Synthesis method of narrow-distribution phenolphthalein-based polyaryletherketone / sulfone

Abstract

The invention provides a synthesis method of narrow-distribution phenolphthalein polyaryletherketone / sulfone, and belongs to the technical field of synthesis methods of polyaryletherketone / sulfone. The method comprises the following steps: adding phenolphthalein, an active double-halogenated aromatic hydrocarbon monomer, a salt-forming agent and a high-boiling-point proton-free strong polar solvent into a reaction kettle, starting stirring, raising the temperature under nitrogen purging, stopping nitrogen purging, opening a pressure reduction function, extracting air to stabilize the vacuum air pressure of a polymerization kettle to-98.5 to-93.5 kPa, maintaining a polymerization system to be slightly boiled, adjusting heat tracing of a rectifying tower, and carrying out heat tracing on the rectifying tower; the temperature of the tower top is maintained at 25-40 DEG C, the state is maintained for 0.4-0.7 h, a nitrogen switch is turned on, negative pressure pumping is stopped, after the normal pressure of the polymerization kettle is recovered, heating is carried out, a viscous polymer product is obtained, heating is stopped, and phenolphthalein-based polyaryletherketone / sulfone is obtained through aftertreatment. According to the method, under the condition that an entrainer is not used, the polyaryletherketone / sulfone with high molecular weight and narrow distribution is efficiently synthesized through cooperation of normal pressure and reduced pressure of a reaction kettle.

Description

Technical Field

[0001] The invention belongs to the technical field of synthesis methods of polyaryletherketone / sulfone, and in particular relates to a synthesis method of narrow-distribution phenolphthalein-based polyaryletherketone / sulfone. Background Art

[0002] At present, the most commonly used synthesis method in the production of commercial phenolphthalein polyaryletherketone is to synthesize by nucleophilic substitution reaction under alkali metal hydroxide / carbonate catalysis. In this production process, byproduct water will be generated, and water is a poor solvent for polymers, and will react with monomers to generate side reactions, resulting in problems such as low polymer molecular weight. Therefore, during the polymerization process, water must be removed as much as possible, especially before high-temperature polymerization. In order to improve the efficiency of water removal, entrainers are usually used in industry, such as toluene, chlorobenzene, xylene and other solutions for azeotropic water removal at normal pressure. For example, in CN85108751B, xylene is used as an entrainer in the synthesis of phenolphthalein polyetheretherketone. Xylene is heated to reflux at the salt-forming temperature, and the water generated by the reaction is taken out at the same time. After the salt-forming is completed, the temperature is continued to be raised to gradually evaporate the xylene. This process uses a large amount of flammable, volatile, and toxic xylene, which increases the subsequent complicated xylene tail gas and recovery process, complicates the reaction system and process, and increases the cost of the production process. In addition, the dehydration temperature is often controlled by the boiling point of the azeotropic agent and cannot be adjusted over a large range. Most dehydration processes have low temperatures and take a long time, resulting in a surge in polymerization side reactions and a broadening of the polymer molecular weight distribution. Summary of the invention

[0003] The invention aims to provide a method for synthesizing phenolphthalein polyaryletherketone / sulfone with narrow distribution. The method, under the condition of not using an azeotropic agent, achieves different dehydration reflux temperatures by combining normal pressure and reduced pressure in a reaction kettle and controllably adjusting the vacuum degree, is suitable for monomers with different activities, quickly removes byproduct water, and efficiently synthesizes polyaryletherketone / sulfone with high molecular weight and narrow distribution. Compared with conventional methods, the method has higher resin purity and better processing fluidity.

[0004] The present invention provides a method for synthesizing narrow distribution phenolphthalein polyaryletherketone / sulfone, comprising:

[0005] Add phenolphthalein, active dihalogenated aromatic hydrocarbon monomer, salt-forming agent and high-boiling proton-free strong polar solvent into the reaction kettle, start stirring, heat up to 160-190°C under nitrogen purge, turn off nitrogen purge, turn on the decompression function, pump air to stabilize the vacuum pressure of the polymerization kettle to -98.5 to -93.5 kPa, maintain the polymerization system to keep a slight boil, adjust the heating of the distillation tower to maintain the top temperature at 25-40°C, maintain this state for 0.4-0.7h, turn on the nitrogen switch, stop pumping negative pressure, after the polymerization kettle returns to normal pressure, heat up to 200-230°C, keep warm for 2-4h to obtain a viscous polymer product, stop heating, and obtain phenolphthalein polyaryletherketone / sulfone through post-treatment.

[0006] Preferably, the active dihalogenated aromatic hydrocarbon monomer is 4,4'-difluorobenzophenone, 4,4'-difluorodiphenyl sulfone, 4,4'-dichlorodiphenyl sulfone, 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile or 2,6-di(4-fluorobenzoyl)triptycene.

[0007] Preferably, the molar ratio of the active dihalogenated aromatic hydrocarbon monomer to phenolphthalein is (1.01-1.04):1.

[0008] Preferably, the amount of the salt-forming agent added is 1.1-1.4 times the molar amount of phenolphthalein.

[0009] Preferably, the salt-forming agent is potassium carbonate or sodium carbonate.

[0010] Preferably, the high boiling point aprotic strong polar solvent is sulfolane, diphenyl sulfone or N-methylpyrrolidone.

[0011] Preferably, the heating is performed under nitrogen purge at a heating rate of 1.5°C / min.

[0012] Preferably, the time for maintaining the polymerization system at a slight boiling point is 0.6 h.

[0013] Preferably, after the polymerization kettle returns to normal pressure, the temperature is increased to 215° C. at a rate of 2.0° C. / min.

[0014] Preferably, the post-treatment process is: after cooling, add N,N-dimethylacetamide to dilute, stir evenly, pour it into ethanol under vigorous stirring to precipitate, filter it and wash it with dilute hydrochloric acid, then repeatedly boil and wash the polymer product with distilled water, and finally dry it.

[0015] Working principle of the present invention

[0016] The synthesis of phenolphthalein-based polyaryletherketone of the present invention belongs to nucleophilic reaction, and in order to improve the reaction activity and reduce the reaction time, the reaction needs to be carried out at a high temperature of more than 200°C, so it needs to be carried out in a high-boiling proton-free strong polar solvent, preferably cyclopentane as a solvent. The reaction is carried out in a reactor with a distillation device to facilitate the continuous removal of side reaction water during the process and promote the reaction. At the beginning of the reaction, nitrogen is first used to purge the polymerization kettle, the distillation tower, etc. to remove oxygen in the air. When the temperature is raised to the salt-forming temperature, most of the water will be generated at this temperature. At this time, the decompression function is slowly turned on to prevent the speed from boiling too fast. When the pressure is reduced to a suitable pressure, the polymerization solvent is maintained to be slightly boiling. At this time, the main solvent cyclopentane boils and surges, bubbles are generated, and the generated water will evaporate. If the decompression measures are not taken, the generated water is wrapped by the unboiling cyclopentane and cannot be removed in time, which will produce side reactions and affect the reaction rate and process. The distillation tower is heated so that the top temperature is maintained at a temperature slightly higher than the boiling point of water under the pressure. Since the boiling points of water and sulfolane are very different, the evaporated sulfolane and water vapor pass through the distillation tower, and the sulfolane will be cooled and refluxed, re-entering the reaction system without causing solvent loss, while the generated water will continuously leave the polymerization system from the top of the tower. After the salt formation stage is over, slowly open the nitrogen switch, stop pumping negative pressure, and continue to heat up to the polymerization temperature after the polymerization kettle returns to normal pressure. After the reaction is completed, add N,N-dimethylacetamide to dilute after cooling, stir evenly, pour it into ethanol for precipitation, filter it, wash it with dilute hydrochloric acid, pure water, and dry it.

[0017] Beneficial effects of the present invention

[0018] 1. The phenolphthalein polyaryletherketone / sulfone prepared by the present invention has a high number average molecular weight of 4w-7w, the water generated by polycondensation is removed in time, the hydrolysis side reaction in the high temperature stage is reduced, the reaction degree is high, and the molecular weight is large.

[0019] 2. There is no xylene and hazardous chemicals in the reaction process, which reduces environmental pollution, improves safety, saves costs, and has high polymer purity.

[0020] 3. The present invention has a fast reaction speed: the produced water is quickly removed in the solvent reflux stage, the reversible reaction is accelerated to the right, the efficiency is improved, the overall solvent reflux quickly takes away the reaction heat, the overall system temperature is more uniform, the molecular weight distribution is narrower, the gel content is lower, and it is suitable for film-grade polyaryletherketone. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a molecular weight distribution curve of the product prepared in Example 1;

[0022] Figure 2 This is a molecular weight distribution curve of the product prepared in Comparative Example 1;

[0023] Figure 3This is the infrared spectrum of the product prepared in Example 1.

[0024] Figure 4 This is the molecular weight distribution curve of the product prepared in Comparative Example 2. DETAILED DESCRIPTION

[0025] The present invention provides a method for synthesizing narrow distribution phenolphthalein polyaryletherketone / sulfone, comprising:

[0026] Phenolphthalein, active dihalogenated aromatic hydrocarbon monomer, salt-forming agent and high-boiling-point proton-free strong polar solvent are added to the reaction kettle, stirring is started, and the temperature is preferably raised to 160-190° C., preferably 170° C., at a rate of 1.5° C. / min under nitrogen purge. At this time, the nitrogen purge is turned off, the decompression function is turned on, and the vacuum pressure of the polymerization kettle is slowly pumped to stabilize to -98.5 to -93.5 kPa, preferably -97.8 kPa, the polymerization system is maintained at a slight boiling, and the heating of the distillation tower is adjusted to maintain the top temperature of the tower at 25-40° C., preferably 28° C. At this time, the solvent and water are in the polymerization reactor. The kettle is continuously boiling and evaporating, but after passing through the distillation tower, the solvent is cooled and refluxed, and the generated water continuously leaves the polymerization system from the top of the tower. This state is maintained for 0.4-0.8h, preferably after 0.6h, when no obvious water is generated in the system, it can be considered that the salt formation stage is over, and the nitrogen switch is slowly opened to stop pumping negative pressure. After the polymerization kettle returns to normal pressure, the temperature is preferably increased to 200-230°C, preferably 215°C, at a rate of 2.0°C / min, and kept warm for 2-4h, preferably 2h, to obtain a viscous polymer product, and the heating is stopped. After post-treatment, phenolphthalein polyaryletherketone / sulfone is obtained.

[0027] According to the present invention, the active dihalogenated aromatic hydrocarbon monomer is preferably 4,4'-difluorobenzophenone, 4,4'-difluorodiphenyl sulfone, 4,4'-dichlorodiphenyl sulfone, 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile or 2,6-di(4-fluorobenzoyl)triptycene; the salt-forming agent is preferably potassium carbonate or sodium carbonate; the high-boiling point proton-free strong polar solvent is preferably sulfolane, diphenyl sulfone or N-methylpyrrolidone, more preferably sulfolane.

[0028] According to the present invention, the molar ratio of phenolphthalein to active dihalogenated aromatic hydrocarbon monomer is (1.01-1.04):1, the salt-forming agent is preferably 1.1 to 1.4 times the molar amount of phenolphthalein, and the amount of solvent added is preferably 28-38% solid content (mass ratio) of the theoretical mass of the generated polymer.

[0029] According to the present invention, the post-treatment process is preferably: after cooling, N,N-dimethylacetamide is added to dilute, stirred evenly, poured into ethanol under vigorous stirring to precipitate, filtered and washed with dilute hydrochloric acid, and then the polymer product is repeatedly boiled and washed with distilled water, and finally dried.

[0030] The synthesis process of the present invention is as follows:

[0031]

[0032] The present invention is further described in detail below with reference to specific examples, and the raw materials involved in the examples are all commercially available.

[0033] Example 1

[0034] 3.91kg phenolphthalein (12.25mol), 2.70kg 4,4'-difluorobenzophenone (12.35mol), 1.90kg potassium carbonate, and 9.18kg solvent sulfolane were added to a 50L reactor with a distillation device. Stirring was started, and the temperature was raised to 170°C at 1.5°C / min under nitrogen purge. At this time, the nitrogen purge was turned off, the decompression function was turned on, and the vacuum pressure of the polymerization kettle was slowly pumped to stabilize to -97.8kPa, the polymerization system was maintained to be slightly boiling, and the distillation tower was adjusted to heat the top of the tower to maintain the temperature at about 28°C. At this time, sulfolane and water continued to boil and evaporate in the polymerization kettle, but after passing through the distillation tower, sulfolane was cooled and refluxed, and the generated water continued to leave the polymerization system from the top of the tower. After maintaining this state for 0.6h, no obvious water was generated in the system, and it can be considered that the salt formation stage is over. Slowly open the nitrogen switch and stop pumping negative pressure. After the polymerization kettle returns to normal pressure, heat it to 215°C at 2.0°C / min and keep it warm for 2 hours. A viscous polymer product is obtained. Stop heating, cool it down, add 20L N,N-dimethylacetamide to dilute it, stir it evenly, pour it into ethanol with vigorous stirring to precipitate it, filter it and wash it with 0.1% dilute hydrochloric acid, then repeatedly boil and wash the polymer product with distilled water, and dry it to obtain irregular particles / powder products. After testing, its number average molecular weight is 4.3w, the molecular weight distribution is 1.3, and the gel content is 0.11%. The molecular weight distribution diagram is as follows Figure 1 As shown, the infrared spectrum is Figure 3 shown.

[0035] Example 2

[0036] The experimental conditions and steps are the same as those in Example 1, except that the type of active dihalogenated aromatic hydrocarbon monomer is changed to 4,4'-dichlorodiphenyl sulfone to prepare phenolphthalein polyarylethersulfone, as shown in Table 1:

[0037] Example 3

[0038] The experimental conditions and steps are the same as those in Example 1, except that the solvent type in Example 1 is changed to diphenyl sulfone, and phenolphthalein polyaryletherketone / sulfone is prepared, as shown in Table 1:

[0039] Example 4

[0040] The experimental conditions and steps are the same as those in Example 1, except that the temperature and pressure of the boiling reflux of the solvent in Example 1 are changed, the vacuum pressure of the polymerization kettle is stabilized to -94.5 kPa, the temperature of the polymerization system is maintained at 187° C., boiling reflux is maintained, and the heating of the distillation tower is adjusted so that the top temperature of the tower is maintained at about 39° C., and phenolphthalein polyaryletherketone / sulfone is prepared, as shown in Table 1:

[0041] Comparative Example 1

[0042] Use conventional entrainer: xylene with water to remove water. After adding the same phenolphthalein, 4,4'-difluorobenzophenone, potassium carbonate, and cyclopentane sulfone as in Example 1 to a 50L reactor equipped with a water separator, add 5.0kg of xylene. Turn on the stirring, and raise the temperature to 150°C at 1.5°C / min under nitrogen purge. Xylene boils, condenses and separates with water, and refluxes back into the system in the upper layer of the water separator, while the generated water leaves the polymerization system in the lower layer of the water separator. After maintaining this state for 2 hours, no obvious water is generated in the system. Continue to raise the temperature to discharge the xylene in the system, raise the temperature to 215°C at 2.0°C / min, and keep warm for 3 hours. Treat the polymer in the same manner as in Example 1. After testing, Figure 2 The number average molecular weight is 4.3w, the molecular weight distribution is 2.0, and the gel content is 0.46%. As shown in Table 1, the xylene isomers are still detected by thermal desorption of the completely dried product at 350°C through gas chromatography-mass spectrometry (GC-MS).

[0043] Comparative Example 2

[0044] The experimental conditions and steps are the same as those in Example 1, except that the reaction system does not use vacuum dehydration, but uses nitrogen to continuously purge the polymerization liquid surface to remove the water generated by the reaction from the polymerization system. The dehydration time is 170°C for 4 hours, and the temperature is raised to 215°C for polymerization for 5 hours. After treatment by the same method, the phenolphthalein polyaryletherketone with a number average molecular weight of 2.4w and a molecular weight distribution coefficient of 2.3 is obtained. Figure 4 , the gel content is 0.32%. The data are shown in Table 1.

[0045] Table 1

[0046]

Claims

1. A method for synthesizing a narrow distribution phenolphthalein-based polyaryletherketone / sulfone, characterized in that: include: Add phenolphthalein, active dihalogenated aromatic hydrocarbon monomer, salt-forming agent and high-boiling proton-free strong polar solvent into the reaction kettle, start stirring, heat up to 160-190°C under nitrogen purge, turn off nitrogen purge, turn on the decompression function, pump air to stabilize the vacuum pressure of the polymerization kettle to -98.5 to -93.5 kPa, maintain the polymerization system to keep a slight boil, adjust the heating of the distillation tower to maintain the top temperature at 25-40°C, maintain this state for 0.4-0.7h, turn on the nitrogen switch, stop pumping negative pressure, after the polymerization kettle returns to normal pressure, heat up to 200-230°C, keep warm for 2-4h to obtain a viscous polymer product, stop heating, and obtain phenolphthalein polyaryletherketone / sulfone through post-treatment.

2. The method for synthesizing a narrow distribution phenolphthalein-based polyaryletherketone / sulfone according to claim 1, characterized in that: The active dihalogenated aromatic hydrocarbon monomer is 4,4'-difluorobenzophenone, 4,4'-difluorodiphenyl sulfone, 4,4'-dichlorodiphenyl sulfone, 2,6-dichlorobenzonitrile, 2,6-difluorobenzonitrile or 2,6-di(4-fluorobenzoyl)triptycene.

3. The method for synthesizing a narrow distribution phenolphthalein-based polyaryletherketone / sulfone according to claim 1, characterized in that: The molar ratio of the active dihalogenated aromatic hydrocarbon monomer to phenolphthalein is (1.01-1.04):

1.

4. The method for synthesizing a narrow distribution phenolphthalein-based polyaryletherketone / sulfone according to claim 1, characterized in that: The amount of the salt-forming agent added is 1.1-1.4 times the molar amount of phenolphthalein.

5. The method for synthesizing a narrow distribution phenolphthalein-based polyaryletherketone / sulfone according to claim 1, characterized in that: The salt-forming agent is potassium carbonate or sodium carbonate.

6. The method for synthesizing a narrow distribution phenolphthalein-based polyaryletherketone / sulfone according to claim 1, characterized in that: The high-boiling-point proton-free strong polar solvent is sulfolane, diphenyl sulfone or N-methylpyrrolidone.

7. The method for synthesizing a narrow distribution phenolphthalein-based polyaryletherketone / sulfone according to claim 1, characterized in that: The temperature is increased under nitrogen purge at a rate of 1.5°C / min.

8. The method for synthesizing a narrow distribution phenolphthalein-based polyaryletherketone / sulfone according to claim 1, characterized in that: The time for maintaining the polymerization system to maintain a slight boiling is 0.6h.

9. The method for synthesizing a narrow distribution phenolphthalein-based polyaryletherketone / sulfone according to claim 1, characterized in that: After the polymerization kettle was restored to normal pressure, the temperature was raised to 215° C. at a rate of 2.0° C. / min.

10. The method for synthesizing a narrow distribution phenolphthalein-based polyaryletherketone / sulfone according to claim 1, characterized in that: The post-treatment process is as follows: after cooling, add N,N-dimethylacetamide to dilute, stir evenly, pour it into ethanol under vigorous stirring to precipitate, filter it and wash it with dilute hydrochloric acid, then repeatedly boil and wash the polymer product with distilled water, and finally dry it.

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