Synthesis process of high-molecular-weight polyether ketone ketone and polyether ketone ketone

Abstract

The synthesis process comprises the following steps: (1) introducing inert gas into a reactor, adding a solvent, a Lewis acid catalyst and diphenyl ether, then dropwise adding an acyl chloride monomer solution, and synthesizing an intermediate M with a short-chain small molecular structure; (2) continuously dropwise adding an acyl chloride monomer solution into the reactor for reaction, and then adding an end-capping reagent for reaction; and (3) quenching, washing and drying the reaction product in the step (2) to obtain the product. Under the condition that only the Lewis acid is used as the catalyst, the one-pot method is adopted for synthesizing PEKK in two steps, side reactions can be reduced, meanwhile, the dosage of the catalyst is reduced, the production cost is reduced, the post-treatment process is simplified, and the obtained polyether ketone ketone is high in molecular weight and good in heat resistance and mechanical performance.

Description

TECHNICAL FIELD

[0001] The application relates to the field of high-performance high-molecular engineering resins, in particular to a high-molecular-weight polyether ketone ketone synthesis process and polyether ketone ketone. BACKGROUND

[0002] Polyether ketone ketone (PEKK) is a high polymer containing two ketone bonds and one ether bond in the main chain structure. PEKK is a special engineering plastic with excellent performance, with a glass transition temperature above 150 DEG C and a melting point between 330-360 DEG C. It has high strength, small density, biocompatibility, corrosion resistance, radiation resistance, fatigue resistance and good wear resistance, and can be used to replace polyimide resin and some metal materials to some extent, as a high-temperature structural material, an electrical insulating material, a biomedical material and a 3D material. The main application fields include aerospace, medical devices, electronics and electrical appliances, automobiles, buildings, chemical industry and the like.

[0003] The synthesis methods of polyether ketone ketone can be divided into nucleophilic substitution method and electrophilic substitution method. The electrophilic substitution synthesis method uses diphenyl ether, terephthaloyl chloride and isophthaloyl chloride as polymerization monomers, aluminum chloride and N,N-dimethylformamide as catalysts, dichloromethane / dichloroethane as solvents, and is obtained through a Friedel-Crafts acylation reaction. The nucleophilic substitution synthesis method uses copolymerization monomers of hydroquinone and p-fluorobenzoyl, uses diphenyl sulfone as a solvent, K2CO3 / NaCO3 as a catalyst, and is polymerized at a reaction temperature of 270-330 DEG C under a nitrogen atmosphere to obtain PEKK. The electrophilic substitution method is suitable for commercial production due to its simple process and low cost, and is a commonly used method, but there are many side reactions in the synthesis, and Al3+ in the product is not easy to remove, which affects the performance of the product.

[0004] The electrophilic substitution reaction mainly includes a two-step method of DuPont Company and a Lewis acid-base co-catalysis one-step method developed by Raychem. The product is easily precipitated in advance in the PEKK synthesis process, which easily causes a scaling and wall-hanging phenomenon, resulting in a low molecular weight of the product. Meanwhile, there are side reactions such as ring formation and branching in the synthesis process of PEKK.

[0005] Authorized patent CN111433254B describes a method for preparing polyetherketone ketone (PEKK) by rapidly removing hydrochloric acid (a byproduct) generated during polymerization and preventing resin particle agglomeration, thereby inhibiting scaling, through simultaneous blowing nitrogen into the liquid reaction medium and stirring. Authorized invention patent CN113336921B discloses a PEVKK and its preparation method. This method controls the reaction temperature of each step of the reaction, adding terephthaloyl chloride, isophthaloyl chloride, and terephthaloyl chloride in stages, with the amount of terephthaloyl chloride added in the first step being the same as that of isophthaloyl chloride. This allows for control over the arrangement of monomers in PEVKKK. At the first temperature, the polymerization reaction proceeds slowly, while at the second temperature, the reaction rate is faster. The PEVKKK prepared using this method exhibits significantly improved monomer arrangement regularity compared to PEVKKK prepared by the traditional one-pot method, and its crystallinity and crystallization rate are also significantly improved compared to traditional methods. Authorized invention patent CN10960827B discloses a production process for polyetherketoneketone (PEKK). First, monomers and Lewis bases are added to a reaction vessel. Then, anhydrous aluminum trichloride dissolved in sulfur dioxide is added dropwise to the reaction vessel. The added aluminum trichloride partially complexes with the Lewis base, partially complexes with the carbonyl group on the acyl chloride, and partially acts as a catalyst. All three reactions are exothermic. The heat causes sulfur dioxide to vaporize and leave the reaction system. The heat absorbed by the vaporization offsets some of the heat released by the addition of aluminum trichloride, resulting in a uniform temperature inside the reaction vessel in the initial stage and reducing the occurrence of side reactions. Furthermore, the monomer is added to the reaction vessel before the reaction begins, ensuring the monomer concentration is at its highest at the start of the reaction. This eliminates the "false dilution" state, reduces the formation of small cyclic polymers, and results in PEVKK with better impact resistance, better toughness, and higher intrinsic viscosity.

[0006] Current research indicates that the one-step production process of polyetherketoneketone (PEKK) all employs the Lewis acid / Lewis base co-catalysis method. The introduction of the Lewis base requires complexation with an equal amount of Lewis acid. Therefore, the amount of Lewis acid catalyst used in the synthesis of PEVKK is particularly large, generally reaching 5-8 times that of the acyl chloride monomer, resulting in high production costs. Furthermore, the excessive introduction of catalyst also requires more washing processes in the post-processing, which also increases production costs. Summary of the Invention

[0007] This application provides a high molecular weight polyether ketone ketone synthesis process and polyether ketone ketone. This application uses only Lewis acid as a catalyst and adopts a "one-pot" two-step synthesis of PEKK, which can reduce the generation of side reactions, reduce the amount of catalyst used, reduce production costs, simplify the post-processing process, and obtain polyether ketone ketone with high molecular weight and good heat resistance and mechanical properties.

[0008] In a first aspect, this application provides a process for synthesizing high molecular weight polyether ketones, employing the following technical solution: A process for synthesizing high molecular weight polyether ketone includes the following steps: (1) An inert gas is introduced into the reactor, and a solvent, Lewis acid catalyst, and diphenyl ether are added. Then, an acyl chloride monomer solution is added dropwise to synthesize a short-chain small molecule intermediate M. The structural formula of M is shown in formula (1): (1); (2) Continue to add acyl chloride monomer solution dropwise to the reactor for reaction, and then add end-capping agent for reaction; (3) Quench, wash and dry the reaction product of step (2) to obtain the product.

[0009] By adopting the above technical solution, the polyether ketone ketone of this application is synthesized via an electrophilic substitution method. The synthesis process employs a one-pot, two-step synthesis. Using only Lewis acids as catalysts, short-chain small molecule structures are synthesized, resulting in reduced reactivity. The second step involves adding acyl chloride, which suppresses side reactions. The dropwise addition of acyl chloride maintains a supply shortage, reducing its attack on the ortho-position of diphenyl ether and inhibiting side reactions. Prolonged low-temperature reaction reduces reactant activity, inhibiting the substitution reaction between acyl chloride and the ortho-hydrogen of diphenyl ether, thereby reducing branching, cross-linking, and cyclization. The resulting product has a more regular molecular structure, a whiter color, and better melt flowability. Continuous nitrogen purging to remove hydrogen chloride promotes the forward reaction and also reduces side reactions. Therefore, the process of this application reduces side reactions, lowers catalyst usage, reduces production costs, and simplifies post-processing.

[0010] Furthermore, the inert gas is nitrogen.

[0011] Further, in step (1), after adding solvent, Lewis acid catalyst and diphenyl ether, the temperature is lowered to -30℃ to 0℃, the acyl chloride monomer solution is added dropwise, the low temperature reaction is maintained for 1-3 hours, and then the temperature is raised to 20-50℃ for 2-6 hours to synthesize short-chain small molecule intermediate.

[0012] Furthermore, in step (1), the molar ratio of acyl chloride monomer to diphenyl ether is 0.3-0.5.

[0013] By adopting the above technical solution and taking advantage of the difference in the ratio of acyl chloride to diphenyl ether, a short-chain small molecule intermediate M can be synthesized using only Lewis acid as a catalyst.

[0014] Further, in step (1), the acyl chloride monomer is at least one of terephthaloyl chloride and isophthaloyl chloride.

[0015] Furthermore, the solvent in step (1) can be one of dichloromethane, dichloroethane, o-dichlorobenzene, tetrachloroethane, or carbon disulfide. Throughout the process, the total amount of solvent is 5-20 times the mass of the reactant monomer, i.e., the acyl chloride monomer, and the total amount of solvent includes the solvent in the acyl chloride monomer solution.

[0016] Further, in step (2), the temperature is lowered to -30℃ to 0℃, and the acyl chloride monomer solution is added dropwise to the reactor. The reaction is maintained at a low temperature of -30℃ to 0℃ for 4-12 hours. Then, the end-capping agent is added, and the temperature is raised to 20-50℃ for another 4-12 hours.

[0017] Furthermore, in step (2), the molar ratio of acyl chloride monomer to diphenyl ether is (0.5~0.7). That is, in steps (1) and (2), the total molar amount of acyl chloride monomer is the same as the molar amount of diphenyl ether.

[0018] Furthermore, in step (1), the acyl chloride monomer solution is added over a period of 2-4 hours. In step (2), the acyl chloride monomer solution is added over a period of 2-5 hours.

[0019] Further, in steps (1) and (2), the Lewis acid catalyst in steps (1) and (2) is one of aluminum chloride, boron trifluoride, antimony pentachloride, ferric bromide, ferric chloride, and tin tetrachloride, and the amount of catalyst used is 2.5-4 times the molar amount of the acyl chloride monomer. The amount of catalyst used is relative to the amount of catalyst used in each step corresponding to the amount of acyl chloride monomer used in the same step.

[0020] Furthermore, the capping agent includes benzoyl chloride.

[0021] Furthermore, in step (3), the quenching solvent is either methanol or ethanol, and the amount of quenching solvent is 1-3 times the mass of the crude product.

[0022] Further, in step (3), the washing can be performed by reflux washing with ethanol hydrochloric acid aqueous solution / or methanol hydrochloric acid aqueous solution at least three times, and reflux washing with ethanol aqueous solution / or methanol aqueous solution at least twice. The amount of washing mixed solvent is 3-10 times that of crude product, and the concentration of hydrochloric acid is 3%-10%.

[0023] Secondly, this application provides a polyether ketone synthesized using the above-described high molecular weight polyether ketone synthesis process.

[0024] In summary, this application has the following beneficial effects: 1. The synthesis process of this application adopts a "one-pot" method to synthesize PEKK in two steps, and only Lewis acid is used as a catalyst. This not only reduces the generation of side reactions, but also reduces the amount of catalyst used, reduces production costs, simplifies the post-processing process, and the resulting polyether ketone has a high molecular weight and good heat resistance and mechanical properties.

[0025] 2. This application synthesizes a short-chain, small-molecule intermediate M with low reactivity by varying the ratio of acyl chloride to diphenyl ether, using only Lewis acid as a catalyst. The subsequent addition of acyl chloride in the second step suppresses side reactions. Furthermore, the dropwise addition of acyl chloride in this synthesis process maintains a supply-demand imbalance, reducing its attack on the ortho-position of diphenyl ether and inhibiting side reactions.

[0026] 3. In the synthesis process of this application, a long-term low-temperature reaction was carried out to reduce the activity of the reactants and inhibit the substitution reaction of acyl chloride and diphenyl ether at the ortho hydrogen, thereby reducing the occurrence of branching, cross-linking and cyclization. The resulting product has a more regular molecular structure, a whiter color, and better melt flowability.

[0027] 3. Compared with the existing Lewis acid / Lewis base co-catalysis method, this application can effectively reduce the amount of catalyst used, reduce production costs, and simplify the post-processing. Detailed Implementation

[0028] The present application will be further described in detail below with reference to the embodiments.

[0029] This application provides a process for synthesizing high molecular weight polyether ketones, including the following steps: (1) Nitrogen gas is introduced into the reactor, and solvent, Lewis acid catalyst, and diphenyl ether are added. Then, acyl chloride monomer solution is added dropwise to synthesize short-chain small molecule intermediates.

[0030] Specifically, after adding the solvent, Lewis acid catalyst, and diphenyl ether, the temperature is lowered to -30℃ to 0℃. After the acyl chloride monomer solution is added dropwise, the reaction is maintained at a low temperature for a period of time, and then the temperature is raised to 20-50℃ for 2-6 hours to synthesize a short-chain small molecule intermediate. The mass concentration of the acyl chloride monomer solution is 10-20%, and the solvent of the acyl chloride monomer solution is the same as the raw material solvent used in step (1).

[0031] The acyl chloride monomer solution is added dropwise over 2-4 hours. The molar ratio of the acyl chloride monomer to diphenyl ether is 0.3-0.5. The acyl chloride monomer is at least one of terephthaloyl chloride and isophthaloyl chloride. The solvent can be one of dichloromethane, dichloroethane, o-dichlorobenzene, tetrachloroethane, and carbon disulfide.

[0032] (2) Continue to add acyl chloride monomer solution to the reactor for reaction, and then add end-capping agent for reaction.

[0033] Specifically, the temperature is lowered to -30℃ to 0℃, and the acyl chloride monomer solution is added dropwise to the reactor. The reaction is maintained at the low temperature of -30℃ to 0℃ for 4-12 hours. Then, the end-capping agent is added, and the temperature is raised to 20-50℃ for another 4-12 hours.

[0034] The acyl chloride monomer solution is added dropwise over 2-5 hours. The molar ratio of acyl chloride monomer to diphenyl ether is 0.5-0.7, and the end-capping agent includes benzoyl chloride.

[0035] (3) Quench, wash and dry the reaction product of step (2) to obtain the product.

[0036] Specifically, in step (3), quenching is performed using either methanol or ethanol, and washing is performed by reflux washing at least three times with an ethanol-hydrochloric acid aqueous solution / or a methanol-hydrochloric acid aqueous solution, and at least twice with an ethanol-hydrochloric acid aqueous solution / or a methanol-hydrochloric acid aqueous solution. The product is then dried in an oven. In step (3), the amount of quenching solvent is 1-3 times the mass of the crude product, the amount of washing mixed solvent is 3-10 times the mass of the crude product, and the concentration of hydrochloric acid is 3%-10%.

[0037] The following explanation is provided through specific examples.

[0038] Example 1 In a dry 2L reactor, nitrogen gas was introduced, and 400g of dichloroethane, 40g of aluminum chloride, and 34.04g of diphenyl ether were added. Stirring was started, and the temperature was lowered to -15℃. A 10% (w / w) solution of 203.02g of dichloroethane terephthaloyl chloride was slowly added dropwise over 2 hours. The reaction was then continued at -15℃ for 2 hours, and then the temperature was slowly raised to 20℃ for 4 hours. The mixture was cooled to -15℃, and 40g of aluminum chloride was added. Within 2 hours, 203.02g of dichloroethane solution (containing 4.06g of terephthaloyl chloride and 16.24g of isophthaloyl chloride) was added dropwise. The reaction was continued at -15℃ for 6 hours. 0.42g of benzoyl chloride was added, and the temperature was raised to 20℃. The reaction was continued for 12 hours. The mixture was then cooled to 0℃, and 500g of ethanol was slowly added to quench the reaction. The product was then filtered and refluxed three times at 110℃ with 500g of a 3.6% hydrochloric acid-ethanol aqueous solution (ethanol:water mass ratio = 6:4). The mixture was then washed twice with 500g of an ethanol-water aqueous solution (ethanol:water mass ratio = 6:4) with stirring. After filtration, the mixture was dried in an oven at 130℃ for 12 hours to obtain product PEKK-1.

[0039] Example 2 Nitrogen gas was introduced into a dry 2L reactor, and 176g of o-dichlorobenzene, 20.34g of boron trifluoride, and 34.04g of diphenyl ether were added. Stirring was started, and the temperature was lowered to -20℃. A 10% o-dichlorobenzene solution was slowly added dropwise over 2 hours. The reaction was then continued at -20℃ for 3 hours, and then the temperature was slowly raised to 30℃ for 5 hours. The temperature was lowered to -15℃, and 20.34g of boron trifluoride was added. 203.02g of o-dichlorobenzene solution (containing 8.12g of terephthaloyl chloride and 12.18g of isophthaloyl chloride) was added dropwise over 3 hours. The reaction was continued at -15℃ for 10 hours. 0.42g of benzoyl chloride was added, and the temperature was raised to 30℃. The reaction was continued for 5 hours. The temperature was lowered to 0℃, and 600g of ethanol was slowly added to quench the reaction. The product was then filtered and refluxed three times at 110℃ with 600g of a 3.6% hydrochloric acid-ethanol aqueous solution (ethanol:water ratio = 6:4). The product was washed twice with 400g of an ethanol-water aqueous solution (ethanol:water ratio = 6:4) with stirring. After filtration, the product was dried in an oven at 130℃ for 12 hours to obtain PEKK-2.

[0040] Example 3 Nitrogen gas was introduced into a dry 2L reactor, and 1127g of dichloromethane, 49.8g of antimony pentachloride, and 34.04g of diphenyl ether were added. Stirring was started, and the temperature was lowered to -30℃. A 10% (w / w) solution of 135.34g of dichloromethane terephthaloyl chloride was slowly added dropwise over 2 hours. The reaction was then continued at -30℃ for 2 hours, and then the temperature was slowly raised to 20℃ for 6 hours. The temperature was lowered to -30℃, and 99.6g of antimony pentachloride was added. 270.69g of dichloromethane solution (containing 5.41g of terephthaloyl chloride and 21.66g of isophthaloyl chloride) was added dropwise over 4 hours. The reaction was continued at -30℃ for another 4 hours. 0.42g of benzoyl chloride was added, and the temperature was raised to 20℃. The reaction was continued for 12 hours. The temperature was lowered to 0℃, and 400g of methanol was slowly added to quench the reaction. The product was then filtered and refluxed three times at 110℃ with 400g of a 3.6% hydrochloric acid-ethanol aqueous solution (methanol:water ratio = 8:2). The product was washed twice with 600g of a methanol-water aqueous solution (methanol:water ratio = 6:4) with stirring. After filtration, the product was dried in an oven at 130℃ for 12 hours to obtain PEKK-3.

[0041] Example 4 Nitrogen gas was introduced into a dry 2L reactor, and 381g of o-dichlorobenzene, 88.6g of ferric bromide, and 34.04g of diphenyl ether were added. Stirring was started, and the temperature was lowered to -10℃. A 10% (w / w) solution of o-dichlorobenzene terephthaloyl chloride was slowly added dropwise over 3 hours. The reaction was then continued at -10℃ for 1 hour, and then the temperature was slowly raised to 30℃ and the reaction was continued for 3 hours. The mixture was cooled to -10℃, and 88.6g of ferric bromide was added. 203.02g of o-dichlorobenzene solution (containing 4.06g of terephthaloyl chloride and 16.24g of isophthaloyl chloride) was added dropwise over 2 hours. The reaction was continued at -10℃ for 6 hours. 0.42g of benzoyl chloride was added, and the mixture was heated to 30℃ and reacted for another 6 hours. The mixture was then cooled to 0℃, and 500g of ethanol was slowly added to quench the reaction. The product was then filtered and refluxed three times at 110℃ with 500g of a 3.6% hydrochloric acid-ethanol aqueous solution (ethanol:water ratio = 6:4). The mixture was then washed twice with 500g of an ethanol-water aqueous solution (ethanol:water ratio = 6:4) with stirring. After filtration, the mixture was dried in an oven at 130℃ for 12 hours to obtain product PEKK-4.

[0042] Example 5 Nitrogen gas was introduced into a dry 2L reactor, and 568g of dichloromethane, 64.8g of ferric chloride, and 34.04g of diphenyl ether were added. Stirring was started, and the temperature was lowered to -5℃. A 10% (w / w) solution of 203.02g of dichloromethane terephthaloyl chloride was slowly added dropwise over 4 hours. The reaction was then continued at -5℃ for 1 hour, and then the temperature was slowly raised to 40℃ for 2 hours. The mixture was cooled to -5℃, and 64.8g of ferric chloride was added. 203.02g of dichloromethane solution (containing 12.18g of terephthaloyl chloride and 8.12g of isophthaloyl chloride) was added dropwise over 3 hours. The reaction was continued at -5℃ for 5 hours. 0.42g of benzoyl chloride was added, and the temperature was raised to 40℃. The reaction was continued for 8 hours. The mixture was then cooled to 0℃, and 500g of ethanol was slowly added to quench the reaction. The product was then filtered and refluxed three times at 110℃ with 500g of a 5.0% hydrochloric acid-ethanol aqueous solution (ethanol:water ratio = 6:4). The mixture was then washed twice with 600g of an ethanol-water aqueous solution (ethanol:water ratio = 6:4) with stirring. After filtration, the product was dried in an oven at 130℃ for 12 hours to obtain PEKK-5.

[0043] Example 6 In a dry 2L reactor, nitrogen gas was introduced, and 257g of dichloromethane, 52g of tin tetrachloride, and 34.04g of diphenyl ether were added. Stirring was started, and the temperature was lowered to 0℃. A 10% (w / w) solution of 135.34g of dichloromethane terephthaloyl chloride was slowly added dropwise over 2 hours. The reaction was then continued at 0℃ for 2 hours, and then the temperature was slowly raised to 20℃ and the reaction was continued for 2 hours. The mixture was cooled to 0℃, and 104g of tin tetrachloride was added. 270.69g of dichloromethane solution (containing 27.07g of terephthaloyl chloride) was added dropwise over 2 hours. The reaction was continued at 0℃ for 9 hours. 0.42g of benzoyl chloride was added, and the temperature was raised to 20℃. The reaction was continued for 6 hours. The mixture was then cooled to 0℃, and 200g of methanol was slowly added to quench the reaction. The product was then filtered and refluxed three times at 110℃ with 800g of a 3.6% hydrochloric acid-ethanol aqueous solution (methanol:water mass ratio = 6:4). The mixture was then washed twice with 500g of an ethanol-water aqueous solution (methanol:water mass ratio = 6:4) with stirring. After filtration, the mixture was dried in an oven at 130℃ for 12 hours to obtain product PEKK-6.

[0044] Example 7 Nitrogen gas was introduced into a dry 2L reactor, and 568g of dichloroethane, 33.2g of aluminum chloride, and 34.04g of diphenyl ether were added. Stirring was started, and the temperature was lowered to -10℃. A 10% (w / w) solution of 203.02g of dichloroethane terephthaloyl chloride was slowly added dropwise over 3 hours. The reaction was then continued at -10℃ for 3 hours, and then the temperature was slowly raised to 50℃ for 5 hours. The temperature was lowered to -10℃, and 33.2g of aluminum chloride was added. 203.02g of dichloroethane solution (20.30g of isophthaloyl chloride) was added dropwise over 2 hours. The reaction was continued at -10℃ for 10 hours. 0.42g of benzoyl chloride was added, and the temperature was raised to 50℃. The reaction was continued for 8 hours. The temperature was lowered to 0℃, and 300g of ethanol was slowly added to quench the reaction. The product was then filtered and refluxed three times at 110℃ with 500g of a 3.6% hydrochloric acid-ethanol aqueous solution (ethanol:water mass ratio = 6:4). The product was washed twice with 500g of an ethanol-water aqueous solution (ethanol:water mass ratio = 6:4) with stirring. After filtration, the product was dried in an oven at 130℃ for 12 hours to obtain PEKK-7.

[0045] Example 8 Nitrogen gas was introduced into a dry 2L reactor, and 210g of carbon disulfide, 23.7g of boron trifluoride, and 34.04g of diphenyl ether were added. Stirring was started, and the temperature was lowered to -15℃. 101.51g of 20% (w / w) terephthaloyl chloride carbon disulfide solution was slowly added dropwise over 2 hours. The reaction was then continued at -15℃ for 2 hours, and then the temperature was slowly raised to 25℃ for 4 hours. The temperature was lowered to -15℃, and 23.7g of boron trifluoride was added. 101.51g of carbon disulfide solution (containing 4.06g of terephthaloyl chloride and 16.24g of isophthaloyl chloride) was added dropwise over 2 hours. The reaction was continued at -15℃ for 10 hours. 0.42g of benzoyl chloride was added, and the temperature was raised to 25℃. The reaction was continued for 7 hours. The temperature was lowered to 0℃, and 500g of ethanol was slowly added to quench the reaction. The product was then filtered and refluxed three times at 110℃ with 100g of a 2.0% hydrochloric acid-ethanol aqueous solution (ethanol:water ratio = 7:3). The product was washed twice with 500g of an ethanol-water aqueous solution (ethanol:water ratio = 7:3) with stirring. After filtration, the product was dried in an oven at 130℃ for 12 hours to obtain PEKK-8.

[0046] Example 9 In a dry 2L reactor, nitrogen gas was introduced, and 306g of dichloroethane, 26.6g of aluminum chloride, and 34.04g of diphenyl ether were added. Stirring was started, and the temperature was lowered to -20℃. A 10% (w / w) solution of 135.34g of dichloroethane terephthaloyl chloride was slowly added dropwise over 3 hours. The reaction was then continued at -20℃ for 2 hours, and then the temperature was slowly raised to 30℃ for 4 hours. The temperature was lowered to -20℃, and 53.4g of aluminum chloride was added. 270.69g of dichloroethane solution (containing 5.41g of terephthaloyl chloride and 21.66g of isophthaloyl chloride) was added dropwise over 5 hours. The reaction was continued at -20℃ for another 5 hours. 0.42g of benzoyl chloride was then added, and the temperature was raised to 30℃. The reaction was continued for 9 hours, then lowered to 0℃. 500g of ethanol was slowly added to quench the reaction. The product was then filtered and refluxed three times at 110℃ with 300g of a 7.2% hydrochloric acid-ethanol aqueous solution (ethanol:water ratio = 6:4). The product was washed twice with 500g of an ethanol-water aqueous solution (ethanol:water ratio = 6:4) with stirring. After filtration, the product was dried in an oven at 130℃ for 12 hours to obtain product PEKK-9.

[0047] Comparative Example Comparative Example 1 In a dry 1L reactor, 800g of dichloroethane, 24.36g of terephthaloyl chloride, 16.24g of isophthaloyl chloride, and 34.04g of diphenyl ether were added. Stirring was started, and the mixture was cooled to -15℃. 80g of aluminum chloride was added, and the mixture was then heated to 20℃ and reacted for 18 hours. The mixture was cooled to 0℃, and 500g of ethanol was slowly added to quench the reaction. The product was then filtered, refluxed three times at 110℃ with 500g of a 3.6% hydrochloric acid-ethanol aqueous solution (ethanol:water mass ratio = 6:4), and washed twice with 500g of an ethanol-water aqueous solution (ethanol:water mass ratio = 6:4). After filtration, the product was dried in an oven at 130℃ for 12 hours to obtain product PEKK-Comparison 1.

[0048] Comparative Example 2 In a dry 1L reactor, add 800g dichloroethane, 24.36g terephthaloyl chloride, 16.24g isophthaloyl chloride, 34.04g diphenyl ether, and 29.2g N,N-dimethylformamide. Start stirring, cool to -15℃, add 133g aluminum chloride, then heat to 20℃ and react for 18h. Cool to 0℃, slowly add 500g ethanol to quench, then filter the product. Reflux five times at 110℃ with 500g of a 7.2% hydrochloric acid-ethanol aqueous solution (ethanol:water mass ratio = 6:4), wash twice with 500g of an ethanol-water aqueous solution (ethanol:water mass ratio = 6:4), stir, filter, and dry in a 130℃ oven for 12h to obtain product PEKK-Comparison 2.

[0049] Comparative Example 3 Nitrogen gas was introduced into a dry 2L reactor, and 400g of dichloroethane, 48g of aluminum chloride, and 34.04g of diphenyl ether were added. Stirring was started, and the temperature was lowered to -15℃. A 10% (w / w) solution of 243.62g of dichloroethane terephthaloyl chloride was slowly added dropwise over 2 hours. The reaction was then continued at -15℃ for 2 hours, and then the temperature was slowly raised to 20℃ for 4 hours. The mixture was cooled to -15℃, and 32g of aluminum chloride was added. 162.42g of dichloroethane solution (containing 16.24g of isophthaloyl chloride) was added dropwise over 2 hours. The reaction was continued at -15℃ for 6 hours. 0.42g of benzoyl chloride was added, and the mixture was then heated to 20℃ and reacted for 12 hours. The mixture was cooled to 0℃, and 500g of ethanol was slowly added to quench the reaction. The product was then filtered and refluxed three times at 110℃ with 500g of a 3.6% hydrochloric acid-ethanol aqueous solution (ethanol:water mass ratio = 6:4). The mixture was then washed twice with 500g of an ethanol-water aqueous solution (ethanol:water mass ratio = 6:4) with stirring. After filtration, the mixture was dried in an oven at 130℃ for 12 hours to obtain product PEKK-Comparative 3.

[0050] Performance testing The products prepared in the examples and comparative examples underwent relevant performance tests, as detailed in Table 1. Differential scanning calorimetry (DSC) was used to test the glass transition temperature and melting temperature of the products, with a heating rate of 10℃ / h and a heating range of 0-400℃. Thermogravimetric analysis (TG) was used to test the thermogravimetric loss at 500℃ under a nitrogen atmosphere, with a heating rate of 20℃ / h and a heating temperature range of 0-950℃. The mechanical properties of the products were tested according to GB / T 1040.1-2018 "Determination of Tensile Properties of Plastics" and GB / T 9341-2000 "Test Method for Bending Properties of Plastics". The molecular weight of the products was determined using an Ubbelohde viscometer. The product was dissolved in concentrated sulfuric acid to prepare a 1% concentrated sulfuric acid solution, and the solution was tested at 25℃ using an Ubbelohde viscometer (inner diameter 0.9-1.0 mm).

[0051] Table 1 PEKK Performance Evaluation Table As can be seen from the performance of the examples in Table 1, this application uses a "one-pot" method to synthesize PEKK in two steps, using only Lewis acid as a catalyst. This not only reduces the generation of side reactions, but also reduces the amount of catalyst used, reduces production costs, simplifies post-processing, and results in polyether ketones with high molecular weight and excellent heat resistance and mechanical properties.

[0052] Further analysis of the comparative samples revealed that samples PEKK-Comparison 1 and PEKK-Comparison 3 were yellow coarse powders, and their thermal and mechanical properties were significantly inferior to the product of the embodiments in this application. This indicates that, for this application, a short-chain small molecule intermediate with low reactivity is synthesized first, followed by the addition of acyl chloride; secondly, the dropwise addition of acyl chloride can also suppress the formation of side reactions; and thirdly, the combination of long-term low-temperature reaction effectively reduces the generation of side reactions, as well as branching, cross-linking, and cyclization phenomena. The resulting product has a more regular molecular structure, a whiter color, better melt flowability, and superior thermal and mechanical properties.

[0053] Further analysis of the performance of Comparative Example 2 revealed that the PEKK samples of Comparative Example 2 had similar appearances, both yielding a fine white powder. Furthermore, while the thermal and mechanical properties of the PEKK sample synthesized in this application were similar to those of PEKK-Comparative Example 2, the overall performance of the PEKK sample synthesized in this application was superior, with a higher molecular weight. Moreover, the synthesis process in this application used only Lewis acid as a catalyst. This indicates that the PEKK synthesized through the process of this application has similar or even better performance than the product synthesized using Lewis acid / Lewis base co-catalysis, and this process uses fewer catalysts, simplifying the raw materials and processing steps for post-processing.

[0054] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A process for synthesizing high molecular weight polyether ketone, characterized in that, Includes the following steps: (1) An inert gas is introduced into the reactor, and a solvent, Lewis acid catalyst, and diphenyl ether are added. Then, an acyl chloride monomer solution is added dropwise to synthesize a short-chain small molecule intermediate M. The structural formula of M is shown in formula (1): （1）； (2) Continue to add acyl chloride monomer solution dropwise to the reactor for reaction, and then add end-capping agent for reaction; (3) Quench, wash and dry the reaction product of step (2) to obtain the product.

2. The high molecular weight polyether ketone ketone synthesis process according to claim 1, characterized in that, In step (1), after adding solvent, Lewis acid catalyst and diphenyl ether, the temperature is lowered to -30℃ to 0℃, the acyl chloride monomer solution is added dropwise, the low temperature reaction is maintained for 1-3 hours, and then the temperature is raised to 20-50℃ for 2-6 hours to synthesize short-chain small molecule intermediate.

3. The high molecular weight polyether ketone synthesis process according to claim 1, characterized in that, In step (1), the molar ratio of acyl chloride monomer to diphenyl ether is 0.3-0.

5.

4. The high molecular weight polyether ketone synthesis process according to claim 3, characterized in that, In step (1), the acyl chloride monomer includes at least one of terephthaloyl chloride and isophthaloyl chloride.

5. The high molecular weight polyether ketone ketone synthesis process according to claim 1, characterized in that, The solvent in step (1) can be one of dichloromethane, dichloroethane, o-dichlorobenzene, tetrachloroethane, or carbon disulfide.

6. The high molecular weight polyether ketone ketone synthesis process according to claim 1, characterized in that, In step (2), the temperature is lowered to -30℃ to 0℃, and the acyl chloride monomer solution is added dropwise to the reactor. The reaction is maintained at a low temperature of -30℃ to 0℃ for 4-12 hours. Then the end-capping agent is added, and the temperature is raised to 20-50℃ for another 4-12 hours.

7. The high molecular weight polyether ketone synthesis process according to claim 6, characterized in that, In step (2), the molar ratio of acyl chloride monomer to diphenyl ether is (0.5~0.7).

8. The high molecular weight polyether ketone ketone synthesis process according to claim 1, characterized in that, In step (1), the acyl chloride monomer solution is added over a period of 2-4 hours; in step (2), the acyl chloride monomer solution is added over a period of 2-5 hours.

9. The high molecular weight polyether ketone ketone synthesis process according to claim 1, characterized in that, In steps (1) and (2), the Lewis acid catalysts in steps (1) and (2) include one of aluminum chloride, boron trifluoride, antimony pentachloride, ferric bromide, ferric chloride, and tin tetrachloride, and the amount of catalyst used is 2.5-4 times the molar amount of acyl chloride monomer.

10. A polyether ketone synthesized by the high molecular weight polyether ketone synthesis process as described in any one of claims 1-9.

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