A method for purifying perfluoropolyether and its application in coolant

Abstract

This invention provides a perfluoropolyether purification method and its application in coolants. This method aims to address the prior art issue of unstable acidification caused by insufficient perfluoropolyether coolant purity, reduce the risk of corrosion and damage to equipment caused by immersion coolants during extended operation, and enhance the long-term stability of the perfluoropolyether coolant. The purification method comprises the multi-step process of oxidizing the fluorinated olefin ether impurities in the perfluoropolyether, neutralizing them, and then washing them with water.

Description

Technical Field

[0001] The present invention relates to the field of chemical industry, and in particular to a method for purifying perfluoropolyether and its application in coolants. Background Art

[0002] With the development of high-performance computers, the Internet of Things, data center servers, and new energy vehicles, addressing heat generation during operation and stabilizing equipment efficiency is crucial. Air-cooled cooling systems used for server cooling equipment are no longer sufficient, and liquid cooling has become the mainstream technology. Direct immersion liquid cooling transfers heat generated by heat-generating components to the liquid coolant by immersing them directly in a non-conductive liquid. This method offers higher heat dissipation efficiency and can reduce energy consumption. This cooling technology places high demands on the coolant's insulation, fluidity, volatility, and chemical stability. Fluorinated liquids are particularly suitable as coolants due to their excellent performance in all these areas.

[0003] Perfluoropolyether compounds, as a type of fluorinated liquid, have the advantages of high thermal stability, chemical stability in highly corrosive media, fire resistance, non-toxicity, good insulation, and low viscosity. They can be used as immersion coolants for electronic devices. However, the impurity perfluoroolefin ether R is easily generated during its preparation. f O[CF(CF3)CF2O] n CF = CF2. Its use in cooling systems can corrode electronic components, cause integrated circuit short circuits, and even completely paralyze servers, resulting in unforeseen losses. Therefore, the present invention proposes a method for purifying high-purity perfluoropolyether coolants and their use in coolants, enabling the preparation of high-purity perfluoropolyether compounds and eliminating the potential risks associated with perfluoroolefin ethers.

[0004] Perfluoropolyether compounds used as coolants can corrode equipment to a certain extent if perfluoroolefin ethers are present. The present invention provides a method for effectively controlling the presence of perfluoroolefin ethers in perfluoropolyether compounds.

[0005] Perfluoropolyether acyl fluoride is neutralized with an alkali solution in a proton polar solvent and decarboxylated to obtain the product. The reaction may produce perfluoroolefin ether (R f O[CF(CF3)CF2O] n CF=CF2) contains double bond structures. The existing technology is to purify them by distillation separation. However, due to the small difference in boiling points between the two, separation is difficult and the purification yield is low, which is also the main disadvantage of the existing technology.

[0006] In the present invention, the inventors utilize the strong oxidizing property of potassium permanganate to oxidize fluorinated olefin ethers in acetic acid or acetonitrile solution to form perfluoropolyether carboxylic acid, which is then neutralized with an alkaline solution in a protonic polar solvent to obtain perfluoropolyether. This method can control the concentration of fluorinated olefin ethers to below 200 ppm. The prepared high-purity perfluoropolyether can be used as coolant in the semiconductor industry, display industry, and data center industry, reducing the risk of corrosion and damage to equipment caused by the coolant under long-term operation. Summary of the Invention

[0007] The present application provides a method for purifying perfluoropolyether, comprising the following steps:

[0008] S1: Take a perfluoropolyether raw material, add a solvent and an oxidant, heat and stir for 3 to 6 hours to generate a perfluoropolyether carboxylic acid, separate the liquid after the reaction, wash the organic phase with water and separate the liquid, and the organic phase is the perfluoropolyether carboxylic acid;

[0009] S2: adding the perfluoropolyether carboxylic acid in step S1 into a protic solvent and an alkaline solution, heating the mixture for reaction, distilling the mixture, and washing the mixture with water until the pH value is neutral, thereby generating a purified perfluoropolyether and a high-purity perfluoropolyether.

[0010] Furthermore, the perfluoropolyether has the general formula R f O[CF(CF3)CF2O] n CFHCF3, where R f =CF3 or C2F5 or C3F7 or C4F9 or C5F 11 , where n=1-12.

[0011] Furthermore, the impurity perfluoroolefin ether R in the high-purity perfluoropolyether f O[CF(CF3)CF2O] n CF=CF2<100ppm, more preferably <20ppm.

[0012] Furthermore, the water content in the high-purity perfluoropolyether is ≤50 ppm, preferably ≤20 ppm; the fluoride ion content in the high-purity perfluoropolyether is ≤50 ppm, preferably ≤2 ppm; and the potassium hydroxide neutralization value in the high-purity perfluoropolyether is ≤0.03%, preferably ≤0.01%.

[0013] Furthermore, the number of impurity particles in the high-purity perfluoropolyether is ≤200, preferably ≤50.

[0014] Furthermore, the solvent in step S1 is one of acetic acid and acetonitrile, preferably acetic acid.

[0015] Furthermore, the oxidant in step S1 is one of potassium permanganate and oxygen, preferably potassium permanganate.

[0016] Furthermore, the molar ratio of the oxidant to the perfluoropolyether raw material in step S1 is 1:10-12.

[0017] Furthermore, the heating temperature in step S1 is 50-120°C;

[0018] Furthermore, the protic solvent in step S2 is at least one of water, ethanol, ethylene glycol, glycerol, and diethylene glycol, preferably ethylene glycol.

[0019] Furthermore, the alkaline solution in step S2 is one of a 2-20 wt% aqueous sodium carbonate solution, a sodium bicarbonate solution, a sodium hydroxide solution or a potassium hydroxide solution, preferably a 5 wt% aqueous sodium hydroxide solution.

[0020] Furthermore, the mass ratio of the perfluoropolyether carboxylic acid, the protic solvent, and the alkaline solution in step S2 is (5-5.5):1:1.

[0021] Furthermore, the heating temperature in step S2 is 110-140°C, preferably 110°C.

[0022] The invention also discloses application of the perfluoropolyether purification method in preparing perfluoropolyether coolant.

[0023] The beneficial effects of the present invention are:

[0024] (1) The present invention can effectively improve the purity of perfluoropolyether products, and its application in industrialization can increase product yield;

[0025] (2) Reduce the risk of equipment corrosion and damage caused by immersion coolant during long-term operation; BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the gas chromatogram of the perfluoropolyether raw material added in Examples 1, 2, and 3.

[0027] Figure 2 This is the gas chromatogram of the perfluoropolyether carboxylic acid in Example 1.

[0028] Figure 3 For the gas chromatography of perfluoropolyether carboxylic acid in Example 2.

[0029] Figure 4 This is the gas chromatogram of perfluoropolyether carboxylic acid in Example 3.

[0030] Figure 5 This is the gas chromatogram of the perfluoropolyether carboxylic acid in Comparative Example 1. DETAILED DESCRIPTION

[0031] Example 1

[0032] S1 In a dry 500mL stirred flask, 500g (0.8mol) of perfluoropolyether raw material (containing 2.7% R f O[CF(CF3)CF2O] n CF=CF2, peak time is 8.486-8.499min), 100g (1.67mol) of acetic acid, 15g (0.096mol) of potassium permanganate, then heating to an internal temperature of 90-100°C, stirring for 4 hours, sampling, and then performing liquid separation to obtain a lower layer material, washing the lower layer material with water and then liquid separation to obtain a perfluoropolyether carboxylic acid solution;

[0033] S2: adding the perfluoropolyether carboxylic acid solution after separation into a three-necked flask, adding 100 g of ethylene glycol and 100 g of a 5 wt% sodium hydroxide aqueous solution, heating to 95-100° C. and reflux reaction for 3 hours, then heating to 110° C. and distilling the material in the flask; after the distillation is completed, the residue is washed with deionized water with stirring; the washed material is heated to boiling again, and the gas phase pH of the material is neutral after pH testing, thereby obtaining the purified perfluoropolyether.

[0034] The perfluoropolyether carboxylic acid solution in step S1 was sampled and tested to have a product purity of 99.98%, which was calculated as the sum of all values ​​in the GCMS spectrum after removing the perfluoroolefin ether impurities; R f O[CF(CF3)CF2O] n CF=CF2 was not detected.

[0035] Example 2

[0036] S1 In a dry 500mL stirred flask, 500g (0.8mol) of perfluoropolyether raw material (containing 2.7% R f O[CF(CF3)CF2O] n CF=CF2, peak time is 8.486-8.499min), 100g (1.67mol) of acetic acid, 15g (0.096mol) of potassium permanganate, potassium permanganate is added in 5 batches on average, 3g (0.032mol) of potassium permanganate is added at an internal temperature of 20°C-25°C, 3g (0.032mol) of potassium permanganate is added at an internal temperature of 40°C-45°C, 3g (0.032mol) of potassium permanganate is added at an internal temperature of 60°C-65°C, 3g (0.032mol) of potassium permanganate is added at an internal temperature of 80°C-85°C, and 3g (0.032mol) of potassium permanganate is added at an internal temperature of 95°C-100°C. After the addition is completed, stirring is performed for 4 hours, sampling is performed, and then liquid separation is performed to obtain a lower layer material, the lower layer material is washed with water, and liquid separation is performed to obtain a perfluoropolyether carboxylic acid solution;

[0037] S2: adding the perfluoropolyether carboxylic acid solution in step S1 to a three-necked flask, adding 100 g of ethylene glycol and 100 g of a 5 wt% sodium hydroxide aqueous solution, heating to 95-100° C. and reflux reaction for 3 hours, then heating to 110° C. and distilling the material in the flask; after the distillation is completed, washing the residue with water three times until it is clean and the liquid phase pH is neutral; after washing, heating to boiling again, the material is tested for pH, and the gas phase pH is neutral, thereby obtaining the purified perfluoropolyether.

[0038] The perfluoropolyether carboxylic acid solution in step S1 was sampled and tested to have a product purity of 99.99%. The purity was calculated as the sum of all values ​​in the GCMS spectrum after removing the perfluoroolefin ether impurities. f O[CF(CF3)CF2O] n CF=CF2 was not detected.

[0039] Example 3

[0040] S1 In a dry 500mL stirred flask, 500g of perfluoropolyether raw material (containing 2.7% R f O[CF(CF3)CF2O] n CF=CF2, peak time is 8.486-8.499min), 100g (2.44mol) acetonitrile, 15g (0.096mol) potassium permanganate, then heating to an internal temperature of 90-100°C, stirring for 4 hours, sampling, and then performing liquid separation to obtain a lower layer material, washing the lower layer material with water and then separating the liquid to obtain a perfluoropolyether carboxylic acid solution;

[0041] S2: The perfluoropolyether carboxylic acid solution in step S1 is added to a three-necked flask, and 100 g of ethylene glycol and 100 g of a 5 wt% sodium hydroxide aqueous solution are added. The temperature is raised to 95-100° C. and refluxed for 3 hours. The temperature is then raised to 110° C. to distill and extract the material in the flask. After the distillation is completed, the residue is washed with water three times until it is clean and the liquid phase pH is neutral. After the washing is completed, the material is heated to boiling again, and the gas phase pH of the material is neutral after pH testing.

[0042] The perfluoropolyether carboxylic acid solution in step S1 was sampled and tested to have a product purity of 99.71%. The purity was calculated as the sum of all values ​​in the GCMS spectrum after removing the perfluoroolefin ether impurities; R f O[CF(CF3)CF2O] n The content of CF=CF2 detected was 0.288%.

[0043] Comparative Example 1

[0044] S1 In a dry 500mL stirred flask, 500g (0.8mol) of perfluoropolyether raw material (containing 2.7% R fO[CF(CF3)CF2O] n CF=CF2, peak time is 8.486-8.499min,), 100g (1.67mol) acetic acid, 6g (0.038mol) potassium permanganate, then heating to an internal temperature of 90-100°C, stirring for 4 hours, sampling, and then performing liquid separation to obtain a lower layer material, washing the lower layer material with water and then separating the liquid to obtain a perfluoropolyether carboxylic acid solution;

[0045] S2: The perfluoropolyether carboxylic acid solution in step S1 is added to a three-necked flask, and 100 g of ethylene glycol and 100 g of a 5 wt% sodium hydroxide aqueous solution are added. The temperature is raised to 95-100° C. and refluxed for 3 hours. The temperature is then raised to 110° C. to distill and extract the material in the flask. After the distillation is completed, the residue is washed with water three times until it is clean and the liquid phase pH is neutral. After the washing is completed, the material is heated to boiling again, and the gas phase pH of the material is neutral after pH testing.

[0046] The perfluoropolyether carboxylic acid solution in step S1 was sampled and tested to have a product purity of 99.61% ( Figure 5 ), the purity is calculated as the sum of all values ​​after removing the perfluoroolefin ether impurities in the GCMS spectrum; R f O[CF(CF3)CF2O] n The content of CF=CF2 detected was 0.386%.

Claims

1. A method for purifying perfluoropolyether, characterized in that: The steps include: S1 Take the perfluoropolyether raw material, add the solvent and oxidant, heat and stir for 3-6 hours, and make the impurity perfluoroolefin ether R f O[CF(CF3)CF2O] n CF = CF2 to generate perfluoropolyether carboxylic acid. After the reaction is completed, the liquid is separated, and the organic phase is washed with water and then separated. The organic phase is a solution containing perfluoropolyether carboxylic acid; S2: adding a protic solvent and an alkaline solution to the solution containing perfluoropolyether carboxylic acid in step S1, heating and reacting for 3-4 hours, distilling, and washing with water until the pH is neutral to generate a purified perfluoropolyether, i.e., a high-purity perfluoropolyether; The impurity perfluoroolefin ether R in the high-purity perfluoropolyether f O[CF(CF3)CF2O] n CF = CF2 < 100ppm; The water content in the high-purity perfluoropolyether is ≤50 ppm, and the fluoride ion content in the high-purity perfluoropolyether is ≤50 ppm; The solvent in step S1 is acetic acid; the oxidant is potassium permanganate; The molar ratio of the oxidant to the perfluoropolyether raw material in step S1 is 1:10-12; the heating temperature in step S1 is 50-120°C; The perfluoropolyether has the general formula R f O[CF(CF3)CF2O] n CFHCF3, where R f =CF3 or C2F5 or C3F7 or C4F9 or C5F 11 , where n = 1-12; The protic solvent in step S2 is at least one of water, ethanol, and ethylene glycol; The alkaline solution in step S2 is one of a sodium carbonate aqueous solution, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution.

2. The purification method according to claim 1, wherein The impurity perfluoroolefin ether R in the high-purity perfluoropolyether f O[CF(CF3)CF2O] n CF=CF2<20ppm.

3. The purification method according to claim 1, wherein The water content in the high-purity perfluoropolyether is ≤20ppm; the fluoride ion content in the high-purity perfluoropolyether is ≤2ppm.

4. Use of the purification method of perfluoropolyether according to any one of claims 1 to 3 in the preparation of perfluoropolyether coolants.

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