A method for purifying a polyaryletherketone

Abstract

The application discloses a kind of purification methods of polyaryletherketone, it belongs to high polymer material purification technical field, comprising the following steps: polyaryletherketone crude product is placed with primary amine compound in organic solvent, with or without catalyst is carried out Schiff base reaction, then is transferred to 2-methyltetrahydrofuran, and soluble polyaryletherimine solution is prepared;Active carbon is added to soluble polyaryletherimine solution and is subjected to adsorption treatment, and adsorption mixed solution is obtained;Solid is separated from adsorption mixed solution, and the solid is subjected to refining treatment, and refined soluble polyaryletherimine is obtained;Refined soluble polyaryletherimine is subjected to deprotection treatment, and the polyaryletherketone after purification is obtained.The application is converted into soluble polyaryletherimine precursor by first polyaryletherketone crude product, breaks original crystalline structure, then simultaneously adsorbs small molecule impurities and abnormal crosslinking structure using active carbon, and high-efficiency purification of polyaryletherketone can be realized under mild conditions, suitable for industrial large-scale application.

Description

Technical Field

[0001] This invention relates to the field of polymer purification technology, specifically a purification method for polyarylether ketones. Background Technology

[0002] Polyaryletherketones, such as polyetheretherketone (PEEK), are a class of semi-crystalline, high-performance thermoplastic engineering plastics composed of alternating aromatic rings, ether bonds, and carbonyl groups. They possess excellent high-temperature resistance (long-term service temperature up to 270℃), chemical corrosion resistance, mechanical strength, and electrical insulation, and are widely used in aerospace structural components, automotive powertrain systems, electronic packaging, petrochemical equipment, and other industrial fields. Currently, the mainstream industrial production process for PEEK is nucleophilic substitution stepwise polymerization, using 4,4'-difluorobenzophenone and hydroquinone as monomers, and carrying out the polymerization reaction in high-temperature solvents such as diphenyl sulfone.

[0003] However, various impurities are inevitably generated during PEEK production: firstly, unreacted monomers, low-molecular-weight oligomers (dimers to decamers), and alkali metal catalyst residues remain from polymerization; secondly, abnormal cross-linking structures of molecular chains are caused by polymerization side reactions and high-temperature shearing during subsequent melt processing. These impurities severely degrade the performance of PEEK: small-molecule impurities can generate bubbles and streaks during melt processing, reducing the mechanical strength and dimensional stability of the product; abnormal cross-linking structures can significantly reduce melt flowability, increase processing temperature, and even lead to stress cracking in the product. Therefore, efficient purification is the core step in ensuring the quality of industrial PEEK products.

[0004] Existing PEEK purification technologies have significant limitations: Solvent extraction: Using solvents such as acetone and ethanol to reflux and extract PEEK particles, it can only remove small molecules attached to the surface, but cannot penetrate into the particle to remove embedded oligomers and cross-linked structures. Moreover, the extraction time is as long as 24 hours or more, resulting in large solvent consumption. High-temperature vacuum devolatilization: Small molecules are removed under high vacuum conditions at 320-350℃, but energy consumption is high, and prolonged high temperature will cause oxidative degradation of PEEK molecular chains, resulting in a decrease in molecular weight and performance. Concentrated sulfuric acid precipitation: PEEK is dissolved in concentrated sulfuric acid and then precipitated. Although it can remove some small molecules, concentrated sulfuric acid will cause PEEK sulfonation reaction and main chain breakage. It is also highly dangerous to operate and difficult to treat waste. Existing activated carbon adsorption technology: It is mainly used for the final cleaning of medical-grade PEEK, and only targets residual endotoxins and trace heavy metals on the surface. It has not optimized the process for the oligomers and cross-linked structures inside the crude industrial PEEK, resulting in low adsorption efficiency and almost no removal effect on cross-linked structures. Summary of the Invention

[0005] The purpose of this invention is to provide a method for purifying polyarylether ketones to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for purifying polyarylether ketones includes the following steps:

[0008] The crude polyaryletherketone was placed in an organic solvent and reacted with a primary amine compound in a Schiff base reaction with or without a catalyst. The mixture was then transferred to 2-methyltetrahydrofuran to prepare a soluble polyaryletherimide solution.

[0009] Activated carbon was added to a soluble polyarylene ether imine solution for adsorption treatment to obtain an adsorption mixture; the amount of activated carbon added was 0.5-5 wt% of the crude polyarylene ether ketone.

[0010] The solid was separated from the adsorption mixture and then purified to obtain purified soluble polyarylene ether imine.

[0011] The purified soluble polyaryletherimide was deprotected to obtain the purified polyarylether ketone.

[0012] Furthermore, the polyaryletherketone includes one or more of polyetheretherketone, polyetherketoneketone, polyetherketone, polyetheretherketoneketone, polyetherketoneketone, biphenyl-type polyetheretherketone, biphenyl-type polyetheretherketoneketone, 1,4-naphthyl polyetherketoneketoneketone, biphenyl / p-phenyl copolymer polyetheretherketone, biphenyl / p-phenyl copolymer polyetheretherketoneketone, and polyetherketone-polyetheretherketone copolymer.

[0013] Furthermore, the mass ratio of the crude polyaryletherketone to the primary amine compound is 1:(1-10); the mass ratio of the crude polyaryletherketone to the organic solvent is 1:(10-50); and the mass percentage concentration of the soluble polyaryletherimide solution is 1%-20%.

[0014] Furthermore, the Schiff base reaction conditions are 150-200℃ and 0.1-5MPa.

[0015] Further, the primary amine compound is cyclohexylamine or an amino acid; a catalyst is selectively added according to the type of the selected primary amine compound, specifically: when the primary amine compound is cyclohexylamine, no catalyst is added, or a weak acid is added as a catalyst; when the primary amine compound is an amino acid, no additional catalyst is required; the weak acid is selected from one or more of citric acid, acetic acid, lactic acid, malic acid, tartaric acid, succinic acid, and ascorbic acid; the mass ratio of the crude polyaryletherketone to the catalyst is 1:(0.01-0.1).

[0016] Furthermore, the amino acid includes one or more of glycine, tryptophan, aspartic acid, glutamic acid, alanine, and valine.

[0017] Furthermore, the organic solvent is one or more of the following: divalent ester, ethylene glycol diacetate, methyl lactate, ethyl lactate, propylene carbonate, dimethyl sulfoxide, N-formylmorpholine, N-butylpyrrolidone, γ-valerolactone, diphenyl sulfone, and benzophenone.

[0018] Further, the steps of separating the solid from the adsorption mixture and purifying the solid specifically include:

[0019] The adsorption mixture was filtered, and the filtrate was added to water to precipitate the solid. The solid was then washed with ethanol and deionized water and dried to obtain the preliminarily purified product.

[0020] The pre-purified product was dissolved and filtered using 2-methyltetrahydrofuran, then the 2-methyltetrahydrofuran was removed, and the product was extracted with ethanol by Soxhlet extraction and dried to obtain purified soluble polyarylene ether imine.

[0021] Furthermore, the method for deprotection treatment is a thermal deprotection method, specifically: heat treatment is performed under a protective atmosphere at 120-140℃.

[0022] Furthermore, the activated carbon is one or more of coconut shell activated carbon, wood-based activated carbon, and coal-based activated carbon; the specific surface area of ​​the activated carbon is 1000-1500 m². 2 / g, with mesopores of 2-50nm accounting for 65%-75%.

[0023] The purification method for polyaryletherketones provided by this invention deeply combines activated carbon adsorption technology with soluble polyarylether imine conversion technology, overcoming the technical bottleneck of traditional activated carbon which can only remove trace impurities on the surface of polyaryletherketones and is unable to simultaneously remove small molecule impurities and abnormal cross-linked structures. This invention first converts crude polyaryletherketones into soluble polyarylether imine precursors, breaking down the original crystalline structure, and then utilizes activated carbon to simultaneously adsorb small molecule impurities and abnormal cross-linked structures. This allows for highly efficient purification of polyaryletherketones under mild conditions, making it suitable for large-scale industrial applications. Attached Figure Description

[0024] Figure 1 This is the 1H NMR spectrum of the soluble polyarylene ether imine in Example 1 of the present invention;

[0025] Figure 2 This is a comparison of the GPC elution curves of PEEK before and after purification in Example 1 of the present invention;

[0026] Figure 3 This is a DSC crystallization curve of the purified PEEK obtained in Example 1 of the present invention. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] In one embodiment of the present invention, a purification method for polyarylether ketones that is simple to operate, efficient, environmentally friendly, and suitable for industrial production is provided. This method aims to solve the problems of existing polyarylether ketone purification technologies, such as difficulty in simultaneously removing small molecule impurities and abnormal cross-linked structures, low purification efficiency, unstable product performance, and complex operation. The purification method specifically includes the following steps:

[0029] S1. At 150-200℃ and 0.1-5MPa pressure, crude polyaryletherketone and a primary amine compound are mixed in an organic solvent at a mass ratio of 1:(1-10). A Schiff base reaction is carried out with or without a catalyst, and then the mixture is transferred to 2-methyltetrahydrofuran to prepare a soluble polyaryletherimide solution with a mass percentage concentration of 1%-20%. The mass ratio of crude polyaryletherketone to the organic solvent is 1:(10-50). The primary amine compound is cyclohexylamine or an amino acid. A catalyst is selectively added according to the type of primary amine compound selected. Specifically: when the primary amine compound is cyclohexylamine, no catalyst is added, or a weak acid is added as a catalyst; when the primary amine compound is an amino acid, no additional catalyst is required; the mass ratio of crude polyaryletherketone to the catalyst is 1:(0.01-0.1).

[0030] S2. Add activated carbon to the above soluble polyarylene ether imine solution and stir at 25-60℃ for adsorption treatment for 1-6 hours to obtain an adsorption mixture; wherein the amount of activated carbon added is 0.5-5 wt% of the crude polyarylene ether ketone.

[0031] S3. Filter the above adsorption mixture, add the filtrate to water to precipitate the solid (precipitate), wash with ethanol and deionized water until neutral, and dry (e.g., vacuum drying at 80-105℃) to obtain a preliminary purified product; then, dissolve and filter the preliminary purified product with 2-methyltetrahydrofuran, remove 2-methyltetrahydrofuran by vacuum distillation, and extract with ethanol using Soxhlet extraction and dry (e.g., vacuum drying at 80-105℃) to obtain a purified soluble polyarylene ether imine;

[0032] S4. The purified soluble polyarylene ether imine is placed in a protective atmosphere (such as nitrogen, argon, etc.) at 120-140℃ for deprotection treatment to obtain purified polyarylene ether ketone.

[0033] Preferably, the aforementioned polyaryletherketone includes one or more of polyetheretherketone, polyetherketoneketone, polyetherketone, polyetheretherketoneketone, polyetherketoneketone, biphenyl-type polyetheretherketone, biphenyl-type polyetheretherketoneketone, 1,4-naphthyl polyetherketoneketoneketone, biphenyl / p-phenyl copolymer polyetheretherketone, biphenyl / p-phenyl copolymer polyetheretherketoneketone, and polyetherketone-polyetheretherketone copolymer. The weak acid is selected from one or more of citric acid, acetic acid, lactic acid, malic acid, tartaric acid, succinic acid, and ascorbic acid. The amino acid includes one or more of glycine, tryptophan, aspartic acid, glutamic acid, alanine, and valine. The organic solvent is one or more of the following: divalent ester (DBE), ethylene glycol diacetate (EGDA), methyl lactate, ethyl lactate, propylene carbonate (PC), dimethyl sulfoxide (DMSO), N-formylmorpholine (NFM), N-butylpyrrolidone (NBP), γ-valerol (GVL), diphenyl sulfone, and benzophenone. The activated carbon is one or more of the following: medical-grade coconut shell activated carbon, wood-based activated carbon, and coal-based activated carbon; the specific surface area of ​​the activated carbon is 1000-1500 m². 2 / g, with mesoporous content of 2-50nm accounting for 65%-75%, ash content ≤0.1wt%, and total heavy metal content ≤10ppm.

[0034] Unless otherwise specified, all raw materials used in the following embodiments are commercially available products and can be purchased through commercial channels. The invention will be described in detail below through specific embodiments in practical applications.

[0035] Example 1: This example provides a purification method for polyetheretherketone, specifically including the following steps:

[0036] 10g of crude polyether ether ketone (PEEK) was pulverized to 200 mesh, and 50g of cyclohexylamine, 0.2g of citric acid, and 300g of divalent ester (DBE) were added to a 500mL high-pressure reactor. Under nitrogen protection, the mixture was heated to 190℃ and stirred for 5h at a pressure of 0.2MPa. The reaction solution changed from an initial heterogeneous mixture to a uniform yellow transparent solution, indicating that PEEK had been completely converted into soluble polyarylene ether imine (Formula I).

[0037] (Formula I);

[0038] The obtained soluble polyarylene ether imine was transferred to 2-methyltetrahydrofuran to prepare a homogeneous solution with a mass percentage concentration of 10%. 0.2 g of medical-grade coconut shell activated carbon (specific surface area 1200 m²) was added to the solution. 2The product contained PEEK (70% mesoporous structure, 0.08 wt% ash, 6 ppm total heavy metals), which was adsorbed at 40℃ for 3 h with stirring. The adsorbed product was filtered through a 0.45 μm microporous membrane to obtain a clear filtrate. The filtrate was slowly added to 1 L of deionized water, and the mixture was precipitated at 10℃ for 1 h with stirring at 400 rpm. The solid was collected by filtration, washed twice with medical-grade ethanol (50 g each time), washed with deionized water until neutral, and dried under vacuum at 100℃ for 12 h to obtain a pre-purified product. The pre-purified product was dissolved again in 2-methyltetrahydrofuran, filtered, and the solvent was removed by vacuum distillation. The product was then extracted with medical-grade ethanol using a Soxhlet extraction method for 8 h, and dried under vacuum at 100℃ for 12 h. Finally, the product was deprotected under nitrogen at 130℃ for 6 h to obtain 9.38 g of high-purity PEEK, with a yield of 93.8%.

[0039] The soluble polyarylene ether imine obtained above was characterized by 1H NMR (400 MHz, CDCl3), and the results are as follows. Figure 1 As shown, this demonstrates the successful preparation of soluble polyarylene ether imine.

[0040] Performance testing: such as Figure 2 As shown, the GPC main peak retention time was 23.2 min, Mn = 27.3 kg / mol, Mw = 47.9 kg / mol, PDI = 1.75, no obvious high molecular weight crosslinking shoulder peak was observed from 18 to 20 min, and the oligomer tailing significantly decreased from 26 to 30 min; HPLC detection showed a monomer residue of 0.07 wt%; GPC-MALLS analysis showed an oligomer content of 0.72 wt%. Figure 3 As shown, the crystallinity detected by DSC was 32.2%; the melt index (380℃ / 5kg) was 10.1g / 10min.

[0041] Example 2: This example provides a purification method for polyether ether ketone, specifically including the following steps:

[0042] 10g of crude polyether ether ketone (PEEK) was pulverized to 250 mesh, and 50g of glycine, 0.3g of acetic acid, and 400g of ethylene glycol diacetate (EGDA) were added to a 500mL high-pressure reactor. Under nitrogen protection, the mixture was heated to 190℃ and stirred for 5h at a pressure of 0.2MPa. The reaction solution changed from an initial heterogeneous mixture to a uniform yellow transparent solution, indicating that PEEK had been completely converted into soluble polyarylene ether imine (Formula II).

[0043] (Formula II);

[0044] The obtained soluble polyarylene ether imine was transferred to 2-methyltetrahydrofuran to prepare a homogeneous solution with a mass percentage concentration of 8%. 0.3 g of medical-grade coconut shell activated carbon (same as in Example 1) was added to the solution, and the mixture was stirred at 45°C for 4 h for adsorption. The solution was then filtered through a 0.22 μm microporous membrane to obtain a clear filtrate. The filtrate was slowly added to 1.2 L of deionized water, and precipitation was carried out at 15°C for 1.5 h with stirring at 450 rpm. The solid was collected by filtration, washed three times with medical-grade ethanol (40 g each time), washed with deionized water until neutral, and dried under vacuum at 95°C for 15 h to obtain a pre-purified product. The pre-purified product was dissolved again in 2-methyltetrahydrofuran, filtered, and the solvent was removed by vacuum distillation. The product was then extracted with medical-grade ethanol using a Soxhlet extraction method for 10 h, and dried under vacuum at 95°C for 12 h. Finally, deprotection treatment was performed at 125°C under nitrogen protection for 7 h to obtain 9.32 g of high-purity PEEK, with a yield of 93.2%.

[0045] Performance testing: GPC main peak retention time 23.1 min, Mn=27.5 kg / mol, Mw=48.4 kg / mol, PDI=1.76, no obvious crosslinking shoulder peak at 18-20 min, oligomer tailing significantly reduced at 26-30 min; HPLC detection showed monomer residue of 0.06 wt%; GPC-MALLS detection showed oligomer content of 0.68 wt%; DSC crystallinity 32.5%; melt index (380℃ / 5 kg) 10.3 g / 10 min.

[0046] Example 3: This example provides a purification method for polyetheretherketone, specifically including the following steps:

[0047] 10g of crude polyether ether ketone (PEEK) was pulverized to 300 mesh, and 50g of tryptophan, 0.5g of lactic acid, and 600g of propylene carbonate (PC) were added to a 1L high-pressure reactor. Under nitrogen protection, the mixture was heated to 190℃ and stirred for 5 hours at a pressure of 0.2MPa. The reaction solution changed from an initial heterogeneous mixture to a uniform yellow transparent solution, indicating that PEEK had been completely converted into soluble polyarylene ether imine (Formula III).

[0048] (Formula III)

[0049] The obtained soluble polyarylene ether imine was transferred to 2-methyltetrahydrofuran to prepare a homogeneous solution with a mass percentage concentration of 5%. 0.1 g of medical-grade wood-based activated carbon (specific surface area 1000 m²) was added to the solution. 2The product contained PEEK (65% mesoporous structure, 0.09 wt% ash, and 8 ppm total heavy metals), which was adsorbed at 50°C for 2 h with stirring. The adsorbed product was filtered through a 0.45 μm microporous membrane to obtain a clear filtrate. The filtrate was slowly added to 1.5 L of deionized water, and the mixture was precipitated at 20°C for 1 h with stirring at 500 rpm. The solid was collected by filtration, washed twice with medical-grade ethanol (60 g each time), washed with deionized water until neutral, and dried under vacuum at 105°C for 10 h to obtain a pre-purified product. The pre-purified product was dissolved again in 2-methyltetrahydrofuran, filtered, and the solvent was removed by vacuum distillation. The product was then extracted with medical-grade ethanol using a Soxhlet extraction method for 6 h, and dried under vacuum at 105°C for 12 h. Finally, the product was deprotected under nitrogen at 135°C for 5 h to obtain 9.27 g of high-purity PEEK, with a yield of 92.7%.

[0050] Performance testing: GPC main peak retention time 23.3 min, Mn=27.2 kg / mol, Mw=48.0 kg / mol, PDI=1.75, no obvious crosslinking shoulder peak at 18-20 min, oligomer tailing significantly reduced at 26-30 min; HPLC detection showed monomer residue of 0.08 wt%; GPC-MALLS detection showed oligomer content of 0.78 wt%; DSC crystallinity 32.9%; melt index (380℃ / 5 kg) 9.9 g / 10 min.

[0051] Example 4: This example provides a purification method for polyether ether ketone, specifically including the following steps:

[0052] 10g of crude polyether ether ketone (PEEK) was pulverized to 200 mesh, and 50g of glutamic acid, 0.1g of malic acid, and 200g of γ-valerol (GVL) were added to a 500mL high-pressure reactor. The mixture was heated to 190℃ and stirred at 0.2MPa pressure for 5h under nitrogen protection. The reaction solution changed from an initial heterogeneous mixture to a uniform yellow transparent solution, indicating that PEEK had been completely converted into soluble polyarylene ether imine (Formula IV).

[0053] (Formula IV);

[0054] The obtained soluble polyarylene ether imine was transferred to 2-methyltetrahydrofuran to prepare a homogeneous solution with a mass percentage concentration of 15%. 0.4 g of medical-grade coal-based activated carbon (specific surface area 1500 m²) was added to the solution. 2The product contained PEEK (75% mesoporous structure, 0.07wt% ash, and 5ppm total heavy metals), which was adsorbed at 35℃ for 5h with stirring. The adsorbed product was filtered through a 0.22μm microporous membrane to obtain a clear filtrate. The filtrate was slowly added to 0.8L of deionized water, and the mixture was precipitated at 5℃ for 2h with stirring at 350rpm. The solid was collected by filtration, washed three times with medical-grade ethanol (50g each time), washed with deionized water until neutral, and dried under vacuum at 90℃ for 18h to obtain a pre-purified product. The pre-purified product was dissolved again in 2-methyltetrahydrofuran, filtered, and the solvent was removed by vacuum distillation. The product was then extracted with medical-grade ethanol using a Soxhlet extractor for 12h and dried under vacuum at 90℃ for 12h. Finally, the product was deprotected under nitrogen at 140℃ for 4h to obtain 9.41g of high-purity PEEK, with a yield of 94.1%.

[0055] Performance testing: GPC main peak retention time 22.9 min, Mn=28.0 kg / mol, Mw=49.5 kg / mol, PDI=1.77, no obvious crosslinking shoulder peak at 18-20 min, oligomer tailing significantly reduced at 26-30 min; HPLC detection showed monomer residue of 0.05 wt%; GPC-MALLS detection showed oligomer content of 0.63 wt%; DSC crystallinity 32.6%; melt index (380℃ / 5 kg) 10.7 g / 10 min.

[0056] Example 5: This example provides a method for purifying polyether ketone, specifically including the following steps:

[0057] 10g of crude polyetherketone (PEK) was pulverized to 250 mesh, and 50g of aspartic acid, 0.8g of tartaric acid, and 800g of N-formylmorpholine (NFM) were added to a 1L high-pressure reactor. Under nitrogen protection, the mixture was heated to 190℃ and stirred for 5 hours at a pressure of 0.2MPa. The reaction solution changed from an initial heterogeneous mixture to a uniform yellow transparent solution, indicating that PEK had been completely converted into soluble polyarylene etherimide (Formula V).

[0058] (Formula V);

[0059] The obtained soluble polyarylene ether imine was transferred to 2-methyltetrahydrofuran to prepare a homogeneous solution with a mass percentage concentration of 3%. 0.05 g of medical-grade coconut shell activated carbon (same as in Example 1) was added to the solution, and the mixture was stirred at 60 °C for 1 h for adsorption. The solution was then filtered through a 0.45 μm microporous membrane to obtain a clear filtrate. The filtrate was slowly added to 2 L of deionized water, and precipitation was carried out at 10 °C for 1.5 h with stirring at 400 rpm. The solid was collected by filtration, washed twice with medical-grade ethanol (70 g each time), washed with deionized water until neutral, and dried under vacuum at 100 °C for 12 h to obtain a pre-purified product. The pre-purified product was dissolved again in 2-methyltetrahydrofuran, filtered, and the solvent was removed by vacuum distillation. The product was then extracted with medical-grade ethanol using a Soxhlet extraction method for 9 h, and dried under vacuum at 100 °C for 12 h. Finally, deprotection treatment was carried out at 130 °C under nitrogen protection for 6 h to obtain 9.25 g of high-purity PEK, with a yield of 92.5%.

[0060] Performance Testing: GPC main peak retention time 23.4 min, Mn = 27.0 kg / mol, Mw = 48.8 kg / mol, PDI = 1.81; no obvious crosslinking shoulder peak at 18-20 min; oligomer tailing significantly reduced at 26-30 min; HPLC detection showed monomer residue of 0.09 wt%; GPC-MALLS detection showed oligomer content of 0.83 wt%; DSC crystallinity 31.9%; melt index (390℃ / 5 kg) 9.8 g / 10 min.

[0061] Example 6: This example provides a method for purifying polyether ketones, specifically including the following steps:

[0062] 10g of crude polyetherketone ketone (PEKK) was pulverized to 300 mesh, and 50g of glutamic acid, 1.0g of succinic acid, and 1000g of N-butylpyrrolidone (NBP) were added to a 2L high-pressure reactor. The mixture was heated to 190℃ and stirred for 5h under nitrogen protection and pressure of 0.2MPa. The reaction solution changed from an initial heterogeneous mixture to a uniform yellow transparent solution, indicating that PEKK had been completely converted into soluble polyarylene ether imine (Formula VI).

[0063] (Form VI);

[0064] The obtained soluble polyarylene ether imine was transferred to 2-methyltetrahydrofuran to prepare a homogeneous solution with a mass percentage concentration of 2%. 0.5 g of medical-grade wood-based activated carbon (same as in Example 3) was added to the solution, and the mixture was stirred at 25°C for 6 h for adsorption. The solution was then filtered through a 0.22 μm microporous membrane to obtain a clear filtrate. The filtrate was slowly added to 2.5 L of deionized water, and precipitation was carried out at 25°C for 0.5 h with stirring at 300 rpm. The solid was collected by filtration, washed three times with medical-grade ethanol (60 g each time), washed with deionized water until neutral, and dried under vacuum at 80°C for 24 h to obtain a pre-purified product. The pre-purified product was dissolved again in 2-methyltetrahydrofuran, filtered, and the solvent was removed by vacuum distillation. The product was then extracted with medical-grade ethanol using a Soxhlet extraction method for 11 h, and dried under vacuum at 80°C for 12 h. Finally, deprotection treatment was performed at 120°C under nitrogen protection for 8 h to obtain 9.19 g of high-purity PEKK, with a yield of 91.9%.

[0065] Performance testing: GPC main peak retention time 23.4 min, Mn=27.1 kg / mol, Mw=48.9 kg / mol, PDI=1.80, no obvious crosslinking shoulder peak at 18-20 min, oligomer tailing significantly reduced at 26-30 min; HPLC detection showed monomer residue of 0.06 wt%; GPC-MALLS detection showed oligomer content of 0.76 wt%; DSC crystallinity 33.0%; melt index (370℃ / 5 kg) 10.0 g / 10 min.

[0066] Example 7: This example provides a method for purifying polyether ketones, specifically including the following steps:

[0067] 10g of crude polyetherketoneketone (PEKK) was pulverized to 200 mesh, and 50g of aspartic acid, 0.4g of ascorbic acid, and 500g of mixed solvent (divalent ester and propylene carbonate mixed at a mass ratio of 50:50) were added to a 1L high-pressure reactor. Under nitrogen protection, the mixture was heated to 190℃ and stirred for 5h at a pressure of 0.2MPa. The reaction solution changed from an initial heterogeneous mixture to a uniform yellow transparent solution, indicating that PEKK had been completely converted into soluble polyarylene etherimide (Formula VII).

[0068] (Formula VII);

[0069] The obtained soluble polyarylene ether imine was transferred to 2-methyltetrahydrofuran to prepare a homogeneous solution with a mass percentage concentration of 12%. 0.25 g of medical-grade coconut shell activated carbon (same as in Example 1) was added to the solution, and the mixture was stirred at 42°C for 3.5 h for adsorption. The solution was then filtered through a 0.45 μm microporous membrane to obtain a clear filtrate. The filtrate was slowly added to 1.1 L of deionized water, and the mixture was stirred at 420 rpm at 12°C for 1.2 h to precipitate. The solid was collected by filtration, washed twice with medical-grade ethanol (55 g each time), washed with deionized water until neutral, and dried under vacuum at 98°C for 13 h to obtain a pre-purified product. The pre-purified product was dissolved again in 2-methyltetrahydrofuran, filtered, and the solvent was removed by vacuum distillation. The product was then extracted with medical-grade ethanol using a Soxhlet extraction method for 7 h, and dried under vacuum at 98°C for 12 h. Finally, the product was deprotected under nitrogen protection at 128°C for 6.5 h to obtain 9.23 g of high-purity PEKK, with a yield of 92.3%.

[0070] Performance testing: GPC main peak retention time 23.1 min, Mn=27.6 kg / mol, Mw=48.9 kg / mol, PDI=1.77, no obvious crosslinking shoulder peak at 18-20 min, oligomer tailing significantly reduced at 26-30 min; HPLC detection showed monomer residue of 0.07 wt%; GPC-MALLS detection showed oligomer content of 0.70 wt%; DSC crystallinity 32.3%; melt index (370℃ / 5 kg) 10.2 g / 10 min.

[0071] Example 8: This example provides a method for purifying polyether ketones, specifically including the following steps:

[0072] 10g of crude polyetherketoneketone (PEKK) was pulverized to 250 mesh, and then added to a 500mL high-pressure reactor along with 50g of alanine, 0.6g of citric acid, and 450g of a mixed solvent (ethylene glycol diacetate and γ-valerolactone mixed at a mass ratio of 60:40). The mixture was heated to 190℃ and stirred for 5 hours under nitrogen protection and pressure of 0.2MPa. The reaction solution changed from an initial heterogeneous mixture to a uniform yellow transparent solution, indicating that PEKK had been completely converted into soluble polyarylene etherimide (Formula VIII).

[0073] (Formula VIII);

[0074] The obtained soluble polyarylene ether imine was transferred to 2-methyltetrahydrofuran to prepare a homogeneous solution with a mass percentage concentration of 18%. 0.35 g of medical-grade coal-based activated carbon (same as in Example 4) was added to the solution, and the mixture was stirred at 38°C for 4.5 h for adsorption. The solution was then filtered through a 0.22 μm microporous membrane to obtain a clear filtrate. The filtrate was slowly added to 0.9 L of deionized water, and the mixture was stirred at 380 rpm for 1.8 h at 8°C to precipitate. The solid was collected by filtration, washed three times with medical-grade ethanol (45 g each time), washed with deionized water until neutral, and dried under vacuum at 92°C for 16 h to obtain a pre-purified product. The pre-purified product was dissolved again in 2-methyltetrahydrofuran, filtered, and the solvent was removed by vacuum distillation. The product was then extracted with medical-grade ethanol using a Soxhlet extraction method for 10.5 h, and dried under vacuum at 92°C for 12 h. Finally, the product was deprotected under nitrogen at 132°C for 5.5 h to obtain 9.30 g of high-purity PEKK, with a yield of 93.0%.

[0075] Performance testing: GPC main peak retention time 23.0 min, Mn=27.8 kg / mol, Mw=49.7 kg / mol, PDI=1.79, no obvious crosslinking shoulder peak at 18-20 min, oligomer tailing significantly reduced at 26-30 min; HPLC detection showed monomer residue of 0.05 wt%; GPC-MALLS detection showed oligomer content of 0.66 wt%; DSC crystallinity 32.2%; melt index (370℃ / 5 kg) 10.4 g / 10 min.

[0076] Example 9: This example provides a method for purifying polyetherketone and polyetherketone, specifically including the following steps:

[0077] 5g of crude polyether ether ketone (PEEK) and 5g of crude PEK were pulverized to 200 mesh. 50g of cyclohexylamine, 0.3g of acetic acid, and 550g of mixed solvent (divalent ester and N-formylmorpholine mixed at a mass ratio of 70:30) were added to a 1L high-pressure reactor. The mixture was heated to 190℃ and stirred for 5 hours under nitrogen protection and pressure of 0.2MPa. The reaction solution changed from an initial heterogeneous mixture to a uniform yellow transparent solution, indicating that the mixed resin had been completely converted into soluble polyarylene ether imine (a mixture of formula I and formula V).

[0078] The obtained soluble polyarylene ether imine was transferred to 2-methyltetrahydrofuran to prepare a homogeneous solution with a mass percentage concentration of 10%. 0.2 g of medical-grade coconut shell activated carbon (same as in Example 1) was added to the solution, and the mixture was stirred at 40°C for 3 h for adsorption. The solution was then filtered through a 0.45 μm microporous membrane to obtain a clear filtrate. Subsequent precipitation, washing, extraction, and deprotection steps were performed as in Example 1, yielding 9.35 g of a high-purity PEEK / PEK blend, with a yield of 93.5%.

[0079] Performance testing: GPC main peak retention time 23.2 min, Mn=27.4 kg / mol, Mw=49.2 kg / mol, PDI=1.80, no obvious crosslinking shoulder peak at 18-20 min, oligomer tailing significantly reduced at 26-30 min; HPLC detection showed monomer residue of 0.07 wt%; GPC-MALLS detection showed oligomer content of 0.71 wt%; DSC crystallinity 32.3%; melt index (385℃ / 5 kg) 10.0 g / 10 min.

[0080] Comparative Example 1 (unpurified crude product): 10g of crude PEEK from the same batch as in Example 1 was directly subjected to performance testing using GPC (test conditions were the same as in Example 1): main peak retention time 23.2min, Mn=23.3kg / mol, Mw=45.5kg / mol, PDI=1.95, no obvious crosslinking shoulder peak at 18-20min, oligomer tailing significantly reduced at 26-30min; monomer residue detected by HPLC was 1.2wt%; oligomer content detected by GPC-MALLS was 3.5wt%; crystallinity by DSC was 31.2%; melt index (380℃ / 5kg) was 12.6g / 10min.

[0081] In summary, this invention addresses the core pain points of existing polyarylether ketone purification technologies by proposing an integrated purification process that combines chemical dissolution and crystal breaking, broad-spectrum activated carbon adsorption, repeated ethanol extraction for deep impurity removal, and deprotection and regeneration. The core innovation lies in the deep integration of activated carbon adsorption technology with soluble polyarylether imine conversion technology and repeated ethanol extraction technology, overcoming the technical bottleneck that traditional activated carbon can only remove trace impurities from the surface of polyarylether ketones. This method has the following significant advantages compared to existing technologies:

[0082] 1. More comprehensive and thorough impurity removal: Existing activated carbon technology is only used for terminal cleaning of medical-grade polyaryletherketones (PAEs), which can only remove surface endotoxins and heavy metals, but cannot access the oligomers and cross-linked structures embedded inside the particles. In this invention, the insoluble PAE is first converted into soluble PAE imine using a primary amine compound, breaking the crystalline structure of PAEs. This allows activated carbon to contact and adsorb unreacted monomers, low-molecular-weight oligomers (dimers to decamers), and abnormal cross-linked structures at the molecular scale. Based on this, a repeated extraction process with medical-grade ethanol is further used to specifically remove trace amounts of soluble small-molecule impurities remaining after activated carbon adsorption. Ultimately, the monomer residue is reduced to below 0.1 wt%, the oligomer content to below 1 wt%, and the abnormal cross-linked structures are almost completely removed, solving the problem that traditional solvent extraction and high-temperature devolatilization methods cannot simultaneously remove two types of impurities.

[0083] 2. More stable and superior product performance: The embodiments of this invention perform adsorption treatment under mild conditions of 25-60℃, avoiding the molecular chain oxidative degradation caused by high-temperature vacuum devolatilization (320-350℃), and also eliminating the sulfonation reaction and main chain breakage caused by concentrated sulfuric acid precipitation. The purified polyarylether ketone retains a molecular weight of ≥98%, the molecular weight distribution is significantly narrowed (PDI decreases by 0.1-0.15), the crystallinity is increased by 3%-5%, the melt flowability is improved by 30%-50%, and the mechanical strength, dimensional stability, and processing performance of the product are all significantly improved.

[0084] 3. Economical and efficient process: The amount of activated carbon used is only 0.5-5 wt% of the crude polyaryletherketone, and it can be recycled through high-temperature calcination; the adsorption time is only 1-6 hours, far shorter than the 24 hours or more of the traditional solvent extraction method; no special high-temperature and high-pressure equipment is required, significantly reducing equipment investment and energy consumption. Comprehensive calculations show that the purification method provided in this embodiment reduces the purification cost by more than 40% compared to traditional methods, enabling continuous industrial production.

[0085] 4. Wide range of applications and strong compatibility: The purification method provided in this invention is not only applicable to the purification of crude polyether ether ketone (PEEK), but can also be extended to the full range of polyarylether ketone materials such as polyether ketone ketone (PEKK), polyether ketone (PEK), and polyether ketone-polyether ether ketone copolymer. It is suitable for products with different polymerization processes (nucleophilic method, electrophilic method) and different molecular weight ranges, and has extremely strong versatility.

[0086] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification.

Claims

1. A method for purifying polyarylether ketones, characterized in that, Includes the following steps: The crude polyaryletherketone was placed in an organic solvent and reacted with a primary amine compound in a Schiff base reaction with or without a catalyst. The mixture was then transferred to 2-methyltetrahydrofuran to prepare a soluble polyaryletherimide solution. Activated carbon was added to a soluble polyarylene ether imine solution for adsorption treatment to obtain an adsorption mixture; the amount of activated carbon added was 0.5-5 wt% of the crude polyarylene ether ketone. The solid was separated from the adsorption mixture and then purified to obtain purified soluble polyarylene ether imine. The purified soluble polyaryletherimide was deprotected to obtain the purified polyarylether ketone.

2. The purification method for polyarylether ketones according to claim 1, characterized in that, The polyaryletherketone includes one or more of polyetheretherketone, polyetherketoneketone, polyetherketone, polyetherketoneketone, biphenyl-type polyetheretherketone, biphenyl-type polyetheretherketoneketone, 1,4-naphthyl polyetherketoneketoneketone, biphenyl / p-phenyl copolymer polyetheretherketone, biphenyl / p-phenyl copolymer polyetheretherketoneketone, and polyetherketone-polyetheretherketone copolymer.

3. The purification method for polyarylether ketones according to claim 1 or 2, characterized in that, The mass ratio of the crude polyaryletherketone to the primary amine compound is 1:(1-10); the mass ratio of the crude polyaryletherketone to the organic solvent is 1:(10-50); and the mass percentage concentration of the soluble polyaryletherimide solution is 1%-20%.

4. The purification method for polyarylether ketones according to claim 1, characterized in that, The conditions for the Schiff base reaction are 150-200℃ and 0.1-5MPa.

5. The purification method for polyarylether ketones according to claim 1, characterized in that, The primary amine compound is cyclohexylamine or an amino acid; a catalyst is selectively added according to the type of the primary amine compound selected. Specifically: when the primary amine compound is cyclohexylamine, no catalyst is added, or a weak acid is added as a catalyst; when the primary amine compound is an amino acid, no additional catalyst is required; the weak acid is selected from one or more of citric acid, acetic acid, lactic acid, malic acid, tartaric acid, succinic acid, and ascorbic acid; the mass ratio of the crude polyaryletherketone to the catalyst is 1:(0.01-0.1).

6. The purification method for polyarylether ketones according to claim 1 or 5, characterized in that, The amino acids include one or more of glycine, tryptophan, aspartic acid, glutamic acid, alanine, and valine.

7. The purification method for polyarylether ketones according to claim 1, characterized in that, The organic solvent is one or more of the following: divalent ester, ethylene glycol diacetate, methyl lactate, ethyl lactate, propylene carbonate, dimethyl sulfoxide, N-formylmorpholine, N-butylpyrrolidone, γ-valerolactone, diphenyl sulfone, and benzophenone.

8. The purification method for polyarylether ketones according to claim 1, characterized in that, The steps of separating the solid from the adsorption mixture and purifying the solid specifically include: The adsorption mixture was filtered, and the filtrate was added to water to precipitate the solid. The solid was then washed with ethanol and deionized water and dried to obtain the preliminarily purified product. The pre-purified product was dissolved and filtered using 2-methyltetrahydrofuran, then the 2-methyltetrahydrofuran was removed, and the product was extracted with ethanol by Soxhlet extraction and dried to obtain purified soluble polyarylene ether imine.

9. The purification method for polyarylether ketones according to claim 1, characterized in that, The method for removing the protective layer is a thermal deprotection method, specifically: heat treatment is performed under a protective atmosphere at 120-140℃.

10. The purification method for polyarylether ketones according to claim 1, characterized in that, The activated carbon is one or more of coconut shell activated carbon, wood-based activated carbon, and coal-based activated carbon; the specific surface area of ​​the activated carbon is 1000-1500 m². 2 / g, with mesopores of 2-50nm accounting for 65%-75%.

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