Synthesis method of polyaryletherketone

Abstract

The invention discloses a synthesis method of polyaryletherketone, relates to the technical field of high polymer material synthesis, and in particular relates to a method for synthesizing polyaryletherketone based on a 4-phenyl benzophenone solvent system. According to the method, 4-phenyl benzophenone is adopted to partially replace traditional diphenyl sulfone to serve as a polymerization solvent, and the prepared product has higher Tg and better toughness. Meanwhile, the solvent system has a higher boiling point, and the reaction activity can be enhanced by increasing the reaction temperature.

Description

Technical Field

[0001] This invention relates to the field of polymer synthesis technology, specifically to a method for synthesizing polyarylether ketone (PAEK) polymers, particularly a method for synthesizing PAEK based on a 4-phenylbenzophenone solvent system. Background Technology

[0002] Polyaryletherketone (PAEK) is a class of high-performance specialty engineering plastics with excellent high-temperature resistance, mechanical strength, chemical stability, and insulation properties. It is widely used in aerospace, electronics, and medical devices. Currently, the mainstream industrial method for synthesizing PAEK is nucleophilic substitution polycondensation, typically using diphenyl sulfone (DPS) as a solvent. DPS has a high boiling point (approximately 379°C), which meets the polymerization temperature requirements of most PAEKs (such as polyetheretherketone, PEEK) (typically between 280-320°C).

[0003] However, with the increasing demands on the performance of PAEK materials, it is necessary to introduce monomers with stronger chain rigidity and greater steric hindrance (e.g., difluoroketone monomers and bisphenol monomers containing naphthalene rings, biphenyl structures, or large side groups). These monomers have low reactivity and high reaction energy barriers. In traditional DPS solvent systems, due to the limitation of DPS boiling point, the polymerization temperature is difficult to increase significantly, leading to difficulties in the polymerization of these high-rigidity monomers, incomplete reactions, and difficulty in achieving high molecular weights, thus limiting the development of high-performance PAEK resins.

[0004] In addition, the DPS solvent system has the following disadvantages: (1) The melting point is relatively high (about 128°C), and the raw materials (especially bisphenol monomers) need to be added in a high-temperature molten solvent. Bisphenols are easily oxidized and discolored by oxygen in the air when in a high-temperature molten state, which causes the polymer product to turn yellow or even black, affecting the product quality. (2) The solubility of high-rigidity PAEK polymerization intermediates is limited. As the degree of polymerization increases, the viscosity of the system increases sharply, which may lead to difficulty in stirring and uneven mass and heat transfer, thereby limiting the increase of the final polymer molecular weight.

[0005] Therefore, developing a novel solvent system that can achieve higher polymerization temperatures, is safer, better suppresses monomer oxidation, and has better solubility for growing polymer chains is of great significance for promoting the advancement of high-performance PAEK material synthesis technology. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a novel method for synthesizing PAEK. This method, by partially replacing the traditional diphenyl sulfone with 4-phenylbenzophenone as the polymerization solvent, produces a product with a higher glass transition temperature (Tg) and better toughness. Simultaneously, this solvent system has a higher boiling point, and the reactivity can be enhanced by increasing the reaction temperature.

[0007] To achieve the above objectives, the present invention adopts the following technical solution.

[0008] PAEK Synthesis Using bisphenol monomers and ketone monomers with difluorobenzene structures as raw materials, 4-phenylbenzophenone and diphenyl sulfone as solvents, and alkali metal carbonates as catalysts, a nucleophilic condensation reaction is carried out. The specific preparation process includes the following steps: 1) Under the condition of argon gas being introduced at 50-100 ml / min throughout the process, the ketone monomer with bisfluorobenzene structure and the alkali metal carbonate are added to the reaction vessel, and molten 4-phenylbenzophenone and diphenyl sulfone mixed solvent are added. The temperature of the reaction vessel is set to 140~160℃. After the system is kept at a constant temperature, the bisphenol structure monomer is added. 2) Continue heating and stirring until the raw materials in the reaction vessel are fully mixed. Raise the temperature of the reaction vessel to 200-220℃ and stir at a constant temperature for 60 minutes; then raise the temperature to 260-270℃ and stir at a constant temperature for 60 minutes; then raise the temperature to 310-340℃ and stir at a constant temperature for 60-120 minutes. During the process, keep argon gas flowing into the reaction vessel at a rate of 50-100 ml / min. 3) Add the capping agent to the reaction system and stir at a constant temperature of 310-340℃ for 30-60 minutes, while keeping argon gas flowing into the reaction vessel at a rate of 50-100 ml / min during the process; 4) Finally, the reaction product is poured into cold water to cool and solidify, then crushed, and impurities are removed by ethanol reflux treatment and water boiling treatment, and then dried to obtain PAEK product.

[0009] Preferably, the molar number of the ketone monomer with the bisfluorobenzene structure is 1.01 to 1.20 times the molar number of the bisphenol monomer.

[0010] Preferably, in the mixed solvent of 4-phenylbenzophenone and diphenyl sulfone, the mass ratio of 4-phenylbenzophenone is 50% to 80%.

[0011] Preferably, the bisphenol monomer is one or more of hydroquinone, biphenyl, and 4,4'-dihydroxybenzophenone.

[0012] Preferably, the ketone monomer with the difluorobenzene structure is one or more of 4,4'-difluorobenzophenone, 4,4'-difluorotriphenyldione, and 4,4'-difluorobiphenyldione.

[0013] Preferably, the alkali metal carbonate is one or both of sodium carbonate and potassium carbonate, and its amount is 1.1 to 1.2 times the total molar amount of the bisphenol structural monomer.

[0014] Preferably, the capping agent is one of 4,4'-difluorobenzophenone, 4-fluorobenzophenone, and benzoyl chloride, and its amount is 3% to 5% of the total molar amount of the bisphenol structural monomer.

[0015] The beneficial effects of this invention are as follows: (1) The boiling point of 4-phenylbenzophenone (420℃) is much higher than that of diphenyl sulfone (379℃). This allows the polymerization reaction to proceed safely and stably at temperatures of 320℃-380℃ or even higher. The high temperature greatly improves the reaction kinetics, effectively reduces the reaction energy barrier of high-rigidity, high-sterile monomers, and ensures the full progress of the reaction, thereby enabling the synthesis of high-performance, high-molecular-weight PAEK resins that are difficult to prepare by traditional methods.

[0016] (2) The melting point of 4-phenylbenzophenone (100℃) is lower than that of diphenyl sulfone (128℃). This means that when adding bisphenol monomers that are sensitive to oxygen and water vapor, the initial temperature of the solvent system can be lower. A lower feeding temperature can significantly slow down the oxidation rate of bisphenol, reduce colored impurities in the polymer from the source, and the resulting PAEK resin has a lighter natural color and better luster, making it suitable for high-end applications with strict color requirements.

[0017] (3) The molecular structure of 4-phenylbenzophenone contains both a benzene ring and a carbonyl group, which is more similar to the main chain structure of PAEK polymer. According to the principle of "like dissolves like", it has better solubility for PAEK polymerization intermediates and products. Better solubility means that, at the same solid content, the viscosity of the reaction system is lower and the flowability is better. This is beneficial to mass transfer and heat transfer in the later stages of the reaction.

[0018] (4) Experiments have shown that, since the solvent system can carry out polymerization at higher temperatures, the product obtained has a small amount of nonlinear structure (such as slight branching) compared with the product of the simple diphenyl sulfone solvent system. This structural change leads to an increase in Tg on the one hand, and breaks the regularity of the polymer chain on the other hand, limiting its excessive crystallization, thereby improving the toughness (impact strength) of the final product while maintaining its strength. Attached Figure Description

[0019] Figure 1 This is the DSC curve of the product in Example 1; Figure 2 The DSC curve is for Comparative Example 1. Detailed Implementation

[0020] The present invention will be further illustrated by specific embodiments below, but the scope of protection of the present invention is not limited thereto. Example 1

[0021] 1) Under the condition of argon gas being introduced at 55 ml / min throughout the process, the raw materials 4,4'-difluorobenzophenone and sodium carbonate were added to the reaction vessel, and molten 4-phenylbenzophenone and diphenyl sulfone mixed solvent were added. The temperature of the reaction vessel was set to 145℃. After the system was kept at a constant temperature, hydroquinone was added. 2) Continue heating and stirring until the raw materials in the reaction vessel are fully mixed. Then, heat the reaction vessel to 200°C and stir at a constant temperature for 60 minutes. Next, heat the vessel to 260°C and stir at a constant temperature for 60 minutes. Then, heat the vessel to 330°C and stir at a constant temperature for 60 minutes. During this process, keep argon gas flowing into the reaction vessel at a rate of 55 ml / min. 3) Add 4-fluorobenzophenone to the reaction system, stir at 330℃ for 30 min, and keep argon gas flowing into the reaction vessel at 55 ml / min during the process; 4) Finally, the reaction product is poured into cold water to cool and solidify, then crushed, and impurities are removed by ethanol reflux treatment and water boiling treatment, and then dried to obtain PEEK product.

[0022] The molar amount of 4,4'-difluorobenzophenone is 1.02 times the molar amount of hydroquinone; the mass ratio of 4-phenylbenzophenone to diphenyl sulfone is 1:1; the amount of sodium carbonate is 1.1 times the total molar amount of the bisphenol structural monomers; and the amount of 4-fluorobenzophenone is 3% of the total molar amount of the bisphenol structural monomers.

[0023] The product underwent DSC testing, and its impact strength was tested using injection-molded impact specimens. Data are available in [link to data]. Figure 1 And Table 1. Example 2

[0024] 1) Under the condition of argon gas being introduced at 95 ml / min throughout the process, the raw materials 4,4'-difluorobenzophenone and sodium carbonate were added to the reaction vessel, and molten 4-phenylbenzophenone and diphenyl sulfone mixed solvent were added. The temperature of the reaction vessel was set to 160℃. After the system was kept at a constant temperature, 4,4'-dihydroxybenzophenone was added. 2) Continue heating and stirring until the raw materials in the reaction vessel are fully mixed. Raise the temperature of the reaction vessel to 210°C and stir for 60 minutes. Then raise the temperature to 270°C and stir for 60 minutes. Then raise the temperature to 330°C and stir for 60 minutes. During the process, keep argon gas flowing into the reaction vessel at 95 ml / min. 3) Add 4-fluorobenzophenone to the reaction system, stir at 330℃ for 55 min, and keep argon gas flowing into the reaction vessel at 95 ml / min during the process; 4) Finally, the reaction product is poured into cold water to cool and solidify, then crushed, and impurities are removed by ethanol reflux treatment and water boiling treatment, and then dried to obtain PEEK product.

[0025] The number of moles of 4,4'-difluorobenzophenone is 1.08 times the number of moles of 4,4'-dihydroxybenzophenone; the mass ratio of 4-phenylbenzophenone to diphenyl sulfone is 3:1; the amount of sodium carbonate is 1.15 times the total molar amount of the bisphenol structural monomers; and the amount of 4-fluorobenzophenone is 5% of the total molar amount of the bisphenol structural monomers.

[0026] The product underwent DSC testing, and its impact strength was tested using injection-molded impact strips. The data are shown in Table 1. Comparative Example 1

[0027] 1) Under the condition of argon gas being introduced at 55 ml / min throughout the process, the raw materials 4,4'-difluorobenzophenone and sodium carbonate were added to the reaction vessel, and molten diphenyl sulfone was added as a solvent. The temperature of the reaction vessel was set to 145℃. After the system was kept at a constant temperature, hydroquinone was added. 2) Continue heating and stirring until the raw materials in the reaction vessel are fully mixed. Then, heat the reaction vessel to 200°C and stir at a constant temperature for 60 minutes. Next, heat the vessel to 260°C and stir at a constant temperature for 60 minutes. Then, heat the vessel to 310°C and stir at a constant temperature for 60 minutes. During this process, keep argon gas flowing into the reaction vessel at a rate of 55 ml / min. 3) Add 4-fluorobenzophenone to the reaction system, stir at 310℃ for 30 min, and keep argon gas flowing into the reaction vessel at 55 ml / min during the process; 4) Finally, the reaction product is poured into cold water to cool and solidify, then crushed, and impurities are removed by ethanol reflux treatment and water boiling treatment, and then dried to obtain PEEK product.

[0028] The molar amount of 4,4'-difluorobenzophenone is 1.02 times the molar amount of hydroquinone; the amount of sodium carbonate is 1.1 times the total molar amount of the bisphenol structural monomers; and the amount of 4-fluorobenzophenone is 3% of the total molar amount of the bisphenol structural monomers.

[0029] The product underwent DSC testing, and its impact strength was tested using injection-molded impact specimens. Data are available in [link to data]. Figure 2 And Table 1.

[0030]

[0031] Comparing Example 1 and Comparative Example 1, it can be found that the PEEK synthesized in the 4-phenylbenzophenone and diphenyl sulfone mixed solvent system (Example 1) has a higher Tg temperature than the PEEK synthesized in the conventional diphenyl sulfone solvent system (Comparative Example 1), but the Tg signal is significantly weakened. This is due to slight branching and crosslinking of the polymer, which may be the result of multiple effects of high reaction temperature and solvent system. Meanwhile, the PEEK material produced in Example 1 has a weak second melting peak and a higher crystallization temperature. This change in crystallization state directly affects the crystallinity and strength of the material. Comparing the impact strength of the materials in Example 1 and Comparative Example 1, it can be found that the PEEK synthesized in the 4-phenylbenzophenone and diphenyl sulfone mixed solvent system has better toughness.

Claims

1. A method for synthesizing polyarylether ketones, characterized in that, Includes the following steps: 1) Under the condition of argon gas being introduced at 50-100 ml / min throughout the process, the ketone monomer with bisfluorobenzene structure and the alkali metal carbonate are added to the reaction vessel, and molten 4-phenylbenzophenone and diphenyl sulfone mixed solvent are added. The temperature of the reaction vessel is set to 140~160℃. After the system is kept at a constant temperature, the bisphenol structure monomer is added. 2) Continue heating and stirring until the raw materials in the reaction vessel are fully mixed. Raise the temperature of the reaction vessel to 200-220℃ and stir at a constant temperature for 60 minutes; then raise the temperature to 260-270℃ and stir at a constant temperature for 60 minutes; then raise the temperature to 310-340℃ and stir at a constant temperature for 60-120 minutes. During the process, keep argon gas flowing into the reaction vessel at a rate of 50-100 ml / min. 3) Add the capping agent to the reaction system and stir at a constant temperature of 310-340℃ for 30-60 minutes, while keeping argon gas flowing into the reaction vessel at a rate of 50-100 ml / min during the process; 4) Finally, the reaction product is poured into cold water to cool and solidify, then crushed, and impurities are removed by ethanol reflux treatment and water boiling treatment, and then dried to obtain PAEK product.

2. The method for synthesizing polyarylether ketone according to claim 1, characterized in that, The molar number of the ketone monomer with the bisfluorobenzene structure is 1.01 to 1.20 times the molar number of the bisphenol monomer.

3. The method for synthesizing polyarylether ketone according to claim 1, characterized in that, In the mixed solvent of 4-phenylbenzophenone and diphenyl sulfone, the mass ratio of 4-phenylbenzophenone is 50% to 80%.

4. The method for synthesizing polyarylether ketone according to claim 1, characterized in that, The bisphenol monomer is one or more of hydroquinone, biphenyl, and 4,4'-dihydroxybenzophenone.

5. The method for synthesizing polyarylether ketone according to claim 1, characterized in that, The ketone monomer with the difluorobenzene structure is one or more of 4,4'-difluorobenzophenone, 4,4'-difluorotriphenyldione, and 4,4'-difluorobiphenyldione.

6. The method for synthesizing polyarylether ketone according to claim 1, characterized in that, The alkali metal carbonate is one or both of sodium carbonate and potassium carbonate, and its amount is 1.1 to 1.2 times the total molar amount of the bisphenol structural monomer.

7. The method for synthesizing polyarylether ketone according to claim 1, characterized in that, The capping agent is one of 4,4'-difluorobenzophenone, 4-fluorobenzophenone, and benzoyl chloride, and its amount is 3% to 5% of the total molar amount of the bisphenol structural monomer.

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