Perfluoropolyether as well as preparation method and application thereof

Abstract

The structure of the perfluoropolyether is shown as follows: CF3O (CF2O) nCF2CF2O (CF( CF3) CF2O) mCF2CF3, n is equal to 1-6, m is equal to 1-3, and n is greater than m. The perfluoropolyether has continuous repetitive units-CF2O-and-CF (CF3) CF2O-, and the content of the repetitive units-CF2O-directly affects the viscosity, the melting point and the boiling point of the perfluoropolyether, that is, under the condition of the same molecular weight, the more the number of the repetitive units-CF2O-is, the higher the boiling point of the perfluoropolyether is, and the higher the melting point of the perfluoropolyether is. A plurality of-CF2O-continuously and repeatedly appear in the structure of the perfluoropolyether, and meanwhile, the number of-CF2O-in a single molecule is far higher than that of-CF3 CF2O-, so that the perfluoropolyether can be ensured to have a lower melting point. Therefore, the boiling point (greater than or equal to 190 DEG C) and the melting point (less than or equal to-100 DEG C) of the repeating units-CF2O <-> and-CF3 CF2O <-> are regularly arranged and are suitable for being used in a heat carrier of a low-temperature chip etching technology when the number of the repeating units is within the range.

Description

Technical Field

[0001] This invention relates to the field of fluorine chemistry, specifically to a perfluoropolyether, its preparation method, and its applications. Background Technology

[0002] The future development of chip etching technology shows a trend towards low-temperature etching, especially in the fields of 3D NAND memory and DRAM manufacturing. Low-temperature etching technology has the following advantages: (1) Higher precision and uniformity: Low temperature environment (such as -60 ℃ to -70 ℃) can reduce chemical reactivity and reduce sidewall deposition, thereby achieving more precise etching, which is suitable for high aspect ratio (HAR) structures (such as memory channel holes of 3D NAND). (2) Higher etching rate: Lam Research’s Lam Cryo 3.0 technology increases the etching rate by 2.5 times compared to traditional processes, while reducing energy consumption by 40% and carbon emissions by 90%; (3) More suitable for multi-layer stacking: As the number of 3D NAND layers moves toward 1000 layers (as Samsung and Kioxia aim), low-temperature etching can effectively solve the problem of uniformity in ultra-deep hole etching.

[0003] Therefore, future low-temperature etching chip technology places even more stringent requirements on key heat transfer fluids: (1) Extreme low temperature adaptability: the temperature range must support the extreme low temperature environment from -80 ℃ to -100 ℃, while being compatible with high temperature switching (such as above 200 ℃) to meet the etching requirements of multilayer stacked chips; the viscosity must be kept stable to avoid solidification or sudden increase in viscosity at low temperature, which would affect the heat transfer efficiency.

[0004] (2) Thermal conduction and temperature uniformity: The thermal conductivity must be ≥0.1 W / m·K to ensure the temperature uniformity of the wafer and avoid local overheating that leads to a decrease in etching accuracy; at the same time, it must have low heat capacity characteristics to shorten the temperature adjustment time and improve etching efficiency.

[0005] (3) Chemical stability and compatibility: It must be able to withstand etching gases such as CF4 and SF6 and high-energy plasma bombardment to avoid decomposition and impurity generation; it should not corrode or degrade when in long-term contact with metals (such as copper and aluminum) and sealing materials (such as fluororubber).

[0006] (4) Environmental and safety indicators: the global warming potential (GWP) must be close to zero to comply with the EU PFAS restriction regulations; the flash point must be "zero" and it must pass RoHS, REACH and other certifications to ensure safe operation.

[0007] (5) Long-term stability and maintenance costs: the service life must exceed 20 years, and the long-term fluctuation of physical properties (such as viscosity and dielectric constant) must not exceed 5%; the system leakage rate must be less than 10%. -6 mbar·L / s, to prevent heat transfer fluid loss due to evaporation.

[0008] Currently, the best solution for the heat transfer medium required for low-temperature etching of chips is perfluoropolyether. However, commercially available perfluoropolyethers cannot operate below -100°C and also cannot meet the requirement of "one liquid, multiple temperatures" (i.e., an operating range of -100 to 200°C). Even though the operating temperature range of DO2 type perfluoropolyether is -70 to 290°C, its boiling point is only 175°C. When the operating temperature reaches above its boiling point, it has a high vapor pressure, and its evaporation loss will increase significantly.

[0009] Therefore, it is necessary to develop perfluoropolyethers that can operate at temperatures of -100 to 200 ℃, have low viscosity, high stability and high boiling point at low temperatures, as key heat carriers for future low-temperature etched chips.

[0010] Chinese patent document CN120157865A discloses a method for synthesizing low molecular weight perfluoropolyether fluoride, comprising the following steps: oxidative polymerization of hexafluoropropylene, oxygen, a catalyst, and a fluorinated solvent; and obtaining low molecular weight perfluoropolyether fluoride with the structure R after the reaction solution is de-lightened and solvent is removed. f -(CF2O) m [CF2CF2O] n [CF(CF3)CF2O] k CF(CF3)COF, where m, n, and k are each independently selected from any integer from 0 to 10, and R f It is CF3O, CF3CF2O or CF3CF2CF2O.

[0011] The aforementioned perfluoropolyether acyl fluoride includes repeating units -CF2O-, -CF2CF2O-, and -CF(CF3)CF2O-, with random repeating numbers and random order. The synthesized product is a mixture with a boiling range distributed over a wide temperature range. It contains a certain number of low-boiling-point perfluoropolyether acyl fluorides, making fluorination end-capping extremely difficult. It is mostly used in the preparation of surfactants. Even if this perfluoropolyether acyl fluoride is used to synthesize a perfluoropolyether with stable end groups, the viscosity increases rapidly at lower temperatures (< -70 °C) due to the large number of -CF(CF3)CF2O- repeating units in the mixture, making it unsuitable for synthesizing heat carriers suitable for low-temperature etching chip technology.

[0012] Chinese patent document CN112876669A discloses a method for fluorinating the end groups of a perfluoropolyether, comprising the following steps: (1) activating a mixture of fluorine gas and inert gas by irradiating it with ultraviolet light; (2) passing the activated mixture into a reaction vessel containing perfluoropolyether acyl fluoride to react and obtain the fluorinated perfluoropolyether, wherein the inert gas is one or more of nitrogen, argon, and helium.

[0013] The above method discloses the activation of a fluorine-nitrogen mixture by ultraviolet light for 80 seconds. This method is only applicable to laboratory operations and cannot process fluorine-nitrogen mixtures of a certain quantity or more. The total flow rate of fluorine and nitrogen does not exceed 100 mL / min. At this flow rate, a high concentration of fluorine-nitrogen mixture (80%, v / v) that is not commercially viable must remain in a photoactivated sealed container for 80 seconds. The processing capacity is low and the operation risk is extremely high.

[0014] Therefore, in order to find a temperature range suitable for the heat transfer medium of low-temperature etching chip technology, it is necessary to develop perfluoropolyethers with different structures than those in the existing ones, and to ensure that the perfluoropolyethers have the physical properties of low melting point and high boiling point. Summary of the Invention

[0015] To address the aforementioned technical problems, this invention provides a perfluoropolyether with a boiling point (≥190℃) and melting point (≤-100℃), which is suitable for use as a heat transfer medium in low-temperature etching chip technology.

[0016] A perfluoropolyether, the structure of which is shown below: CF3O(CF2O) n CF2CF2O(CF(CF3)CF2O) m CF2CF3, Where n = 1~6, m = 1~3, and n > m.

[0017] In this invention, the perfluoropolyether has continuous repeating units -CF2O- and -CF(CF3)CF2O-. The content of the repeating unit -CF2O- directly affects the viscosity, melting point, and boiling point of the perfluoropolyether. That is, for the same molecular weight, the more repeating units -CF2O-, the higher the boiling point and melting point of the perfluoropolyether. The presence of multiple consecutive -CF2O- repeating units in the perfluoropolyether structure, coupled with the significantly higher number of -CF2O- units in a single molecule compared to -CF(CF3)CF2O-, ensures a lower melting point for the perfluoropolyether.

[0018] Therefore, the repeating units -CF2O- and -CF(CF3)CF2O- in this application are arranged in a regular pattern. When the number is within the above range, the boiling point (≥190 ℃) and melting point (≤-100 ℃) are suitable for the heat carrier in low-temperature etching chip technology.

[0019] Preferably, n=5 or 6, m=1 or 2.

[0020] Preferably, the perfluoropolyether has a melting point ≤ -100 ℃ and a boiling point ≥ 190 ℃.

[0021] The present invention also provides a method for preparing the above-mentioned perfluoropolyether, comprising the following steps: (1) Using KF as a catalyst, CF3O(CF2O) n CF2COF and hexafluoropropylene oxide are reacted in an aprotic polar solvent to produce perfluoropolyether fluoride. (2) A fluorine-nitrogen mixture is introduced into a reactor containing the perfluoropolyether acyl fluoride obtained in step (1) to react and obtain perfluoropolyether.

[0022] The specific reaction formula is as follows: In this invention, CF3O (CF2O) n CF2COF reacts with KF in an aprotic solvent to generate alkoxy anion active centers. The generated alkoxy anion active centers continue to react with hexafluoropropylene oxide (HFPO), causing HFPO to undergo ring-opening addition, resulting in perfluoropolyether acyl fluoride containing continuous repeating units of -CF2O- and -CF(CF3)CF2O-. After fluorination end-capping, a perfluoropolyether with low melting point and high boiling point is obtained.

[0023] In this invention, CF3O (CF2O) is used. n CF2COF can be produced simultaneously during the preparation of hexafluoropropylene to hexafluoropropylene oxide.

[0024] Preferably, in step (1), the CF3O (CF2O) n The molar ratio of CF2COF, hexafluoropropylene oxide, and KF is 1:2~3:1~1.5.

[0025] Preferably, in step (1), the aprotic polar solvent is diethylene glycol dimethyl ether (code DG), triethylene glycol dimethyl ether (code TrG), or tetraethylene glycol dimethyl ether (code TeG).

[0026] Preferably, in step (1), the mass ratio of KF and aprotic polar solvent is 1~3:10.

[0027] More preferably, the aprotic polar solvent is diethylene glycol dimethyl ether, and the mass ratio of KF to diethylene glycol dimethyl ether is 1~1.5:10.

[0028] Preferably, in step (1), the temperature of the addition reaction is -30 to 10 °C.

[0029] Preferably, in step (1), the structure of the perfluoropolyether fluoride is CF3O(CF2O). n CF2CF2O(CF(CF3)CF2O) m CF(CF3)COF.

[0030] Preferably, in step (2), the fluorine-nitrogen mixture is commercially available commercial-grade fluorine-nitrogen gas, wherein the proportion of fluorine is 19.9~20.1 vol.

[0031] Preferably, in step (2), the mass ratio of fluorine gas to perfluoropolyether fluoride in the fluorine-nitrogen mixture is 1~1.75:1.

[0032] Preferably, in step (2), the reaction temperature is 180~220 ℃ and the reaction time is 12~20 h.

[0033] This invention also provides the application of the aforementioned perfluoropolyether in the preparation of heat transfer fluids for low-temperature etching chip technology. The perfluoropolyether of this invention combines a low melting point (≤-100 ℃) and a high boiling point (≥190 ℃), which can meet the operating temperature of -100~200 ℃ for heat transfer fluids in low-temperature etching chip technology, thus satisfying the requirement of a single liquid for multiple temperatures.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: In this invention, the perfluoropolyether has continuous repeating units -CF2O- and -CF(CF3)CF2O-. The content of the repeating unit -CF2O- directly affects the viscosity, melting point, and boiling point of the perfluoropolyether. Specifically, for the same molecular weight, the more repeating units -CF2O-, the higher the boiling point and melting point of the perfluoropolyether. The perfluoropolyether structure contains multiple consecutive -CF2O- repeating units, and the number of -CF2O- units in a single molecule is much higher than the number of -CF(CF3)CF2O- units, ensuring a lower melting point for the perfluoropolyether. Therefore, the repeating units -CF2O- and -CF(CF3)CF2O- in this application are arranged in a regular pattern, and when their number is within the above-mentioned range, the boiling point (≥190 °C) and melting point (≤-100 °C) are suitable for use as heat transfer media in low-temperature etching chip technology. Attached Figure Description

[0035] Figure 1 The image shows the NMR fluorine spectrum of the raw material PX-5 (CF3O(CF2O)5CF2COF) in Example 1, where A is the original spectrum and B and C are the interpreted spectra of the original spectrum.

[0036] Figure 2The image shows the NMR fluorine spectrum of PX-52 obtained in Example 1. From top to bottom, the images are the original spectrum and the interpreted spectrum of the original spectrum. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited to the following embodiments.

[0038] All raw materials used in this invention are commercially available.

[0039] To facilitate differentiation, compounds are labeled according to the following rules: Among them, the raw material is CF3O (CF2O). n CF2COF, denoted as PX-n, where n is the number of repeating -CF2O- units in the structural formula, n=1~6; Perfluoropolyether acyl fluoride CF3O (CF2O) n CF2CF2O(CF(CF3)CF2O) m CF(CF3)COF, denoted as PX-nx, where n is the number of -CF2O- repeating units in the structural formula, and x is the number of -CF2O- repeating units in the structural formula + 1, i.e. x = m + 1, n = 1~6, m = 1~3; Perfluoropolyether products CF3O (CF2O) n CF2CF2O(CF(CF3)CF2O) m CF2CF3, denoted as P-nx, where n is the number of repeating -CF2O- units in the structural formula, and x is the number of repeating -CF2O- units in the structural formula plus 1, i.e., x=m+1, n=1~6, m=1~3.

[0040] Example 1: Preparation of perfluoropolyether acyl fluoride PX-52 Under a nitrogen atmosphere, dried diethylene glycol dimethyl ether (100 g, hereinafter referred to as DG, with a moisture content of less than 20 ppm) and dried KF (15 g, 0.258 mol, with a moisture content of less than 15 ppm) were added to a dry 500 mL glass reactor. Then, stirring and a low-temperature circulating bath were started. After the reaction system temperature dropped to -20 °C, CF3O(CF2O)5CF2COF (denoted as PX-5, 132 g, 0.258 mol) was slowly added dropwise to the reactor. After the addition was completed, stirring was continued for 60 min. Then, HFPO (85.6 g, 0.516 mol) was slowly introduced into the reactor. During the addition process, the reaction temperature was controlled at -20 to -15 °C. After the HFPO was completely introduced, the reaction continued for 4 h. After the reaction was completed, the reaction solution was slowly raised to room temperature, and nitrogen was introduced to replace and remove the HFPO. After stirring was stopped and the mixture was allowed to stand and separate into layers, 216.5 g of perfluoropolyether fluoride was obtained, with a yield of 99.0%.

[0041] Referring to the methods of Chinese patents (application numbers CN202311365939.3 and CN202411617906.8), the content of the above-mentioned perfluoropolyether acyl fluoride component was determined by gas chromatography after methanol esterification, wherein the structure is CF3O(CF2O). n CF2CF2O(CF(CF3)CF2O) m The content of CF(CF3)COF (where n=5, m=1, denoted as PX-52) is 99.14%, the content of raw material PX-5 is 0.07%, and the total content of by-products PX-51 and PX-53 is 0.42%.

[0042] The NMR fluorine spectrum of the raw material PX-5 (CF3O(CF2O)5CF2COF) is shown below. Figure 1 As shown in A, the specific spectral diagram is as follows: Figure 1 As shown in B and C, the NMR fluorine spectrum of product PX-52 is detailed in [reference needed]. Figure 2 From top to bottom, the images are the original spectrum and the interpreted spectrum.

[0043] Example 2: Preparation of perfluoropolyether acyl fluoride PX-52 The preparation method is the same as in Example 1, except that the reaction temperature is controlled at -15 to -10 °C.

[0044] The content was determined according to the test method of Example 1, wherein the content of PX-52 was 98.2%, the content of raw material PX-5 was 0.07%, and the total content of by-products PX-51 and PX-53 was 0.53%.

[0045] Example 3: Preparation of perfluoropolyether fluoride PX-52 The preparation method is the same as in Example 1, except that the reaction temperature is controlled at -10~0 ℃.

[0046] The content was determined according to the test method of Example 1, wherein the content of PX-52 was 95.2%, the content of raw material PX-5 was 0.08%, and the total content of by-products PX-51 and PX-53 was 1.1%.

[0047] Example 4: Preparation of perfluoropolyether acyl fluoride PX-52 The preparation method is the same as in Example 1, except that the reaction temperature is controlled at 0~10 ℃.

[0048] The content was determined according to the test method of Example 1, wherein the content of PX-52 was 90.5%, the content of raw material PX-5 was 0.03%, the total content of by-products PX-51 and PX-53 was 2.5%, and the content of by-product HFPO dimer was 0.05%.

[0049] Example 5: Preparation of perfluoropolyether fluoride PX-52 The preparation method is the same as in Example 1, except that the reaction temperature is controlled at -30 to -25 °C.

[0050] The content was determined according to the test method of Example 1, wherein the content of PX-52 was 99.8%, the content of raw material PX-5 was 0.02%, and the total content of by-products PX-51 and PX-53 was 0.12%.

[0051] Example 6: Preparation of perfluoropolyether fluoride PX-52 The preparation method is the same as in Example 1, except that the aprotic polar solvent is tetraethylene glycol dimethyl ether.

[0052] The content was determined according to the test method of Example 1, wherein the content of PX-52 was 99.5%, the content of raw material PX-5 was 0.08%, and the total content of by-products PX-51 and PX-53 was 0.42%.

[0053] Example 7: Preparation of perfluoropolyether acyl fluoride PX-52 The preparation method is the same as in Example 1, except that the aprotic polar solvent is triethylene glycol dimethyl ether.

[0054] The content was determined according to the test method of Example 1, wherein the content of PX-52 was 99.5%, the content of raw material PX-5 was 0.08%, and the total content of by-products PX-51 and PX-53 was 0.43%.

[0055] Example 8: Preparation of perfluoropolyether acyl fluoride PX-52 The preparation method is the same as in Example 1, except that the amount of KF used is 16.5 g, that is, the molar ratio of raw material PX-5 to KF is 1:1.1.

[0056] The content was determined according to the test method of Example 1, wherein the content of PX-52 was 97.9%, the content of raw material PX-5 was 0.05%, the total content of by-products PX-51 and PX-53 was 0.21%, and the content of by-product HFPO dimer was 1.2%.

[0057] Example 9: Preparation of perfluoropolyether acyl fluoride PX-52 The preparation method is the same as in Example 1, except that the amount of KF used is 15.75 g, that is, the molar ratio of raw material PX-5 to KF is 1:1.05.

[0058] The content was determined according to the test method of Example 1, wherein the content of PX-52 was 99.2%, the content of raw material PX-5 was 0.08%, the total content of by-products PX-51 and PX-53 was 0.21%, and the content of by-product HFPO dimer was 0.11%.

[0059] Example 10: Preparation of perfluoropolyether acyl fluoride PX-52 The preparation method is the same as in Example 1, except that the amount of PX-5 used is 264 g, and the molar ratio of raw materials PX-5, KF and HFPO is 1:1:2.2.

[0060] The content was determined according to the test method in Example 1, wherein the content of PX-52 was 96.3%, the content of raw material PX-5 was 0.08%, the total content of by-products PX-51 and PX-53 was 0.21%, and the content of by-product HFPO dimer was 1.2%.

[0061] Example 11: Preparation of perfluoropolyether acyl fluoride PX-52 The preparation method is the same as in Example 1, except that the amount of PX-5 used is 264 g, and the molar ratio of raw materials PX-5, KF and HFPO is 1:1:2.4.

[0062] The content was determined according to the test method of Example 1, wherein the content of PX-52 was 96.5%, the content of raw material PX-5 was 0.05%, the total content of by-products PX-51 and PX-53 was 0.22%, and the content of by-product HFPO dimer was 2.5%.

[0063] Example 12: Preparation of perfluoropolyether acyl fluoride PX-52 The preparation method is the same as in Example 1, except that the amount of PX-5 used is 88 g, and the molar ratio of raw materials PX-5, KF and HFPO is 1:1:2.

[0064] The content was determined according to the test method of Example 1, wherein the content of PX-52 was 99.6%, the content of raw material PX-5 was 0.08%, and the total content of by-products PX-51 and PX-53 was 0.12%.

[0065] Example 13: Preparation of perfluoropolyether fluoride PX-52 The preparation method is the same as in Example 1, except that the amount of catalyst used is 40 g, the amount of PX-5 used is 264 g, and the molar ratio of raw materials PX-5, KF and HFPO is 1:1.33:2.2.

[0066] The content was determined according to the test method of Example 1, wherein the content of PX-52 was 96.5%, the content of raw material PX-5 was 0.07%, the total content of by-products PX-51 and PX-53 was 0.21%, and the content of by-product HFPO dimer was 1.3%.

[0067] Example 14: Preparation of perfluoropolyether acyl fluoride PX-53 The preparation method is the same as in Example 1, except that the amount of PX-5 used is 132 g, and the molar ratio of raw materials PX-5, KF and HFPO is 1:1:3.

[0068] The content was determined according to the test method in Example 1, wherein the content of PX-53 was 96.1%, the content of raw material PX-5 was 0.07%, the content of by-product PX-51 was 0.05%, the content of by-product PX-53 was 1.5%, and the content of by-product HFPO dimer was 2.2%.

[0069] Example 15: Preparation of perfluoropolyether fluoride PX-62 The preparation method is the same as in Example 1, except that the amount of raw material CF3O(CF2O)6CF2COF (denoted as PX-6) is 149 g (0.258 mol).

[0070] The content was determined according to the test method of Example 1, wherein the content of PX-62 was 99.5%, the content of raw material PX-6 was 0.03%, and the total content of by-products PX-61 and PX-63 was 0.42%.

[0071] Example 16: Preparation of perfluoropolyether fluorinated fluoride PX-63 The preparation method is the same as in Example 15, except that the amount of raw material PX-6 used is 149 g, and the molar ratio of PX-6, KF and HFPO is 1:1:3.

[0072] The content was determined according to the test method in Example 1, wherein the content of PX-63 was 94.5%, the content of raw material PX-6 was 0.05%, the content of by-product PX-61 was 0.06%, the content of by-product PX-62 was 1.8%, and the content of by-product HFPO dimer was 3.2%.

[0073] Example 17: Preparation of perfluoropolyether fluoride PX-63 The preparation method is the same as in Example 16, except that the reaction temperature is controlled at -30 to -25 °C.

[0074] The content was determined according to the test method in Example 1, wherein the content of PX-63 was 96.3%, the content of raw material PX-6 was 0.05%, the content of by-product PX-61 was 0.05%, the content of by-product PX-62 was 1.9%, and the content of by-product HFPO dimer was 1.2%.

[0075] Example 18: Preparation of perfluoropolyether acyl fluoride PX-63 The preparation method is the same as in Example 16, except that the aprotic polar solvent is triethylene glycol dimethyl ether.

[0076] The content was determined according to the test method in Example 1, wherein the content of PX-63 was 95.3%, the content of raw material PX-6 was 0.07%, the content of by-product PX-61 was 0.05%, the content of by-product PX-62 was 0.98%, and the content of by-product HFPO dimer was 2.1%.

[0077] Example 19: Preparation of perfluoropolyether fluoride PX-63 The preparation method is the same as in Example 17, except that the amount of PX-6 used is 100 g, and the molar ratio of PX-6, KF and HFPO is 1:1:3.

[0078] The content was determined according to the test method in Example 1, wherein the content of PX-63 was 97.4%, the content of raw material PX-6 was 0.05%, the content of by-product PX-61 was 0.05%, the content of by-product PX-62 was 0.88%, and the content of by-product HFPO dimer was 0.41%.

[0079] Example 20: Preparation of perfluoropolyether acyl fluoride PX-63 The preparation method was the same as in Example 17, except that the amount of PX-6 used was 298,000 g, the molar ratio of PX-6, KF, and HFPO was 1:1:3, the mass ratio of KF to diethylene glycol dimethyl ether was 1:10, and the reaction was carried out at 1.2 m 3 The reaction is carried out inside the reactor.

[0080] The content was determined according to the test method of Example 1, wherein the content of PX-63 was 95.3%, the content of raw material PX-6 was 0.07%, the content of by-product PX-61 was 0.4%, the content of by-product PX-62 was 1.2%, and the content of by-product HFPO dimer was 0.4%.

[0081] Example 21: Preparation of perfluoropolyether acyl fluoride PX-52 The preparation method was the same as in Example 17, except that the amount of PX-5 used was 396,000 g, the molar ratio of PX-5, KF, and HFPO was 1:1:2, the mass ratio of KF to diethylene glycol dimethyl ether was 1.5:10, and the reaction was carried out at 1.2 m 3 The reaction is carried out inside the reactor.

[0082] The content was determined according to the test method of Example 1, wherein the content of PX-52 was 98.5%, the content of raw material PX-5 was 0.07%, and the content of by-products PX-51 and PX-53 was 0.61%.

[0083] Example 22: Preparation of perfluoropolyether acyl fluoride PX-52 The preparation method was the same as in Example 1, except that the amount of PX-5 used was 792,000 g, the molar ratio of PX-5, KF, and HFPO was 1:1:2.2, the mass ratio of KF to diethylene glycol dimethyl ether was 3:10, and the reaction was carried out at 1.2 m 3 The reaction is carried out inside the reactor.

[0084] The content was determined according to the test method in Example 1, wherein the content of PX-52 was 95.6%, the content of raw material PX-5 was 0.07%, and the content of by-products PX-51 and PX-53 was 0.22%. The content of by-product HFPO dimer was 2.3%.

[0085] Example 23: Preparation of perfluoropolyether acyl fluoride PX-52 The preparation method is the same as in Example 21, except that the reaction temperature is controlled at -30 to -25 °C.

[0086] The content was determined according to the test method of Example 1, wherein the content of PX-52 was 99.2%, the content of raw material PX-6 was 0.07%, and the total content of by-products PX-51 and PX-53 was 0.42%.

[0087] Example 24: Preparation of perfluoropolyether acyl fluoride PX-62 The preparation method was the same as in Example 15, except that the amount of PX-6 used was 447,000 g, the molar ratio of PX-6, KF, and HFPO was 1:1:2, the mass ratio of KF to diethylene glycol dimethyl ether was 1.5:10, and the reaction was carried out at 1.2 m 3 The reaction is carried out inside the reactor.

[0088] The content was determined according to the test method of Example 1, wherein the content of PX-62 was 98.7%, the content of raw material PX-6 was 0.07%, and the total content of by-products PX-61 and PX-63 was 0.61%.

[0089] Example 25: Preparation of perfluoropolyether fluoride PX-62 The preparation method is the same as in Example 15, except that the reaction temperature is controlled at -30 to -25 °C.

[0090] The content was determined according to the test method of Example 1, wherein the content of PX-62 was 99.2%, the content of raw material PX-6 was 0.07%, and the total content of by-products PX-61 and PX-63 was 0.22%.

[0091] Example 26: Preparation of perfluoropolyether P-63 The perfluoropolyether fluoride PX-63 (550 kg) prepared in Example 20 was transferred to a reactor resistant to hydrogen fluoride and fluorine corrosion. A fluorine-nitrogen mixture containing 20% ​​(v / v) fluorine was continuously introduced into the reactor at 210 °C at a rate of 93 L / min for 15 h. The final product was purified to obtain 525 kg of perfluoropolyether with a yield of 97.8%.

[0092] The content was determined according to the test method of Example 1, wherein the structure is CF3O(CF2O). n CF2CF2O(CF(CF3)CF2O) m The content of CF2CF3 (where n=6, m=2, denoted as P-63) is 96.5%, the content of byproduct P-61 is 0.07%, and the content of P-62 is 1.58%.

[0093] Example 27: Preparation of perfluoropolyether P-52 The perfluoropolyether acyl fluoride PX-52 (650 kg) prepared in Example 21 was transferred to a reactor resistant to hydrogen fluoride and fluorine corrosion. A fluorine-nitrogen mixture containing 20% ​​(v / v) fluorine was continuously introduced into the reactor at 200 °C at a rate of 93 L / min for 15 h. The final product was purified to obtain 613 kg of perfluoropolyether, with a yield of 97.3%.

[0094] The content was determined according to the test method of Example 1, wherein the structure is CF3O(CF2O). n CF2CF2O(CF(CF3)CF2O) m The content of CF2CF3 (where n=5, m=1, denoted as P-52) was 98.2%, and the total content of byproducts P-51 and P-52 was 0.42%.

[0095] Example 28: Preparation of perfluoropolyether P-52 The perfluoropolyether acyl fluoride PX-52 (650 kg) prepared in Example 21 was transferred to a reactor resistant to hydrogen fluoride and fluorine corrosion. A fluorine-nitrogen mixture containing 20% ​​(v / v) fluorine was continuously introduced into the reactor at 180 °C at a rate of 93 L / min for 15 h. The final product was purified to obtain 617 kg of perfluoropolyether with a yield of 97.88%.

[0096] The content was determined according to the test method of Example 1, wherein the content of P-52 was 98.2%, the total content of byproducts P-51 and P-52 was 0.42%, and trace amounts of PX-52 residue were present.

[0097] Example 29: Preparation of perfluoropolyether P-52 The perfluoropolyether acyl fluoride PX-52 (650 kg) prepared in Example 22 was transferred to a reactor resistant to hydrogen fluoride and fluorine corrosion. A fluorine-nitrogen mixture containing 20% ​​(v / v) fluorine was continuously introduced into the reactor at a rate of 93 L / min at 220 °C for 15 h. The final product was purified to obtain 612 kg of perfluoropolyether, with a yield of 97.1%.

[0098] The content was determined according to the test method of Example 1, wherein the content of P-52 was 98.2% and the total content of byproducts P-51 and P-52 was 0.42%.

[0099] Example 30: Preparation of perfluoropolyether P-52 The perfluoropolyether acyl fluoride PX-52 (650 kg) prepared in Example 23 was transferred to a reactor resistant to hydrogen fluoride and fluorine corrosion. A fluorine-nitrogen mixture containing 20% ​​(v / v) fluorine was continuously introduced into the reactor at 220 °C at a rate of 93 L / min for 15 h. The final product was purified to obtain 612 kg of perfluoropolyether, with a yield of 97.1%.

[0100] The content was determined according to the test method of Example 1, wherein the content of P-52 was 99.1% and the total content of byproducts P-51 and P-52 was 0.42%.

[0101] Example 31: Preparation of perfluoropolyether P-62 The perfluoropolyether acyl fluoride PX-62 (650 kg) prepared in Example 24 was transferred to a reactor resistant to hydrogen fluoride and fluorine corrosion. A fluorine-nitrogen mixture containing 20% ​​(v / v) fluorine was continuously introduced into the reactor at 210 °C at a rate of 93 L / min for 15 h. The final product was purified to obtain 614 kg of perfluoropolyether, with a yield of 97.2%.

[0102] The content was determined according to the test method of Example 1, wherein the content of P-62 was 99.1% and the total content of byproducts P-61 and P-63 was 0.42%.

[0103] Example 32: Preparation of perfluoropolyether P-62 The perfluoropolyether acyl fluoride PX-62 (650 kg) prepared in Example 25 was transferred to a reactor resistant to hydrogen fluoride and fluorine corrosion. A fluorine-nitrogen mixture containing 20% ​​(v / v) fluorine was continuously introduced into the reactor at 205 °C at a rate of 90 L / min for 15 h. The final product was purified to obtain 617 kg of perfluoropolyether, with a yield of 97.8%.

[0104] The content was determined according to the test method of Example 1, wherein the content of P-62 was 99.1% and the total content of byproducts P-61 and P-63 was 0.42%.

[0105] The boiling point, melting point and molecular weight of the products P-52, P-63 and P-62 of the above embodiments were tested, and the results are shown in Table 1.

[0106] Table 1: Structure and physical properties of perfluoropolyethers The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A perfluoropolyether, characterized in that, The structure of the perfluoropolyether is shown below: CF3O(CF2O) n CF2CF2O(CF(CF3)CF2O) m CF2CF3, Where n = 1~6, m = 1~3, and n > m.

2. The perfluoropolyether according to claim 1, characterized in that, The perfluoropolyether has a melting point ≤ -100 ℃ and a boiling point ≥ 190 ℃.

3. The method for preparing perfluoropolyether according to claim 1 or 2, characterized in that, Includes the following steps: (1) Using KF as a catalyst, CF3O(CF2O) n CF2COF and hexafluoropropylene oxide are reacted in an aprotic polar solvent to produce perfluoropolyether fluoride. (2) A fluorine-nitrogen mixture is introduced into a reactor containing the perfluoropolyether acyl fluoride obtained in step (1) to react and obtain perfluoropolyether.

4. The method for preparing perfluoropolyether according to claim 3, characterized in that, In step (1), the CF3O (CF2O) n The molar ratio of CF2COF, hexafluoropropylene oxide, and KF is 1:2~3:1~1.

5.

5. The method for preparing perfluoropolyether according to claim 3, characterized in that, In step (1), the aprotic polar solvent is diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, or tetraethylene glycol dimethyl ether.

6. The method for preparing perfluoropolyether according to claim 3, characterized in that, In step (1), the mass ratio of KF and aprotic polar solvent is 1~3:

10.

7. The method for preparing perfluoropolyether according to claim 3, characterized in that, In step (1), the temperature of the addition reaction is -30 to 10 °C.

8. The method for preparing perfluoropolyether according to claim 3, characterized in that, In step (1), the structure of the perfluoropolyether fluoride is CF3O(CF2O). n CF2CF2O(CF(CF3)CF2O) m CF(CF3)COF.

9. The method for preparing perfluoropolyether according to claim 3, characterized in that, In step (2), the molar ratio of fluorine gas to perfluoropolyether fluoride in the fluorine-nitrogen mixed gas is 1~1.75:

1.

10. The application of the perfluoropolyether according to claim 1 or 2 in the preparation of a heat carrier for low-temperature etching chip technology.

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