Process for preparing perfluoropolyether from hexafluoropropylene

Abstract

The invention discloses a process for preparing perfluoropolyether from hexafluoropropylene, and relates to the field of fluorine-containing organic matters. The method comprises the following specific steps: introducing hexafluoropropylene, chlorotrifluoroethylene and a third monomer into a photochemical reaction kettle, continuously introducing high-purity oxygen, maintaining the pressure of the reaction kettle, reacting for 4-8 hours at a set temperature, and recovering an unreacted hexafluoropropylene monomer after the reaction is completed; feeding a product in the reaction kettle into a deoxidizing kettle, heating the deoxidizing kettle for deoxidizing, transferring the finished product to a rectification system, collecting a fraction at a target temperature, and hydrolyzing and washing to obtain the perfluoropolyether. The perfluoropolyether prepared by the method has excellent heat resistance, chemical stability and oxidation stability, and in addition, the method effectively improves the raw material conversion rate and the product yield.

Description

Technical Field

[0001] The invention relates to the field of fluorine-containing organic matter, in particular to a process for preparing perfluoropolyether from hexafluoropropylene. Background Art

[0002] Perfluoropolyether (PFPE, English name Perfluom Polyethers) was first studied in the 1960s. It is a special type of perfluoropolymer compound with an average molecular weight ranging from 500 to 15,000. There are only three elements C, F, and O in the molecule. It has the characteristics of heat resistance, oxidation resistance, radiation resistance, corrosion resistance, and non-flammability. It has been used as a very reliable lubricant in cutting-edge fields such as military, aerospace, and nuclear industry for decades. Today, perfluoropolyether is widely used in the fields of chemical industry, electronics, electrical appliances, machinery, nuclear industry, and aerospace.

[0003] The preparation method of perfluoropolyether polyurea grease and the preparation method of perfluoropolyether polyurea grease (Chinese patent application number: CN113583736A) include the following steps: (1) polymerizing hexafluoropropylene with oxygen to obtain a perfluoropolyether intermediate I with an acyl fluoride terminal group, the structural formula of which is

[0004]

[0005] wherein Rf is CF3-[O-CF(CF3)-CF2]m-(O-CF2)n-, m=20-60, n=10-30; (2) reacting the perfluoropolyether intermediate Ι obtained in step (1) with a dibasic organic amine to obtain an intermediate product ΙΙ;

[0006]

[0007] (3) reacting the intermediate product II obtained in step (2) with diisocyanate to obtain a perfluoropolyether polyurea compound III;

[0008]

[0009] (4) The perfluoropolyether polyurea compound II:II obtained in step (3) is mixed with a perfluoropolyether base oil and refined at a constant temperature to obtain a perfluoropolyether polyurea grease.

[0010] A binary copolymer perfluoropolyether and a preparation method thereof (Chinese patent application number: CN114456369A) discloses a preparation method as follows: first, adding perfluoro-n-pentadialkoxy cesium salt to a dry low-temperature and pressure-resistant polymerization reactor under an inert gas atmosphere, starting stirring and a low-temperature circulation bath, and after the system drops to the reaction temperature, first adding a certain amount of pure hexafluoropropylene to the reactor, and then adding pure tetrafluoroethylene oxide and perfluorooxetane monomers respectively, and reacting for a certain time after the addition is completed; then slowly heating the reaction solution to room temperature and reducing the pressure to remove the hexafluoropropylene; finally, using F2 to stabilize the synthesized polymer in a reactor resistant to hydrogen fluoride and fluorine gas corrosion to obtain the binary copolymer perfluoropolyether.

[0011] A production method of perfluoropolyether (Chinese patent application number: CN116715839A) comprises the following steps: 1) firstly, using hexafluoropropylene as a raw material, generating perfluoro-2-methyl-4-pentene and perfluoro-2-methyl-2-pentene through liquid phase polymerization; 2) then, in a polar aprotic solvent, converting perfluoro-2-methyl-4-pentene into perfluoro-2-methyl-2-pentene; 3) then using perfluoro-2-methyl-2-pentene as a raw material, obtaining a perfluoro-2-methyl-2-pentene solution, and passing it into a tubular reaction device for synthetic reaction to obtain a reaction product; 4) cooling the obtained reaction product, standing it for stratification, and distilling the lower layer to obtain the perfluoropolyether.

[0012] However, in the existing disclosed process for preparing perfluoropolyether, the product is doped with a lot of metal ions, which affects the subsequent use of the product; the product yield and conversion rate of the preparation process are poor, and the economic benefits need to be further improved. Summary of the invention

[0013] The main purpose of the present invention is to provide a process for preparing perfluoropolyether from hexafluoropropylene to overcome the shortcomings of the prior art.

[0014] Another object of the present invention is to provide perfluoropolyether (Y type) prepared by the above method.

[0015] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0016] The embodiment of the present invention provides a process for preparing perfluoropolyether from hexafluoropropylene, and the operation steps are as follows:

[0017] Step 1: Into a photochemical reactor, 20-30 parts of hexafluoropropylene, 1-3 parts of chlorotrifluoroethylene and 0.006-0.07 parts of a third monomer are introduced according to mass, high-purity oxygen is continuously introduced, the pressure of the reactor is maintained, the reaction is carried out at a set temperature for 4-8 hours, and after the reaction is completed, the unreacted hexafluoropropylene monomer is recovered;

[0018] Step 2: The product of the reactor is fed into the deoxygenation kettle, the deoxygenation kettle is heated up, and the product is transferred to the distillation system. The fractions at the target temperature are collected, and the perfluoropolyether is obtained through hydrolysis and washing.

[0019] Furthermore, the preparation method of the third monomer is:

[0020] In parts by mass, 2-5 parts of 1-allyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt, 10-17 parts of cysteamine, 0.02-0.5 parts of tributyl vinyl tin, 2-5 parts of triethylamine, and 120-130 parts of toluene are introduced into a reaction kettle, stirred at 70-90° C. for 30-100 minutes, and toluene is removed by reduced pressure distillation to obtain a third monomer.

[0021] Furthermore, in the step 1, the reaction pressure is 10-50 kPa.

[0022] Furthermore, the reaction temperature in step 1 is -35 to -65°C.

[0023] Furthermore, the ultraviolet light wavelength used in the photooxidation reaction in step 1 is 150-600nm, and the light source power is 200-600w.

[0024] Furthermore, in the step 2, the temperature of the deoxygenation kettle is 80-320° C., and the deoxygenation time is 32-64 hours.

[0025] Furthermore, in step 2, the target fraction temperature is 100-240°C.

[0026] Furthermore, in the hydrolysis operation step of step 2, the target temperature fraction product is added dropwise into high-purity water, and the temperature is controlled at 50-80°C.

[0027] Furthermore, in the washing step in step 2, the product is washed 3-6 times with 45-80° C. high-purity water.

[0028] The third monomer preparation mechanism:

[0029] First, the reaction mechanism of 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt with cysteamine involves a typical Michael addition reaction, in which the amine group of cysteamine performs a nucleophilic attack on the allyl double bond in 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt to form a new CN bond. Subsequently, through the thiol-vinyl addition reaction mechanism, the thiol group on cysteamine reacts with the remaining double bond in tributyl vinyl tin to further modify the third monomer.

[0030] Technical effect:

[0031] 1. Heat resistance: Due to its special chemical structure, perfluoropolyether has excellent high temperature resistance. After the introduction of the third monomer, its heat resistance can be further improved, making it stable at higher temperatures and suitable for applications in high temperature environments.

[0032] 2. Chemical stability: Perfluoropolyether itself has excellent chemical stability and is not easy to react with other chemicals. The addition of a third monomer may further enhance this stability, allowing perfluoropolyether to maintain its performance in harsh chemical environments.

[0033] 3. Oxidative stability: The oxidative stability of perfluoropolyether refers to its stability under oxidative conditions. The addition of a third monomer may enhance the antioxidant capacity of perfluoropolyether and extend its service life, making it particularly suitable for applications that require long-term exposure to oxidative environments.

[0034] 4. This method effectively improves the raw material conversion rate and product yield. DETAILED DESCRIPTION

[0035] In view of the deficiencies in the prior art, the inventor of this case, after long-term research and extensive practice, was able to propose the technical solution of the present invention. The technical solution, its implementation process and principle, etc. will be further explained as follows.

[0036] Example 1

[0037] A process for preparing perfluoropolyether from hexafluoropropylene, the operating steps of which are:

[0038] Step 1: introduce 20 kg of hexafluoropropylene, 1 kg of chlorotrifluoroethylene and 0.006 kg of the third monomer into a photochemical reactor, continuously introduce high-purity oxygen, maintain the pressure of the reactor, react at a set temperature for 4 hours, and recover the unreacted hexafluoropropylene monomer after the reaction is completed;

[0039] Step 2: The product of the reactor is fed into the deoxygenation kettle, the deoxygenation kettle is heated up, and the product is transferred to the distillation system. The fractions at the target temperature are collected, and the perfluoropolyether is obtained through hydrolysis and washing.

[0040] The preparation method of the third monomer is:

[0041] 2 kg of 1-allyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt, 10 kg of cysteamine, 0.02 kg of tributyl vinyl tin, 2 kg of triethylamine and 120 kg of toluene were introduced into a reaction kettle, stirred at 70° C. for 30 minutes, and toluene was removed by vacuum distillation to obtain a third monomer.

[0042] The reaction pressure in step 1 is 10 kPa.

[0043] The reaction temperature in the step 1 is -35°C.

[0044] The wavelength of ultraviolet light used in the photooxidation reaction in step 1 is 150nm, and the power of the light source is 200w.

[0045] In the step 2, the temperature of the deoxygenation kettle is 80° C., and the deoxygenation time is 64 hours.

[0046] The hydrolysis operation step in step 2 is as follows: the target temperature fraction product is added dropwise into high-purity water, and the temperature is controlled at 50°C.

[0047] In the washing step in step 2, the mixture is washed three times with 45° C. high-purity water.

[0048] Example 2

[0049] A process for preparing perfluoropolyether from hexafluoropropylene, the operating steps of which are:

[0050] Step 1: introduce 25 kg of hexafluoropropylene, 2 kg of chlorotrifluoroethylene and 0.02 kg of the third monomer into a photochemical reactor, continuously introduce high-purity oxygen, maintain the pressure of the reactor, react at a set temperature for 6 hours, and recover the unreacted hexafluoropropylene monomer after the reaction is completed;

[0051] Step 2: The product of the reactor is fed into the deoxygenation kettle, the deoxygenation kettle is heated up, and the product is transferred to the distillation system. The fractions at the target temperature are collected, and the perfluoropolyether is obtained through hydrolysis and washing.

[0052] The preparation method of the third monomer is:

[0053] 3 kg of 1-allyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt, 12 kg of cysteamine, 0.2 kg of tributyl vinyl tin, 3 kg of triethylamine and 125 kg of toluene were introduced into a reaction kettle, stirred at 80° C. for 55 minutes, and toluene was removed by vacuum distillation to obtain a third monomer.

[0054] The reaction pressure in step 1 is 25 kPa.

[0055] The reaction temperature in step 1 is -45°C.

[0056] The wavelength of ultraviolet light used in the photooxidation reaction in step 1 is 300nm, and the power of the light source is 350w.

[0057] In the step 2, the temperature of the deoxygenation kettle is 180° C., and the deoxygenation time is 48 hours.

[0058] The hydrolysis operation step in step 2 is as follows: the target temperature fraction product is added dropwise into high-purity water, and the temperature is controlled at 60°C.

[0059] In the washing step in step 2, the mixture is washed 4 times with 60° C. high-purity water.

[0060] Example 3

[0061] A process for preparing perfluoropolyether from hexafluoropropylene, the operating steps of which are:

[0062] Step 1: introduce 25 kg of hexafluoropropylene, 2 kg of chlorotrifluoroethylene and 0.05 kg of the third monomer into a photochemical reactor, continuously introduce high-purity oxygen, maintain the pressure of the reactor, react at a set temperature for 6 hours, and recover the unreacted hexafluoropropylene monomer after the reaction is completed;

[0063] Step 2: The product of the reactor is fed into the deoxygenation kettle, the deoxygenation kettle is heated up, and the product is transferred to the distillation system. The fractions at the target temperature are collected, and the perfluoropolyether is obtained through hydrolysis and washing.

[0064] The preparation method of the third monomer is:

[0065] 4 kg of 1-allyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt, 15 kg of cysteamine, 0.4 kg of tributyl vinyl tin, 4 kg of triethylamine and 125 kg of toluene were introduced into a reaction kettle, stirred at 80° C. for 75 minutes, and toluene was removed by vacuum distillation to obtain a third monomer.

[0066] The reaction pressure in step 1 is 40 kPa.

[0067] The reaction temperature in step 1 is -55°C.

[0068] The wavelength of ultraviolet light used in the photooxidation reaction in step 1 is 450nm, and the power of the light source is 500w.

[0069] In the step 2, the temperature of the deoxygenation kettle is 260° C., and the deoxygenation time is 40 hours.

[0070] The hydrolysis operation step in step 2 is: adding the target temperature fraction product dropwise into high-purity water, and the temperature is controlled at 70°C.

[0071] In the washing step in step 2, the mixture is washed 5 times with 70° C. high-purity water.

[0072] Example 4

[0073] A process for preparing perfluoropolyether from hexafluoropropylene, the operating steps of which are:

[0074] Step 1: 30 kg of hexafluoropropylene, 3 kg of chlorotrifluoroethylene and 0.07 kg of the third monomer are introduced into a photochemical reactor, high-purity oxygen is continuously introduced, the pressure of the reactor is maintained, and the reaction is carried out at a set temperature for 8 hours. After the reaction is completed, the unreacted hexafluoropropylene monomer is recovered;

[0075] Step 2: The product of the reactor is fed into the deoxygenation kettle, the deoxygenation kettle is heated up, and the product is transferred to the distillation system. The fractions at the target temperature are collected, and the perfluoropolyether is obtained through hydrolysis and washing.

[0076] The preparation method of the third monomer is:

[0077] 5 kg of 1-allyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt, 17 kg of cysteamine, 0.5 kg of tributyl vinyl tin, 5 kg of triethylamine and 130 kg of toluene were introduced into a reaction kettle, stirred at 90° C. for 100 minutes, and toluene was removed by vacuum distillation to obtain a third monomer.

[0078] The reaction pressure in step 1 is 50 kPa.

[0079] The reaction temperature in step 1 is -65°C.

[0080] The wavelength of ultraviolet light used in the photooxidation reaction in step 1 is 600nm, and the power of the light source is 600w.

[0081] In the step 2, the temperature of the deoxygenation kettle is 320° C., and the deoxygenation time is 32 hours.

[0082] The hydrolysis operation step in step 2 is: adding the target temperature fraction product dropwise into high-purity water, and the temperature is controlled at 80°C.

[0083] In the washing step in step 2, the mixture is washed 6 times with 80° C. high-purity water.

[0084] Comparative Example 1

[0085] This example is a comparative example of Example 1, which is basically the same as Example 1, except that the third monomer is not added.

[0086] Comparative Example 2

[0087] This example is a comparative example of Example 1, which is basically the same as Example 1, except that tributyl vinyl tin is not added during the preparation of the third monomer.

[0088] After calculation, the yield and conversion rate of the above embodiment are shown in the following table:

[0089] Yield % Conversion Rate % Example 1 85.5 99.91 Example 2 87.2 99.94 Example 3 86.9 99.93 Example 4 88.4 99.94 Comparative Example 1 82.9 99.87 Comparative Example 2 84.4 99.89

[0090] It can be seen from the test results of the above examples that the perfluoropolyether prepared by this method has a higher yield and raw material conversion rate.

[0091] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for preparing perfluoropolyether from hexafluoropropylene, the operating steps of which are: Step 1: Into a photochemical reactor, 20-30 parts of hexafluoropropylene, 1-3 parts of chlorotrifluoroethylene and 0.006-0.07 parts of a third monomer are introduced according to mass, high-purity oxygen is continuously introduced, the pressure of the reactor is maintained, the reaction is carried out at a set temperature for 4-8 hours, and after the reaction is completed, the unreacted hexafluoropropylene monomer is recovered; Step 2: The product from the reactor is discharged into a deoxygenation reactor, which is heated to deoxygenate. The product is transferred to a distillation system, and the fractions at the target temperature are collected. Perfluoropolyether is obtained through hydrolysis and washing.

2. The process for preparing perfluoropolyether from hexafluoropropylene according to claim 1, characterized in that: The preparation method of the third monomer in step 1 is: In parts by mass, 2-5 parts of 1-allyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt, 10-17 parts of cysteamine, 0.02-0.5 parts of tributyl vinyl tin, 2-5 parts of triethylamine, and 120-130 parts of toluene are introduced into a reaction kettle, stirred at 70-90° C. for 30-100 minutes, and toluene is removed by reduced pressure distillation to obtain a third monomer.

3. The process for preparing perfluoropolyether from hexafluoropropylene according to claim 1, characterized in that: The reaction pressure in step 1 is 10-50 kPa.

4. The process for preparing perfluoropolyether from hexafluoropropylene according to claim 1, characterized in that: The reaction temperature in step 1 is -35 to -65°C.

5. The process for preparing perfluoropolyether from hexafluoropropylene according to claim 1, characterized in that: The ultraviolet light wavelength used in the photooxidation reaction in step 1 is 150-600nm, and the light source power is 200-600w.

6. The process for preparing perfluoropolyether from hexafluoropropylene according to claim 1, characterized in that: In the step 2, the temperature of the deoxygenation kettle is 80-320° C., and the deoxygenation time is 32-64 hours.

7. The process for preparing perfluoropolyether from hexafluoropropylene according to claim 1, characterized in that: The target fraction temperature in step 2 is 100-240°C.

8. The process for preparing perfluoropolyether from hexafluoropropylene according to claim 1, characterized in that: The hydrolysis operation step in step 2 is: adding the target temperature fraction product dropwise into high-purity water, and the temperature is controlled at 50-80°C.

9. The process for preparing perfluoropolyether from hexafluoropropylene according to claim 1, characterized in that: In the washing step of step 2, the product is washed 3-6 times with 45-80° C. high-purity water.

Images