Separation of inert perfluoropolyether and active perfluoropolyether carboxylate salts by ion complexation extraction

Abstract

The application discloses a method for separating inert perfluoropolyether and active perfluoropolyether carboxylate by ion complex extraction, which comprises the following steps: dissolving a mixture containing inert perfluoropolyether and active perfluoropolyether carboxylate in a fluorine-containing solvent, contacting the mixture with an ion complex extraction agent, collecting the ion complex extraction agent phase after extraction equilibrium to obtain enriched active perfluoropolyether carboxylate, and collecting the fluorine-containing solvent phase to obtain enriched high-purity inert perfluoropolyether; the active perfluoropolyether carboxylate is perfluoropolyether with a carboxylate end group; the fluorine-containing solvent is one or more of a hydrofluoroether, a fluorine-containing ester, a perfluorinated or partially fluorinated alkane, and a perfluorinated or partially fluorinated aromatic solvent; and the ion complex extraction agent is an aqueous solution containing one or more of an ionic compound, a polyelectrolyte, and a guanidine compound.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of separation of perfluoropolyether mixtures, and particularly relates to a method for ion complex extraction separation of inert perfluoropolyether and active perfluoropolyether carboxylate. BACKGROUND

[0002] Inert perfluoropolyether (PFPE) oil is often used as high-end lubricating oil, such as magnetic recording medium, heat transfer fluid lubricant, elastomer and pump fluid under harsh conditions. The active perfluoropolyether with end group functionalization can be further modified and used as raw material for various downstream application products, for example, perfluoropolyether carboxylic compounds including monocarboxylic acid PFPE and dicarboxylic acid PFPE can be used as intermediates or additives of resins such as polyurethane and coatings, which can significantly improve the performance of the resins. However, the inert PFPE needs to be removed to prepare high-purity carboxylic acid PFPE, and it is difficult to separate due to the similar properties of inert PFPE and carboxylic acid PFPE, which is a challenge.

[0003] At present, the separation of inert and active perfluoropolyether mixtures mainly includes adsorption separation, chromatographic separation or chemical reaction separation technology, and so far there is still no separation technology for end group carboxylate PFPE. Patent WO2014067981A discloses a method for purifying perfluoropolyether compounds with carboxylate end groups using silica gel, silicate or activated alumina as solid carrier and using intermittent chromatography method, but there are problems such as low yield and serious loss of material consumption. European patent EP2905298A discloses a chromatography method for purifying carboxylic perfluoropolyether using supercritical carbon dioxide as mobile phase and silica gel as stationary phase, but it has the disadvantages of large equipment investment, and the content of perfluoropolyether with single carboxyl group in the product composition is high, and the loss of perfluoropolyether with double carboxyl groups is serious. Patent WO2015025930A discloses a method for separating perfluoropolyether carboxylic compounds by thin layer chromatography using silica gel as carrier, although the inert perfluoropolyether dissolved in fluorine-containing solvent and polar solvent has a higher yield, but the single-functional and double-functional carboxylic perfluoropolyether is absorbed by the silica gel group, so the yield of perfluoropolyether carboxylic compounds is low.

[0004] In addition, patent WO2010130625A discloses a method for purifying polyol perfluoropolyether derivatives from perfluoropolyether base mixture by chemical reaction of alcohol with aldehyde / ketone. Patent WO2018038213A discloses a method for separating non-alcohol perfluoropolyether and perfluoropolyether monoalcohol and dialcohol mixture by chromatography, but the yield is less than 50%. These methods can be used when the end group of perfluoropolyether is alcohol or amine, but they are not suitable for perfluoropolyether mixture with carboxylate end group, and the reactive separation technology limits the yield to some extent, so it is urgent to develop an efficient separation method for inert and active perfluoropolyether carboxylate compounds. SUMMARY

[0005] In view of the above technical problems and deficiencies in the art, the present application provides a method for separating inert perfluoropolyether and active perfluoropolyether carboxylate by ion complex extraction, which is simple to operate, has high product yield and purity, and stable and controllable quality.

[0006] The specific technical solutions are as follows:

[0007] The method for separating inert perfluoropolyether and active perfluoropolyether carboxylate by ion complex extraction comprises: dissolving a mixture containing inert perfluoropolyether and active perfluoropolyether carboxylate in a fluorine-containing solvent, contacting with an ion complex extraction agent, collecting the ion complex extraction agent phase after extraction equilibrium to obtain enriched active perfluoropolyether carboxylate, and collecting the fluorine-containing solvent phase to obtain enriched high-purity inert perfluoropolyether.

[0008] The active perfluoropolyether carboxylate is a perfluoropolyether compound having a carboxylate end group.

[0009] The fluorine-containing solvent is one or more of a hydrofluoroether, a fluorine-containing ester, a perfluorinated or partially fluorinated alkane, and a perfluorinated or partially fluorinated aromatic solvent.

[0010] The ion complex extraction agent is an aqueous solution containing one or more of an ionic compound, a polyelectrolyte, and a guanidine compound.

[0011] The ionic compound includes at least one of a pyridine-based ionic liquid and an imidazole-based ionic liquid.

[0012] The polyelectrolyte includes at least one of polyvinylamine, polyvinylpyridine, polyethyleneimine, polyvinylpyridine butyl quaternary ammonium salt, cationic polyacrylamide, amphoteric polyacrylamide, and cationic polyvinylpyrrolidone.

[0013] The guanidine compound includes at least one of polyhexamethylene biguanide, polyhexamethylene guanidine, polyhexamethylene biguanide, and polyamine propyl biguanide.

[0014] The perfluoropolyether compound having a carboxylate end group and the inert perfluoropolyether have very small differences in molecular structure and physicochemical properties, making separation difficult. Unlike perfluoropolyether compounds with carboxylic acid end groups, which can interact with basic substances, carboxylate compounds are difficult to separate. Based on the ionic properties of the carboxylate perfluoropolyether end group, the present application uses ion complex extraction for separation. Ion complex extraction is a non-reactive extraction separation method that can efficiently identify structurally similar compounds through interionic electrostatic interactions. It has high selectivity, relatively simple stripping and regeneration processes, high yield, little secondary pollution, and low operating cost.

[0015] The key of ion complex extraction is the selection of ion complex extractant, and a good complexing agent should have high selective recognition ability for the components to be separated. The ion complex extractant described in the application is an aqueous solution containing one or more ionic compounds, polyelectrolytes, guanidine compounds. The aqueous solution of the above specific compounds as the ion complex extractant for liquid-liquid extraction has the advantages of high selectivity, fast reaction rate, etc. The properties of the ion complex extractant can be adjusted by changing the types and structures of the cations, and the concentration, phase ratio, etc. parameters can be adjusted to achieve better extraction and separation effect.

[0016] In a preferred embodiment, in the mixture containing inert perfluoropolyether and active perfluoropolyether carboxylate, the content of the inert perfluoropolyether is 6wt%-94wt%.

[0017] The inert perfluoropolyether can conform to the structure shown in the following formula (I):

[0018] X1-R f1 -X2(I)

[0019] In formula (I):

[0020] X1 and X2 are independently -F, -CF3, -CF2CF3, -CF2Cl, -CF2CF2Cl or C1-C4 perfluoroalkyl (including linear and branched);

[0021] R f1 is a fluoropolyether main chain with a number average molecular weight of 300-25000, and the chemical formula is as follows:

[0022] -O(CF2O) a -(C2F4O) b -(C3F6O) c -(C4F8O) d -

[0023] wherein a, b, c and d are independently selected from integers of 0-300, and the sum of a, b, c and d is greater than 2; the order of the existence of the above repeating units (CF2O), (C2F4O), (C3F6O) and (C4F8O) is arbitrary, and the repeating unit (C3F6O) includes one or more of the following structures: (CF2CF2CF2O), (CF2CF(CF3)O) and (CF(CF3)CF2O).

[0024] The active perfluoropolyether carboxylate can conform to the structure shown in the following formula (II):

[0025] Y-R f2 -Z(II)

[0026] In formula (II):

[0027] Y and Z are end groups, same or different from each other, selected from -CF3, -CF2Cl, -CF2CF3, -CF2CF2Cl or -CFTCOOM, and at least one of Y and Z is -CFTCOOM, wherein T is F or CF2, and M is Na + , K + , Rb + , Cs + ;

[0028] R f2 is a fluoropolyether backbone having a number average molecular weight of 300 to 25,000 and having the chemical formula:

[0029] -O(CF2O) a -(C2F4O) b -(C3F6O) c -(C4F8O) d -

[0030] wherein: a, b, c, d are independently selected from integers of 0 to 300, and the sum of a, b, c, d is greater than 2; the order of the repeating units (CF2O), (C2F4O), (C3F6O), (C4F8O) is arbitrary, and the repeating unit (C3F6O) includes one or more of the following structures: (CF2CF2CF2O), (CF2CF(CF3)O) and (CF(CF3)CF2O).

[0031] As a preference, the concentration of the ion complexing extractant is 10 to 1000 mg / g water.

[0032] The hydrofluoroether preferably includes at least one of perfluorobutyl methyl ether, perfluorobutyl ethyl ether, AE-3000, 3-methoxy perfluorohexane.

[0033] The fluorine-containing ester preferably includes at least one of ethyl trifluoroacetate, methyl pentafluoropropionate.

[0034] The perfluorinated or partially fluorinated alkane preferably includes at least one of heptafluorocyclopentane, perfluorohexane, HCFC-225, trichlorotrifluoroethane, pentafluorobutane.

[0035] If the phase ratio is too low, the product purity will be reduced; if the phase ratio is too high, the product yield will be reduced. The phase ratio (volume ratio) of the ion complexing extractant and the fluorine-containing solvent is preferably 1:1 to 10.

[0036] If the temperature is too low, the two-phase mass transfer rate will be reduced, and it will take a long time to reach extraction equilibrium, which is not conducive to production operation; if the temperature is too high, the distribution coefficient and selectivity of extraction will be reduced. The ion complexing extraction temperature is preferably 10 to 80°C, and further preferably 20 to 80°C.

[0037] The method for separating inert perfluoropolyether and active perfluoropolyether carboxylate by ion complex extraction according to the present application, the collected ion complex extraction agent phase is washed with the fluorine-containing solvent, the obtained aqueous phase extraction liquid after acidification is back-extracted with the fluorine-containing solvent, and the obtained fluorine-containing solvent phase after concentration and drying can obtain the active perfluoropolyether carboxylate product with a purity of not less than 98%, and the yield of the active perfluoropolyether carboxylate is greater than 80%.

[0038] The present application has the following beneficial effects:

[0039] 1) The present application first separates the mixture of inert perfluoropolyether and perfluoropolyether with carboxylate end group by ion complex extraction method, and realizes high selective recognition and separation through ion association mechanism based on the nature of the end group carboxylate of functionalized perfluoropolyether.

[0040] 2) The ion complex extraction process route adopted in the present application is easy to industrialize, and can obtain high-purity perfluoropolyether with carboxylate end group (more than 98%), which is superior to the existing patent technology disclosed by chromatographic separation and other technologies, and the solvent consumption is less. DETAILED DESCRIPTION

[0041] The present application will be further described below in combination with specific examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application.

[0042] In the present application, the mixture containing inert perfluoropolyether and perfluoropolyether with carboxylate end group is mixed with fluorine-containing solvent to form raw material liquid, which is contacted with ion complex extraction agent, and the ion complex extraction agent phase is collected after extraction equilibrium to obtain enriched active perfluoropolyether carboxylate. After acidification and back-extraction treatment, high-purity active perfluoropolyether carboxylate product is obtained. Ion complex extraction can efficiently recognize fluorine-containing polyether compounds with similar structures through intermolecular electrostatic interaction, and has the advantages of high selectivity, high product purity (not less than 98%), high yield, and low operation cost.

[0043] In the following examples, 19 F NMR is used to determine the relative amount of carboxylate end group and non-functional end group in the product, so as to determine the content of perfluoropolyether carboxylate compound.

[0044] In the following examples, "%" is based on molar basis unless otherwise specified.

[0045] Example 1

[0046] A mixture containing 30% inert perfluoropolyether and 70% active perfluoropolyether carboxylate was prepared into a feed solution with a total feed concentration of 100 mg / mL, a volume of 100 mL, and 100 mL of an aqueous solution of polyvinylpyridine with a concentration of 500 mg / g water was added, and ion complex extraction was performed at 15°C. After the extraction equilibrium, the aqueous phase was separated, and perfluorobutyl ether was added for washing, and the perfluorobutyl ether raffinate was vacuum concentrated to obtain the inert perfluoropolyether. The aqueous phase extract was further acidified, and the perfluoropolyether carboxylate compound was back extracted twice with perfluorobutyl ether, and the perfluorobutyl ether phase was vacuum concentrated and dried to obtain the product perfluoropolyether carboxylate compound. The purity of the perfluoropolyether carboxylate compound was 99% by19F NMR analysis, and the yield was 87%. 19 F NMR analysis, the purity of the perfluoropolyether carboxylate compound was 99%, and the yield was 87%.

[0047] Example 2

[0048] A mixture containing 60% inert perfluoropolyether and 40% active perfluoropolyether carboxylate was prepared into a feed solution with a total feed concentration of 150 mg / mL, and an aqueous solution of polyacrylamide with a concentration of 200 mg / g water was added, and the phase ratio of the aqueous phase to the fluorine-containing solvent phase was 1:5, and ion complex extraction was performed at 30°C. After the extraction equilibrium, the aqueous phase was separated, and AC-6000 (CF3CF2CF2CF2CF2CF2CH2CH3) was added for washing, and the AC-6000 raffinate was vacuum concentrated to obtain the inert perfluoropolyether. The aqueous phase extract was further acidified, and the perfluoropolyether carboxylate compound was back extracted twice with AC-6000, and the AC-6000 phase was vacuum concentrated and dried to obtain the product perfluoropolyether carboxylate compound. The purity of the perfluoropolyether carboxylate compound was 98.5% by19F NMR analysis, and the yield was 89%. 19 F NMR analysis, the purity of the perfluoropolyether carboxylate compound was 99%, and the yield was 87%.

[0049] Example 3

[0050] A mixture containing 70% inert perfluoropolyether and 30% active perfluoropolyether carboxylate was prepared into a feed solution with a total feed concentration of 50 mg / mL, and an aqueous solution of polyvinylamine with a concentration of 600 mg / g water was added, and the phase ratio of the aqueous phase to the fluorine-containing solvent phase was 1:3, and ion complex extraction was performed at 45°C. After the extraction equilibrium, the aqueous phase was separated, and hexafluoroxylene was added for washing, and the hexafluoroxylene raffinate was vacuum concentrated to obtain the inert perfluoropolyether. The aqueous phase extract was further acidified, and the perfluoropolyether carboxylate compound was back extracted twice with hexafluoroxylene, and the hexafluoroxylene phase was vacuum concentrated and dried to obtain the product perfluoropolyether carboxylate compound. The purity of the perfluoropolyether carboxylate compound was 99% by19F NMR analysis, and the yield was 91%. 19 F NMR analysis, the purity of the perfluoropolyether carboxylate compound was 99%, and the yield was 87%.

[0051] Example 4

[0052] A mixture containing 20% inert perfluoropolyether and 80% active perfluoropolyether carboxylate salt was prepared into a feed solution with a total feed concentration of 200 mg / mL using C6F6. A cationic polyvinylpyridine quaternary ammonium salt solution was added at a concentration of 1000 mg / g water. The phase ratio of the aqueous phase to the fluorosolvent phase was 1:8. The ion complex extraction was carried out at 60°C. After the extraction equilibrium, the aqueous phase was separated and washed with C6F6. The C6F6 raffinate was vacuum concentrated to obtain the inert perfluoropolyether. The aqueous extract was acidified and the perfluoropolyether carboxylate salt compound was back extracted twice using C6F6. The C6F6 phase was vacuum concentrated and dried to obtain the product perfluoropolyether carboxylate salt compound. The purity of the perfluoropolyether carboxylate salt compound was 98% and the yield was 89% as determined by19F NMR analysis. 19 F NMR analysis, the purity of the perfluoropolyether carboxylate salt compound was 99% and the yield was 87%.

[0053] Example 5

[0054] A mixture containing 10% inert perfluoropolyether and 90% active perfluoropolyether carboxylate salt was prepared into a feed solution with a total feed concentration of 200 mg / mL using heptafluorocyclopentane. A cationic polyvinylpyrrolidone solution was added at a concentration of 50 mg / g water. The phase ratio of the aqueous phase to the fluorosolvent phase was 1:2. The ion complex extraction was carried out at 35°C. After the extraction equilibrium, the aqueous phase was separated and washed with heptafluorocyclopentane. The heptafluorocyclopentane raffinate was vacuum concentrated to obtain the inert perfluoropolyether. The aqueous extract was acidified and the perfluoropolyether carboxylate salt compound was back extracted twice using heptafluorocyclopentane. The heptafluorocyclopentane phase was vacuum concentrated and dried to obtain the product perfluoropolyether carboxylate salt compound. The purity of the perfluoropolyether carboxylate salt compound was 99% and the yield was 87% as determined by19F NMR analysis. 19 F NMR analysis, the purity of the perfluoropolyether carboxylate salt compound was 99% and the yield was 87%.

[0055] Example 6

[0056] A mixture containing 50% inert perfluoropolyether and 50% active perfluoropolyether carboxylate salt was prepared into a feed solution with a total feed concentration of 500 mg / mL using HCFC-225 (CF3CF2CHCl2). A polyhexamethylene biguanide solution was added at a concentration of 500 mg / g water. The phase ratio of the aqueous phase to the fluorosolvent phase was 1:6. The ion complex extraction was carried out at 40°C. After the extraction equilibrium, the aqueous phase was separated and washed with HCFC-225. The HCFC-225 raffinate was vacuum concentrated to obtain the inert perfluoropolyether. The aqueous extract was acidified and the perfluoropolyether carboxylate salt compound was back extracted twice using HCFC-225. The HCFC-225 phase was vacuum concentrated and dried to obtain the product perfluoropolyether carboxylate salt compound. The purity of the perfluoropolyether carboxylate salt compound was 99% and the yield was 86% as determined by19F NMR analysis. 19 F NMR analysis, the purity of the perfluoropolyether carboxylate salt compound was 99% and the yield was 87%.

[0057] Example 7

[0058] A mixture containing 55% inert perfluoropolyether and 45% active perfluoropolyether carboxylate salt was prepared into a feed solution with a total feed concentration of 50 mg / mL, and a polyamine propyl biguanide solution with a concentration of 650 mg / g water was added. The phase ratio of the aqueous phase to the fluorine-containing solvent phase was 1:3, and ion complex extraction was carried out at 45°C. After the extraction equilibrium, the aqueous phase was separated, and AE-3000 was added for washing. The AE-3000 raffinate was vacuum concentrated to obtain the inert perfluoropolyether. The aqueous phase extract was acidified again, and AE-3000 was added to strip the perfluoropolyether carboxylate compound twice. The AE-3000 phase was vacuum concentrated and dried to obtain the product perfluoropolyether carboxylate compound. The purity of the perfluoropolyether carboxylate compound was 98% by19F NMR analysis, and the yield was 90%. 19 F NMR analysis, the purity of the perfluoropolyether carboxylate compound was 98%, and the yield was 90%.

[0059] Example 8

[0060] A mixture containing 15% inert perfluoropolyether and 85% active perfluoropolyether carboxylate was prepared into a feed solution with a total feed concentration of 50 mg / mL, and a polyethyleneimine solution with a concentration of 800 mg / g water was added. Ion complex extraction was carried out at 35°C. After the extraction equilibrium, the aqueous phase was separated, and methyl pentadecafluoroheptyl ketone was added for washing. The methyl pentadecafluoroheptyl ketone raffinate was vacuum concentrated to obtain the inert perfluoropolyether. The aqueous phase extract was acidified again, and methyl pentadecafluoroheptyl ketone was added to strip the perfluoropolyether carboxylate compound twice. The methyl pentadecafluoroheptyl ketone phase was vacuum concentrated and dried to obtain the product perfluoropolyether carboxylate compound. The purity of the perfluoropolyether carboxylate compound was 98% by19F NMR analysis, and the yield was 90%. 19 F NMR analysis, the purity of the perfluoropolyether carboxylate compound was 98%, and the yield was 90%.

[0061] It should also be understood that various changes and modifications can be made to the application described herein, and that the scope of the present application is not to be considered limited to the particular examples contained herein, but is defined by the appended claims.

Claims

1. A method for separating inert perfluoropolyether and active perfluoropolyether carboxylate salt by ion complexation extraction, characterized by, The application relates to a method for separating inert perfluoropolyether and active perfluoropolyether carboxylate. The active perfluoropolyether carboxylate is perfluoropolyether with carboxylate end groups. The fluorine-containing solvent is one or more of hydrogen fluoride ether, fluorine-containing ester, perfluorinated or partially fluorinated alkane, perfluorinated or partially fluorinated aromatic solvent. The ion complexing extractant is an aqueous solution containing one or more of ionic compounds, polyelectrolyte and guanidines. The ionic compounds include at least one of pyridine ionic liquid and imidazole ionic liquid. The polyelectrolyte includes at least one of polyvinylamine, polyvinylpyridine, polyethyleneimine, polyvinylpyridine butyl quaternary ammonium salt, cationic polyacrylamide, amphoteric polyacrylamide and cationic polyvinylpyrrolidone. The guanidines include at least one of polyhexamethylene biguanide, polyhexamethylene guanidine, polyhexamethylene biguanide and polyamine propyl biguanide. The inert perfluoropolyether conforms to the structure shown in the following formula (I):

2. The method of ion complexation extraction separation of inert perfluoropolyether and active perfluoropolyether carboxylate salt according to claim 1, characterized in that, In the formula (I), X1 and X2 are independently -F, -CF3, -CF2CF3, -CF2Cl, -CF2CF2Cl or C1-C4 perfluoroalkyl; X1-R f1 -X2(I) Wherein a, b, c and d are independently selected from integers of 0-300, and the sum of a, b, c and d is greater than 2; the sequence of the repeating units (CF2O), (C2F4O), (C3F6O) and (C4F8O) is arbitrary, and the repeating unit (C3F6O) includes one or more of the following structures: (CF2CF2CF2O), (CF2CF(CF3)O) and (CF(CF3)CF2O). The active perfluoropolyether carboxylate conforms to the structure shown in the following formula (II): R f1 fluoropolyether having a number average molecular weight of 300 to 25,000 and having the following chemical formula: -0(CF2O) a -(C2F4O) b -(C3F6O) c -(C4F8O) d - In the formula (II), X1 and X2 are independently -F, -CF3, -CF2CF3, -CF2Cl, -CF2CF2Cl or C1-C4 perfluoroalkyl; 3. The method of ion complexation extraction separation of inert perfluoropolyether and active perfluoropolyether carboxylate salt according to claim 1 or 2, characterized in that, Wherein a, b, c and d are independently selected from integers of 0-300, and the sum of a, b, c and d is greater than 2; the sequence of the repeating units (CF2O), (C2F4O), (C3F6O) and (C4F8O) is arbitrary, and the repeating unit (C3F6O) includes one or more of the following structures: (CF2CF2CF2O), (CF2CF(CF3)O) and (CF(CF3)CF2O). Y-R f2 -Z (II) The concentration of the ion complexing extractant is 10-1000 mg / g water. Y and Z are terminal groups, equal to or different from each other, selected from -CF3, -CF2CI, -CF2CF3, -CF2CF2CI or -CFTCOOM, and at least one of Y and Z is -CFTCOOM, wherein T is F or CF2, and M is Na + , K + , Rb + , Cs + ; R f2 fluoropolyether having a number average molecular weight of 300 to 25,000 and having the following chemical formula: -0(CF2O) a -(C2F4O) b -(C3F6O) c -(C4F8O) d - The hydrogen fluoride ether includes at least one of perfluorobutyl methyl ether, perfluorobutyl ethyl ether, AE-3000 and 3-methoxy perfluorohexane.

4. The method of claim 1, wherein the inert perfluoropolyether and the active perfluoropolyether carboxylate salt are separated by ion complexation extraction, and wherein the inert perfluoropolyether is a perfluoroalkyl ether. The fluorine-containing ester includes at least one of trifluoroacetic acid ethyl ester and pentafluoropropionic acid methyl ester.

5. The method of ion complexation extraction separation of inert perfluoropolyether and active perfluoropolyether carboxylate salt according to claim 1, characterized in that, The perfluorinated or partially fluorinated alkane includes at least one of heptafluorocyclopentane, perfluorohexane, HCFC-225, trichlorotrifluoroethane and pentafluorobutane.

6. The method of ion complexation extraction separation of inert perfluoropolyether and active perfluoropolyether carboxylate salt according to claim 1, characterized in that, In the mixture containing inert perfluoropolyether and active perfluoropolyether carboxylate, the content of the inert perfluoropolyether is 6wt%-94wt%.

7. The method of ion complexation extraction separation of inert perfluoropolyether and active perfluoropolyether carboxylate salt according to claim 1, characterized in that, ​ 8. The method of claim 1, wherein the inert perfluoropolyether and the active perfluoropolyether carboxylate salt are separated by ion complexation extraction, and wherein the inert perfluoropolyether is a perfluoroalkyl ether. ​ The ratio of the ion complexing extractant to the fluorine-containing solvent is 1:1-10.

9. The method of claim 1 wherein the inert perfluoropolyether and the active perfluoropolyether carboxylate salt are separated by ion complexation extraction, characterized in that, The ion complexing extraction temperature is 10-80℃.

10. The method of claim 9, wherein the inert perfluoropolyether and the active perfluoropolyether carboxylate salt are separated by ion complexation extraction. The ion complexing extraction temperature is 20-80℃.

11. The method of ion complexation extraction separation of inert perfluoropolyether and active perfluoropolyether carboxylate salt according to claim 1, characterized in that, The collected ion complexing extractant phase is washed with the fluorine-containing solvent, the obtained aqueous phase extract is acidified and back-extracted with the fluorine-containing solvent, the obtained fluorine-containing solvent phase is concentrated and dried to obtain an active perfluoropolyether carboxylate product with a purity of not less than 98%, and the yield of the active perfluoropolyether carboxylate is greater than 80%.