Process for refining polyetherketoneketone and polyetherketoneketone refined product

Abstract

This application relates to the field of polymers and discloses a method for refining polyether ketone ketone and a refined polyether ketone ketone product. The method includes (1) treating the polyether ketone ketone complex with a pretreatment agent; (2) mixing the crude polyether ketone ketone with a mixed chain-supporting solution and washing to obtain a first product, wherein the mixed chain-supporting solution includes a main chain-supporting agent and a co-solvent, wherein the main chain-supporting agent includes one or more selected from p-chlorophenol, trifluoroacetic acid, difluoroacetic acid, dichloroacetic acid, and chloroacetic acid, and the co-solvent includes one or more selected from N,N-dimethylformamide, dimethyl sulfoxide, water, N-methylpyrrolidone, and N-methylformamide; (3) adding a mixed aqueous solution to the first product to remove at least some metal ions to obtain a second product; and (4) washing the second product multiple times with an organic solvent, followed by washing with water and drying to obtain the refined polyether ketone ketone. The polyether ketone ketone obtained by this method has a low aluminum ion content.

Description

Technical Field

[0001] This application relates to the field of polymers, specifically to a method for refining polyether ketone ketone and the refined polyether ketone ketone product. Background Technology

[0002] Polyetherketoneketone (PEKK), a high-performance engineering plastic, is widely used in aerospace, automotive manufacturing, and electronics industries due to its high-temperature resistance, good self-lubrication, chemical resistance, radiation resistance, and good mechanical properties. Electrophilic substitution is one method for preparing PEKK, typically employing Friedel-Crafts acylation. PEKK is prepared using diphenyl ether and terephthaloyl chloride as monomers in a nitrobenzene solution, with aluminum trichloride as a catalyst to catalyze the reaction of the acyl chloride functional groups. However, due to the entanglement of the large molecular chains, a portion of the catalyst used in the reaction is firmly encapsulated within the polymer, inevitably resulting in residual Al in the polymer. 3+ Higher Al 3 + This can lead to a decrease in PEKK viscosity, a reduction in molecular weight, changes in product structure, and secondary catalytic effects during high-temperature use and processing, resulting in polymer cross-linking, discoloration, or localized micro-decomposition of the product, and a decrease in the polymer's thermal stability. Therefore, refining the crude PEKK is a crucial post-processing step in the PEKK preparation process.

[0003] Currently removing residual Al 3+ The purification methods for crude PEKK often employ organic solvent treatment to dissolve or swell the molecular chains. For example, DMSO solution is used in conjunction with a metal chelating agent, or a mixture of PEKK and diphenyl sulfone in dichloromethane is heated under reflux and then combined with 2-phosphonobutane-1,2,4-tricarboxylic acid to remove aluminum ions. However, these processes have limitations. Firstly, the swelling effect of organic solvents on the molecular weight of PEKK is limited, making it difficult to fully expose impurities such as aluminum ions within the molecular weight. Secondly, organic solvents are prone to phase separation in subsequent processes. Furthermore, single organometallic chelating agents have limited chelating effect on aluminum ions, and these purification methods often require sequential washing with multiple solvents, resulting in numerous side reactions and poor system stability.

[0004] Therefore, current purification methods still need improvement, and there is an urgent need to propose an effective crude product purification process to effectively remove residual Al from the polymer. 3+ . Summary of the Invention

[0005] In view of the above problems, this application provides a method for refining polyetherketoneketone and a refined polyetherketoneketone product. The polyetherketoneketone obtained by this refining method has a low aluminum ion content.

[0006] In one aspect of this application, a method for refining polyether ketone ketone is provided. The method includes: (1) treating the polyether ketone ketone complex with a pretreatment agent comprising a polar organic solvent and an inorganic acid to obtain crude polyether ketone ketone;

[0007] (2) The crude polyether ketone ketone and the mixed chain-supporting solution are mixed and washed to obtain the first product. The mixed chain-supporting solution includes a main chain-supporting agent and a co-solvent. The mass ratio of the main chain-supporting agent and the co-solvent is 1:0.5 to 1:10. The mass ratio of the mixed chain-supporting solution and the crude polyether ketone ketone is 5:1 to 35:1. The main chain-supporting agent includes one or more selected from p-chlorophenol, trifluoroacetic acid, difluoroacetic acid, dichloroacetic acid, and chloroacetic acid. The co-solvent includes one or more selected from N,N-dimethylformamide, dimethyl sulfoxide, water, N-methylpyrrolidone, and N-methylformamide.

[0008] (3) Add a mixed aqueous solution containing phosphide and organic acids and / or organic acid salts to the first product to remove some metal ions, stir and heat to obtain a second product, wherein the heating temperature is 40~150℃, and the metal ions include Al 3+ The mass fraction of the phosphide in the mixed aqueous solution is 6% to 20%, and the mass fraction of the organic acid and / or organic acid salt in the mixed aqueous solution is 2% to 5%.

[0009] (4) The second product is washed multiple times with an organic solvent and then dried with water to obtain the polyether ketone ketone refined product.

[0010] This method, through optimizing the purification process, can effectively remove Al from crude polyetherketoneketone. 3+ By eliminating residual solvents and other pollutants, the purity of the product can be improved. Furthermore, by rationally controlling the material ratio, temperature, and time of each step, the stability and efficiency of the refining process can be ensured, ultimately obtaining high-purity polyether ketone ketone products and enhancing their performance and application value.

[0011] According to an embodiment of the present invention, in step (1), the polar organic solvent includes icy methanol and at least one selected from acetone and methanol.

[0012] According to an embodiment of the present invention, in step (1), the inorganic acid includes hydrochloric acid, wherein the mass percentage of HCl in the hydrochloric acid is 0.1-10%.

[0013] According to an embodiment of the present invention, step (1) includes: adding icy methanol to the polyether ketone complex for decomplexing treatment; adding at least one of acetone and methanol to the polyether ketone after the decomplexing treatment and washing 1 to 3 times; acid washing the treated polyether ketone with hydrochloric acid, washing with water, and drying to obtain the crude polyether ketone.

[0014] According to an embodiment of the present invention, ice-cold methanol is added to the polyether ketone complex and mixed and reacted at -25~5°C for 0.5~2 hours to perform decomplexation treatment, wherein the mass ratio of ice-cold methanol to the polyether ketone complex is 10:1 to 20:1.

[0015] According to an embodiment of the present invention, at least one of acetone and methanol is added to the polyetherketone ketone that has undergone the decomplexing treatment for washing.

[0016] According to an embodiment of the present invention, impurities are removed by washing 1 to 3 times with at least one of acetone and methanol, with each washing session lasting 10 to 30 minutes.

[0017] According to an embodiment of the present invention, the mass ratio of the detergent used for washing with at least one of acetone and methanol and the polyether ketone ketone that has undergone the decomplexing treatment is 8:1 to 15:1.

[0018] According to an embodiment of the present invention, the mass ratio of hydrochloric acid to crude polyether ketone in step (1) is 15:1 to 30:1.

[0019] According to an embodiment of the present invention, the pickling temperature is 40~100℃, the number of pickling cycles is 1-5, and the pickling time for each cycle is 0.5-1.5 hours.

[0020] According to an embodiment of the present invention, after pickling and cooling, the product is subjected to 1-5 water washes at a temperature of 40-100°C, and the amount of water used each time is 15-30 times the mass of polyetherketoneketone.

[0021] According to an embodiment of the present invention, in step (2), the main supporting agent includes p-chlorophenol and the cosolvent includes DMF.

[0022] According to an embodiment of the present invention, the mass ratio of the mixed chain-supporting solution to the crude polyether ketone is 5:1 to 30:1, preferably 10:1 to 20:1.

[0023] According to an embodiment of the present invention, the mass ratio of the mixed chain-supporting solution to the crude polyether ketone is 10:1 to 20:1.

[0024] According to an embodiment of the present invention, the mass ratio of the mixed chain-supporting solution to the crude polyether ketone is 15:1.

[0025] According to an embodiment of the present invention, the mass ratio of the main chain-supporting agent to the co-solvent in the mixed chain-supporting solution is 1:3 to 1:5.

[0026] According to an embodiment of the present invention, the mass ratio of the main chain-supporting agent to the co-solvent in the mixed chain-supporting solution is 1:4.

[0027] According to an embodiment of the present invention, in step (2), the washing process is a heated reflux washing, which is performed 1 to 3 times, and each time lasts 1 to 3 hours.

[0028] According to an embodiment of the present invention, in step (3), the mass ratio of the mixed aqueous solution to the first product is 10:1 to 20:1.

[0029] According to an embodiment of the present invention, the organic acid in step (3) includes one or more of benzoic acid, benzoate, salicylic acid, salicylate, para-dibenzoic acid, para-dibenzoate, and o-dibenzoic acid.

[0030] According to an embodiment of the present invention, the phosphide includes one or more of hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, aminotrimethylidene phosphate, and hydroxyethyl ethylenediamine trimethylidene phosphonic acid.

[0031] According to an embodiment of the present invention, the organic acid has a mass fraction of 2.5-3.5% in the mixed aqueous solution.

[0032] According to an embodiment of the present invention, the phosphide in the mixed aqueous solution has a mass fraction of 8-15%.

[0033] According to an embodiment of the present invention, the organic acid has a mass fraction of 3% in the mixed aqueous solution, and the phosphide has a mass fraction of 10% in the mixed aqueous solution.

[0034] According to an embodiment of the present invention, step (4) includes: washing the second product three times with N,N-dimethylformamide (DMF); washing the second product washed with N,N-dimethylformamide (DMF) with water 1-5 times; and drying the washed second product to obtain the refined polyether ketone ketone.

[0035] According to an embodiment of the present invention, in step (4), the mass ratio of N,N-dimethylformamide (DMF) to the second product is 10:1 to 20:1, the washing time is 10 to 40 minutes each time, and the washing temperature is 40 to 150°C.

[0036] According to an embodiment of the present invention, in step (4), the water washing is performed 3 times, and the amount of water used in each water washing is 15 to 30 times the mass of the product, and the temperature is 40 to 100°C.

[0037] In another aspect of this application, a polyetherketone ketone refined product is provided, which is prepared using the method described above.

[0038] According to an embodiment of the present invention, the aluminum ion content in the polyether ketone ketone refined product is not greater than 50 ppm. Detailed Implementation

[0039] The technical solution of this application will be described in detail below with reference to the embodiments. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the protection scope of this application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the description and claims of this application are intended to cover non-exclusive inclusion.

[0041] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0042] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0043] In the description of the embodiments of this application, the terms "multiple" or "repeatedly" refer to two or more times (including two), and similarly, "multiple groups" refer to two or more groups (including two groups).

[0044] Unless otherwise stated, the terms used in this application have the common meanings understood by those skilled in the art. Unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0045] In one aspect of this application, a method for purifying polyether ketone is provided. The method includes:

[0046] (1) The polyether ketone complex is treated with a pretreatment agent, which includes a polar organic solvent and an inorganic acid, to obtain crude polyether ketone.

[0047] (2) The crude polyether ketone ketone and the mixed chain-supporting solution are mixed and washed to obtain the first product. The mixed chain-supporting solution includes a main chain-supporting agent and a co-solvent. The mass ratio of the main chain-supporting agent and the co-solvent is 1:0.5 to 1:10. The mass ratio of the mixed chain-supporting solution and the crude polyether ketone ketone is 5:1 to 35:1. The main chain-supporting agent includes one or more selected from p-chlorophenol, trifluoroacetic acid, difluoroacetic acid, dichloroacetic acid, and chloroacetic acid. The co-solvent includes one or more selected from N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), water, N-methylpyrrolidone, and N-methylformamide.

[0048] (3) Add a mixed aqueous solution containing phosphide and selected organic acids and / or organic acid salts to the first product to remove at least some of the metal ions, stir and heat to obtain a second product, wherein the heat treatment temperature is 40~150°C, and the metal ions include Al 3+ The mass fraction of the phosphide in the mixed aqueous solution is 6% to 20%, and the mass fraction of the organic acid and / or organic acid salt in the mixed aqueous solution is 2% to 5%.

[0049] (4) The second product is washed multiple times with an organic solvent and then dried with water to obtain the polyether ketone ketone refined product.

[0050] This method, through optimizing the purification process, can effectively remove Al from crude polyetherketoneketone. 3+ By eliminating residual solvents and other pollutants, the purity of the product can be improved. Furthermore, by rationally controlling the material ratio, temperature, and time of each step, the stability and efficiency of the refining process can be ensured, ultimately obtaining high-purity polyether ketone ketone products and enhancing their performance and application value.

[0051] As mentioned earlier, the preparation of PEKK using the electrophilic substitution method typically involves the addition of Lewis acids and Lewis bases. The combined action of these two substances causes the polymer to form a complex system in solution, as shown in the typical reaction equation below:

[0052]

[0053] Specifically, electrophilic substitution typically involves preparing PEKK using diphenyl ethers and acyl chlorides under the co-catalysis of Lewis acids and Lewis bases. In the Lewis acid-base co-catalysis method for preparing polyether ketones, the Lewis acid (AlCl3) and Lewis base (DMF) primarily provide suitable conditions for the reaction through synergistic effects. The process involves adding the acyl chloride and solvent first, followed by DMF. DMF forms a stable complex with the subsequently added AlCl3, regulating the activity of aluminum trichloride; aluminum trichloride, in turn, activates the acyl chloride to generate a highly reactive intermediate, promoting Friedel-Crafts acylation with the last added diphenyl ether to form the PEKK backbone. These two components do not directly constitute the PEKK backbone, and after polymerization, the system exhibits a gel-like state due to the partial dissolution of the PEKK and Lewis acid-base complex. The Lewis acid AlCl3 used in the reaction is entangled into the macromolecular chain, with some encapsulated within the polymer, inevitably resulting in residual aluminum ions within the polymer.

[0054] This application employs a mixed chain-strengthening solution to support the polymer chains. The mixture of the main chain-strengthening agent and the co-solvent more effectively swells the PEKK molecular chains. The main chain-strengthening agent contains strongly polar -COOH, -OH groups, which act as proton donors and can bind to the polar sites (carbonyl groups and ether bonds) on the PEKK molecular chains through strong hydrogen bonding, weakening the intermolecular forces of PEKK, opening the gaps between the PEKK molecular chains, and thus swelling the main chain. The co-solvent is, for example, a high-boiling-point solvent; therefore, the reflux temperature of the DMF solution can reach 100°C during reflux, resulting in better dissolution. Furthermore, the main impurity in the system, aluminum chloride, is a Lewis acid, while the co-solvents such as DMF act as Lewis bases. The two will coordinate, resulting in better washing effects. DMF can dissolve low molecular weight PEKK under hot reflux, and can separate high and low molecular weight PEKK during washing, while also narrowing the molecular weight distribution of the product. Furthermore, compared to solvents such as diphenyl sulfone, the aforementioned cosolvents, such as DMF, have better water solubility. Therefore, after using them to swell the PEKK chains, the subsequently added complexing agent aqueous solution and the DMF organic phase form a homogeneous phase system, which can significantly reduce the risk of phase separation. Moreover, this invention utilizes the synergistic effect of organic acids and phosphides to remove Al. 3+ The removal of impurities enhances the chelating effect, ensuring the stability of the PEKK molecular chain structure while increasing the chelating activity of phosphides and removing impurities. After drying, a high-performance PEKK product is obtained.

[0055] According to an embodiment of the present invention, the weight-average molecular weight of polyether ketone ketone in the polyether ketone complex can be 10,000-250,000, and the main impurities include aluminum chloride, ferric chloride, organic solvents, diphenyl ether, acyl chloride, HCl, etc.

[0056] According to an embodiment of the present invention, in step (1), the polar organic solvent includes icy methanol and at least one selected from acetone and methanol.

[0057] According to an embodiment of the present invention, step (1) may specifically include:

[0058] (a) Adding ice-cold methanol to the polyether ketone ketone complex to de-complex. Specifically, ice-cold methanol can be added to the polyether ketone ketone complex and reacted at -25 to 5°C for 0.5 to 2 hours to perform de-complexation treatment, wherein the mass ratio of ice-cold methanol to the polyether ketone ketone complex is 10:1 to 20:1. Specifically, the mass ratio of ice-cold methanol to the polyether ketone ketone complex can be 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, etc. The reaction temperature can be -25°C, -20°C, -15°C, -10°C, -5°C, 0°C, or 5°C.

[0059] (b) Add at least one of acetone and methanol to the polyether ketone ketone that has undergone the decomplexing treatment and wash 1 to 3 times to remove impurities. Specifically, the mass ratio of the washing solvent to the polyether ketone ketone that has undergone the decomplexing treatment is 8:1 to 15:1, for example 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, and the washing time for each wash is 10 to 30 minutes.

[0060] (c) The treated polyetherketone ketone is acid-washed using the hydrochloric acid. The mass fraction of HCl in the hydrochloric acid is 0.1-10%. The mass ratio of hydrochloric acid to crude polyetherketone ketone is 15:1 to 30:1, for example, 15:1, 20:1, 25:1, 30:1, etc. The acid washing temperature is 40-100°C, and the number of washes is 1-5 times, with each wash lasting 0.5-1.5 hours. After cooling, 1-5 more water washes can be performed. The water washing temperature is 40-100°C, and the amount of water used each time is 15-30 times the mass of the polyetherketone ketone. The product is then dried to obtain the crude polyetherketone ketone.

[0061] Using ice-cold methanol for decomplexing effectively breaks the bond between impurities and the polymer, laying the foundation for subsequent impurity removal. Preliminary washing with acetone or methanol removes residual ice-cold methanol and some low-molecular-weight impurities readily soluble in organic solvents, such as unreacted monomers, facilitating subsequent processing. Multiple, prolonged washes with hydrochloric acid effectively reduce residual metal ions.

[0062] Specifically, in step (a), the polar protic solvent, ice-cold methanol, is used to break down the Lewis acid-base complex in the crude PEKK. On the one hand, the lone pair of electrons on the oxygen atom in the methanol molecule makes it Lewis basic, allowing it to compete with PEKK for the binding of Lewis acids (such as AlCl3), forming a more stable methanol-Lewis acid complex. On the other hand, the polarity of methanol and hydrogen bonding can effectively solubilize the complex, promoting its separation from PEKK and its stable existence in the solvent. In addition, the decomplexation process is exothermic, and ice-cold methanol can absorb the heat, maintaining the system temperature stability and reducing the probability of side reactions.

[0063] Step (b) involves washing the decomplexed crude PEKK with acetone or methanol. The purpose is to further remove any remaining organic components that were not completely removed in the previous step through the secondary dissolution effect of the polar solvent, thereby reducing the impurity content in the crude PEKK. These organic impurities include trace amounts of Lewis acid-base complexes that were not completely decomplexed, the methanol-Lewis acid complexes generated in step (a), free DMF molecules, residual icy methanol, and low-molecular-weight organic byproducts. First, acetone and methanol can dissolve the above impurities through solvation. Both are polar solvents, with methanol being a polar protic solvent and acetone being a polar aprotic solvent. The polar groups in their molecular structures (-OH in methanol and C=O in acetone) can form stable interactions with the electronegative sites in the residual complexes through hydrogen bonding or dipole-dipole interactions. This interaction can break the weak adsorption force between the complexes and the surface of the PEKK molecules, causing the complexes to dissolve. Simultaneously, DMF molecules, containing strongly polar C=O bonds and lone pair electrons on their N atoms, can form hydrogen bonds with the -OH group of methanol and dipole-dipole interactions with the C=O group of acetone, thus achieving efficient dissolution. The dissolution of low-molecular-weight organic byproducts follows a similar principle; this selective interaction ensures that residual complexes, free DMF molecules, and low-molecular-weight organic byproducts all enter the solvent phase. Furthermore, the residual icy methanol from step (a) and the acetone added in step (b) exhibit good miscibility; therefore, during the washing process, acetone can rapidly mix with the residual icy methanol in the system and carry it away from the system.

[0064] Meanwhile, PEKK molecules have extremely strong intermolecular forces, and although they are polar, their overall solubility is extremely low. Their solubility in acetone or methanol is negligible. Therefore, the solvent selectively dissolves impurities without damaging the PEKK matrix, thus achieving the goal of dissolving impurities while preserving the separation effect of PEKK.

[0065] In step (c), the chemical properties of dilute hydrochloric acid are utilized to remove inorganic impurities through acid-base reactions and dissolution. These inorganic impurities mainly consist of residual Lewis acid aluminum trichloride, its hydrolysis products, and any metal ion impurities that may be present in the system. Aluminum trichloride readily hydrolyzes in water to form sparingly soluble aluminum hydroxide; the reaction equation is as follows:

[0066] AlCl3 + 3H2O Al(OH)3 + 3HCl

[0067] Hydrochloric acid provides H+ + It can inhibit the forward hydrolysis reaction of AlCl3, effectively suppressing the formation of Al(OH)3 precipitate. Simultaneously, the Cl in hydrochloric acid... - Able to interact with free Al 3+ They combine to form stable soluble complex ions (such as [AlCl4)). - [AlCl6] 3- Al can be made more likely to undergo competitive coordination. 3+ It enters the solution.

[0068] According to an embodiment of the present invention, in step (2), the main chain-supporting agent preferably includes p-chlorophenol, and the co-solvent includes DMF. Specifically, the mass ratio of the mixed chain-supporting solution to the crude polyether ketone ketone is 5:1 to 30:1, for example, 10:1 to 20:1, more specifically, 15:1. According to an embodiment of the present invention, the mass ratio of the main chain-supporting agent to the co-solvent in the mixed chain-supporting solution is 1:3 to 1:5, for example, 1:4. The washing method can be heated reflux washing.

[0069] In step (2), the heating and reflux washing is performed 1 to 3 times, and each time lasts 1 to 3 hours.

[0070] The core purpose of step (2) is to reduce the intermolecular forces of PEKK molecules by utilizing the effects of strongly polar protic solvents, polar aprotic solvents, and weakly polar diluents in a specific mixed solvent, thereby promoting swelling and releasing and removing trace metal ions, salts, or organic impurities that were trapped inside the PEKK molecular chains in previous steps and failed to be washed out. For example, trifluoroacetic acid contains strongly polar -COOH and p-chlorophenol contains polar -OH, both of which are proton donors. They can bind to the polar sites (carbonyl and ether bonds) on the PEKK molecular chains through strong hydrogen bonds, weakening the intermolecular forces of PEKK, opening up the gaps between the PEKK molecular chains, and swelling the main chain. In particular, co-solvents such as DMF or DMSO play a role in assisting penetration and dissolving impurities, solving the problem of slow penetration and insufficient local swelling caused by the high viscosity of a single highly polar solvent. Both DMF and DMSO are high-boiling-point solvents, reaching 100°C during reflux, resulting in better dissolution. Traditional solvents like dichloromethane and dichloroethane, with lower boiling points, are less effective. Both DMF and DMSO can be used as Lewis bases, and aluminum chloride, the main impurity in crude PEKK, is a Lewis acid. The two solvents coordinate, leading to better washing results, an effect not seen in solvents like dichloromethane. DMF can dissolve low-molecular-weight PEKK under hot reflux, separating high and low molecular weight PEKK during washing, narrowing the product distribution and further improving the performance of the purified product. DMF and DMSO have good water solubility, while dichloromethane has poor solubility. During subsequent phosphoric acid washing, solvents like dichloromethane pose a risk of phase separation, while DMF and similar solvents are homogeneous systems, thus reducing this risk.

[0071] According to an embodiment of the present invention, step (3) employs a mixed aqueous solution containing a phosphide and at least one selected from organic acids and organic acid salts (i.e., a mixed solution containing a phosphide and an organic acid / organic acid salt) to remove at least a portion of the metal ions in the system, such as aluminum ions. The organic acid and organic acid salt may include one or more of benzoic acid, benzoate, salicylic acid, salicylate, para-dibenzoic acid, para-dibenzoate, and o-dibenzoic acid. The phosphide includes one or more of hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, aminotrimethylphosphonic acid, and hydroxyethylethylenediaminetrimethylidene phosphonic acid. The mass fraction of the organic acid in the mixed aqueous solution is 2.5-3.5%, for example, 3%. The mass fraction of the phosphide in the mixed aqueous solution is 8-15%, for example, 10%. The mass ratio of the mixed aqueous solution to the crude polyetherketone ketone is 10:1 to 20:1, for example, 10:1, 15:1, or 20:1.

[0072] Specifically, in step (3), the above-mentioned mixed aqueous solution can be used for reflux washing 1 to 3 times, with a time of 1 to 3 hours. The preferred number of reflux washing cycles is 2. The reflux temperature can be 20-100℃, for example, 80-100℃.

[0073] Step (3) is a key step in the PEKK purification process for targeted removal of metal impurities, mainly removing Al from Lewis acid AlCl3. 3+ It also includes other metal ions that may be introduced during the synthesis process. Through the synergistic effect of organic acids and phosphorus compounds (strong chelating agents), impurities are removed while ensuring the stability of the PEKK molecular chain structure. After swelling treatment, the PEKK molecular chain has been stretched. The molecular structures of benzoic acid or salicylic acid contain benzene rings and carboxyl groups, which are similar to the PEKK molecular chain structure. Both have an aromatic ring skeleton connecting the carbonyl group and the ether bond. This similarity of "aromatic ring + polar group" leads to good miscibility. At the same time, organic acids provide a weakly acidic environment, which is conducive to the chelating activity of phosphorus compounds. The chelating groups of phosphorus compounds (such as -PO3H2) need to remain protonated under weakly acidic conditions in order to form stable six- or eight-membered ring chelates with free metal ions. The weak acidity of organic acids avoids the damage of strong acids to the PEKK ether bonds and inhibits the hydrolysis of metal ions to form insoluble hydroxides (such as Al(OH)3), ensuring that they are bound to phosphorus compounds in a free state. Ultimately, through the synergistic effect of organic acids in regulating pH, maintaining swelling, aiding dispersion, and strongly chelating with phosphorus compounds, residual metal impurities are directionally converted into soluble chelates, which can be completely removed in subsequent washing-filtration operations. The metal ion content in the PEKK obtained after this treatment can be reduced to below 50 ppm, while the molecular chain structure remains intact, providing a core guarantee for obtaining high-performance PEKK products after final drying.

[0074] According to an embodiment of the present invention, the organic solvent used in step (4) may include DMF. In this step, the second product is washed with DMF and water. Specifically, the product may be washed three times with DMF, and the second product washed with DMF may be washed with water one to five times. The second product washed with water may be dried to obtain the purified polyether ketone.

[0075] According to an embodiment of the present invention, in step (4), the mass ratio of DMF to the second product is 10:1 to 20:1, the washing time is 10 to 40 minutes each time, and the washing temperature is 40 to 150°C. The water is washed 3 times, and the amount of water used in each wash is 15 to 30 times the mass of the second product, and the temperature is 40 to 100°C.

[0076] This step utilizes the high solubility and penetrating power of DMF to thoroughly remove residual organic acids and phosphorus compounds from previous steps, including unchelated free phosphorus compounds and chelates formed with metal ions. It also removes trace amounts of highly polar proton solvents, such as trifluoroacetic acid and p-chlorophenol, that may remain from previous steps, laying the foundation for successful water washing in subsequent steps. As a polar aprotic solvent, DMF possesses the dual advantages of strong dissolving power and mild compatibility. On the one hand, the carbonyl group (C=O) and nitrogen atom in the DMF molecule can form stable interactions with target impurities through dipole-dipole interactions and hydrogen bonding. The carboxyl group (-COOH) in the benzoic acid molecule can form hydrogen bonds with the polar sites of DMF. The benzene ring structure, due to its weak compatibility with DMF, assists in dissolution, allowing benzoic acid attached to the surface or interstitial spaces of PEKK to quickly detach and enter the DMF phase. The chelating groups of phosphorus compounds themselves are highly polar and can form a strong solvation effect with DMF. Although metal chelates have a more complex structure, DMF's strong solvation ability can form a stable solvation layer by encapsulating the polar sites on the chelate surface, inhibiting the chelate from reattaching to the PEKK surface and ensuring its uniform dispersion in DMF. On the other hand, the moderate compatibility between DMF and PEKK avoids problems such as molecular chain aggregation and secondary encapsulation of impurities due to excessively strong solvent-PEKK compatibility, or inability to reach deep residual impurities due to insufficient compatibility.

[0077] Finally, repeated water washing can thoroughly remove trace amounts of ionic impurities and polar solvents remaining from previous steps, reducing the conductivity of the washing solution to below 10 μS / cm, thereby ensuring the high purity and application performance of PEKK. Ionic impurities may include Cl- that was not completely removed after hydrochloric acid washing. - Trace amounts of metal cations (such as Al) may dissociate after phosphorus compounds chelate metal ions. 3 + Fe 3+ Ions such as DMF, if left behind, can increase the conductivity of PEKK, affecting its electrical insulation and other properties. Additionally, trace amounts of polar solvents, such as DMF, remaining from previous steps are also present. Water washing is the main step in removing residual DMF, which is highly hydrophilic. Furthermore, high temperatures can increase the ion diffusion rate and the solubility of impurities in water. Combined with real-time conductivity monitoring, this ensures that ion residues meet standards.

[0078] In another aspect of this application, a polyetherketone ketone refined product is provided, which is prepared using the method described above.

[0079] According to an embodiment of the present invention, the aluminum ion content in the polyether ketone ketone refined product is not greater than 50 ppm.

[0080] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0081] ICP testing for aluminum ion content:

[0082] Aluminum ion content was detected using inductively coupled plasma optical emission spectrometry (ICP-OES): high-purity argon was used as the working gas, and a concentric quartz nebulizer was employed. The test conditions were: RF power 1000-1300W, plasma gas flow 10-15L / min, auxiliary gas flow 0.5-1.0L / min, nebulizer gas flow 0.5-0.8L / min, pump speed 10-15rpm, axial observation, and analysis wavelength 396.152nm. Samples were digested using a nitric acid and hydrogen peroxide system via microwave, and then diluted to volume with ultrapure water. A first-order polynomial calibration curve (I=a) was plotted using an aluminum element standard solution. C+b (C unit: mg / L), linear correlation coefficient ≥0.999, data processing was performed using ICP-OES software to calculate the aluminum ion content in the sample.

[0083] Example 1

[0084] (1) Provide crude polyetherketoneketone products

[0085] The polyether ketone ketone complex was decomplexed as follows: 100g of the polyether ketone ketone complex was added to 750g of ice-cold methanol (0℃), soaked for 1 hour, and then filtered to collect the filter cake. The filter cake was washed twice with acetone, 500g each time for 15 minutes, and then filtered again to remove the filter cake. The filter cake was then washed three times with 3% hydrochloric acid at 80℃, 1000g of hydrochloric acid each time for 1 hour. After cooling and filtration, the filter cake was washed three times with water at 70℃, 1000g of water each time. After decomplexation, crude polyether ketone ketone was obtained. This crude polyether ketone ketone was dried at 110℃ for 12 hours. ICP analysis showed that residual Al... 3+ The content is approximately 1400 ppm, and the weight-average molecular weight is 141175 according to GPC analysis.

[0086] (2) Purification of crude polyether ketone ketone

[0087] 50g of the crude polyetherketone ketone was purified as follows: A mixed solvent of p-chlorophenol and DMF was added, and the mixture was washed twice at 100°C, with 150g of p-chlorophenol and 600g of DMF used each time, for a washing time of 3 hours. After cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each time for 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure polyetherketone ketone was obtained. ICP analysis showed that the aluminum ion content was 36ppm.

[0088] Example 2

[0089] 50g of the crude polyetherketone ketone obtained in step (1) of Example 1 was purified as follows: a mixed solvent of p-chlorophenol and DMF was added, and the mixture was washed twice at 100°C, with 100g of p-chlorophenol and 400g of DMF used each time, for a washing time of 3 hours; after cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour; after cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, for a washing time of 30 minutes each time; after cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing liquid was lower than 10μs / cm, with 1000g of water used each time, and then dried to obtain pure polyetherketone ketone. ICP analysis showed that the aluminum ion content was 47ppm.

[0090] Example 3

[0091] 50g of the crude polyether ketone obtained in step (1) of Example 1 was purified as follows: a mixed solvent of p-chlorophenol and DMF was added, and the mixture was washed twice at 100°C, with 200g of p-chlorophenol and 800g of DMF used each time for 3 hours; after cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour; after cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each time for 30 minutes; after cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing liquid was less than 10μs / cm, with 1000g of water used each time, and then dried to obtain pure polyether ketone. ICP analysis showed that the aluminum ion content was 35ppm.

[0092] Example 4

[0093] 50g of the crude polyetherketone ketone obtained in step (1) of Example 1 was purified as follows: a mixed solvent of p-chlorophenol and DMF was added, and the mixture was washed twice at 100°C, with 187.5g of p-chlorophenol and 562.5g of DMF used each time, and the washing time was 3 hours; after cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour; after cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, with each washing time being 30 minutes; after cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing liquid was lower than 10μs / cm, with 1000g of water used each time, and the product was dried to obtain pure polyetherketone ketone. The aluminum ion content was 37ppm according to ICP analysis.

[0094] Example 5

[0095] 50g of the crude polyetherketone ketone obtained in step (1) of Example 1 was purified as follows: a mixed solvent of p-chlorophenol and DMF was added, and the mixture was washed twice at 100°C, with 125g of p-chlorophenol and 625g of DMF used each time, for a washing time of 3 hours; after cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour; after cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, for a washing time of 30 minutes each time; after cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing liquid was lower than 10μs / cm, with 1000g of water used each time, and then dried to obtain pure polyetherketone ketone. ICP analysis showed that the aluminum ion content was 41ppm.

[0096] Example 6

[0097] The procedure for providing crude polyetherketone ketone is the same as in Example 1. The crude polyetherketone ketone was obtained, and ICP analysis showed residual Al. 3+ The content is approximately 1400 ppm, and the weight-average molecular weight is 141175.

[0098] Purification of crude polyether ketone ketone

[0099] Take the above crude polyetherketoneketone (Al 3+The following steps were taken to purify 50g of a product containing approximately 1400ppm of aluminum ketone (PAK) as follows: A mixed solvent of p-chlorophenol and DMF was added, and the product was washed twice at 100°C, with 500g of P-chlorophenol and 250g of DMF used each time, for 3 hours. After cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each time for 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure PAK was obtained. ICP analysis showed an aluminum ion content of 81ppm.

[0100] Example 7

[0101] The procedure for providing crude polyetherketone ketone is the same as in Example 1. The crude polyetherketone ketone was obtained, and ICP analysis showed residual Al. 3+ The content is approximately 1400 ppm, and the weight-average molecular weight is 141175.

[0102] Purification of crude polyether ketone ketone

[0103] Take the above crude polyetherketoneketone (Al 3+ The following steps were taken to purify 50g of a product containing approximately 1400ppm of aluminum ketone (PAK) as follows: A mixed solvent of p-chlorophenol and DMF was added, and the product was washed twice at 100°C, with 68.2g of P-chlorophenol and 681.8g of DMF used each time, for a total washing time of 3 hours. After cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each time for 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure PAK was obtained. ICP analysis showed an aluminum ion content of 112ppm.

[0104] Example 8

[0105] The procedure for providing crude polyetherketone ketone is the same as in Example 1. The crude polyetherketone ketone was obtained, and ICP analysis showed residual Al. 3+ The content is approximately 1400 ppm, and the weight-average molecular weight is 141175.

[0106] The crude polyetherketoneketone product was purified (using a mixed solvent of main chain support agent and co-solvent: crude polyetherketoneketone product at a mass ratio of 5:1).

[0107] Take the above crude polyetherketoneketone (Al 3+The following steps were taken to purify 50g of a product containing approximately 1400ppm of aluminum ketone (PAK). The product was first purified by adding a mixed solvent of p-chlorophenol and DMF, and then washing twice at 100°C. Each wash consisted of 50g of p-chlorophenol and 200g of DMF, with a washing time of 3 hours. After cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each wash lasting 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure PAK was obtained. ICP analysis showed an aluminum ion content of 164ppm.

[0108] Example 9

[0109] The procedure for providing crude polyetherketone ketone is the same as in Example 1. The crude polyetherketone ketone was obtained, and ICP analysis showed residual Al. 3+ The content is approximately 1400 ppm, and the weight-average molecular weight is 141175.

[0110] The crude polyetherketoneketone product is purified (mixed solvent of main chain supporter and co-solvent: crude polyetherketoneketone product mass ratio 30:1).

[0111] Take the above crude polyetherketoneketone (Al 3+ The following steps were taken to purify 50g of a product containing approximately 1400ppm of aluminum ketone (PAK) as follows: A mixed solvent of p-chlorophenol and DMF was added, and the product was washed twice at 100°C, with 300g of P-chlorophenol and 1200g of DMF used each time, for 3 hours. After cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each time for 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure PAK was obtained. ICP analysis showed an aluminum ion content of 30ppm.

[0112] Example 10

[0113] The procedure for providing crude polyetherketone ketone is the same as in Example 1. The crude polyetherketone ketone was obtained, and ICP analysis showed residual Al. 3+ The content is approximately 1400 ppm, and the weight-average molecular weight is 141175.

[0114] Purification of crude polyether ketone ketone

[0115] Take the above crude polyetherketoneketone (Al 3+The following steps were taken to purify 50g of a product containing approximately 1400ppm of aluminum ketone (PAK) as follows: A mixed solvent of p-chlorophenol and DMF was added, and the product was washed once at 100°C. Each wash consisted of 150g of p-chlorophenol, 600g of DMF, and a washing time of 3 hours. After cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each wash lasting 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure PAK was obtained. ICP analysis showed an aluminum ion content of 184ppm.

[0116] Example 11

[0117] The procedure for providing crude polyetherketone ketone is the same as in Example 1. The crude polyetherketone ketone was obtained, and ICP analysis showed residual Al. 3+ The content is approximately 1400 ppm, and the weight-average molecular weight is 141175.

[0118] Purification of crude polyether ketone ketone

[0119] Take the above crude polyetherketoneketone (Al 3+ The following steps were taken to purify 50g of a product containing approximately 1400ppm of aluminum ketone (PAK). The product was first purified by adding a mixed solvent of p-chlorophenol and DMF, and then washing three times at 100°C. Each time, 150g of P-chlorophenol and 600g of DMF were used, with a washing time of 3 hours. After cooling, an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each time for 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure PAK was obtained. ICP analysis showed an aluminum ion content of 33ppm.

[0120] Example 12

[0121] The procedure for providing crude polyetherketone ketone is the same as in Example 1. The crude polyetherketone ketone was obtained, and ICP analysis showed residual Al. 3+ The content is approximately 1400 ppm, and the weight-average molecular weight is 141175.

[0122] Purification of crude polyether ketone ketone

[0123] Take the above crude polyetherketoneketone (Al 3+The following steps were taken to purify 50g of a product containing approximately 1400ppm of aluminum ketone (PAK) as follows: A mixed solvent of p-chlorophenol and DMF was added, and the product was washed twice at 100°C, with 150g of P-chlorophenol and 600g of DMF used each time, for 3 hours. After cooling, 750g of an aqueous solution containing 15g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each time for 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure PAK was obtained. ICP analysis showed an aluminum ion content of 67ppm.

[0124] Example 13

[0125] The procedure for providing crude polyetherketone ketone is the same as in Example 1. The crude polyetherketone ketone was obtained, and ICP analysis showed residual Al. 3+ The content is approximately 1400 ppm, and the weight-average molecular weight is 141175.

[0126] Purification of crude polyether ketone ketone

[0127] Take the above crude polyetherketoneketone (Al 3+ The following steps were taken to purify 50g of a product containing approximately 1400ppm of aluminum ketone (PAK) as follows: A mixed solvent of p-chlorophenol and DMF was added, and the product was washed twice at 100°C, with 150g of P-chlorophenol and 600g of DMF used each time, for 3 hours. After cooling, 750g of an aqueous solution containing 37.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each time for 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure PAK was obtained. ICP analysis showed an aluminum ion content of 35ppm.

[0128] Example 14

[0129] The procedure for providing crude polyetherketone ketone is the same as in Example 1. The crude polyetherketone ketone was obtained, and ICP analysis showed residual Al. 3+ The content is approximately 1400 ppm, and the weight-average molecular weight is 141175.

[0130] Take the above crude polyetherketoneketone (Al 3+The following steps were taken to purify 50g of a product containing approximately 1400ppm of aluminum ketone (PAK) as follows: A mixed solvent of p-chlorophenol and DMF was added, and the product was washed twice at 100°C, with 150g of P-chlorophenol and 600g of DMF used each time, for 3 hours. After cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 150g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each time for 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure PAK was obtained. ICP analysis showed an aluminum ion content of 33ppm.

[0131] Example 15

[0132] 50g of the crude polyether ketone obtained in step (1) of Example 1 was purified as follows: a mixed solvent of chloroacetic acid and DMF was added, and the mixture was washed twice at 100°C, with 150g of chloroacetic acid and 600g of DMF used each time for 3 hours; after cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour; after cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each time for 30 minutes; after cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing liquid was less than 10μs / cm, with 1000g of water used each time, and then dried to obtain pure polyether ketone. ICP analysis showed that the aluminum ion content was 126ppm.

[0133] Example 16

[0134] 50g of the crude polyetherketone ketone obtained in step (1) of Example 1 was purified as follows: a mixed solvent of p-chlorophenol and DMSO was added, and the mixture was washed twice at 100°C, with 150g of p-chlorophenol and 600g of DMSO used each time for 3 hours; after cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour; after cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMSO for 30 minutes each time; after cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing liquid was less than 10μs / cm, with 1000g of water used each time, and then dried to obtain pure polyetherketone ketone. ICP analysis showed that the aluminum ion content was 58ppm.

[0135] Example 17

[0136] (1) Provide crude polyetherketoneketone products

[0137] The polyether ketone ketone complex was decomplexed as follows: 100g of the polyether ketone ketone complex was added to 750g of ice-cold methanol (0℃), soaked for 1 hour, and then filtered to collect the filter cake. The filter cake was washed twice with acetone, 500g each time for 15 minutes, and then filtered again to remove the filter cake. The filter cake was then washed three times with 3% hydrochloric acid at 80℃, 1000g each time for 1 hour. After cooling and filtration, the filter cake was washed three times with water at 70℃, 2000g each time. After decomplexation, crude polyether ketone ketone was obtained. This crude polyether ketone ketone was dried at 110℃ for 12 hours. ICP analysis showed that residual Al... 3+ The content is approximately 1400 ppm, and the weight-average molecular weight is 144435 according to GPC analysis.

[0138] (2) Purification of crude polyether ketone ketone

[0139] 50g of the crude polyetherketone ketone was purified as follows: A mixed solvent of p-chlorophenol and DMF was added, and the mixture was washed twice at 100°C, with 150g of p-chlorophenol and 600g of DMF used each time, for a washing time of 3 hours. After cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each time for 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure polyetherketone ketone was obtained. ICP analysis showed that the aluminum ion content was 37ppm.

[0140] Comparative Example 1

[0141] Take the above crude polyetherketoneketone (Al 3+ The following steps are involved in the refining process of 50g of a substance with a content of approximately 1400ppm:

[0142] A mixed solvent of p-chlorophenol and DMF was added, and the mixture was washed twice at 100°C, with 150g of p-chlorophenol and 600g of DMF used each time, for 3 hours each time. After cooling, 750g of an aqueous solution containing 22.5g of benzoic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times with 500g of DMF at 70°C, for 30 minutes each time. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure polyetherketone ketone was obtained. ICP analysis showed that the aluminum ion content was 364ppm.

[0143] Comparative Example 2

[0144] Take the above crude polyetherketoneketone (Al 3+ The following steps were taken to purify 50g of a product containing approximately 1400ppm of aluminum ketone (PAK). The product was first purified by adding a mixed solvent of p-chlorophenol and DMF, and then washing twice at 100°C. Each wash consisted of 150g of p-chlorophenol and 600g of DMF, with a washing time of 3 hours. After cooling and filtration, 750g of an aqueous solution containing 75g of hydroxyethylidene diphosphonic acid was added to the filter cake, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each wash lasting 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure PAK was obtained. ICP analysis showed an aluminum ion content of 74ppm.

[0145] Comparative Example 3

[0146] Take the above crude polyetherketoneketone (Al 3+ The following steps were taken to purify 50g of a product containing approximately 1400ppm of aluminum ketone: p-chlorophenol was added, and the product was washed twice at 100℃, with 150g of p-chlorophenol used each time for 3 hours. After cooling, an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100℃ for 1 hour. After cooling and filtration, the filter cake was washed with water at 70℃ until the conductivity of the washing liquid was below 10μs / cm, using 1000g of water each time. After drying, pure polyetherketone ketone was obtained. ICP analysis showed an aluminum ion content of 76ppm.

[0147] Comparative Example 4

[0148] Take the above crude polyetherketoneketone (Al 3+ The following steps were taken to purify 50g of a product containing approximately 1400ppm of aluminum ketone (PAK). The product was first purified by adding a mixed solvent of p-chlorophenol and dichloroethane, and then refluxed and washed three times, each time using 150g of P-chlorophenol and 600g of dichloroethane for 3 hours. After cooling, an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100℃ for 1 hour. After cooling and filtration, the filter cake was washed three times with 500g of dichloroethane at 70℃ for 30 minutes each time. After cooling and filtration, the filter cake was washed with water at 70℃ until the conductivity of the washing solution was below 10μs / cm, using 1000g of water each time. After drying, pure PAK was obtained. ICP analysis showed an aluminum ion content of 63ppm.

[0149] Comparative Example 5

[0150] The procedure for providing crude polyetherketone ketone is the same as in Example 1. The crude polyetherketone ketone was obtained, and ICP analysis showed residual Al. 3+ The content is approximately 1400 ppm.

[0151] Purification of crude polyether ketone ketone

[0152] Take the above crude polyetherketoneketone (Al 3+ The following steps were taken to purify 50g of a product containing approximately 1400 ppm of aluminum ketone (PAK). The product was then washed twice at 100°C, with 150g of PAK and 600g of DMF used each time, for 3 hours. After cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 37.5g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each time for 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10 μS / cm, using 1000g of water each time. After drying, pure PAK was obtained. ICP analysis showed an aluminum ion content of 271 ppm.

[0153] Comparative Example 6

[0154] 50g of the polyetherketone-ketone complex from Example 1 was directly purified without prior soaking in ice-cold methanol, washing with acetone, or acid washing with hydrochloric acid. The steps were as follows: A mixed solvent of p-chlorophenol and DMF was added to the polyetherketone-ketone complex, and it was washed twice at 100°C, with 300g of p-chlorophenol and 1200g of DMF used each time, for a washing time of 3 hours. After cooling, 750g of an aqueous solution containing 22.5g of benzoic acid and 75g of hydroxyethylidene diphosphonic acid was added, and the mixture was stirred thoroughly at 100°C for 1 hour. After cooling and filtration, the filter cake was washed three times at 70°C with 500g of DMF, each time for 30 minutes. After cooling and filtration, the filter cake was washed with water at 70°C until the conductivity of the washing solution was below 10μs / cm, with 1000g of water used each time. After drying, pure polyetherketone-ketone was obtained. ICP analysis showed that the aluminum ion content was 1860ppm.

[0155] Therefore, it can be seen that using a main chain-supporting agent and a co-solvent during the chain-supporting process has a better chain-supporting effect, resulting in more thorough removal of metal impurity ions. The synergistic use of organic acids and phosphorus-containing compounds can enhance the removal of aluminum ions, and the initial processes of icy methanol, acetone, and water washing can also improve the purification effect. Further adjustments to the ratio of the main chain-supporting agent and co-solvent, as well as the content of organic acids and phosphorus-containing compounds, can further improve the purification effect. After the polymerization reaction, the polyether ketone ketone complex forms a stable gel-like system, in which the polymer molecular chains are tightly bound to the Lewis acid catalyst and Lewis base through coordination and intermolecular forces, forming a dense three-dimensional network structure that tightly encapsulates metal impurities such as aluminum ions within the molecular chains. Comparative Example 6, without treatment with icy methanol, acetone, and hydrochloric acid, exhibits a highly cross-linked state, making solvent penetration difficult and severely hindering mass transfer. The solvent cannot effectively enter the polymer interior, resulting in extremely low aluminum ion removal efficiency.

[0156] In summary, the polyether ketone ketone purified by the method proposed in this application has a low aluminum ion content, can effectively remove different types of impurities, and has better adaptability to crude PEKK from different sources.

[0157] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for purifying polyether ketone, characterized in that, include: (1) The polyether ketone complex is treated with a pretreatment agent, which includes a polar organic solvent and an inorganic acid, to obtain crude polyether ketone. (2) The crude polyether ketone ketone and the mixed chain-supporting solution are mixed and washed to obtain the first product. The mixed chain-supporting solution includes a main chain-supporting agent and a co-solvent. The mass ratio of the main chain-supporting agent and the co-solvent is 1:0.5 to 1:

10. The mass ratio of the mixed chain-supporting solution and the crude polyether ketone ketone is 5:1 to 35:

1. The main chain-supporting agent includes one or more selected from p-chlorophenol, trifluoroacetic acid, difluoroacetic acid, dichloroacetic acid, and chloroacetic acid. The co-solvent includes one or more selected from N,N-dimethylformamide, dimethyl sulfoxide, water, N-methylpyrrolidone, and N-methylformamide. (3) Add a mixed aqueous solution containing phosphide and organic acid and / or organic acid salt to the first product to remove some metal ions, stir and heat to obtain a second product, wherein the heating temperature is 40~150℃, and the metal ions include Al 3+ The mass fraction of the phosphide in the mixed aqueous solution is 6% to 20%, and the mass fraction of the organic acid and / or organic acid salt in the mixed aqueous solution is 2% to 5%. The phosphide includes one or more of hydroxyethylidene diphosphonic acid, aminotrimethylene phosphonic acid, and hydroxyethyl ethylenediamine trimethylidene phosphonic acid. (4) The second product is washed multiple times with an organic solvent and then dried with water to obtain the polyether ketone ketone refined product.

2. The method according to claim 1, characterized in that, In step (1), the polar organic solvent includes icy methanol and at least one selected from acetone and methanol, and the inorganic acid includes hydrochloric acid, wherein the mass fraction of HCl in the hydrochloric acid is 0.1-10%.

3. The method according to claim 2, characterized in that, Step (1) includes: Ice-cold methanol was added to the polyether ketone ketone complex, and the mixture was reacted at -25 ~ 5°C for 0.5 ~ 2 hours to perform decomplexation treatment. The mass ratio of ice-cold methanol to the polyether ketone ketone complex was 10:1 to 20:

1. Add acetone and / or methanol to the decomplexed polyether ketone ketone and wash 1 to 3 times to remove impurities. The mass ratio of the washing solvent to the decomplexed polyether ketone ketone is 8:1 to 15:1, and the washing time for each wash is 10 to 30 minutes. The treated polyetherketone ketone is pickled using hydrochloric acid, wherein the mass ratio of hydrochloric acid to crude polyetherketone ketone is 15:1 to 30:1, the pickling temperature is 40 to 100°C, the number of pickling cycles is 1 to 5, and the pickling time for each cycle is 0.5 to 1.5 hours. After cooling, it is washed with water 1 to 5 times, wherein the temperature of the water washing is 40 to 100°C, and the amount of water used each time is 15 to 30 times the mass of polyetherketone ketone. Finally, it is dried to obtain the crude polyetherketone ketone.

4. The method according to claim 1, characterized in that, In step (2), the main supporting agent includes p-chlorophenol. The co-solvent includes N,N-dimethylformamide.

5. The method according to claim 1, characterized in that, In step (2), the mass ratio of the mixed chain-supporting solution to the crude polyether ketone is 5:1 to 30:1; The mass ratio of the main chain-supporting agent to the co-solvent in the mixed chain-supporting solution is 1:3 to 1:

5.

6. The method according to claim 1, characterized in that, In step (2), the washing process is a heated reflux washing process, which is repeated 1 to 3 times, with each time lasting 1 to 3 hours.

7. The method according to claim 1, characterized in that, In step (3), the mass ratio of the mixed aqueous solution to the first product is 10:1 to 20:

1.

8. The method according to claim 7, characterized in that, The organic acid mentioned in step (3) includes one or more of benzoic acid, salicylic acid, para-benzoic acid, and o-benzoic acid; Organic acid salts include one or more of benzoates, salicylates, and parabens.

9. The method according to claim 8, characterized in that, The organic acid has a mass fraction of 2.5-3.5% in the mixed aqueous solution, and the phosphide has a mass fraction of 8-15% in the mixed aqueous solution.

10. The method according to claim 1, characterized in that, Step (4) includes: The second product was washed three times with N,N-dimethylformamide; The second product washed with N,N-dimethylformamide is then washed with water 1-5 times. The second product after washing with water is dried to obtain the refined polyether ketone ketone product.

11. The method according to claim 10, characterized in that, The mass ratio of N,N-dimethylformamide to the second product is 10:1 to 20:1, the washing time is 10 to 40 minutes, and the washing temperature is 40 to 150°C. The washing process is repeated three times, with each wash using 15 to 30 times the mass of the product, and the temperature is 40 to 100°C.

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