Fluororubber for high-temperature oxygen sensor and processing technology thereof

Abstract

The application relates to the technical field of rubber materials, and discloses fluorine rubber for high-temperature oxygen sensors and a processing technology thereof. The processing technology comprises the following steps: S1: fluorinated modified methyl vinyl silicone rubber is prepared from methyl vinyl silicone rubber and 1H, 1H, 2H, 2H-perfluorodecanethiol; S2: glycerol modified silicone rubber is prepared from methyl vinyl silicone rubber and 1-thioglycerol; the glycerol modified silicone rubber is taken, mixed uniformly in a mixed solvent of tetrahydrofuran and water, urea is added, phosphoric acid is added dropwise under heating, and the mixture is kept for reaction, the solvent is removed, and the mixture is dried to obtain phosphoric acid ester modified methyl vinyl silicone rubber; S3: the fluorine rubber after being broken, the fluorinated modified methyl vinyl silicone rubber and the phosphoric acid ester modified methyl vinyl silicone rubber are added into an open mill and mixed uniformly, a composite filler and magnesium oxide are added, mixing is carried out, a vulcanizing agent and a crosslinking aid are added, mixing is carried out uniformly, and vulcanization is carried out to obtain the fluorine rubber for high-temperature oxygen sensors.

Description

Technical Field

[0001] This invention relates to the field of rubber materials technology, and discloses a fluororubber for high-temperature oxygen sensors and its processing technology. Background Technology

[0002] High-temperature oxygen sensors are widely used in aerospace, metallurgy, chemical and other industries, playing a vital role in the safe operation of equipment and the control of production processes. Fluororubber segments, with carbon atoms bonded to fluorine atoms, possess excellent properties and can be used to prepare sealing and insulating materials for high-temperature oxygen sensors.

[0003] High-temperature oxygen sensors are frequently exposed to high temperatures and strong oxidizing atmospheres during operation. Existing fluororubber materials still have room for improvement in performance under these conditions, exhibiting issues such as insufficient mechanical strength leading to safety problems and susceptibility to aging at high temperatures resulting in short service life. Therefore, researching a fluororubber for high-temperature oxygen sensors with good mechanical strength, high-temperature resistance, and heat aging resistance, along with its processing technology, is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide a fluororubber for a high-temperature oxygen sensor and its processing technology, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a processing technology for fluororubber for high-temperature oxygen sensors, comprising the following steps:

[0006] S1: Add methyl vinyl silicone rubber to tetrahydrofuran and stir until uniform. Add 1H,1H,2H,2H-perfluorodecyl mercaptan and stir until uniform. Add a photoinitiator and initiate the reaction by ultraviolet light irradiation. Remove the solvent and dry to obtain fluorinated modified methyl vinyl silicone rubber.

[0007] S2: Add methyl vinyl silicone rubber to tetrahydrofuran and stir until homogeneous. Add 1-thioglycerol and stir until homogeneous. Add a photoinitiator and initiate the reaction by ultraviolet light irradiation. Remove the solvent and dry to obtain glycerol-modified silicone rubber. Take the glycerol-modified silicone rubber and add it to a mixed solvent of tetrahydrofuran and water. Stir until homogeneous. Add urea, heat and add phosphoric acid dropwise. Keep the reaction at this temperature. Remove the solvent and dry to obtain phosphate-modified methyl vinyl silicone rubber.

[0008] S3: Add the broken fluororubber, fluorinated modified methyl vinyl silicone rubber, and phosphate modified methyl vinyl silicone rubber to a two-roll mill and mix evenly. Add composite filler and magnesium oxide, mix, add vulcanizing agent and crosslinking agent, mix evenly, and vulcanize to obtain fluororubber for high-temperature oxygen sensors.

[0009] A more optimized process for breaking down the rubber is as follows: the gap between the rollers of the open mill is adjusted to 0.8 mm to break down fluororubber 246 at a temperature of 50-70°C for 5-15 minutes.

[0010] In a more optimized manner, the fluororubber for the high-temperature oxygen sensor comprises the following raw materials, by mass parts: 60-70 parts fluororubber, 20-25 parts fluorinated modified methyl vinyl silicone rubber, 10-15 parts phosphate ester modified methyl vinyl silicone rubber, 20-30 parts composite filler, 5-8 parts magnesium oxide, 2-5 parts vulcanizing agent, and 0.3-0.5 parts co-crosslinking agent.

[0011] In a more optimized manner, the double bond content in the fluorinated modified methyl vinyl silicone rubber is 10%; the mass ratio of methyl vinyl silicone rubber to tetrahydrofuran is 1:(8-12); and the molar ratio of double bonds in the photoinitiator, 1H,1H,2H,2H-perfluorodecyl mercaptan, and methyl vinyl silicone rubber is (0.01-0.02):(0.3-0.6):1.

[0012] In a more optimized manner, the double bond content of methyl vinyl silicone rubber in glycerol-modified silicone rubber is 10%; the mass ratio of methyl vinyl silicone rubber to tetrahydrofuran is 1:(8-12); and the molar ratio of double bonds in photoinitiator, 1-thioglycerol, and methyl vinyl silicone rubber is (0.01-0.02):(0.6-0.8):1.

[0013] Phosphate-modified methyl vinyl silicone rubber comprises the following raw materials, by weight: 10-15 parts glycerol-modified silicone rubber, 60-80 parts tetrahydrofuran, 20-30 parts water, 10-15 parts urea, and 10-15 parts 85% phosphoric acid.

[0014] More preferably, the composite filler is a composition of silicon nitride, silica, modified POSS, and methacryloyloxypropyl POSS;

[0015] The preparation of modified POSS includes the following steps: trihydroxyheptaoctyl POSS and sodium carbonate are added to tetrahydrofuran, methyl dichlorooctadecanoate is added, the mixture is mixed evenly, and the reaction is carried out at 50-60℃ for 3-5 hours. The solvent is removed to obtain modified POSS.

[0016] The optimal molar ratio of trihydroxyheptaoctylposs, methyl dichlorooctadecanoate, and sodium carbonate is 1:(1-1.5):(1-1.5).

[0017] The optimal mass ratio of silicon nitride, silica, modified POSS, and methacryloyloxypropyl POSS is (10-15):(5-10):(1-3):(0.5-1).

[0018] In a more optimized manner, the vulcanizing agent is a combination of bis-25 and BIBP; the co-crosslinking agent is triallyl isocyanurate.

[0019] In a more optimized manner, silicon nitride is added after modification. The specific steps are as follows: add silicon nitride to an aqueous ethanol solution with a mass of 5 to 10 times its weight, add 1 to 5% of the silicon nitride mass of vinyltrimethoxysilane, heat to 60 to 70°C and stir for 4 to 6 hours, filter, wash with water and dry to complete the modification.

[0020] After modification, silica is added. The specific steps are as follows: silica is added to an ethanol aqueous solution with a mass of 5 to 10 times its weight, vinyltrimethoxysilane is added at a mass of 1 to 5% of silica, the temperature is raised to 60 to 70°C and stirred for 4 to 6 hours, filtered, washed with water and dried, and the modification is completed.

[0021] In a more optimized manner, the double bond content in the methyl vinyl silicone rubber is 10%. The preparation steps refer to the existing technology, specifically: octamethylcyclotetrasiloxane and tetramethylammonium hydroxide pentahydrate with a molar ratio of 800:1 are mixed evenly, stirred at 80°C and nitrogen gas is introduced for 5 min, vacuum is drawn to a negative pressure of -0.098 MPa, and the reaction is continued for 4 h to obtain the catalyst;

[0022] 90 mol of octamethylcyclotetrasiloxane and 10 mol of tetramethyltetravinylcyclotetrasiloxane were mixed and stirred at 80°C until homogeneous. Nitrogen gas was introduced, and the system was evacuated to -0.098 MPa for 1.5 h to remove water. After the system was restored to normal pressure by introducing nitrogen gas, the temperature was raised to 113°C, and 0.03 mol of catalyst and 0.06 mol of end-capping agent decamethyltetrasiloxane were added. The mixture was kept at this temperature and stirred for 3 h. The temperature was raised to 163°C, the nitrogen gas was turned off, and the system was evacuated to -0.098 MPa for 2.5 h to remove impurities, resulting in methyl vinyl silicone rubber with a double bond content of 10%.

[0023] Compared with the prior art, the beneficial effects achieved by this invention are as follows: Fluororubber 246, fluorinated modified methyl vinyl silicone rubber, and phosphate-modified methyl vinyl silicone rubber are added to the fluororubber used in high-temperature oxygen sensors. The blend of these three components yields a rubber matrix with good mechanical properties, good high and low temperature resistance, and good aging resistance. To improve the compatibility between fluororubber and silicone rubber, the methyl vinyl silicone rubber is fluorinated to obtain fluorinated modified methyl vinyl silicone rubber, which has good compatibility with the fluororubber matrix, eliminating the need for additional compatibilizers. Furthermore, the fluorinated modified methyl vinyl silicone rubber itself can act as a compatibilizer, improving the compatibility between fluororubber and phosphate-modified methyl vinyl silicone rubber. The phosphorus-containing structure in the phosphate-modified methyl vinyl silicone rubber helps improve the overall flame retardancy and heat resistance stability, and also has a certain improvement effect on low-temperature flexibility. The proportion of the three components needs to be controlled; too little fluorinated modified methyl vinyl silicone rubber or too much phosphate-modified methyl vinyl silicone rubber will lead to compatibility problems and affect the overall performance.

[0024] The composite filler contains modified POSS and methacryloyloxypropyl POSS. The modified POSS, modified with methyl dichlorooctadecanoate (MCD), a chlorinated fatty acid ester, is an excellent heat-resistant additive. The structure of POSS also helps improve the overall mechanical properties and thermal stability of the rubber. Methacryloxypropyl POSS contains multiple double bonds and can act as a co-crosslinking agent. Existing technology shows that triallyl isocyanurate is not stable enough at high temperatures when used as a co-crosslinking agent, while the Si-O bond energy in methacryloyloxypropyl POSS is larger, which can form a more stable network structure. Therefore, this scheme reduces the amount of triallyl isocyanurate added and uses methacryloyloxypropyl POSS to achieve the co-crosslinking effect. While acting as a co-crosslinking agent, methacryloyloxypropyl POSS can also improve the compatibility of the modified POSS in the composite filler with the whole. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] It should be noted that there are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: 1H,1H,2H,2H-perfluorodecyl mercaptan (Shanghai Yuanye S46155); photoinitiator (benzoin dimethyl ether CAS: 24650-42-8); 1-thioglycerol (CAS: 96-27-5); urea (CAS: 57-13-6); methacryloyloxypropyl poss (… POSS102); Ethanol (CAS: 64-17-5); Vinyltrimethoxysilane (CAS: 2768-02-7); Trihydroxyheptaoctylposs (JH-P302); Methyl dichlorooctadecanoate (CAS: 27986-38-5); Fluororubber (Fluororubber 246); Magnesium oxide (Jiamusi ZHM-2); Vulcanizing agent Bi-25 (CAS: 78-63-7); Vulcanizing agent BIBP (CAS: 2212-81-9); Triallyl isocyanurate (CAS: 1025-15-6); 85% phosphoric acid (Shandong Jinyueyuan New Material Co., Ltd.); Silicon nitride (Si3N4-0020); Silica (IOTAFINE) SIL518); Sodium carbonate (CAS: 497-19-8); Octamethylcyclotetrasiloxane (CAS: 556-67-2); Tetramethylammonium hydroxide pentahydrate (CAS: 10424-65-4); Tetramethyltetravinylcyclotetrasiloxane (CAS: 2554-06-5); Decamethyltetrasiloxane (CAS: 141-62-8);

[0027] Unless otherwise specified, all figures below are parts by weight or mass ratios.

[0028] The double bond content of methyl vinyl silicone rubber is 10%. The specific preparation steps are as follows: Octamethylcyclotetrasiloxane and tetramethylammonium hydroxide pentahydrate with a molar ratio of 800:1 are mixed evenly, stirred at 80°C and nitrogen gas is introduced for 5 min. The system is then evacuated to a negative pressure of -0.098 MPa and the reaction is continued for 4 h to obtain the catalyst. 90 mol of octamethylcyclotetrasiloxane and 10 mol of tetramethyltetravinylcyclotetrasiloxane are mixed, stirred evenly at 80°C, nitrogen gas is introduced, and the system is evacuated to -0.098 MPa to remove water for 1.5 h. After the system is restored to normal pressure by introducing nitrogen gas, the temperature is raised to 113°C, 0.03 mol of catalyst and 0.06 mol of end-capping agent decamethyltetrasiloxane are added, the temperature is maintained and stirred for 3 h, the temperature is raised to 163°C, the nitrogen gas is turned off, and the system is evacuated to -0.098 MPa to remove impurities for 2.5 h to obtain methyl vinyl silicone rubber with a double bond content of 10%.

[0029] The silicon nitride was modified and then added. The specific steps were as follows: silicon nitride was added to 50wt% ethanol aqueous solution at 10 times its mass, and 2% vinyltrimethoxysilane by mass of silicon nitride was added. The mixture was heated to 60℃ and stirred for 5 hours. After filtration, washing with water and drying, the modification was completed.

[0030] After modification, silica is added. The specific steps are as follows: silica is added to 50wt% ethanol aqueous solution at 10 times its mass, vinyltrimethoxysilane at 2% of the silica mass is added, the temperature is raised to 60℃ and stirred for 5 hours, filtered, washed with water and dried, and the modification is completed.

[0031] Breaking steps for fluororubber: Adjust the roll gap of the open mill to 0.8mm to break up the fluororubber at a temperature of 70℃ for 10 minutes.

[0032] Example 1: S1: 1 part of methyl vinyl silicone rubber was added to 10 parts of tetrahydrofuran and stirred evenly. 1-Thioglycerol was added and stirred evenly. Benzoin dimethyl ether, a photoinitiator, was added and irradiated with 365nm ultraviolet light for 6 min to initiate the reaction. The photoinitiator and unreacted small molecules were removed, the solvent was removed, and the mixture was dried to obtain glycerol-modified silicone rubber. The molar ratio of double bonds in the photoinitiator, 1-thioglycerol, and methyl vinyl silicone rubber was 0.01:0.8:1.

[0033] S2: Take 12 parts of glycerol-modified silicone rubber, add it to a mixed solvent of 70 parts tetrahydrofuran and 30 parts water, stir evenly, add 15 parts urea, heat to 90℃, add 12 parts of 85% phosphoric acid dropwise over 40 min, keep warm for 3 h, remove the solvent, dry, and obtain phosphate ester-modified methyl vinyl silicone rubber.

[0034] S3: Add 1 part of methyl vinyl silicone rubber to 10 parts of tetrahydrofuran, stir well, add 1H,1H,2H,2H-perfluorodecyl mercaptan, stir well, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for 8min to remove photoinitiator and unreacted small molecules, remove solvent, and dry to obtain fluorinated modified methyl vinyl silicone rubber; the molar ratio of double bonds in photoinitiator, 1H,1H,2H,2H-perfluorodecyl mercaptan, and methyl vinyl silicone rubber is 0.01:0.6:1;

[0035] S4: Take trihydroxyheptaoctylposs, methyl dichlorooctadecanoate, and sodium carbonate in a molar ratio of 1:1:1, add them to tetrahydrofuran in a mixture of 6 times the total mass of trihydroxyheptaoctylposs, methyl dichlorooctadecanoate, and sodium carbonate, mix well, react at 60°C for 5 hours, remove the solvent, and obtain the modified poss.

[0036] S5: Mix silicon nitride, silica, modified POSS, and methacryloyloxypropyl POSS in a mass ratio of 12:8:2:0.5 to obtain a composite filler.

[0037] S6: Add 65 parts of broken fluororubber, 25 parts of fluorinated modified methyl vinyl silicone rubber, and 12 parts of phosphate modified methyl vinyl silicone rubber to a two-roll mill and mix evenly. Add 22.5 parts of composite filler and 6 parts of magnesium oxide, and mix at 160°C for 1 hour. Add 2 parts of vulcanizing agent bis-25, 1 part of vulcanizing agent BIBP, and 0.5 parts of triallyl isocyanurate, mix evenly, and vulcanize at 10 MPa and 165°C for 15 minutes, and then vulcanize at 200°C for 3 hours to obtain fluororubber for high-temperature oxygen sensors.

[0038] Example 2: S1: Add 1 part of methyl vinyl silicone rubber to 10 parts of tetrahydrofuran, stir evenly, add 1-thioglycerol, stir evenly, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for 6 min to initiate, remove photoinitiator and unreacted small molecules, remove solvent, dry, and obtain glycerol modified silicone rubber; the molar ratio of double bonds in photoinitiator, 1-thioglycerol, and methyl vinyl silicone rubber is 0.01:0.6:1;

[0039] S2: Take 15 parts of glycerol-modified silicone rubber, add it to a mixed solvent of 70 parts tetrahydrofuran and 30 parts water, stir evenly, add 10 parts urea, heat to 90℃, add 10 parts of 85% phosphoric acid dropwise over 40 min, keep warm for 3 h, remove the solvent, dry, and obtain phosphate ester-modified methyl vinyl silicone rubber.

[0040] S3: Add 1 part of methyl vinyl silicone rubber to 10 parts of tetrahydrofuran, stir evenly, add 1H,1H,2H,2H-perfluorodecyl mercaptan, stir evenly, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for 8 min, remove photoinitiator and unreacted small molecules, remove solvent, dry, and obtain fluorinated modified methyl vinyl silicone rubber; the molar ratio of double bonds in photoinitiator, 1H,1H,2H,2H-perfluorodecyl mercaptan, and methyl vinyl silicone rubber is 0.01:0.6:1;

[0041] S4: Take trihydroxyheptaoctylposs, methyl dichlorooctadecanoate, and sodium carbonate in a molar ratio of 1:1.5:1.5, add them to tetrahydrofuran in a mass ratio of 6 times the total mass of trihydroxyheptaoctylposs, methyl dichlorooctadecanoate, and sodium carbonate, mix well, react at 60°C for 5 hours, remove the solvent, and obtain modified poss.

[0042] S5: Mix silicon nitride, silica, modified POSS, and methacryloyloxypropyl POSS in a mass ratio of 15:10:1:1 to obtain a composite filler.

[0043] S6: Add 70 parts of broken fluororubber, 25 parts of fluorinated modified methyl vinyl silicone rubber, and 10 parts of phosphate modified methyl vinyl silicone rubber to a two-roll mill and mix evenly. Add 27 parts of composite filler and 6 parts of magnesium oxide, and mix at 160°C for 1 hour. Add 2 parts of vulcanizing agent bis-25, 1 part of vulcanizing agent BIBP, and 0.5 parts of triallyl isocyanurate, mix evenly, and vulcanize at 10 MPa and 165°C for 15 minutes, and then vulcanize at 200°C for 3 hours to obtain fluororubber for high-temperature oxygen sensors.

[0044] Example 3: S1: Add 1 part of methyl vinyl silicone rubber to 10 parts of tetrahydrofuran, stir evenly, add 1-thioglycerol, stir evenly, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for 6 min to initiate, remove photoinitiator and unreacted small molecules, remove solvent, dry, and obtain glycerol modified silicone rubber; the molar ratio of double bonds in photoinitiator, 1-thioglycerol, and methyl vinyl silicone rubber is 0.01:0.8:1;

[0045] S2: Take 12 parts of glycerol-modified silicone rubber, add it to a mixed solvent of 70 parts tetrahydrofuran and 30 parts water, stir evenly, add 15 parts urea, heat to 90℃, add 15 parts 85% phosphoric acid dropwise over 40 min, keep warm for 3 h, remove the solvent, dry, and obtain phosphate ester-modified methyl vinyl silicone rubber.

[0046] S3: Add 1 part of methyl vinyl silicone rubber to 10 parts of tetrahydrofuran, stir well, add 1H,1H,2H,2H-perfluorodecyl mercaptan, stir well, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for 8 min, remove the photoinitiator and unreacted small molecules, remove the solvent, and dry to obtain fluorinated modified methyl vinyl silicone rubber; the molar ratio of double bonds in the photoinitiator, 1H,1H,2H,2H-perfluorodecyl mercaptan, and methyl vinyl silicone rubber is 0.01:0.5:1;

[0047] S4: Take trihydroxyheptaoctylposs, methyl dichlorooctadecanoate, and sodium carbonate in a molar ratio of 1:1:1, add them to tetrahydrofuran in a mixture of 6 times the total mass of trihydroxyheptaoctylposs, methyl dichlorooctadecanoate, and sodium carbonate, mix well, react at 60°C for 5 hours, remove the solvent, and obtain the modified poss.

[0048] S5: Mix silicon nitride, silica, modified POSS, and methacryloyloxypropyl POSS in a mass ratio of 12:8:3:1 to obtain a composite filler:

[0049] S6: Add 65 parts of broken fluororubber, 20 parts of fluorinated modified methyl vinyl silicone rubber, and 15 parts of phosphate modified methyl vinyl silicone rubber to a two-roll mill and mix evenly. Add 24 parts of composite filler and 6 parts of magnesium oxide, and mix at 160°C for 1 hour. Add 2 parts of vulcanizing agent bis-25, 1 part of vulcanizing agent BIBP, and 0.5 parts of triallyl isocyanurate, mix evenly, and vulcanize at 10 MPa and 165°C for 15 minutes, and then vulcanize at 200°C for 3 hours to obtain fluororubber for high-temperature oxygen sensors.

[0050] Comparative Example 1 (the amounts of fluororubber, fluorinated modified methyl vinyl silicone rubber, and phosphate modified methyl vinyl silicone rubber were changed, and the remaining steps were the same as in Example 1): S1: 1 part of methyl vinyl silicone rubber was added to 10 parts of tetrahydrofuran and stirred evenly. 1-Thioglycerol was added and stirred evenly. The photoinitiator dimethyl benzoate was added and irradiated with 365nm ultraviolet light for 6 min to initiate the reaction. The photoinitiator and unreacted small molecules were removed, the solvent was removed, and the mixture was dried to obtain glycerol modified silicone rubber. The molar ratio of double bonds in the photoinitiator, 1-thioglycerol, and methyl vinyl silicone rubber was 0.01:0.8:1.

[0051] S2: Take 12 parts of glycerol-modified silicone rubber, add it to a mixed solvent of 70 parts tetrahydrofuran and 30 parts water, stir evenly, add 15 parts urea, heat to 90℃, add 12 parts of 85% phosphoric acid dropwise over 40 min, keep warm for 3 h, remove the solvent, dry, and obtain phosphate ester-modified methyl vinyl silicone rubber.

[0052] S3: Add 1 part of methyl vinyl silicone rubber to 10 parts of tetrahydrofuran, stir evenly, add 1H,1H,2H,2H-perfluorodecyl mercaptan, stir evenly, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for 8 min, remove photoinitiator and unreacted small molecules, remove solvent, dry, and obtain fluorinated modified methyl vinyl silicone rubber; the molar ratio of double bonds in photoinitiator, 1H,1H,2H,2H-perfluorodecyl mercaptan, and methyl vinyl silicone rubber is 0.01:0.6:1;

[0053] S4: Take trihydroxyheptaoctylposs, methyl dichlorooctadecanoate, and sodium carbonate in a molar ratio of 1:1:1, add them to tetrahydrofuran, which is 6 times the total mass of the three substances, mix them evenly, react at 60°C for 5 hours, remove the solvent, and obtain the modified poss.

[0054] S5: Mix silicon nitride, silica, modified POSS, and methacryloyloxypropyl POSS in a mass ratio of 12:8:2:0.5 to obtain a composite filler.

[0055] S6: Add 70 parts of broken fluororubber, 15 parts of fluorinated modified methyl vinyl silicone rubber, and 17 parts of phosphate modified methyl vinyl silicone rubber to a two-roll mill and mix evenly. Add 22.5 parts of composite filler and 6 parts of magnesium oxide, and mix at 160°C for 1 hour. Add 2 parts of vulcanizing agent bis-25, 1 part of vulcanizing agent BIBP, and 0.5 parts of triallyl isocyanurate, mix evenly, and vulcanize at 10 MPa and 165°C for 15 minutes, and then vulcanize at 200°C for 3 hours to obtain fluororubber for high-temperature oxygen sensors.

[0056] Comparative Example 2 (without adding methacryloyloxypropyl poss, the remaining steps are the same as in Example 1): S1: Add 1 part of methyl vinyl silicone rubber to 10 parts of tetrahydrofuran, stir evenly, add 1-thioglycerol, stir evenly, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for 6 min to initiate, remove the photoinitiator and unreacted small molecules, remove the solvent, dry, and obtain glycerol modified silicone rubber; the molar ratio of double bonds in photoinitiator, 1-thioglycerol, and methyl vinyl silicone rubber is 0.01:0.8:1;

[0057] S2: Take 12 parts of glycerol-modified silicone rubber, add it to a mixed solvent of 70 parts tetrahydrofuran and 30 parts water, stir evenly, add 15 parts urea, heat to 90℃, add 12 parts of 85% phosphoric acid dropwise over 40 min, keep warm for 3 h, remove the solvent, dry, and obtain phosphate ester-modified methyl vinyl silicone rubber.

[0058] S3: Add 1 part of methyl vinyl silicone rubber to 10 parts of tetrahydrofuran, stir evenly, add 1H,1H,2H,2H-perfluorodecyl mercaptan, stir evenly, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for 8 min, remove photoinitiator and unreacted small molecules, remove solvent, dry, and obtain fluorinated modified methyl vinyl silicone rubber; the molar ratio of double bonds in photoinitiator, 1H,1H,2H,2H-perfluorodecyl mercaptan, and methyl vinyl silicone rubber is 0.01:0.6:1;

[0059] S4: Take trihydroxyheptaoctylposs, methyl dichlorooctadecanoate, and sodium carbonate in a molar ratio of 1:1:1, add them to tetrahydrofuran, which is 6 times the total mass of the three substances, mix them evenly, react at 60°C for 5 hours, remove the solvent, and obtain the modified poss.

[0060] S5: Mix silicon nitride, silica, and modified POSS in a mass ratio of 12:8:2.5 to obtain a composite filler.

[0061] S6: Add 65 parts of broken fluororubber, 25 parts of fluorinated modified methyl vinyl silicone rubber, and 12 parts of phosphate modified methyl vinyl silicone rubber to a two-roll mill and mix evenly. Add 22.5 parts of composite filler and 6 parts of magnesium oxide, and mix at 160°C for 1 hour. Add 2 parts of vulcanizing agent bis-25, 1 part of vulcanizing agent BIBP, and 0.5 parts of triallyl isocyanurate, mix evenly, and vulcanize at 10 MPa and 165°C for 15 minutes, and then vulcanize at 200°C for 3 hours to obtain fluororubber for high-temperature oxygen sensors.

[0062] Comparative Example 3 (methyl dichlorooctadecanoate replaced modified POSS, and the remaining steps were the same as in Example 1): S1: 1 part of methyl vinyl silicone rubber was added to 10 parts of tetrahydrofuran and stirred evenly. 1-Thioglycerol was added and stirred evenly. The photoinitiator dimethyl benzoate was added and irradiated with 365 nm ultraviolet light for 6 min to initiate the reaction. The photoinitiator and unreacted small molecules were removed, the solvent was removed, and the mixture was dried to obtain glycerol-modified silicone rubber. The molar ratio of double bonds in the photoinitiator, 1-thioglycerol, and methyl vinyl silicone rubber was 0.01:0.8:1.

[0063] S2: Take 12 parts of glycerol-modified silicone rubber, add it to a mixed solvent of 70 parts tetrahydrofuran and 30 parts water, stir evenly, add 15 parts urea, heat to 90℃, add 12 parts of 85% phosphoric acid dropwise over 40 min, keep warm for 3 h, remove the solvent, dry, and obtain phosphate ester-modified methyl vinyl silicone rubber.

[0064] S3: Add 1 part of methyl vinyl silicone rubber to 10 parts of tetrahydrofuran, stir evenly, add 1H,1H,2H,2H-perfluorodecyl mercaptan, stir evenly, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for 8 min, remove photoinitiator and unreacted small molecules, remove solvent, dry, and obtain fluorinated modified methyl vinyl silicone rubber; the molar ratio of double bonds in photoinitiator, 1H,1H,2H,2H-perfluorodecyl mercaptan, and methyl vinyl silicone rubber is 0.01:0.6:1;

[0065] S4: Mix silicon nitride, silica, methyl dichlorooctadecanoate, and methacryloyloxypropyl POSS in a mass ratio of 12:8:0.5:0.5 to obtain a composite filler.

[0066] S5: Add 65 parts of broken fluororubber, 25 parts of fluorinated modified methyl vinyl silicone rubber, and 12 parts of phosphate modified methyl vinyl silicone rubber to a two-roll mill and mix evenly. Add 22.5 parts of composite filler and 6 parts of magnesium oxide, and mix at 160°C for 1 hour. Add 2 parts of vulcanizing agent bis-25, 1 part of vulcanizing agent BIBP, and 0.5 parts of triallyl isocyanurate, mix evenly, and vulcanize at 10 MPa and 165°C for 15 minutes, and then vulcanize at 200°C for 3 hours to obtain fluororubber for high-temperature oxygen sensors.

[0067] Comparative Example 4 (the amounts of fluororubber, fluorinated modified methyl vinyl silicone rubber, and phosphate modified methyl vinyl silicone rubber were changed, and the remaining steps were the same as in Example 1): S1: 1 part of methyl vinyl silicone rubber was added to 10 parts of tetrahydrofuran and stirred evenly. 1-Thioglycerol was added and stirred evenly. The photoinitiator dimethyl benzoate was added and irradiated with 365nm ultraviolet light for 6 min to initiate the reaction. The photoinitiator and unreacted small molecules were removed, the solvent was removed, and the mixture was dried to obtain glycerol modified silicone rubber. The molar ratio of double bonds in the photoinitiator, 1-thioglycerol, and methyl vinyl silicone rubber was 0.01:0.8:1.

[0068] S2: Take 12 parts of glycerol-modified silicone rubber, add it to a mixed solvent of 70 parts tetrahydrofuran and 30 parts water, stir evenly, add 15 parts urea, heat to 90℃, add 12 parts of 85% phosphoric acid dropwise over 40 min, keep warm for 3 h, remove the solvent, dry, and obtain phosphate ester-modified methyl vinyl silicone rubber.

[0069] S3: Add 1 part of methyl vinyl silicone rubber to 10 parts of tetrahydrofuran, stir well, add 1H,1H,2H,2H-perfluorodecyl mercaptan, stir well, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for 8 min, remove the initiator and unreacted small molecules, remove the solvent, and dry to obtain fluorinated modified methyl vinyl silicone rubber; the molar ratio of photoinitiator, 1H,1H,2H,2H-perfluorodecyl mercaptan, and double bonds in methyl vinyl silicone rubber is 0.01:0.6:1;

[0070] S4: Take trihydroxyheptaoctylposs, methyl dichlorooctadecanoate, and sodium carbonate in a molar ratio of 1:1:1, add them to tetrahydrofuran, which is 6 times the total mass of the three substances, mix them evenly, react at 60°C for 5 hours, remove the solvent, and obtain the modified poss.

[0071] S5: Mix silicon nitride, silica, modified POSS, and methacryloyloxypropyl POSS in a mass ratio of 12:8:2:0.5 to obtain a composite filler.

[0072] S6: Add 65 parts of broken fluororubber, 25 parts of fluorinated modified methyl vinyl silicone rubber, and 18 parts of phosphate modified methyl vinyl silicone rubber to a two-roll mill and mix evenly. Add 22.5 parts of composite filler and 6 parts of magnesium oxide, and mix at 160°C for 1 hour. Add 2 parts of vulcanizing agent bis-25, 1 part of vulcanizing agent BIBP, and 0.5 parts of triallyl isocyanurate, mix evenly, and vulcanize at 10 MPa and 165°C for 15 minutes, and then vulcanize at 200°C for 3 hours to obtain fluororubber for high-temperature oxygen sensors.

[0073] Performance testing: Take the fluororubber for high-temperature oxygen sensors prepared in Examples 1-3 and Comparative Examples 1-4; (1) Test the tensile strength with a universal testing machine according to standard GB / T528-2009, with a tensile speed of 500 mm / min; (2) Aging in an aging chamber at 300℃ for 100 h, take it out, let it stand at room temperature for 30 h, and obtain the aged sample. Test the tensile strength again; see Table 1 for details.

[0074] Table 1:

[0075]

[0076] Conclusions: Comparative Example 1, by varying the amounts of fluororubber, fluorinated modified methyl vinyl silicone rubber, and phosphate-modified methyl vinyl silicone rubber, reduced the amount of fluorinated modified methyl vinyl silicone rubber, decreasing the compatibility of the fluororubber and phosphate-modified methyl vinyl silicone rubber, leading to a decline in performance. Comparative Example 2, without the addition of methacryloxypropyl POSS, showed inferior performance compared to the examples. Comparative Example 3, using methyl dichlorooctadecanoate instead of modified POSS, experienced a performance decline due to dispersibility issues. Comparative Example 4, by increasing the amount of phosphate-modified methyl vinyl silicone rubber, actually resulted in a performance decline, indicating that the amount added needs to be controlled. In summary, the fluororubber for high-temperature oxygen sensors prepared by this invention exhibits excellent mechanical properties and heat aging resistance.

[0077] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are 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 processing method of fluoroelastomer for high-temperature oxygen sensors, characterized by: It comprises the following steps: S1: methyl vinyl silicone rubber is added into tetrahydrofuran and stirred uniformly, 1H, 1H, 2H, 2H-perfluorodecanethiol is added and stirred uniformly, a photoinitiator is added, ultraviolet light is irradiated, the solvent is removed, and drying is performed to obtain fluorinated modified methyl vinyl silicone rubber; S2: methyl vinyl silicone rubber is added into tetrahydrofuran and stirred uniformly, 1-thioglycerol is added and stirred uniformly, a photoinitiator is added, ultraviolet light is irradiated, the solvent is removed, and drying is performed to obtain glycerol modified silicone rubber; the glycerol modified silicone rubber is taken, mixed solvents of tetrahydrofuran and water are added and stirred uniformly, urea is added, phosphoric acid is added dropwise under heating, and reaction is performed under heating, the solvent is removed, and drying is performed to obtain phosphoric acid ester modified methyl vinyl silicone rubber; S3: 60-70 parts of broken fluororubber, 20-25 parts of fluorinated modified methyl vinyl silicone rubber, and 10-15 parts of phosphoric acid ester modified methyl vinyl silicone rubber are added into an open mill and mixed uniformly, 20-30 parts of composite filler and 5-8 parts of magnesium oxide are added and mixed, 2-5 parts of vulcanizing agent and 0.3-0.5 part of auxiliary crosslinking agent are added and mixed uniformly, and vulcanization is performed to obtain fluororubber for high-temperature oxygen sensors. In the fluorinated modified methyl vinyl silicone rubber, the content of double bonds in the methyl vinyl silicone rubber is 10%, the mass ratio of the methyl vinyl silicone rubber to tetrahydrofuran is 1:(8-12), and the molar ratio of the photoinitiator, 1H, 1H, 2H, 2H-perfluorodecanethiol, and double bonds in the methyl vinyl silicone rubber is (0.01-0.02):(0.3-0.6):1; The composite filler is a combination of silicon nitride, white carbon black, modified poss, and methyl acryloyloxypropyl poss. The preparation of the modified poss comprises the following steps: trihydroxy heptaoctyl poss and sodium carbonate are added into tetrahydrofuran, methyldichlorooctadecanoate is added and mixed uniformly, reaction is performed at 50-60℃ for 3-5h, and the solvent is removed to obtain the modified poss; the molar ratio of trihydroxy heptaoctyl poss, methyldichlorooctadecanoate, and sodium carbonate is 1:(1-1.5):(1-1.5); The mass ratio of the silicon nitride, white carbon black, modified poss, and methyl acryloyloxypropyl poss is (10-15):(5-10):(1-3):(0.5-1).

2. The processing method of the fluoroelastomer for high-temperature oxygen sensors according to claim 1, characterized by: In the glycerol modified silicone rubber, the content of double bonds in the methyl vinyl silicone rubber is 10%, the mass ratio of the methyl vinyl silicone rubber to tetrahydrofuran is 1:(8-12), and the molar ratio of the photoinitiator, 1-thioglycerol, and double bonds in the methyl vinyl silicone rubber is (0.01-0.02):(0.6-0.8):

1. The phosphoric acid ester modified methyl vinyl silicone rubber comprises the following raw materials in parts by mass: 10-15 parts of glycerol modified silicone rubber, 60-80 parts of tetrahydrofuran, 20-30 parts of water, 10-15 parts of urea, and 10-15 parts of phosphoric acid.

3. The process for processing fluoroelastomer for high temperature oxygen sensor according to claim 1, wherein: The modified silicon nitride is added, and the specific steps are as follows: the silicon nitride is added into an ethanol aqueous solution with 5-10 times of the mass of the silicon nitride, 1-5% of vinyl trimethoxysilane of the mass of the silicon nitride is added, the temperature is increased to 60-70 DEG C, and stirring is performed for 4-6 hours; then, the modified silicon nitride is obtained by filtration, water washing and drying. The modified white carbon black is added, and the specific steps are as follows: the white carbon black is added into an ethanol aqueous solution with 5-10 times of the mass of the white carbon black, 1-5% of vinyl trimethoxysilane of the mass of the white carbon black is added, the temperature is increased to 60-70 DEG C, and stirring is performed for 4-6 hours; then, the modified white carbon black is obtained by filtration, water washing and drying.

4. The process for processing fluoroelastomer for high temperature oxygen sensor according to claim 1, wherein: The vulcanizing agent is a combination of bis-25 and BIBP; and the auxiliary crosslinking agent is triallyl isocyanurate.

5. The high-temperature oxygen sensor fluorine rubber prepared by the processing technology according to any one of claims 1-4.

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