane; The content of N,N-dimethylacetamide in the mixed solvent is 50-70v%.

8. The method for preparing polysulfone by temperature-stage polymerization according to claim 1, characterized in that: In the step S10, the molar ratio of bisphenol A, 4,4'-dichlorodiphenyl sulfone, alkaline catalyst and solvent is (1.01-1.05):1:(1.2-1.4):(3.5-4.5).

9. The method for preparing polysulfone by temperature-stage polymerization according to claim 1, characterized in that: In the steps S20 to S40, the reaction is carried out under a nitrogen atmosphere and stirring.

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