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CN-117586446-B - Method for preparing perfluoroether rubber by soap-free emulsion polymerization

CN117586446BCN 117586446 BCN117586446 BCN 117586446BCN-117586446-B

Abstract

The application provides a method for preparing perfluoroether rubber by soap-free emulsion polymerization, which aims to solve the problem that the conventional peroxide-vulcanized solvent-resistant perfluoroether rubber product is difficult to use at a high temperature of more than 310 ℃ for a long time and has poor heat resistance, and comprises the following steps of mixing deionized water, a first monomer and a pH regulator to obtain mixed liquid, heating the mixed liquid to a reaction temperature, introducing a second monomer and a third monomer into the mixed liquid to the reaction pressure, adding an initiator into the mixed liquid to perform polymerization reaction, obtaining emulsion after the reaction is finished, and performing post-treatment on the emulsion to obtain the perfluoroether rubber, wherein the first monomer is a compound shown as a formula 1, CF 2 ＝CFO(CF 2 ) nCOOH, wherein n is an integer of 1-4, the second monomer is tetrafluoroethylene, and the third monomer is perfluoroalkyl vinyl ether. The perfluoro ether rubber prepared by the preparation method provided by the application can be vulcanized by peroxide without using a crosslinking aid, so that a solvent-resistant perfluoro ether rubber product with more excellent heat resistance is obtained.

Inventors

  • MENG XIANGQING
  • Xue Danwei
  • CHEN ZHIFENG

Assignees

  • 福建海德福新材料有限公司

Dates

Publication Date
20260508
Application Date
20231128

Claims (10)

  1. 1. A method for preparing perfluoroether rubber by soap-free emulsion polymerization, which is characterized by comprising the following steps: Mixing deionized water, a first monomer and a pH regulator to obtain mixed liquid; Heating mixed liquid to a reaction temperature, introducing a second monomer and a third monomer into the mixed liquid to a reaction pressure, adding an initiator into the mixed liquid to perform polymerization reaction, obtaining emulsion after the reaction is finished, and performing post-treatment on the emulsion to obtain perfluoroether rubber; The first monomer is a compound shown in a formula 1, CF 2 ＝CFO(CF 2 ) nCOOH, formula 1 Wherein n is an integer of 1 to 4; The second monomer is tetrafluoroethylene, and the third monomer is perfluoroalkyl vinyl ether.
  2. 2. The method for preparing perfluoroether rubber by soap-free emulsion polymerization according to claim 1, wherein the reaction temperature is 70-90 ℃ and the reaction pressure is 2.0-3.0 mpa.
  3. 3. The method for preparing perfluoroether rubber by soap-free emulsion polymerization according to claim 1, wherein the step of introducing the second monomer and the third monomer to the mixed liquid to a reaction pressure, adding an initiator to the mixed liquid to perform polymerization, comprises the steps of: and introducing an initial mixed monomer containing a second monomer and a third monomer into the mixed liquid until the reaction pressure is 2.0-3.0 MPa, adding an initiator into the mixed liquid to perform polymerization reaction, continuously adding a complementary mixed monomer containing the second monomer and the third monomer in the reaction process, and maintaining the pressure at 2.0-3.0 MPa.
  4. 4. The method for producing a perfluoroether rubber by soap-free emulsion polymerization according to claim 3, wherein the molar ratio of the second monomer and the third monomer in the initial mixed monomer is (30-50): (50-70); In the additional mixed monomer, the molar ratio of the second monomer to the third monomer is (60-70): 30-40.
  5. 5. The method for preparing the perfluoroether rubber by soap-free emulsion polymerization according to claim 1, wherein the step of mixing deionized water, a first monomer and a pH regulator comprises the steps of adding the deionized water, the first monomer and the pH regulator into a reaction vessel, and evacuating and replacing until the oxygen content is less than or equal to 20ppm, wherein the addition amount of the deionized water is 40-60% of the volume of the reaction vessel; the resistivity of the deionized water is more than or equal to 18MΩ & M; the pH regulator is one or more selected from ammonium carbonate, ammonium bicarbonate, dipotassium hydrogen phosphate and disodium hydrogen phosphate, and the adding amount of the pH regulator is 0.01-0.5% of the mass of the deionized water; The addition amount of the first monomer is 0.05-0.8% of the mass of the deionized water.
  6. 6. The method for preparing perfluoroether rubber by soap-free emulsion polymerization according to claim 1 or 5, wherein the addition amount of the first monomer is 0.05-0.2% of the mass of deionized water; The pH regulator is ammonium carbonate; the addition amount of the pH regulator is 0.05-0.1% of the mass of the deionized water.
  7. 7. The method for preparing perfluoro ether rubber by soap-free emulsion polymerization according to claim 1, wherein the perfluoro alkyl vinyl ether is selected from the group consisting of C1-5 perfluoro alkyl vinyl ethers.
  8. 8. The method of soap-free emulsion polymerization to make perfluoroether rubber according to claim 1 or 7, wherein the perfluoroalkyl vinyl ether comprises one or more of PPVE, PEVE, PMVE.
  9. 9. The method for preparing perfluoroether rubber by soap-free emulsion polymerization according to claim 1, wherein the initiator is persulfate, and the addition amount of the initiator is 0.01% -0.02% of the mass of the deionized water; the initiator is added in a one-time adding mode, a batch adding mode or a continuous adding mode; The step of adding the initiator in batches comprises the steps of preparing the initiator into an aqueous solution to obtain an aqueous solution of the initiator, and adding the aqueous solution of the initiator every 25-35 min after the polymerization reaction starts.
  10. 10. The method for preparing perfluoroether rubber by soap-free emulsion polymerization according to claim 1, wherein the emulsion has a solid content of 15% -30%; The step of obtaining the perfluoroether rubber by post-treatment of the emulsion comprises the following steps of sequentially cooling, condensing, washing, drying and heat-treating the emulsion to obtain the perfluoroether rubber capable of being vulcanized by peroxide; in the cooling step, the emulsion is cooled to 20-25 ℃; The coagulation mode is to coagulate the emulsion by using 3wt% nitric acid aqueous solution; the washing solvent used for washing is deionized water, ethanol or a mixed solution of ethanol and water, wherein the mass ratio of the ethanol to the water in the mixed solution is (30-70) (70-30); the drying temperature is 95-105 ℃, and the drying time is 24-48 h; the temperature of the heat treatment is 280-320 ℃, and the heat treatment time is 25-60 min.

Description

Method for preparing perfluoroether rubber by soap-free emulsion polymerization Technical Field The invention belongs to the technical field of perfluoroether rubber, and particularly relates to a method for preparing perfluoroether rubber by soap-free emulsion polymerization. Background Perfluoroether rubbers have been widely used in various fields where application conditions are severe, for example, in O-rings, valve stem seals, shaft seals, gaskets, and the like, because of their excellent heat resistance, chemical resistance, and permeation resistance. The vulcanization system used in solvent-resistant perfluoroether rubbers greatly affects the properties of the final product, and the products obtained from peroxide vulcanization systems have the most extensive chemical resistance, whereas the co-crosslinking agents used affect the heat resistance of the final product, and the products obtained from currently used multi-functional co-crosslinking agents such as triallyl isocyanurate (TAIC), diolefins (as disclosed in patents such as EP661304, EP784064 and EP 769521) are difficult to use for a long period of time at a high temperature of 310 ℃ or more, and have poor heat resistance, which limits their use. Furthermore, solvent-resistant perfluoroether rubbers are generally obtained by emulsion polymerization in the presence of fluorinated surfactants, however, the use of fluorinated surfactants has an influence on the environment and their residue in the perfluoroether rubber has an influence on the purity, electrical and physical properties of the perfluoroether rubber. Disclosure of Invention The application aims to solve the problems that the traditional solvent-resistant perfluoroether rubber product vulcanized by peroxide is difficult to use at a high temperature of more than 310 ℃ for a long time and has poor heat resistance, and provides a method for preparing perfluoroether rubber by soap-free emulsion polymerization. In order to solve the technical problems, the application provides a method for preparing perfluoro ether rubber by soap-free emulsion polymerization, which comprises the following steps: Mixing deionized water, a first monomer and a pH regulator to obtain mixed liquid; Heating mixed liquid to a reaction temperature, introducing a second monomer and a third monomer into the mixed liquid to a reaction pressure, adding an initiator into the mixed liquid to perform polymerization reaction, obtaining emulsion after the reaction is finished, and performing post-treatment on the emulsion to obtain perfluoroether rubber; The first monomer is a compound shown in a formula 1, CF 2＝CFO(CF2) nCOOH, formula 1 Wherein n is an integer of 1 to 4; The second monomer is tetrafluoroethylene, and the third monomer is perfluoroalkyl vinyl ether. Preferably, the reaction temperature is 70-90 ℃, and the reaction pressure is 2.0-3.0 mpa. Preferably, the second monomer and the third monomer are introduced into the mixed liquid to the reaction pressure, and an initiator is added into the mixed liquid to perform the polymerization reaction, and the method specifically comprises the following steps: and introducing an initial mixed monomer containing a second monomer and a third monomer into the mixed liquid until the reaction pressure is 2.0-3.0 MPa, adding an initiator into the mixed liquid to perform polymerization reaction, continuously adding a complementary mixed monomer containing the second monomer and the third monomer in the reaction process, and maintaining the pressure at 2.0-3.0 MPa. Preferably, in the initial mixed monomer, the molar ratio of the second monomer to the third monomer is (30-50): (50-70); In the additional mixed monomer, the molar ratio of the second monomer to the third monomer is (60-70): 30-40. Preferably, the step of mixing deionized water, a first monomer and a pH regulator comprises the steps of adding the deionized water, the first monomer and the pH regulator into a reaction container, and evacuating and replacing until the oxygen content is less than or equal to 20ppm, wherein the addition amount of the deionized water is 40-60% of the volume of the reaction container; the resistivity of the deionized water is more than or equal to 18MΩ & M; the pH regulator is one or more selected from ammonium carbonate, ammonium bicarbonate, dipotassium hydrogen phosphate and disodium hydrogen phosphate, and the adding amount of the pH regulator is 0.01-0.5% of the mass of the deionized water; The addition amount of the first monomer is 0.05-0.8% of the mass of the deionized water. Preferably, the addition amount of the first monomer is 0.05-0.2% of the mass of the deionized water; The pH regulator is ammonium carbonate; the addition amount of the pH regulator is 0.05-0.1% of the mass of the deionized water. Preferably, the perfluoroalkyl vinyl ether is selected from perfluoroalkyl vinyl ethers having 1 to 5 carbon atoms. Preferably, the perfluoroalkyl vinyl ether comprises one or more