Liquid-liquid extraction process for separating monofunctional active perfluoropolyether and bifunctional active perfluoropolyether

Abstract

The application discloses a liquid-liquid extraction method for separating monofunctional group active perfluoropolyether and difunctional group active perfluoropolyether, which comprises the following steps: mixing a mixture containing monofunctional group active perfluoropolyether and difunctional group active perfluoropolyether with light and heavy phase solvents, collecting the heavy phase to obtain a product containing high-purity monofunctional group active perfluoropolyether, and collecting the light phase to obtain a product containing difunctional group active perfluoropolyether after extraction equilibrium; the functional group in the monofunctional group active perfluoropolyether is -COOH, -CH2OH or -NH2; the functional group in the difunctional group active perfluoropolyether is one or two of -COOH, -CH2OH and -NH2; the light phase solvent is composed of a fluorine ion-containing polar solvent and a fluorine atom-containing polar solvent; and the heavy phase solvent is composed of a fluorine atom-containing non-polar solvent and a fluorine atom-containing polar solvent.

Description

Technical Field

[0001] This invention relates to the field of perfluoropolyether (PFPE) separation technology, specifically to a liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers. Background Technology

[0002] Functionalized active perfluoropolyethers possess excellent thermal stability, superior chemical inertness, and low surface energy, leading to their widespread application in high-tech fields: as high-performance lubricants, in the automotive, aerospace, petrochemical, microelectronics, chemical engineering (high-performance membranes), textile treatment, protective architectural coatings (e.g., UV-resistant and graffiti-resistant paints or films), and optics (fiber optic cores and cladding). The preparation of high-purity functionalized perfluoropolyethers facilitates product refining and optimizes the properties of end products.

[0003] Functionalized perfluoropolyether mixtures typically contain both monofunctional and difunctional perfluoropolyethers, each with different properties and applications. Enriching and purifying perfluoropolyethers with target functionalities is crucial for industrial applications. Currently, much research focuses on the separation of active perfluoropolyether mixtures, primarily isolating hydroxyl and carboxyl groups as active end groups. Patents also exist for the separation of amino-functionalized perfluoropolyethers.

[0004] Patents US20060009660A1, US5246588A, US5910614A, JP2018035348A, WO2010130628A1, and EP2100910A1 address the separation of mixtures of monofunctional or difunctional perfluoropolyethers containing hydroxyl groups, primarily employing adsorption separation and chromatographic separation techniques. Specifically, patent US20060009660A1 uses adsorption separation to separate hydroxyl perfluoropolyethers with the desired functionality from a mixture of nonfunctional and monofunctional hydroxyl perfluoropolyethers. Patent US5910614A also uses adsorption separation to separate difunctional hydroxyl perfluoropolyethers from a mixture of nonfunctional, monofunctional, and difunctional perfluoropolyethers, requiring multiple stationary phase adsorption-solid separation operations. Patent US5246588A uses chromatographic separation technology, adding a mixture of hydroxyl-terminated perfluoropolyethers into a column chromatogram, and using a non-polar fluorinated solvent alone or a mixture of a non-polar fluorinated solvent and a polar solvent as the eluent to separate the components from each other. WO2010130628A1 and EP2100910A1 both disclose a technique involving chemical protection to separate a polyol perfluoropolyether with a specific structure from a mixture of hydroxyl-terminated perfluoropolyether derivatives. This method involves reacting the mixture with a ketone or aldehyde to protect the active hydroxyl groups, adding silica gel to the reaction mixture to adsorb the perfluoropolyether with protected hydroxyl-terminated groups, separating the adsorbed and unadsorbed phases, and hydrolyzing the adsorbed phase to obtain a polyol perfluoropolyether with a specific structure.

[0005] For the separation of terminal amino-terminated perfluoropolyethers, patent JP2019214704A employs adsorption separation technology to separate and purify single-terminated amino-active perfluoropolyethers, double-terminated amino-active perfluoropolyethers, and inert mixtures. This method involves mixing the mixture with a stationary phase adsorbent containing primary amines. The amino-terminated perfluoropolyethers can form salts with the primary amines and adsorb onto the stationary phase, while the non-functional perfluoropolyethers do not react with the primary amines, thus achieving the separation of non-functional and amino-functionalized perfluoropolyethers. Patent US5262057A uses chromatographic separation technology to separate perfluoropolyethers with different functionalities, where the terminal substituents are hydroxyl or amino. The key to this method is adding the mixture to a stationary phase suspension with active sites. The active sites on the stationary phase interact with the functional groups of the perfluoropolyethers through hydrogen bonding, achieving the separation of perfluoropolyethers with different functionalities.

[0006] In summary, current methods for separating mixtures of perfluoropolyethers with different functionalities and types of active end groups mainly rely on adsorption and chromatographic separation. However, these methods are quite cumbersome, requiring multiple adsorption and elution processes, resulting in high solvent consumption and low yields. Summary of the Invention

[0007] To address the aforementioned technical problems and shortcomings in the field, this invention provides a liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers. This method is simple to operate, has stable processes, high quality, low cost, and good separation effect.

[0008] The specific technical solution is as follows:

[0009] A liquid-liquid extraction method for separating monofunctional active perfluoropolyether and difunctional active perfluoropolyether includes: contacting and mixing a mixture containing monofunctional active perfluoropolyether and difunctional active perfluoropolyether with a light and heavy phase solvent; collecting the heavy phase after extraction equilibrium to obtain a product containing high-purity monofunctional active perfluoropolyether; and collecting the light phase to obtain a product containing difunctional active perfluoropolyether.

[0010] The functional groups in the monofunctional active perfluoropolyether are -COOH, -CH2OH or -NH2;

[0011] The functional groups in the bifunctional active perfluoropolyether are one or two of -COOH, -CH2OH, and -NH2;

[0012] The light phase solvent is composed of a fluorine-ionized polar solvent and a fluorine-atom-containing polar solvent; the fluorine-ionized polar solvent is an ionic liquid, wherein the cation contains fluorine atoms, and the anion contains fluorine atoms and / or fluoride ions;

[0013] Heavy phase solvents consist of nonpolar solvents containing fluorine atoms and polar solvents containing fluorine atoms.

[0014] Fluorinated solvents can dissolve active perfluoropolyether mixtures well.

[0015] Perfluoropolyether compounds with monofunctional end groups and perfluoropolyether compounds with bifunctional end groups have extremely similar structures and properties, making separation difficult. The liquid-liquid extraction separation technology of this invention can achieve highly selective identification of differences in the end groups of functionalized perfluoropolyethers by precisely fine-tuning the composition and properties of the two-phase system, thus achieving efficient separation. Furthermore, the liquid-liquid extraction system of this invention has high processing efficiency, a simple process, low operating costs, and high yield.

[0016] In a preferred embodiment, the content of the monofunctional active perfluoropolyether and the difunctional active perfluoropolyether in the mixture is 6 wt% to 94 wt%.

[0017] The monofunctional active perfluoropolyether and the difunctional active perfluoropolyether can each independently have the main chain structure shown below:

[0018] -O(CF2O)a -(C2F4O) b -(C3F6O) c -(C4F8O) d -

[0019] Wherein: a, b, c, and d are each independently selected from integers from 0 to 300, and the sum of a, b, c, and d is greater than 3; the order 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).

[0020] In a preferred embodiment, the cation in the ionic liquid is one or more of the following: imidazole cation, pyridine cation, quaternary phosphorus cation, quaternary ammonium cation, choline cation, and pyrrole cation, and the anion is one or more of the following: tetrafluoroborate, hexafluorophosphate, trifluoromethanesulfonylimide, and fluoride ion.

[0021] In a preferred embodiment, the polar solvent containing fluorine atoms is one or more of the following: alcohols containing fluorine atoms, acids containing fluorine atoms, ketones containing fluorine atoms, and amines containing fluorine atoms.

[0022] In a preferred embodiment, the nonpolar solvent containing fluorine atoms is one or more of the following: saturated haloalkanes, perfluoroalkanes, unsaturated haloalkanes, perfluorinated or partially fluorinated aromatic solvents, fluorinated ethers, and fluorinated esters.

[0023] The liquid-liquid extraction method may be one or a combination of batch extraction, cross-flow extraction, countercurrent extraction, and fractionation extraction.

[0024] If the ratio between the light and heavy phase solvents during extraction is too low or too high, it will lead to poor extraction results or require an increase in solvent dosage. Therefore, the ratio needs to be determined based on the partition coefficients of the monofunctional and difunctional active perfluoropolyether compounds in each phase solvent system. The preferred volume ratio (of the light and heavy phase solvents) is 0.5–2.5:1, more preferably 1–2.5:1.

[0025] Temperature affects the phase equilibrium of monofunctional and difunctional active perfluoropolyether compounds in a two-phase solvent. Appropriately increasing the extraction operating temperature can accelerate the mass transfer rate between the two phases, while the operating temperature should be lower than the boiling point of the selected solvent. The preferred extraction temperature is 10–60°C, more preferably 20–40°C.

[0026] The liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers according to the present invention, wherein the purity of the monofunctional active perfluoropolyether in the product containing high-purity monofunctional active perfluoropolyether is not less than 95%.

[0027] The beneficial effects of this invention are:

[0028] 1. This invention is the first to use liquid-liquid extraction technology, resulting in high product purity, high production capacity, and low cost after extraction.

[0029] 2. The present invention uses commonly used industrial solvents, and the solvents used are easy to recycle and process.

[0030] 3. The present invention has a simple process, stable operation, low energy consumption, and good separation effect. It can separate monofunctional active perfluoropolyether with a purity of not less than 95% from a mixture containing monofunctional active perfluoropolyether and difunctional active perfluoropolyether, while having a high yield. Detailed Implementation

[0031] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0032] In the following embodiments, unless otherwise specified, "%" is based on molar reference.

[0033] Example 1

[0034] Three grams of a Y-type perfluoropolyether mixture containing 70% mono-terminated carboxylic acid and 30% di-terminated carboxylic acid, with a number-average molecular weight Mn of approximately 3600, were mixed with 80 mL of ionic liquid (1,3-diperfluoropropylimidazolium cation + tetrafluoroborate anion), 80 mL of pentafluoropropanol, and 100 mL of CF3CHFCHFC2F5. The mixture was extracted at 15 °C, allowed to separate phases, and the extract and raffinate were collected. After concentration, a monofunctional perfluoropolyether carboxylic acid product with a purity of 97% was obtained.

[0035] Example 2

[0036] 3 grams of a Z-type perfluoropolyether mixture containing 75% mono- and 25% di-amino groups, with a number-average molecular weight (Mn) of approximately 4500, was mixed with 80 mL of ionic liquid (tetrafluorobutylammonium + trifluoromethanesulfonylimide), 80 mL of pentafluoroacetone, and 150 mL of... The mixture was mixed with HFE 7200 and extracted at 25°C. After phase separation, the extract and raffinate were collected and concentrated to obtain a monofunctional perfluoropolyether amine product with a purity of 98%.

[0037] Example 3

[0038] 3.5 g of a mixture containing 65% K-type single-terminal active perfluoropolyether and 35% K-type double-terminal active perfluoropolyether, with the active group being -CH2OH, was mixed with 100 mL of ionic liquid (perfluoroalkyl tributylphosphine + tetrafluoroborate), 100 mL of pentafluoropropanol, and 180 mL of heptafluorocyclopentane. The mixture was extracted at 20 °C, allowed to separate into two phases, and the extract and raffinate were collected. After concentration, a monofunctional perfluoropolyether active product with a purity of 96% was obtained.

[0039] Example 4

[0040] 3.5 g of a mixture of 50% D-type single-terminated active perfluoropolyether and 50% D-type double-terminated perfluoropolyether, with the active group being -NH2, was mixed with 120 mL of ionic liquid (1,3-diperfluoroethylimidazolium cation + trifluoromethanesulfonylimide), 120 mL of trifluoroethanol, and 150 mL of m-trifluorotoluene. The mixture was extracted at 25 °C, allowed to separate into two phases, and the extract and raffinate were collected. After concentration, a monofunctional perfluoropolyether active product with a purity of 95% was obtained.

[0041] Example 5

[0042] 3 grams of a mixture containing 50% Y-type single-ended active perfluoropolyether and 50% Y-type double-ended perfluoropolyether, with carboxyl groups as the active group, are mixed with 100 mL of ionic liquid (N-perfluoropropylN-methylpyrrolidine + hexafluorophosphate), 80 mL of trifluoroethanol, and 150 mL of... The mixture of HFE 7100 was extracted at 45°C, allowed to separate into two phases, and the extract and raffinate were collected and concentrated to obtain a monofunctional perfluoropolyether active product with a purity of 95%.

[0043] Example 6

[0044] Six grams of a Y-type perfluoropolyether mixture containing 60% mono-terminated carboxylic acid and 40% di-terminated carboxylic acid were mixed with 80 mL of ionic liquid (1-perfluorobutylpyridine cation + tetrafluoroborate anion), 80 mL of pentafluoropropanol, and 100 mL of CF3CHFCHFC2F5. The mixture was extracted at 15 °C, allowed to separate into two phases, and the extract and raffinate were collected. After concentration, a monofunctional perfluoropolyether carboxylic acid product with a purity of 97% was obtained.

[0045] Example 7

[0046] 4 grams of a mixture containing 80% Z-type single-ended active perfluoropolyether and 20% Z-type double-ended perfluoropolyether, with the active group being -CH2OH, were mixed with 120 mL of ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide), 120 mL of trifluoroethanol, and 180 mL of... The mixture was mixed with HFE 7300 and extracted at 20°C. After phase separation, the extract and raffinate were collected and concentrated to obtain a monofunctional perfluoropolyether active product with a purity of 95.6%.

[0047] Example 8

[0048] Three grams of a mixture of D-type perfluoropolyether containing 50% mono- and 50% di-amino groups, with a number-average molecular weight (Mn) of approximately 4500, were mixed with 80 mL of ionic liquid (1-perfluorooctyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide), 80 mL of pentafluoroacetone, and 150 mL of CF3CHFCHFC2F5. The mixture was extracted at 25 °C, allowed to separate into two phases, and the extract and raffinate were collected. After concentration, a monofunctional perfluoropolyether amine product with a purity of 95% was obtained.

[0049] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers, characterized in that, include: A mixture of monofunctional and difunctional active perfluoropolyethers was contacted and mixed with a light and heavy phase solvent. After extraction equilibrium, the heavy phase was collected to obtain a product containing high-purity monofunctional active perfluoropolyether, and the light phase was collected to obtain a product containing difunctional active perfluoropolyether. The functional groups in the monofunctional active perfluoropolyether are -COOH, -CH2OH or -NH2; The functional groups in the bifunctional active perfluoropolyether are one or two of -COOH, -CH2OH, and -NH2; The light phase solvent is composed of a fluorine-ionized polar solvent and a fluorine-atom-containing polar solvent; the fluorine-ionized polar solvent is an ionic liquid, wherein the cation contains fluorine atoms, and the anion contains fluorine atoms and / or fluoride ions; Heavy phase solvents consist of nonpolar solvents containing fluorine atoms and polar solvents containing fluorine atoms.

2. The liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers according to claim 1, characterized in that, In the mixture containing monofunctional active perfluoropolyether and difunctional active perfluoropolyether, the content of monofunctional active perfluoropolyether is 6wt%~94wt%.

3. The liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers according to claim 1, characterized in that, The monofunctional active perfluoropolyether and the difunctional active perfluoropolyether each independently have the main chain structure shown below: -O(CF2O) a -(C2F4O) b -(C3F6O) c -(C4F8O) d - Wherein: a, b, c, and d are each independently selected from integers from 0 to 300, and the sum of a, b, c, and d is greater than 3; the order 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).

4. The liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers according to claim 1, characterized in that, The cations in the ionic liquid are one or more of the following: imidazole cations, pyridine cations, quaternary phosphorus cations, quaternary ammonium cations, choline cations, and pyrrole cations with fluorine-containing substituents; and the anions are one or more of the following: tetrafluoroborate, hexafluorophosphate, trifluoromethanesulfonylimide, and fluoride ions.

5. The liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers according to claim 1, characterized in that, The polar solvent containing fluorine atoms is one or more of the following: alcohols, acids, ketones, and amines containing fluorine atoms.

6. The liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers according to claim 1, characterized in that, The nonpolar solvent containing fluorine atoms is one or more of the following: saturated haloalkanes, perfluoroalkanes, unsaturated haloalkanes, perfluorinated or partially fluorinated aromatic solvents, fluorinated ethers, and fluorinated esters.

7. The liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers according to claim 1, characterized in that, The liquid-liquid extraction method is one or a combination of batch extraction, cross-flow extraction, countercurrent extraction, and fractionation extraction.

8. The liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers according to claim 1, characterized in that, The ratio of the light phase solvent to the heavy phase solvent is 0.5 to 2.5:

1.

9. The liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers according to claim 8, characterized in that, The ratio of the light phase solvent to the heavy phase solvent is 1~2.5:

1.

10. The liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers according to claim 1, characterized in that, The extraction temperature is 10~60℃.

11. The liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers according to claim 10, characterized in that, The extraction temperature is 20~40℃.

12. The liquid-liquid extraction method for separating monofunctional active perfluoropolyethers and difunctional active perfluoropolyethers according to claim 1, characterized in that, In the products containing high-purity monofunctional active perfluoropolyether, the purity of the monofunctional active perfluoropolyether is not less than 95%.