Perfluoropolyether and preparation method thereof
Perfluoropolyether is prepared through the oxidative polymerization reaction of hexafluoropropylene and the third monomer, which solves the complex and cost-effective synthesis problems in the prior art, and achieves high-performance and low-cost perfluoropolyether production.
Patent Information
- Application Number
- CN202510826833.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-19
- Publication Date
- 2025-08-08
AI Technical Summary
The existing perfluoropolyether synthesis methods are complex and have high production costs, making it difficult to achieve large-scale production.
Hexafluoropropylene, a third monomer (such as difluoroethylene oxide or trifluoropropylene) is used to mix with fluorine salts, and perfluoropolyester is prepared through oxidative polymerization, avoid the use of excessive oxygen, reduce the post-treatment process, and introduce C-O bonds to improve performance.
The prepared perfluoropolyethers have higher thermal stability and low temperature flow, simplifying the synthesis process and reducing production costs.
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of fluorine chemical industry, and in particular relates to a perfluoropolyether and a preparation method thereof. Background Art
[0002] Perfluoropolyether molecules contain only three elements: carbon (C), fluorine (F), and oxygen (O). They exhibit strong chemical inertness to most corrosive chemicals, such as acids, bases, and oxidants. They also possess excellent electrical insulation properties and a wide operating temperature range. Consequently, perfluoropolyethers are widely used in extreme operating conditions in industries such as aerospace, nuclear power, and machinery.
[0003] The synthesis methods of perfluoropolyethers include anionic ring-opening polymerization and photooxidative polymerization, among which K-type and D-type are anionic ring-opening polymerization, and Y-type and Z-type are photooxidative polymerization. The existing Y-type perfluoropolyether synthesis methods include the following types: 1. Using hexafluoropropylene, trifluorochloroethylene and a third monomer to synthesize perfluoropolyether, but its third monomer is obtained by reacting 1-allyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt, cysteamine, tributyl vinyl tin and triethylamine. The synthesis of the third monomer is relatively complicated and the cost of industrial production is high. 2. Using a supported metal compound catalyst to react with perfluoropolyether acyl fluoride, the catalyst and perfluoropolyether acyl fluoride raw materials are expensive, and the product is not suitable for large-scale production.
[0004] Therefore, there is a need in the art for a perfluoropolyether with simple synthesis and low product cost. Summary of the Invention
[0005] In view of the problems of complex synthesis methods and high production costs of perfluoropolyether in the prior art, the present invention provides a perfluoropolyether and a preparation method thereof.
[0006] The technical solutions adopted by the present invention to solve the above technical problems are as follows: In one aspect, the present invention provides a perfluoropolyether, the structural formula of the perfluoropolyether is shown in Formula 1, CF3O(C3F6O) m (CF2O) n (C x F 2x O) k CF3 formula 1; Among them, m+n+k=10~70, m / n=1~20, (m+n):k=(1~20):1, and m, n, k are all greater than 0, and x is 2~4.
[0007] Optionally, the perfluoropolyether has a molecular weight of 1300-10000 g / mol.
[0008] On the other hand, the present invention provides a method for preparing the perfluoropolyether as described above, comprising the following steps: mixing hexafluoropropylene, a third monomer, and a fluoride salt to obtain a mixed material; the third monomer comprises at least one of difluoroethylene oxide and trifluoropropylene oxide; continuously introducing oxygen into the mixture, and then conducting an oxidative polymerization reaction under ultraviolet light to obtain a crude product; The crude product is sequentially fluorinated and post-treated to obtain perfluoropolyether.
[0009] Optionally, the molar ratio of the hexafluoropropylene to the third monomer is (5-20): (1-3).
[0010] Optionally, the reaction temperature of the oxidative polymerization reaction is -60 to -80°C, the reaction time is 1 to 24 hours, and the reaction pressure is 50 kPa to 150 kPa; The wavelength of the ultraviolet light is 2000-3000 Å.
[0011] Optionally, the fluoride salt includes at least one of sodium fluoride, potassium fluoride, and cesium fluoride.
[0012] Optionally, the molar ratio of the fluoride salt to the third monomer is (1-3): (10-20).
[0013] Optionally, the oxygen introduction rate is 0-100 mL / min.
[0014] Optionally, the fluorination comprises the following steps: The crude product is fluorinated using a fluorine-nitrogen mixed gas at 120-200° C. for 12-18 hours; The molar ratio of fluorine gas to nitrogen in the fluorine-nitrogen mixed gas is (1-4): (1-9).
[0015] Optionally, the post-processing comprises the following steps: Washing the material obtained after fluorination until the acidity of the material is less than 10 ppm; The material is fractionally distilled to obtain perfluoropolyether.
[0016] In the present invention, compared with the perfluoropolyether synthesized without adding the third monomer, the proportion of CO bonds in the perfluoropolyether of the present application is increased, and the perfluoropolyether has higher thermal stability and better fluidity at low temperatures.
[0017] In addition, compared with the existing perfluoropolyether synthesis method, which involves photo-oxidative polymerization of hexafluoropropylene monomer with excess oxygen, the product obtained by this process will contain peroxide OO, which needs to be removed by light irradiation or high-temperature treatment in the post-treatment process. In the preparation process of the perfluoropolyether of the present invention, no excess oxygen is added. Instead, a third monomer, difluoroethylene oxide and / or trifluoropropylene oxide, is introduced to increase CO bonds to improve product performance. At the same time, no peroxide is generated during the reaction process, which reduces the post-treatment process, and the synthesis method is simple and the production cost is low. DETAILED DESCRIPTION
[0018] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.
[0019] An embodiment of the present invention provides a perfluoropolyether, the structural formula of the perfluoropolyether is shown in Formula 1, CF3O(C3F6O) m (CF2O) n (C x F 2x O) k CF3 formula 1; Among them, m+n+k=10~70, m / n=1~20, (m+n):k=(1~20):1, and m, n, k are all greater than 0, and x is 2~4.
[0020] In this embodiment, compared with the existing perfluoropolyether, the perfluoropolyether of the present application has an increased proportion of CO bonds, has higher thermal stability, and has better fluidity at low temperatures.
[0021] In some embodiments, the molecular weight of the perfluoropolyether is 1300-10000 g / mol. It is understood that perfluoropolyethers of different molecular weights can be fractionated to obtain perfluoropolyethers of corresponding molecular weights, and then the perfluoropolyethers can be divided into different grades of products according to different boiling points and viscosities.
[0022] One embodiment of the present invention provides a method for preparing the perfluoropolyether as described above, comprising the following steps: mixing hexafluoropropylene, a third monomer, and a fluoride salt to obtain a mixed material; wherein the third monomer comprises at least one of difluoroethylene oxide and trifluoropropylene oxide; continuously introducing oxygen into the mixture, and then conducting an oxidative polymerization reaction under ultraviolet light to obtain a crude product; The crude product is sequentially fluorinated and post-treated to obtain perfluoropolyether.
[0023] In this embodiment, compared to the existing perfluoropolyether synthesis method, that is, photo-oxidative polymerization of hexafluoropropylene monomer with excess oxygen, the product obtained by this process will have peroxide OO, which needs to be removed by light irradiation or high-temperature treatment in the post-treatment process. In the process of preparing the perfluoropolyether of the present invention, no excess oxygen is added, but a third monomer difluoroethylene oxide and / or trifluoropropylene oxide is introduced to increase CO bonds to improve product performance. At the same time, no peroxide is generated during the reaction process, the post-treatment process is reduced, the synthesis method is simple, and the production cost is low.
[0024] In one embodiment, the molar ratio of hexafluoropropylene to the third monomer is (5-20):(1-3). By adjusting the molar ratio of hexafluoropropylene to the third monomer, the CO bond ratio in the prepared perfluoropolyether is increased. At the same molecular weight, the perfluoropolyether of the present application has better thermal stability and better fluidity at low temperatures.
[0025] Specifically, the molar ratio of hexafluoropropylene to the third monomer includes, but is not limited to, 5:1, 5:2, 5:3, 10:1, 10:1.5, 10:3, 15:1, 15:2, 15:3, 20:1, 20:1.5 or 20:3.
[0026] In one embodiment, the reaction temperature of the oxidative polymerization reaction is -60 to -80°C, the reaction time is 1 to 24 hours, and the reaction pressure is 50 kPa to 150 kPa. Specifically, the oxidative polymerization reaction is carried out in a photochemical reactor.
[0027] The wavelength of the ultraviolet light is 2000-3000 Å.
[0028] Furthermore, before the oxidative polymerization reaction, hexafluoropropylene and the third monomer are mixed in advance according to a certain ratio and introduced into the reactor during the reaction to avoid uneven mixing of the reactants and deterioration of the synthesized perfluoropolyether chain segment structure.
[0029] In one embodiment, the fluoride salt includes at least one of sodium fluoride, potassium fluoride, and cesium fluoride. By selecting a fluoride salt as a catalyst, the introduction of other impurities during the reaction is avoided.
[0030] In one embodiment, the molar ratio of the fluoride salt to the third monomer is (1-3):(10-20). By adjusting the molar ratio of the third monomer to the fluoride salt within the above range, the third monomer and hexafluoropropylene can be polymerized.
[0031] To increase the CO bond content in the fluorinated polyether, in a preferred embodiment, the molar amount of the fluoride salt added is one tenth of that of the third monomer.
[0032] In one embodiment, the oxygen introduction rate is 0-100 mL / min. By controlling the oxygen introduction rate, excessive oxygen introduction is avoided, thereby preventing the formation of peroxides. Specifically, the oxygen introduction rate is related to the introduction rate of hexafluoropropylene. In a preferred embodiment, the oxygen introduction rate is 1 / 10 to 1 / 8 of the number of moles of hexafluoropropylene per hour.
[0033] In one embodiment, the fluorination comprises the following steps: The crude product is fluorinated using a fluorine-nitrogen mixed gas at 120-200° C. for 12-18 hours; The molar ratio of fluorine gas to nitrogen in the fluorine-nitrogen mixed gas is (1-4): (1-9).
[0034] In the fluorination reaction of this embodiment, the fluorination time is prolonged under low temperature conditions to fully react and obtain a structurally stable perfluoropolyether oil.
[0035] Specifically, the molar ratio of fluorine gas to nitrogen gas includes but is not limited to 1:1, 1:4, 1:9, 2.5:1, 2.5:4, 2.5:9, 4:1, 4:2 or 4:9.
[0036] To ensure complete fluorination, in a preferred embodiment, the molar ratio of fluorine gas to nitrogen gas is 1:4.
[0037] Furthermore, in one embodiment, the fluorination reaction is carried out in a collection tank, and the liquid crude product obtained by the oxidative polymerization reaction enters the collection tank. The collection tank is heated to 20° C., and the unreacted hexafluoropropylene is recovered in a condenser above the collection tank, thereby reducing raw material loss and saving costs.
[0038] In one embodiment, the post-processing comprises the following steps: Washing the material obtained after fluorination, specifically, washing with water until the acidity of the material is less than 10 ppm; The material is fractionally distilled to obtain perfluoropolyether.
[0039] The present invention is further described below with reference to the following examples.
[0040] Example 1 (1) Synthesis of perfluoropolyether Hexafluoropropylene, a third monomer, difluoroethylene oxide, and potassium fluoride were added to a photochemical reactor, with a molar ratio of hexafluoropropylene to the third monomer of 13:1 and a molar ratio of potassium fluoride to the third monomer of 1:10. After the reactor reached -60°C, stirring and a UV light source were activated. Oxygen was introduced through a coil at the bottom of the reactor at a rate of one-tenth the number of moles of hexafluoropropylene per hour. After 12 hours of reaction, oxygen was discontinued and the crude product was placed in a collection tank, which was then heated to room temperature to recover unreacted hexafluoropropylene.
[0041] (2) Post-processing A fluorination device is placed on the collection tank containing the crude product. Stirring is initiated. The fluorination temperature is 180°C and the pressure is 0.1-0.4 MPa. A fluorine-nitrogen mixture is introduced through a coil below the device, with a fluorine-to-nitrogen molar ratio of 1:4. The fluorination time is 12-18 hours. The fluorinated material is then washed with pure water in a water washing device, repeatedly washed until the acidity is below 10 ppm. The material is then distilled in a molecular distillation apparatus to obtain perfluoropolyether oils with different boiling ranges.
[0042] (3) Identification Nuclear magnetic resonance and infrared spectroscopy revealed a perfluoropolyether oil structure with m = 50, n = 15, k = 5, and an average molecular weight of 10,100 g / mol. Its kinematic viscosity at 20°C is 2,200 cSt, its pour point is -20°C, and its maximum operating temperature is 320°C.
[0043] Example 2 The process is basically the same as Example 1, except that the molar ratio of hexafluoropropylene to the third monomer difluoroethylene oxide is 6.5:1, the oxygen introduction rate is one eighth of the moles of hexafluoropropylene per hour, and the reaction time is 10 hours.
[0044] Nuclear magnetic resonance and infrared spectroscopy revealed a perfluoropolyether oil structure with m=35, n=30, and k=5, with an average molecular weight of 8500 g / mol. Its kinematic viscosity at 20°C is 1600 cSt, its pour point is -40°C, and its maximum operating temperature is 280°C.
[0045] Example 3 The process is essentially the same as Example 1, except that the molar ratio of hexafluoropropylene to the third monomer, trifluoropropylene oxide, is 11.5:1, the oxygen introduction rate is one-eighth the number of moles of hexafluoropropylene per hour, the fluorination temperature is 150° C., and the fluorination time is 18 hours.
[0046] Nuclear magnetic resonance and infrared spectroscopy revealed a perfluoropolyether oil structure with m=38, n=28, and k=4, with an average molecular weight of 8700 g / mol. Its kinematic viscosity at 20°C is 1800 cSt, its pour point is -30°C, and its maximum operating temperature is 290°C.
[0047] Example 4 The reaction was essentially the same as in Example 1, except that hexafluoropropylene was mixed with two third monomers (difluoroethylene oxide and trifluoropropylene oxide) at a molar ratio of 7.5:1:1, the oxygen introduction rate was one-eighth the number of moles of hexafluoropropylene per hour, and the reaction time was 16 hours. The fluorination temperature was 150°C, and the fluorination time was 18 hours.
[0048] Nuclear magnetic resonance and infrared spectroscopy revealed a perfluoropolyether oil structure with m=36, n=30, and k=4, with an average molecular weight of 8500 g / mol. Its kinematic viscosity at 20°C is 2000 cSt, its pour point is -36°C, and its maximum operating temperature is 320°C.
[0049] Example 5 The method is basically the same as Example 1, except that the molar ratio of hexafluoropropylene to the third monomer difluoroethylene oxide is 15:1.
[0050] Nuclear magnetic resonance and infrared spectroscopy revealed a perfluoropolyether oil structure with m=5, n=4, and k=1, and an average molecular weight of 2600 g / mol. Its kinematic viscosity at 20°C is 1400 cSt, its pour point is -28°C, and its maximum operating temperature is 270°C.
[0051] Example 6 The method is basically the same as Example 1, except that the molar ratio of hexafluoropropylene to the third monomer difluoroethylene oxide is 5:3.
[0052] Nuclear magnetic resonance and infrared spectroscopy revealed a perfluoropolyether oil structure with m=36, n=32, and k=2, with an average molecular weight of 8800 g / mol. Its kinematic viscosity at 20°C is 1700 cSt, its pour point is -35°C, and its maximum operating temperature is 290°C.
[0053] Example 7 The method is basically the same as Example 1, except that the molar ratio of hexafluoropropylene to the third monomer difluoroethylene oxide is 20:1.
[0054] Nuclear magnetic resonance and infrared spectroscopy revealed a perfluoropolyether oil structure with m=35, n=25, and k=3, with an average molecular weight of 9800 g / mol. Its kinematic viscosity at 20°C is 2100 cSt, its pour point is -45°C, and its maximum operating temperature is 300°C.
[0055] Comparative Example 1 The process is basically the same as Example 1, except that the third monomer is not added, and hexafluoropropylene and potassium fluoride are added to the photochemical reactor, wherein the molar ratio of hexafluoropropylene to potassium fluoride is 180:1.
[0056] Nuclear magnetic resonance and infrared spectroscopy revealed a perfluoropolyether oil structure with m=37, n=28, k=0, and an average molecular weight of 7800 g / mol. Its kinematic viscosity at 20°C is 2800 cSt, its pour point is -28°C, and its maximum operating temperature is 240°C.
[0057] It can be seen from the evaluation results of the above embodiments and comparative examples that the perfluoropolyether product produced by the present invention has better fluidity and thermal stability than that of the comparative example.
[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A perfluoropolyether, characterized in that The structural formula of the perfluoropolyether is shown in Formula 1, CF3O(C3F6O) m (CF2O) n (C x F 2x O) k CF3 Formula 1; Among them, m+n+k=10~70, m / n=1~20, (m+n):k=(1~20):1, and m, n, k are all greater than 0, and x is 2~4.
2. The perfluoropolyether according to claim 1, characterized in that The molecular weight of the perfluoropolyether is 1300-10000 g / mol.
3. The method for preparing a perfluoropolyether according to claim 1 or 2, wherein: The following steps are involved: Mixing hexafluoropropylene, a third monomer and a fluoride salt to obtain a mixed material; the third monomer comprises at least one of difluoroethylene oxide and trifluoropropylene oxide; continuously introducing oxygen into the mixture, and then conducting an oxidative polymerization reaction under ultraviolet light to obtain a crude product; The crude product is sequentially fluorinated and post-treated to obtain perfluoropolyether.
4. The method for preparing perfluoropolyether according to claim 3, wherein: The molar ratio of the hexafluoropropylene to the third monomer is (5-20): (1-3).
5. The method for preparing perfluoropolyether according to claim 3, wherein: The reaction temperature of the oxidative polymerization reaction is -60 to -80°C, the reaction time is 1 to 24 hours, and the reaction pressure is 50 kPa to 150 kPa; The wavelength of the ultraviolet light is 2000-3000 Å.
6. The method for preparing perfluoropolyether according to claim 3, wherein: The fluoride salt includes at least one of sodium fluoride, potassium fluoride and cesium fluoride.
7. The method for preparing perfluoropolyether according to claim 3, wherein: The molar ratio of the fluoride salt to the third monomer is (1-3): (10-20).
8. The method for preparing perfluoropolyether according to claim 3, wherein: The oxygen introduction rate is 0-100 mL / min.
9. The method for preparing perfluoropolyether according to claim 3, wherein: The fluorination comprises the following steps: The crude product is fluorinated using a fluorine-nitrogen mixed gas at 120-200° C. for 12-18 hours; The molar ratio of fluorine gas to nitrogen in the fluorine-nitrogen mixed gas is (1-4): (1-9).
10. The method for preparing perfluoropolyether according to claim 3, wherein: The post-processing comprises the following steps: Washing the material obtained after fluorination until the acidity of the material is less than 10 ppm; The material is fractionally distilled to obtain perfluoropolyether.