Method for preparing polyetherketoneketone by using microchannel reactor

Abstract

The invention discloses a method for preparing polyetherketoneketone by using a microchannel reactor, and belongs to the technical field of polymer synthesis, a certain amount of sulfur dioxide and Lewis base are added in the reaction to improve the catalytic activity of Lewis acid, improve the selectivity, increase the solubility of a polymer and avoid precipitation of a product in a microchannel; the reaction selectivity is improved through the micro-channel reactor, generation of side reaction impurities of tonnage alcohols is avoided, the obtained product is high in purity, and the step of purifying the intermediate 1, 4-bis (4-phenoxybenzoyl) benzene is omitted; the molecular weight distribution of the product is narrower; the materials are all fed in a liquid mode after being dissolved, and introduction of Lewis acid and mechanical impurities in other raw materials and reagents is avoided through filter pressing; and continuous production can be realized, the production efficiency is improved, and the production cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer synthesis, and in particular is a method for preparing polyetherketoneketone by using a microchannel reactor. Background Art

[0002] Polyetherketoneketone (PEKK) polymers have many properties that make them useful in applications involving exposure to high temperatures or high thermal or chemical stresses. For example, they are used in the aerospace industry, offshore drilling, and medical devices.

[0003] One known route to prepare polyetherketoneketone polymers relies on nucleophilic substitution by fluorinated monomers. This method requires specific fluorinated and chlorinated monomers; in addition, the reaction is carried out under harsh conditions (350-400°C in diphenyl sulfone) and requires restrictive purification steps to remove salts and solvents.

[0004] Another approach to prepare polyetherketoneketones relies on an electrophilic substitution reaction between an aromatic acid chloride and an aromatic ether in the presence of a Lewis acid. This method is described in US4841013; US4816556; US4912181; US4698393; US4716211 and WO2011 / 004164, and this approach allows the reaction to be carried out at moderate temperatures (-20 to 120°C), which limits the production of by-products, and in addition, monomers and solvents are readily available.

[0005] However, the existing method of using diphenyl ether and terephthaloyl chloride as raw materials to prepare 1,4-bis(4-phenoxybenzoyl)benzene will produce some impurities such as xanthanol as a side reaction. If there are impurities such as xanthanol in 1,4-bis(4-phenoxybenzoyl)benzene, when preparing polyketone ketone (PEKK), structures such as xanthanol will be formed at the end of polyetherketoneketone (PEKK), which is unstable at high temperature and will break to form small molecular benzene ring substances, which will further undergo side reactions such as cross-linking and grafting with the polymer, affecting the thermal stability of the material; and the side reaction impurities such as xanthanol are difficult to remove, and the removal steps are complicated and cannot be completely removed.

[0006] In the prior art method for preparing 1,4-bis(4-phenoxybenzoyl)benzene, there are many tert-butyl alcohol side reaction impurities in the preparation of 1,4-bis(4-phenoxybenzoyl)benzene, which affect the thermal stability of the synthesized polyetherketoneketone (PEKK); in addition, the step of removing the tert-butyl alcohol side reaction impurities is added, resulting in an increase in the number of processes and an increase in cost; in addition, the use of excessive diphenyl ether will also cause a large amount of raw material waste. Therefore, it is of great significance to develop a new method for preparing polyetherketoneketone. Summary of the invention

[0007] In order to solve the problems of many alcohol side reaction impurities, long reaction time, many purification steps, high production cost and poor product performance in the above-mentioned traditional polyetherketoneketone synthesis process, the purpose of the present invention is to provide a method for preparing polyetherketoneketone using a microchannel reactor. The method has the advantages of simple operation, short reaction time, high product purity, high product performance and continuous production.

[0008] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0009] A method for preparing polyetherketoneketone by using a microchannel reactor comprises the following steps: diphenyl ether, sulfur dioxide, a Lewis base and a Lewis acid are stirred and dissolved into a homogeneous solution; terephthaloyl chloride is dissolved in an aprotic organic solvent, respectively introduced into a microchannel reactor through metering pumps, mixed and contacted in a microchannel for Friedel-Crafts acylation reaction, and 1,4-bis(4-phenoxybenzoyl)benzene-Lewis acid complex is obtained; terephthaloyl chloride, isophthaloyl chloride, an aprotic organic solvent and a Lewis acid are stirred and dissolved into a homogeneous solution, respectively introduced into a microchannel reactor through metering pumps, mixed and contacted in a microchannel for preliminary polymerization, and the reaction liquid of the preliminary polymerization is transferred to a maturation kettle for further polymerization; after the reaction is completed, the reaction liquid is transferred to a dilute hydrochloric acid solution for hydrolysis, and finally filtered, washed and dried to obtain a polyetherketoneketone product.

[0010] The method for preparing polyetherketoneketone using a microchannel reactor comprises the following steps:

[0011] 1) adding diphenyl ether, Lewis base and Lewis acid to sulfur dioxide, stirring at -15 to 10° C. to obtain a homogeneous solution, and filtering by heat preservation to obtain solution 1;

[0012] 2) adding terephthaloyl chloride to an aprotic organic solvent, stirring at 10-30° C. to obtain a homogeneous solution, and filtering by heat preservation to obtain solution 2;

[0013] 3) adding terephthaloyl chloride, isophthaloyl chloride and Lewis acid to an aprotic organic solvent, stirring at 10 to 35° C. to obtain a homogeneous solution, and filtering by pressure while keeping the temperature to obtain solution 3;

[0014] 4) The solution 1 obtained in step 1) and the solution 2 obtained in step 2) are respectively pumped into the microchannel reactor 1 through metering pumps, and Friedel-Crafts acylation reaction is carried out at a pressure of 0.4 to 0.8 MPa and a temperature of -15 to -10°C with a residence time of 6 to 10 seconds to obtain a reaction solution 1;

[0015] 5) injecting the solution 3 obtained in step 3) and the reaction solution 1 obtained in step 4) into the microchannel reactor 2 through a metering pump, and performing a preliminary polymerization reaction at a pressure of 0.4-0.8 MPa and 0-15° C. for a residence time of 6-10 seconds to obtain a reaction solution 2;

[0016] 6) The reaction solution 2 obtained in step 5) is transferred to a aging kettle, a capping agent is added, and a polymerization reaction is carried out at 20 to 40° C. for 4 to 6 hours to obtain a polymerization solution; the hydrogen chloride gas and sulfur dioxide gas generated during the polymerization reaction enter a sulfur-chlorine recycling system for recovery;

[0017] 7) transferring the polymer solution obtained in step 6) to a hydrolysis kettle, and then adding dilute hydrochloric acid with a mass concentration of 1 to 10% to carry out a hydrolysis reaction for 1 to 2 hours to obtain a hydrolyzate;

[0018] 8) The hydrolyzate obtained in step 7) is filtered, and the filter cake obtained is transferred to a washing kettle, and washed with purified water and anhydrous ethanol for 2 to 3 times by reflux, respectively, and then dried at 80 to 100° C. for 6 to 10 hours to obtain polyetherketoneketone.

[0019] The Lewis acid in step 1) and step 3) is one or two of aluminum trichloride, titanium tetrachloride, ferric trichloride, tin tetrachloride, boron trifluoride and zinc chloride.

[0020] The Lewis base in step 1) is a sulfone or sulfoxide compound, and its structural formula is shown in I and II below: Wherein R1 and R2 are alkyl or aromatic functions.

[0021] In step 1), the mass ratio of sulfur dioxide to diphenyl ether is 10-15:1; the molar ratio of diphenyl ether, Lewis base and Lewis acid is 2:1-3::6-8.

[0022] The molar ratio of the terephthaloyl chloride in step 2) to the diphenyl ether in step 1) is 0.45-0.5:1; the mass ratio of the aprotic organic solvent to the terephthaloyl chloride is 2.5-3.5:1. It should be noted that if the amount of terephthaloyl chloride is too much, polymers will be generated due to insufficient diphenyl ether, and if the amount is too little, more diphenyl ether will remain, which will have an adverse effect on the next step reaction.

[0023] The aprotic organic solvent in step 2) and step 3) is one or two of dichloromethane, 1,2-dichloroethane and o-dichlorobenzene.

[0024] The total molar amount of the terephthaloyl chloride, isophthaloyl chloride and the terephthaloyl chloride in step 2) in step 3) is the same as the molar amount of diphenyl ether in step 1).

[0025] The molar amount of the Lewis acid in step 3) is the same as the total molar amount of terephthaloyl chloride and isophthaloyl chloride in step 3); the added amount of the aprotic organic solvent is 2.5 to 3.5 times the total mass of terephthaloyl chloride, isophthaloyl chloride and Lewis acid.

[0026] The end-capping agent in step 6) is benzoyl chloride, p-fluorobenzoyl chloride, p-chlorobenzoyl chloride, benzenesulfonyl chloride, 4-chlorobiphenyl or 4-phenoxybenzophenone, and the molar ratio of the end-capping agent to the diphenyl ether in step 1) is 0.005-0.05:1.

[0027] The mass ratio of the dilute hydrochloric acid to the polymerization solution in step 7) is 5 to 10:1.

[0028] Preferably, the Lewis acid in step 1) is aluminum trichloride.

[0029] Preferably, in step 2), stirring is performed at 15-20° C. to obtain a homogeneous solution.

[0030] Preferably, in step 3), stirring is performed at 20-30° C. to obtain a homogeneous solution.

[0031] Preferably, in step 5), the preliminary polymerization reaction is carried out at 5-10°C.

[0032] Preferably, the polymerization reaction in step 6) is carried out at 25-30°C.

[0033] Preferably, the mass concentration of the dilute hydrochloric acid in step 7) is 3-6%.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] According to the method for preparing polyetherketoneketone by using a microchannel reactor, a certain amount of sulfur dioxide and Lewis base are added in the reaction, which not only improves the catalytic activity of the Lewis acid and improves the selectivity, but also increases the solubility of the polymer, thereby avoiding the precipitation of the product in the microchannel; the highly efficient mass transfer and heat transfer effects of the microchannel reactor further improve the selectivity of the reaction, avoids the generation of alcohol side reaction impurities, obtains a product with high purity, saves the purification step of the intermediate 1,4-bis(4-phenoxybenzoyl)benzene, and also makes the molecular weight distribution of the product narrower.

[0036] The method for preparing polyetherketoneketone by using a microchannel reactor of the present invention dissolves the materials and feeds them all in liquid form, thereby avoiding the introduction of Lewis acid and mechanical impurities in other raw materials and reagents through filtering.

[0037] The method for preparing polyetherketoneketone by using a microchannel reactor of the present invention uses a microchannel reactor for reaction. Due to its efficient mass transfer effect, combined with temperature control at different reaction stages and removal of sulfur dioxide from the system during the aging process, the activity of the Lewis acid is released, the aging process is completed, and the molecular weight distribution of the product is narrow.

[0038] The method for preparing polyetherketoneketone by using a microchannel reactor of the present invention uses a microchannel reactor for reaction, which can realize continuous production, improve production efficiency and reduce production cost; the method has the advantages of simple operation, short reaction time, high product purity, high product performance and continuous production. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a process flow chart of the method for preparing polyetherketoneketone using a microchannel reactor. DETAILED DESCRIPTION

[0040] In order to better understand the technical solution of the present invention, the above content of the present invention is further described in detail below through specific implementation methods in the form of embodiments, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies realized based on the above content of the present invention belong to the scope of the present invention.

[0041] Example 1: 5 kg of diphenyl ether, 3.2 kg of diphenyl sulfone and 11.75 kg of aluminum chloride were added to 50 kg of sulfur dioxide, stirred at -15 ° C to obtain a homogeneous solution, and filtered under heat to obtain solution 1;

[0042] Add 2.68 kg of terephthaloyl chloride to 6.7 kg of dichloromethane, stir at 10°C to obtain a homogeneous solution, and filter under the same temperature to obtain solution 2;

[0043] 0.28 kg of terephthaloyl chloride, 3 kg of isophthaloyl chloride and 2.16 kg of aluminum chloride were added to 13.6 kg of dichloromethane, and the mixture was stirred at 10°C to obtain a homogeneous solution, and the solution was filtered under the same temperature to obtain solution 3;

[0044] Such as process flow Figure 1As shown, solution 1 and solution 2 are respectively pumped into microchannel reactor 1 through metering pumps, and Friedel-Crafts acylation reaction is carried out at a pressure of 0.4 MPa and a temperature of -15°C for a residence time of 6 seconds to obtain reaction solution 1; solution 3 and reaction solution 1 are pumped into microchannel reactor 2 through metering pumps, and a preliminary polymerization reaction is carried out at a pressure of 0.4 MPa and 0°C for a residence time of 6 seconds to obtain reaction solution 2; reaction solution 2 is transferred to a maturation kettle, 0.02 kg of benzoyl chloride is added, and a polymerization reaction is carried out at 20°C for a reaction time of The polymerization reaction was carried out for 4 hours to obtain a polymerization liquid; the hydrogen chloride gas and sulfur dioxide gas generated during the polymerization reaction were recycled into the sulfur-chlorine recycling system; the obtained polymerization liquid was transferred to a hydrolysis kettle, and then diluted hydrochloric acid with a mass concentration of 1% was added for hydrolysis reaction for 2 hours, wherein the mass ratio of diluted hydrochloric acid to polymerization liquid was 5:1, and a hydrolyzate was obtained; the obtained hydrolyzate was filtered, and the obtained filter cake was transferred to a washing kettle, and washed with purified water and anhydrous ethanol reflux twice, respectively, separated, and then dried at 80°C for 10 hours to obtain polyetherketoneketone. Product viscosity: 1.00dL / g, weight average molecular weight: 98300, number average molecular weight: 60300, Mw / Mn=1.63.

[0045] Example 2 8.3 kg of diphenyl ether, 4.59 kg of dimethyl sulfone and 32 kg of titanium tetrachloride were added to 100 kg of sulfur dioxide, and the mixture was stirred at -10°C to obtain a homogeneous solution, which was filtered under a heat-insulated pressure to obtain a solution 1;

[0046] 4.55 kg of terephthaloyl chloride was added to 12.74 kg of 1,2-dichloroethane, and the mixture was stirred at 15°C to obtain a homogeneous solution, which was filtered under a pressure while maintaining the temperature to obtain Solution 2;

[0047] 0.35 kg of terephthaloyl chloride, 5 kg of isophthaloyl chloride and 5.0 kg of titanium tetrachloride were added to 29 kg of 1,2-dichloroethane, and the mixture was stirred at 15°C to obtain a homogeneous solution, and the solution was filtered under the same temperature to obtain a solution 3;

[0048] Solution 1 and solution 2 were respectively pumped into microchannel reactor 1 through metering pumps, and Friedel-Crafts acylation reaction was carried out at a pressure of 0.5 MPa and a temperature of -13°C with a residence time of 7 seconds to obtain reaction solution 1; solution 3 and reaction solution 1 were pumped into microchannel reactor 2 through metering pumps, and a preliminary polymerization reaction was carried out at a pressure of 0.6 MPa and 5°C with a residence time of 8 seconds to obtain reaction solution 2; reaction solution 2 was transferred to a aging kettle, 0.08 kg of p-chlorobenzoyl chloride was added, and a polymerization reaction was carried out at 25°C with a reaction time of The reaction time is 4.5 hours to obtain a polymerization liquid; the hydrogen chloride gas and sulfur dioxide gas generated during the polymerization reaction enter the sulfur-chlorine recycling system for recovery; the obtained polymerization liquid is transferred to a hydrolysis kettle, and then 3% dilute hydrochloric acid is added for hydrolysis reaction for 1.2 hours, wherein the mass ratio of dilute hydrochloric acid to polymerization liquid is 6:1, to obtain a hydrolyzate; the obtained hydrolyzate is filtered, and the obtained filter cake is transferred to a washing kettle, and washed with purified water and anhydrous ethanol for 3 times, respectively, and then dried at 85°C for 9 hours to obtain polyether ketone ketone. Product viscosity: 0.99dL / g, weight average molecular weight: 98800, number average molecular weight: 58500, Mw / Mn=1.69.

[0049] Example 3: 6.25 kg of diphenyl ether, 7.81 kg of ethyl phenyl sulfone and 35.87 kg of tin tetrachloride were added to 85 kg of sulfur dioxide, stirred at 0°C to obtain a homogeneous solution, and filtered under the temperature to obtain solution 1;

[0050] Add 3.5 kg of terephthaloyl chloride to 10.5 kg of o-dichlorobenzene, stir at 20°C to obtain a homogeneous solution, and filter under the same temperature to obtain solution 2;

[0051] 2.35 kg of terephthaloyl chloride, 1.6 kg of isophthaloyl chloride and 2.59 kg of aluminum trichloride were added to 20 kg of o-dichlorobenzene, and the mixture was stirred at 20°C to obtain a homogeneous solution, and the solution was filtered under the same temperature to obtain solution 3;

[0052] Solution 1 and solution 2 were respectively pumped into microchannel reactor 1 through metering pumps, and Friedel-Crafts acylation reaction was carried out at a pressure of 0.6 MPa and a temperature of -14°C with a residence time of 8 seconds to obtain reaction solution 1; solution 3 and reaction solution 1 were pumped into microchannel reactor 2 through metering pumps, and a preliminary polymerization reaction was carried out at a pressure of 0.6 MPa and 10°C with a residence time of 7 seconds to obtain reaction solution 2; reaction solution 2 was transferred to a aging kettle, and 0.14 kg 4-Chlorobiphenyl, polymerize at 30℃, the reaction time is 5h, and obtain polymer solution; hydrogen chloride gas and sulfur dioxide gas generated during the polymerization reaction enter the sulfur-chlorine recycling system for recovery; the obtained polymer solution is transferred to a hydrolysis kettle, and then dilute hydrochloric acid with a mass concentration of 6% is added for hydrolysis reaction for 1.5h, wherein the mass ratio of dilute hydrochloric acid to polymer solution is 7:1, to obtain a hydrolyzate; the obtained hydrolyzate is filtered, and the obtained filter cake is transferred to a washing kettle, and washed with purified water and anhydrous ethanol reflux for 3 times respectively, and then dried at 90℃ for 8h to obtain polyetherketoneketone. Product viscosity: 0.98dL / g, weight average molecular weight: 95600, number average molecular weight: 54300, Mw / Mn=1.76.

[0053] Example 4: 5.55 kg of diphenyl ether, 8.9 kg of diphenyl sulfone and 16.67 kg of zinc chloride were added to 77 kg of sulfur dioxide, stirred at 5°C to obtain a homogeneous solution, and filtered under the same temperature to obtain Solution 1;

[0054] Add 3.18 kg of terephthaloyl chloride to 10.2 kg of dichloromethane, stir at 25°C to obtain a homogeneous solution, and filter under the same temperature to obtain solution 2;

[0055] 2.44 kg of terephthaloyl chloride, 1 kg of isophthaloyl chloride and 2.31 kg of zinc chloride were added to 18.4 kg of dichloromethane, and the mixture was stirred at 30°C to obtain a homogeneous solution, and the solution was filtered under the same temperature to obtain solution 3;

[0056] Solution 1 and solution 2 were respectively pumped into microchannel reactor 1 through metering pumps, and Friedel-Crafts acylation reaction was carried out at a pressure of 0.7 MPa and a temperature of -12°C with a residence time of 9 seconds to obtain reaction solution 1; solution 3 and reaction solution 1 were pumped into microchannel reactor 2 through metering pumps, and a preliminary polymerization reaction was carried out at a pressure of 0.7 MPa and 12°C with a residence time of 9 seconds to obtain reaction solution 2; reaction solution 2 was transferred to a aging kettle, and 0.27 kg 4-phenoxybenzophenone, polymerization reaction at 35 ℃, reaction time is 5.5h, obtain polymerization liquid; hydrogen chloride gas and sulfur dioxide gas generated in the polymerization reaction process enter sulfur chlorine recycling system for recovery; the obtained polymerization liquid is transferred to a hydrolysis kettle, and then 8% dilute hydrochloric acid is added for hydrolysis reaction for 1.8h, wherein the mass ratio of dilute hydrochloric acid to polymerization liquid is 8:1, to obtain hydrolyzate; the obtained hydrolyzate is filtered, and the obtained filter cake is transferred to a washing kettle, and washed with purified water and anhydrous ethanol reflux for 3 times respectively, and then dried at 95 ℃ for 7h to obtain polyether ketone ketone. Product viscosity: 0.98dL / g, weight average molecular weight: 93800, number average molecular weight: 52700, Mw / Mn=1.78.

[0057] Example 5: 5 kg of diphenyl ether, 9.62 kg of diphenyl sulfone and 7.97 kg of boron trifluoride were added to 75 kg of sulfur dioxide, stirred at 10° C. to obtain a homogeneous solution, and filtered under the same temperature to obtain Solution 1;

[0058] Add 2.98 kg of terephthaloyl chloride to 10.4 kg of dichloromethane, stir at 30°C to obtain a homogeneous solution, and filter under the same temperature to obtain solution 2;

[0059] 0.49 kg of terephthaloyl chloride, 2.49 kg of isophthaloyl chloride and 1.0 kg of boron trifluoride were added to 13.9 kg of 1,2-dichloroethane, and the mixture was stirred at 35°C to obtain a homogeneous solution, which was filtered under a pressure while maintaining the temperature to obtain a solution 3;

[0060] Solution 1 and solution 2 were respectively pumped into microchannel reactor 1 through metering pumps, and Friedel-Crafts acylation reaction was carried out at a pressure of 0.8 MPa and a temperature of -10°C with a residence time of 10 s to obtain reaction solution 1; solution 3 and reaction solution 1 were pumped into microchannel reactor 2 through metering pumps, and a preliminary polymerization reaction was carried out at a pressure of 0.8 MPa and 15°C with a residence time of 10 s to obtain reaction solution 2; reaction solution 2 was transferred to a aging kettle, and 0.4 kg 4-phenoxybenzophenone is polymerized at 40°C for 6 hours to obtain a polymerization liquid; the hydrogen chloride gas and sulfur dioxide gas generated during the polymerization reaction enter the sulfur-chlorine recycling system for recovery; the obtained polymerization liquid is transferred to a hydrolysis kettle, and then 10% dilute hydrochloric acid is added for hydrolysis reaction for 1 hour, wherein the mass ratio of dilute hydrochloric acid to the polymerization liquid is 10:1 to obtain a hydrolyzate; the obtained hydrolyzate is filtered, and the obtained filter cake is transferred to a washing kettle, and washed with purified water and anhydrous ethanol for 3 times, respectively, and then dried at 100°C for 6 hours to obtain polyetherketoneketone. Product viscosity: 1.00dL / g, weight average molecular weight: 96200, number average molecular weight: 57200, Mw / Mn=1.68.

[0061] Although the above describes the specific implementation methods of the present invention, it does not limit the scope of protection of the present invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A method for preparing polyetherketoneketone using a microchannel reactor, characterized in that: The diphenyl ether, sulfur dioxide, Lewis base and Lewis acid are stirred and dissolved into a homogeneous solution, and then terephthaloyl chloride is dissolved in an aprotic organic solvent, respectively pumped into a microchannel reactor through a metering pump, mixed and contacted in the microchannel for Friedel-Crafts acylation reaction, and 1,4-bis(4-phenoxybenzoyl)benzene-Lewis acid complex is obtained; terephthaloyl chloride, isophthaloyl chloride, aprotic organic solvent and Lewis acid are stirred and dissolved into a homogeneous solution, and then pumped into a microchannel reactor with the 1,4-bis(4-phenoxybenzoyl)benzene-Lewis acid complex through a metering pump, respectively, mixed and contacted in the microchannel for preliminary polymerization, and then the reaction liquid of the preliminary polymerization is transferred to a maturation kettle for further polymerization, and after the reaction is completed, it is transferred to a dilute hydrochloric acid solution for hydrolysis, and finally filtered, washed and dried to obtain a polyetherketoneketone product.

2. The method for preparing polyetherketoneketone using a microchannel reactor as claimed in claim 1, characterized in that: The following steps are involved: 1) Add diphenyl ether, Lewis base and Lewis acid to sulfur dioxide, stir at -15 to 10°C to obtain a homogeneous solution, and filter under the same temperature to obtain solution 1; 2) adding terephthaloyl chloride to an aprotic organic solvent, stirring at 10-30° C. to obtain a homogeneous solution, and filtering by heat preservation to obtain solution 2; 3) adding terephthaloyl chloride, isophthaloyl chloride and Lewis acid to an aprotic organic solvent, stirring at 10-35° C. to obtain a homogeneous solution, and filtering by pressure while keeping the temperature to obtain solution 3; 4) The solution 1 obtained in step 1) and the solution 2 obtained in step 2) are respectively pumped into the microchannel reactor 1 through metering pumps, and Friedel-Crafts acylation reaction is carried out at a pressure of 0.4 to 0.8 MPa and a temperature of -15 to -10°C with a residence time of 6 to 10 seconds to obtain a reaction solution 1; 5) injecting the solution 3 obtained in step 3) and the reaction solution 1 obtained in step 4) into the microchannel reactor 2 through a metering pump, and performing a preliminary polymerization reaction at a pressure of 0.4-0.8 MPa and 0-15° C. for a residence time of 6-10 seconds to obtain a reaction solution 2; 6) transferring the reaction solution 2 obtained in step 5) to a aging kettle, adding a capping agent, and performing a polymerization reaction at 20 to 40° C. for 4 to 6 hours to obtain a polymerization solution; 7) transferring the polymer solution obtained in step 6) to a hydrolysis kettle, and then adding dilute hydrochloric acid with a mass concentration of 1 to 10% to carry out a hydrolysis reaction for 1 to 2 hours to obtain a hydrolyzate; 8) The hydrolyzate obtained in step 7) is filtered, and the filter cake obtained is transferred to a washing kettle, and reflux-washed with purified water and anhydrous ethanol for 2 to 3 times, respectively, and then dried at 80 to 100° C. for 6 to 10 hours to obtain polyetherketoneketone.

3. The method for preparing polyetherketoneketone using a microchannel reactor as claimed in claim 2, characterized in that: The Lewis acid in step 1) and step 3) is one or two of aluminum trichloride, titanium tetrachloride, ferric trichloride, tin tetrachloride, boron trifluoride and zinc chloride; the Lewis base in step 1) is a sulfone or sulfoxide compound, and its structural formula is as follows: I, II As shown: Wherein R1 and R2 are alkyl or aromatic functions.

4. The method for preparing polyetherketoneketone using a microchannel reactor as claimed in claim 2, characterized in that: In step 1), the mass ratio of sulfur dioxide to diphenyl ether is 10-15:1; the molar ratio of diphenyl ether, Lewis base and Lewis acid is 2:1-3::6-8.

5. The method for preparing polyetherketoneketone using a microchannel reactor as claimed in claim 2, characterized in that: The molar ratio of the terephthaloyl chloride in step 2) to the diphenyl ether in step 1) is 0.45-0.5:1; the mass ratio of the aprotic organic solvent to the terephthaloyl chloride is 2.5-3.5:

1.

6. The method for preparing polyetherketoneketone using a microchannel reactor as claimed in claim 2, characterized in that: The aprotic organic solvent in step 2) and step 3) is one or two of dichloromethane, 1,2-dichloroethane and o-dichlorobenzene.

7. The method for preparing polyetherketoneketone using a microchannel reactor as claimed in claim 2, characterized in that: The total molar amount of terephthaloyl chloride, isophthaloyl chloride and terephthaloyl chloride in step 2) in step 3) is the same as the molar amount of diphenyl ether in step 1); the molar amount of Lewis acid in step 3) is the same as the total molar amount of terephthaloyl chloride and isophthaloyl chloride in step 3); the amount of the aprotic organic solvent added in step 3) is 2.5 to 3.5 times the total mass of terephthaloyl chloride, isophthaloyl chloride and Lewis acid.

8. The method for preparing polyetherketoneketone using a microchannel reactor as claimed in claim 2, characterized in that: The end-capping agent in step 6) is benzoyl chloride, p-fluorobenzoyl chloride, p-chlorobenzoyl chloride, benzenesulfonyl chloride, 4-chlorobiphenyl or 4-phenoxybenzophenone, and the molar ratio of the end-capping agent to the diphenyl ether in step 1) is 0.005-0.05:

1.

9. The method for preparing polyetherketoneketone using a microchannel reactor as claimed in claim 2, characterized in that: The mass ratio of the dilute hydrochloric acid to the polymerization solution in step 7) is 5 to 10:

1.

10. The method for preparing polyetherketoneketone using a microchannel reactor as claimed in claim 2, characterized in that: The Lewis acid in step 1) is aluminum chloride; in step 2), stirring is performed at 15 to 20° C. to obtain a homogeneous solution; in step 3), stirring is performed at 20 to 30° C. to obtain a homogeneous solution; in step 5), a preliminary polymerization reaction is performed at 5 to 10° C.; in step 6), a polymerization reaction is performed at 25 to 30° C.; in step 7), the mass concentration of the dilute hydrochloric acid is 3 to 6%.

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