Fluororubber for high-temperature oxygen sensor and processing technology of fluororubber

Abstract

The invention relates to the technical field of rubber materials, and discloses fluororubber for a high-temperature oxygen sensor and a processing technology of the fluororubber. The processing technology comprises the following steps: S1, preparing fluorinated modified methyl vinyl silicone rubber from methyl vinyl silicone rubber and 1H, 1H, 2H, 2H-perfluorodecanethiol; s2, preparing glycerol modified silicone rubber from methyl vinyl silicone rubber and 1-thioglycerol; taking glycerol modified silicone rubber, adding into a mixed solvent of tetrahydrofuran and water, uniformly stirring, adding urea, heating, dropwise adding phosphoric acid, carrying out heat preservation reaction, removing the solvent, and drying to obtain phosphate modified methyl vinyl silicone rubber; and S3, adding the broken fluororubber, the fluorinated modified methyl vinyl silicone rubber and the phosphate modified methyl vinyl silicone rubber into an open mill, uniformly mixing, adding the composite filler and magnesium oxide, mixing, adding the vulcanizing agent and the assistant crosslinking agent, uniformly mixing, and vulcanizing to obtain the fluororubber for the high-temperature oxygen sensor.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of rubber materials and discloses fluorine rubber for high-temperature oxygen sensors and a processing technology thereof. BACKGROUND

[0002] High-temperature oxygen sensors are widely used in the fields of aerospace, metallurgy and chemical industry and play an important role in safe operation of equipment and production process control. Fluorine rubber has excellent performance due to the connection of fluorine atoms to carbon atoms in the chain segment and can be used for preparing sealing and insulating materials of high-temperature oxygen sensors.

[0003] The high-temperature oxygen sensor is often exposed to high temperature and strong oxidizing atmosphere during operation. The performance of the existing fluorine rubber material under the working condition still needs to be improved, for example, the mechanical strength is insufficient, leading to safety problems, and the service life is short due to easy aging at high temperature. Therefore, it is of great significance to study fluorine rubber for high-temperature oxygen sensors and a processing technology thereof, which has good mechanical strength, good high-temperature resistance and good heat aging resistance. SUMMARY

[0004] The application aims to provide fluorine rubber for high-temperature oxygen sensors and a processing technology thereof to solve the problems in the background.

[0005] In order to solve the above technical problems, the application provides the following technical scheme: a processing technology of fluorine rubber for high-temperature oxygen sensors, comprising the following steps:

[0006] 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 to initiate, and the solvent is removed and dried to obtain fluorinated modified methyl vinyl silicone rubber;

[0007] 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 to initiate, the solvent is removed and dried to obtain glycerol modified silicone rubber; the glycerol modified silicone rubber is taken out, added into a mixed solvent of tetrahydrofuran and water, stirred uniformly, urea is added, phosphoric acid is added dropwise under heating, and the reaction is carried out under heating, the solvent is removed and dried to obtain phosphoric acid ester modified methyl vinyl silicone rubber;

[0008] S3: the broken fluorine rubber, 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, composite fillers and magnesium oxide are added and mixed, a vulcanizing agent and a crosslinking aid are added and mixed uniformly, and vulcanization is carried out to obtain fluorine rubber for high-temperature oxygen sensors.

[0009] More preferably, the breaking process is as follows: the fluorine rubber 246 is broken by adjusting the roll gap of the open mill to 0.8 mm, the temperature is 50-70 DEG C, and the time is 5-15 min.

[0010] More optimally, the fluororubber for high-temperature oxygen sensor includes the following raw materials, calculated by mass: 60-70 parts of fluororubber, 20-25 parts of fluorinated modified methyl vinyl silicone rubber, 10-15 parts of phosphate modified methyl vinyl silicone rubber, 20-30 parts of composite filler, 5-8 parts of magnesium oxide, 2-5 parts of vulcanizing agent, and 0.3-0.5 parts of cross-linking agent.

[0011] More optimally, in the fluorinated modified methyl vinyl silicone rubber, the double bond content in the 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 the double bonds in the photoinitiator, 1H,1H,2H,2H-perfluorodecanethiol, and methyl vinyl silicone rubber is (0.01~0.02):(0.3~0.6):1.

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

[0013] The phosphate-modified methyl vinyl silicone rubber includes the following raw materials, calculated by mass: 10-15 parts of glycerin-modified silicone rubber, 60-80 parts of tetrahydrofuran, 20-30 parts of water, 10-15 parts of urea, and 10-15 parts of 85% phosphoric acid.

[0014] More optimally, the composite filler is a composition of silicon nitride, white carbon black, modified poss, and methacryloyloxypropyl poss;

[0015] The preparation of modified poss includes the following steps: taking trihydroxy heptaoctyl poss and sodium carbonate into tetrahydrofuran, adding dichlorooctadecanoic acid methyl ester, mixing evenly, reacting at 50-60°C for 3-5h, and removing the solvent to obtain modified poss.

[0016] More optimally, the molar ratio of trihydroxyheptaoctyl poss, dichlorooctadecanoic acid methyl ester, and sodium carbonate is 1: (1-1.5): (1-1.5).

[0017] More optimally, the mass ratio of silicon nitride, white carbon black, modified poss, and methacryloyloxypropyl poss is (10-15): (5-10): (1-3): (0.5-1).

[0018] More optimally, the vulcanizing agent is a combination of bis-25 and BIBP; and the auxiliary cross-linking agent is triallyl isocyanurate.

[0019] More optimally, silicon nitride is added after modification, specifically by adding silicon nitride to an ethanol aqueous solution 5 to 10 times its mass, adding vinyltrimethoxysilane 1 to 5% of the mass of silicon nitride, heating to 60 to 70°C and stirring for 4 to 6 hours, filtering out, washing with water, and drying to complete the modification;

[0020] The modified silica is added, and the specific steps are: adding silica to an ethanol aqueous solution 5 to 10 times its mass, adding vinyltrimethoxysilane 1 to 5% of the mass of silica, heating to 60 to 70°C and stirring for 4 to 6 hours, filtering out, washing with water, and drying, and the modification is completed.

[0021] More optimally, the double bond content in the methyl vinyl silicone rubber is 10%. The preparation steps are as follows: octamethylcyclotetrasiloxane and tetramethylammonium hydroxide pentahydrate at a molar ratio of 800:1 are uniformly mixed, stirred at 80° C. and nitrogen is introduced for 5 minutes, the system is evacuated to a negative pressure of -0.098 MPa, and the reaction is continued for 4 hours to obtain a catalyst;

[0022] Mix 90 mol of octamethylcyclotetrasiloxane and 10 mol of tetramethyltetravinylcyclotetrasiloxane, stir evenly at 80°C, introduce nitrogen, evacuate to -0.098 MPa to remove water for 1.5 hours, introduce nitrogen to restore the system to normal pressure, heat to 113°C, add 0.03 mol of catalyst and 0.06 mol of end-capping agent decamethyltetrasiloxane, keep warm and stir for 3 hours, heat to 163°C, turn off nitrogen, evacuate to -0.098 MPa to remove impurities for 2.5 hours, and obtain methyl vinyl silicone rubber with a double bond content of 10%.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: fluororubber 246, fluorinated modified methyl vinyl silicone rubber, and phosphate modified methyl vinyl silicone rubber are added to the fluororubber for high-temperature oxygen sensors, and the three are blended to obtain a rubber matrix with good mechanical properties, good high and low temperature resistance, and good aging resistance; in order to improve the compatibility problem between fluororubber and silicone rubber, methyl vinyl silicone rubber is fluorinated to obtain fluorinated modified methyl vinyl silicone rubber, which has good compatibility with the fluororubber matrix and does not require the addition of an additional compatibilizer. The fluorinated modified methyl vinyl silicone rubber itself can be used as a compatibilizer to improve the compatibility between fluororubber and phosphate modified methyl vinyl silicone rubber; the phosphorus-containing structure in phosphate modified methyl vinyl silicone rubber helps to improve the overall flame retardancy and heat stability, and also has a certain improvement effect on low-temperature flexibility; the addition ratio of the three needs to be controlled. Adding too little fluorinated modified methyl vinyl silicone rubber or adding too much phosphate modified methyl vinyl silicone rubber will lead to compatibility problems, affecting the overall performance;

[0024] The composite filler contains modified POSS and methacryloyloxypropyl POSS. The modified POSS is modified with methyl dichlorooctadecanoate, a chlorinated fatty acid ester, and is a good heat-resistant additive. The structure of POSS also helps to improve the mechanical properties and thermal stability of the rubber as a whole. The methacryloyloxypropyl POSS contains multiple double bonds and can be used as a cross-linking agent. The existing technology shows that when triallyl isocyanurate is used as a cross-linking agent, it is not stable enough under high temperature conditions. The Si-O bond energy in methacryloyloxypropyl POSS is larger and can form a more stable network structure. Therefore, this solution reduces the amount of triallyl isocyanurate added and uses methacryloyloxypropyl POSS to achieve the cross-linking effect. While using methacryloyloxypropyl POSS as a cross-linking agent, it can also improve the compatibility of the modified POSS in the composite filler with the overall structure. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0026] It should be noted that the raw materials involved in the present invention are purchased from any manufacturer without any special restrictions, and illustratively include: 1H,1H,2H,2H-perfluorodecanethiol (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); trihydroxyheptaoctyl poss (JH-P302); methyl dichlorooctadecanoate (CAS: 27986-38-5); fluororubber (fluororubber 246); magnesium oxide (Jiamusi ZHM-2); curing agent bis-25 (CAS: 78-63-7); curing agent BIBP (CAS: 2212-81-9); triallyl isocyanurate (CAS: 1025-15-6); 85% phosphoric acid (Shandong Jinyueyuan New Materials Co., Ltd.); silicon nitride (Si3N4-0020); white carbon black (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, the following are parts by mass and mass ratios;

[0028] The double bond content in the methyl vinyl silicone rubber is 10%. The preparation steps are as follows: octamethylcyclotetrasiloxane and tetramethylammonium hydroxide pentahydrate in a molar ratio of 800:1 are mixed evenly, stirred at 80°C and nitrogen is introduced for 5 minutes, evacuated to a negative pressure of -0.098 MPa, and the reaction is continued for 4 hours to obtain a catalyst; 90 mol of octamethylcyclotetrasiloxane and 10 mol of tetramethyltetravinylcyclotetrasiloxane are mixed, stirred evenly at 80°C, nitrogen is introduced, evacuated to -0.098 MPa to remove water for 1.5 hours, nitrogen is introduced to restore the system to normal pressure, 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 kept and stirred for 3 hours, the temperature is raised to 163°C, the nitrogen is turned off, the temperature is evacuated to -0.098 MPa to remove impurities for 2.5 hours, and a methyl vinyl silicone rubber with a double bond content of 10% is obtained;

[0029] Silicon nitride is added after modification, specifically by adding silicon nitride to a 50wt% ethanol aqueous solution 10 times its mass, adding vinyltrimethoxysilane 2% by mass of silicon nitride, heating to 60°C and stirring for 5h, filtering out, washing with water, and drying to complete the modification;

[0030] The modified silica is added in the following steps: adding silica to a 50wt% ethanol aqueous solution with a mass of 10 times the silica mass, adding vinyltrimethoxysilane with a mass of 2% of the silica mass, heating to 60°C and stirring for 5h, filtering out, washing with water, and drying to complete the modification;

[0031] Fluororubber breaking steps: adjust the roller distance of the open mill to 0.8mm to break the fluororubber, the temperature is 70℃, and the processing time is 10min;

[0032] Example 1: S1: 1 part of methyl vinyl silicone rubber was added to 10 parts of tetrahydrofuran, stirred evenly, 1-thioglycerol was added, stirred evenly, a photoinitiator, benzoin dimethyl ether, was added, and irradiated with 365 nm ultraviolet light for initiation for 6 minutes. The photoinitiator and unreacted small molecules were removed, the solvent was removed, and the product was dried to obtain a glycerol-modified silicone rubber; the molar ratio of the photoinitiator, 1-thioglycerol, and double bonds in the 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 of tetrahydrofuran and 30 parts of water, stir evenly, add 15 parts of urea, raise the temperature to 90°C, add 12 parts of 85% phosphoric acid dropwise over 40 minutes, keep the temperature for reaction for 3 hours, remove the solvent, and dry to obtain phosphate-modified methyl vinyl silicone rubber;

[0034] S3: Add 1 part of methyl vinyl silicone rubber to 10 parts of tetrahydrofuran, stir evenly, add 1H,1H,2H,2H-perfluorodecanethiol, stir evenly, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for 8 minutes, remove the photoinitiator 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-perfluorodecanethiol, and double bonds in methyl vinyl silicone rubber is 0.01:0.6:1;

[0035] S4: Take trihydroxy heptaoctyl poss, dichlorooctadecanoic acid methyl ester, and sodium carbonate in a molar ratio of 1:1:1, add trihydroxy heptaoctyl poss, dichlorooctadecanoic acid methyl ester, and tetrahydrofuran (6 times the total mass of sodium carbonate), mix well, react at 60°C for 5h, remove the solvent, and obtain modified poss;

[0036] S5: Silicon nitride, white carbon black, modified poss, and methacryloyloxypropyl poss in a mass ratio of 12:8:2:0.5 are mixed 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 into an open mill and mix evenly. Add 22.5 parts of composite filler and 6 parts of magnesium oxide, mix at 160°C for 1 hour, add 2 parts of vulcanizing agent bis-25, 1 part of vulcanizing agent BIBP, and 0.5 part of triallyl isocyanurate, mix evenly, 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 sensor.

[0038] Example 2: S1: 1 part of methyl vinyl silicone rubber was added to 10 parts of tetrahydrofuran, stirred evenly, 1-thioglycerol was added, stirred evenly, a photoinitiator, benzoin dimethyl ether, was added, and irradiated with 365 nm ultraviolet light for initiation for 6 minutes. The photoinitiator and unreacted small molecules were removed, the solvent was removed, and the product was dried to obtain a glycerol-modified silicone rubber; the molar ratio of the photoinitiator, 1-thioglycerol, and double bonds in the methyl vinyl silicone rubber was 0.01:0.6:1;

[0039] S2: Take 15 parts of glycerol-modified silicone rubber, add it to a mixed solvent of 70 parts of tetrahydrofuran and 30 parts of water, stir evenly, add 10 parts of urea, raise the temperature to 90°C, add 10 parts of 85% phosphoric acid dropwise over 40 minutes, keep the temperature and react for 3 hours, remove the solvent, and dry to obtain phosphate-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-perfluorodecanethiol, stir evenly, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for initiation for 8 minutes, remove the photoinitiator 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-perfluorodecanethiol, and double bonds in methyl vinyl silicone rubber is 0.01:0.6:1;

[0041] S4: Take trihydroxy heptaoctyl poss, dichlorooctadecanoic acid methyl ester, and sodium carbonate in a molar ratio of 1:1.5:1.5, add trihydroxy heptaoctyl poss, dichlorooctadecanoic acid methyl ester, and sodium carbonate in tetrahydrofuran (6 times the total mass), mix well, react at 60°C for 5h, remove the solvent, and obtain modified poss;

[0042] S5: Silicon nitride, white carbon black, modified poss, and methacryloyloxypropyl poss are mixed 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 into an open mill and mix evenly. Add 27 parts of composite filler and 6 parts of magnesium oxide, 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, 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 sensor.

[0044] Example 3: S1: 1 part of methyl vinyl silicone rubber was added to 10 parts of tetrahydrofuran, stirred evenly, 1-thioglycerol was added, stirred evenly, a photoinitiator, benzoin dimethyl ether, was added, and irradiated with 365 nm ultraviolet light for initiation for 6 minutes. The photoinitiator and unreacted small molecules were removed, the solvent was removed, and the product was dried to obtain a glycerol-modified silicone rubber; the molar ratio of the photoinitiator, 1-thioglycerol, and double bonds in the methyl vinyl silicone rubber was 0.01:0.8:1;

[0045] S2: Take 12 parts of glycerol-modified silicone rubber, add it to a mixed solvent of 70 parts of tetrahydrofuran and 30 parts of water, stir evenly, add 15 parts of urea, raise the temperature to 90°C, add 15 parts of 85% phosphoric acid dropwise over 40 minutes, keep the temperature and react for 3 hours, remove the solvent, and dry to obtain phosphate-modified methyl vinyl silicone rubber;

[0046] S3: Add 1 part of methyl vinyl silicone rubber to 10 parts of tetrahydrofuran, stir evenly, add 1H,1H,2H,2H-perfluorodecanethiol, stir evenly, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for initiation for 8 minutes, remove the photoinitiator 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-perfluorodecanethiol, and double bonds in methyl vinyl silicone rubber is 0.01:0.5:1;

[0047] S4: Take trihydroxy heptaoctyl poss, dichlorooctadecanoic acid methyl ester, and sodium carbonate in a molar ratio of 1:1:1, add trihydroxy heptaoctyl poss, dichlorooctadecanoic acid methyl ester, and tetrahydrofuran (6 times the total mass of sodium carbonate), mix well, react at 60°C for 5h, remove the solvent, and obtain modified poss;

[0048] S5: Silicon nitride, white carbon black, modified poss, and methacryloyloxypropyl poss in a mass ratio of 12:8:3:1 are mixed 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 into an open mill and mix evenly. Add 24 parts of composite filler and 6 parts of magnesium oxide, 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 sensor.

[0050] Comparative Example 1 (changing the amount of fluororubber, fluorinated modified methyl vinyl silicone rubber, and phosphate-modified methyl vinyl silicone rubber added, and the remaining method steps are consistent with Example 1): S1: 1 part of methyl vinyl silicone rubber is added to 10 parts of tetrahydrofuran, stirred evenly, 1-thioglycerol is added, stirred evenly, a photoinitiator benzoin dimethyl ether is added, and 365 nm ultraviolet light is irradiated for initiation for 6 minutes. The photoinitiator and unreacted small molecules are removed, the solvent is removed, and the product is dried to obtain a glycerol-modified silicone rubber; the molar ratio of the photoinitiator, 1-thioglycerol, and double bonds in the methyl vinyl silicone rubber is 0.01:0.8:1;

[0051] S2: Take 12 parts of glycerol-modified silicone rubber, add it to a mixed solvent of 70 parts of tetrahydrofuran and 30 parts of water, stir evenly, add 15 parts of urea, raise the temperature to 90°C, add 12 parts of 85% phosphoric acid dropwise over 40 minutes, keep the temperature for reaction for 3 hours, remove the solvent, and dry to obtain phosphate-modified methyl vinyl silicone rubber;

[0052] S3: 1 part of methyl vinyl silicone rubber was added into 10 parts of tetrahydrofuran, stirred uniformly, 1H, 1H, 2H, 2H-perfluorodecanethiol was added, stirred uniformly, photoinitiator benzpinacol was added, 365 nm ultraviolet light was irradiated for 8 min to initiate, the photoinitiator and unreacted small molecules were removed, the solvent was removed, dried, and fluorinated modified methyl vinyl silicone rubber was obtained; the molar ratio of photoinitiator, 1H, 1H, 2H, 2H-perfluorodecanethiol, and double bonds in methyl vinyl silicone rubber was 0.01:0.6:1;

[0053] S4: 1:1:1 molar ratio of trihydroxy heptadecyl poss, dichlorooctadecanoic acid methyl ester, and sodium carbonate was taken, added into 6 times the total mass of the above three substances of tetrahydrofuran, mixed uniformly, reacted at 60°C for 5 h, the solvent was removed, and modified poss was obtained;

[0054] S5: silicon nitride, white carbon black, modified poss, and methacryloyloxypropyl poss were mixed in a mass ratio of 12:8:2:0.5 to obtain a composite filler:

[0055] S6: 70 parts of broken fluororubber, 15 parts of fluorinated modified methyl vinyl silicone rubber, and 17 parts of phosphate modified methyl vinyl silicone rubber were added into an open mill and mixed uniformly, 22.5 parts of composite filler and 6 parts of magnesium oxide were added, mixed at 160°C for 1 h, 2 parts of vulcanizing agent bis-25, 1 part of vulcanizing agent BIBP, and 0.5 parts of triallyl isocyanurate were added and mixed uniformly, vulcanized at 10 MPa and 165°C for 15 min, and vulcanized at 200°C for 3 h to obtain fluororubber for high-temperature oxygen sensors.

[0056] Comparative Example 2 (without adding methacryloyloxypropyl poss, and the remaining method steps were consistent with those of Example 1): S1: 1 part of methyl vinyl silicone rubber was added into 10 parts of tetrahydrofuran, stirred uniformly, 1-thioglycerol was added, stirred uniformly, photoinitiator benzpinacol was added, 365 nm ultraviolet light was irradiated for 6 min to initiate, the photoinitiator and unreacted small molecules were removed, the solvent was removed, and glycerol modified silicone rubber was obtained; the molar ratio of photoinitiator, 1-thioglycerol, and double bonds in methyl vinyl silicone rubber was 0.01:0.8:1;

[0057] S2: 12 parts of glycerol modified silicone rubber were taken, added into a mixed solvent of 70 parts of tetrahydrofuran and 30 parts of water, stirred uniformly, 15 parts of urea were added, heated to 90°C, 12 parts of 85% phosphoric acid were added dropwise in 40 min, and the reaction was kept for 3 h, the solvent was removed, and dried to obtain phosphate 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-perfluorodecanethiol, stir evenly, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for initiation for 8 minutes, remove the photoinitiator 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-perfluorodecanethiol, and double bonds in methyl vinyl silicone rubber is 0.01:0.6:1;

[0059] S4: Take trihydroxyheptaoctyl poss, dichlorooctadecanoic acid methyl ester and sodium carbonate in a molar ratio of 1:1:1, add them into tetrahydrofuran (6 times the total mass of the above three substances), mix them evenly, react at 60°C for 5h, and remove the solvent to obtain modified poss;

[0060] S5: Silicon nitride, white carbon black and modified poss are mixed 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 into an open mill and mix evenly. Add 22.5 parts of composite filler and 6 parts of magnesium oxide, mix at 160°C for 1 hour, add 2 parts of vulcanizing agent bis-25, 1 part of vulcanizing agent BIBP, and 0.5 part of triallyl isocyanurate, mix evenly, 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 sensor.

[0062] Comparative Example 3 (methyl dichlorooctadecanoate was used instead of modified POSS, and the remaining steps were the same as those in Example 1): S1: 1 part of methyl vinyl silicone rubber was added to 10 parts of tetrahydrofuran, and the mixture was stirred evenly. 1-thioglycerol was added and stirred evenly. A photoinitiator, benzoin dimethyl ether, was added and the mixture was irradiated with 365 nm ultraviolet light for 6 minutes. 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 the photoinitiator, 1-thioglycerol, and double bonds in the 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 of tetrahydrofuran and 30 parts of water, stir evenly, add 15 parts of urea, raise the temperature to 90°C, add 12 parts of 85% phosphoric acid dropwise over 40 minutes, keep the temperature for reaction for 3 hours, remove the solvent, and dry to obtain phosphate-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-perfluorodecanethiol, stir evenly, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for initiation for 8 minutes, remove the photoinitiator 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-perfluorodecanethiol, and double bonds in methyl vinyl silicone rubber is 0.01:0.6:1;

[0065] S4: Silicon nitride, white carbon black, methyl dichlorooctadecanoate, and methacryloyloxypropyl poss are mixed 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 into an open mill and mix evenly. Add 22.5 parts of composite filler and 6 parts of magnesium oxide, mix at 160°C for 1 hour, add 2 parts of vulcanizing agent bis-25, 1 part of vulcanizing agent BIBP, and 0.5 part of triallyl isocyanurate, mix evenly, 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 sensor.

[0067] Comparative Example 4 (changing the amount of fluororubber, fluorinated modified methyl vinyl silicone rubber, and phosphate-modified methyl vinyl silicone rubber added, and the remaining method steps are consistent with Example 1): S1: 1 part of methyl vinyl silicone rubber is added to 10 parts of tetrahydrofuran, stirred evenly, 1-thioglycerol is added, stirred evenly, a photoinitiator benzoin dimethyl ether is added, and 365 nm ultraviolet light is irradiated for 6 minutes to initiate, the photoinitiator and unreacted small molecules are removed, the solvent is removed, and the product is dried to obtain glycerol-modified silicone rubber; the molar ratio of the double bonds in the photoinitiator, 1-thioglycerol, and methyl vinyl silicone rubber is 0.01:0.8:1;

[0068] S2: Take 12 parts of glycerol-modified silicone rubber, add it to a mixed solvent of 70 parts of tetrahydrofuran and 30 parts of water, stir evenly, add 15 parts of urea, raise the temperature to 90°C, add 12 parts of 85% phosphoric acid dropwise over 40 minutes, keep the temperature for reaction for 3 hours, remove the solvent, and dry to obtain phosphate-modified methyl vinyl silicone rubber;

[0069] S3: Add 1 part of methyl vinyl silicone rubber to 10 parts of tetrahydrofuran, stir evenly, add 1H,1H,2H,2H-perfluorodecanethiol, stir evenly, add photoinitiator benzoin dimethyl ether, irradiate with 365nm ultraviolet light for initiation for 8 minutes, 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-perfluorodecanethiol, and double bonds in methyl vinyl silicone rubber is 0.01:0.6:1;

[0070] S4: Take trihydroxyheptaoctyl poss, dichlorooctadecanoic acid methyl ester and sodium carbonate in a molar ratio of 1:1:1, add them into tetrahydrofuran (6 times the total mass of the above three substances), mix them evenly, react at 60°C for 5h, and remove the solvent to obtain modified poss;

[0071] S5: Silicon nitride, white carbon black, modified poss, and methacryloyloxypropyl poss in a mass ratio of 12:8:2:0.5 are mixed 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 into an open mill and mix evenly. Add 22.5 parts of composite filler and 6 parts of magnesium oxide, mix at 160°C for 1 hour, add 2 parts of vulcanizing agent bis-25, 1 part of vulcanizing agent BIBP, and 0.5 part 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 sensor.

[0073] Performance test: Take the fluororubber for high-temperature oxygen sensor prepared in Examples 1 to 3 and Comparative Examples 1 to 4; (1) refer to the standard GB / T528-2009 and test the tensile strength using a universal testing machine at a tensile speed of 500 mm / min; (2) age in an aging oven at 300°C for 100 h, remove, and let stand at room temperature for 30 h, obtain the aged sample, and test the tensile strength again; see Table 1 for details;

[0074] Table 1:

[0075]

[0076] Conclusion: In Comparative Example 1, the addition amounts of fluororubber, fluorinated modified methyl vinyl silicone rubber, and phosphate modified methyl vinyl silicone rubber are changed, and the fluorinated modified methyl vinyl silicone rubber is reduced, which reduces the compatibility of fluororubber and phosphate modified methyl vinyl silicone rubber, resulting in a decrease in performance; in Comparative Example 2, no methacryloyloxypropyl POSS is added, and the performance is not as good as that of the embodiment; in Comparative Example 3, methyl dichlorooctadecanoate is used instead of modified POSS, and the performance is decreased due to dispersibility and other problems; in Comparative Example 4, the addition amount of phosphate modified methyl vinyl silicone rubber is increased, which leads to a decrease in performance, so it can be seen that the addition amount needs to be controlled; in summary, the fluororubber for high-temperature oxygen sensor prepared by the present invention has good 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 aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A processing technology for fluororubber for high-temperature oxygen sensors, characterized by: The following steps are involved: S1: Add methyl vinyl silicone rubber to tetrahydrofuran and stir evenly, add 1H,1H,2H,2H-perfluorodecanethiol and stir evenly, add photoinitiator, irradiate with ultraviolet light, remove the solvent and dry to obtain fluorinated modified methyl vinyl silicone rubber; S2: adding methyl vinyl silicone rubber to tetrahydrofuran and stirring evenly, adding 1-thioglycerol, stirring evenly, adding a photoinitiator, irradiating with ultraviolet light, removing the solvent, and drying to obtain glycerol-modified silicone rubber; taking the glycerol-modified silicone rubber, adding it to a mixed solvent of tetrahydrofuran and water, stirring evenly, adding urea, heating and adding phosphoric acid dropwise, keeping the temperature to react, removing the solvent, and drying to obtain phosphate-modified methyl vinyl silicone rubber; S3: Add the broken fluororubber, fluorinated modified methyl vinyl silicone rubber, and phosphate modified methyl vinyl silicone rubber into an open mill and mix them evenly, add composite filler and magnesium oxide, mix them, add vulcanizing agent and cross-linking agent, mix them evenly, and vulcanize to obtain fluororubber for high-temperature oxygen sensor.

2. The processing technology of fluororubber for high-temperature oxygen sensor according to claim 1, characterized in that: The fluororubber for high-temperature oxygen sensors includes the following raw materials, calculated by mass: 60 to 70 parts of fluororubber, 20 to 25 parts of fluorinated modified methyl vinyl silicone rubber, 10 to 15 parts of phosphate-modified methyl vinyl silicone rubber, 20 to 30 parts of composite filler, 5 to 8 parts of magnesium oxide, 2 to 5 parts of vulcanizing agent, and 0.3 to 0.5 parts of cross-linking aid.

3. The processing technology of fluororubber for high-temperature oxygen sensor according to claim 1, characterized in that: In the fluorinated modified methyl vinyl silicone rubber, the double bond content 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 the double bond in the methyl vinyl silicone rubber is (0.01-0.02):(0.3-0.6):

1.

4. The processing technology of fluororubber for high-temperature oxygen sensor according to claim 1, characterized in that: In the glycerol-modified silicone rubber, the double bond content in the methyl vinyl silicone rubber is 10%; the mass ratio of the methyl vinyl silicone rubber to tetrahydrofuran is 1:(8-12); the molar ratio of the photoinitiator, 1-thioglycerol, and the double bond in the methyl vinyl silicone rubber is (0.01-0.02):(0.6-0.8):1; The phosphate-modified methyl vinyl silicone rubber includes the following raw materials, calculated by mass: 10 to 15 parts of glycerin-modified silicone rubber, 60 to 80 parts of tetrahydrofuran, 20 to 30 parts of water, 10 to 15 parts of urea, and 10 to 15 parts of phosphoric acid.

5. The processing technology of fluororubber for high-temperature oxygen sensor according to claim 1, characterized in that: The composite filler is a composition of silicon nitride, white carbon black, modified poss, and methacryloyloxypropyl poss; The preparation of modified poss includes the following steps: taking trihydroxy heptaoctyl poss and sodium carbonate into tetrahydrofuran, adding dichlorooctadecanoic acid methyl ester, mixing evenly, reacting at 50-60°C for 3-5h, and removing the solvent to obtain modified poss.

6. The processing technology of fluororubber for high-temperature oxygen sensor according to claim 5, characterized in that: The molar ratio of trihydroxy heptaoctyl poss, dichlorooctadecanoic acid methyl ester and sodium carbonate is 1: (1-1.5): (1-1.5).

7. The processing technology of fluororubber for high-temperature oxygen sensor according to claim 5, characterized in that: The mass ratio of silicon nitride, white carbon black, modified poss and methacryloyloxypropyl poss is (10-15): (5-10): (1-3): (0.5-1).

8. The processing technology of fluororubber for high-temperature oxygen sensor according to claim 1, characterized in that: The vulcanizing agent is a combination of bis-25 and BIBP; the auxiliary cross-linking agent is triallyl isocyanurate.

9. The processing technology of fluororubber for high-temperature oxygen sensor according to claim 5, characterized in that: Silicon nitride is added after modification, specifically by adding silicon nitride to an ethanol aqueous solution 5 to 10 times its mass, adding vinyltrimethoxysilane 1 to 5% of the mass of silicon nitride, heating to 60 to 70° C. and stirring for 4 to 6 hours, filtering out, washing with water, and drying to complete the modification; The modified silica is added, and the specific steps are: adding silica to an ethanol aqueous solution 5 to 10 times its mass, adding vinyltrimethoxysilane 1 to 5% of the mass of silica, heating to 60 to 70°C and stirring for 4 to 6 hours, filtering out, washing with water, and drying, and the modification is completed.

10. Fluororubber for high-temperature oxygen sensors prepared by the processing technology for fluororubber for high-temperature oxygen sensors according to any one of claims 1 to 9.

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