Fluororubber resistant to high-temperature water vapor and preparation method thereof
By using a rare-earth hybrid fluororubber raw material preparation method, the problem of insufficient aging resistance of fluororubber in high-temperature water vapor environment was solved, and the mechanical properties and high-temperature water vapor resistance of fluororubber were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHANGSHU 3F ZHENFU NEW MATERIALS CO LTD
- Filing Date
- 2026-02-28
- Publication Date
- 2026-05-12
AI Technical Summary
Existing fluororubber has insufficient aging resistance in high-temperature water vapor environments. In particular, it is prone to hydrolysis when exposed to high-temperature water vapor for a long time, which can lead to seal failure. Furthermore, uneven dispersion of nanofillers affects performance.
A method for preparing rare earth hybrid fluororubber raw rubber is adopted, which involves mixing modified rare earth complex solution with fluororubber emulsion in solution and utilizing the nanoscale dispersion advantage of emulsion to ensure uniform introduction of modifier, thereby preparing high-temperature water vapor resistant fluororubber.
It improves the mechanical properties and high-temperature water vapor resistance of fluororubber. The tensile strength retention rate and elongation at break are excellent after high-temperature aging, showing good resistance to high-temperature oxidation and high-temperature water vapor degradation.
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Figure CN122011634A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fluororubber technology, specifically to a fluororubber resistant to high-temperature water vapor and its preparation method. Background Technology
[0002] Fluororubber, especially vinylidene fluoride-hexafluoropropylene copolymer and perfluoroether rubber, is widely used in sealing components in aerospace, automotive, and petrochemical industries due to its excellent high-temperature resistance, oil resistance, and chemical resistance. In many harsh operating conditions, long-term exposure to high-temperature steam environments (such as steam pipelines, high-temperature reactors, and geothermal equipment) is one of the ultimate tests of the aging resistance of fluororubber materials. Under the synergistic effect of high-temperature steam, the material not only faces thermo-oxidative aging but also undergoes hydrolysis, leading to main chain breakage and cross-linking network destruction, ultimately causing seal failure.
[0003] Existing technologies have made many improvements to fluororubber. For example, Chinese patent CN116410555B discloses a preparation process for high-temperature resistant special fluororubber. Through in-situ polymerization, 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene and dianhydride monomers undergo in-situ polymerization grafting reaction on the surface of graphene to obtain fluorinated polyimide-grafted graphene. Finally, it is blended and modified with polyethylene wax, bisphenol AF, ethylene propylene rubber, etc., to obtain high-temperature resistant special fluororubber. After fluorinated polyimide grafting modification, graphene oxide has good compatibility with fluororubber, which improves the dispersion effect of graphene nanoparticles in fluororubber. At the same time, the surface-grafted fluorinated polyimide molecular chains have interaction forces with fluororubber, forming cross-linking sites. Under the synergistic effect, the mechanical strength and high-temperature resistance of fluororubber are improved, and excellent mechanical properties are maintained even at high temperatures.
[0004] However, it still has the following shortcomings in practical applications: 1. In the preparation process of high-temperature resistant special fluororubber, all solid / liquid raw materials are mixed at once on a two-roll mill. For blends with high amounts of nanofillers and rubber, it is difficult to ensure uniform dispersion, which will affect the performance of fluororubber. 2. Further efforts are needed to improve the resistance of fluororubber to high-temperature water vapor and its resistance to hydrolysis and aging.
[0005] Based on this, the present invention designs a fluororubber resistant to high temperature water vapor and its preparation method to solve the above problems. Summary of the Invention
[0006] In view of the above-mentioned shortcomings of the existing technology, the present invention provides a fluororubber resistant to high temperature water vapor and a method for preparing the same.
[0007] To achieve the above objectives, the present invention provides the following technical solution: A type of fluororubber resistant to high-temperature water vapor is obtained by mixing rare earth hybrid fluororubber raw rubber on a two-roll mill, adding additives and then vulcanizing. The rare earth hybrid fluororubber raw rubber is prepared from fluororubber emulsion and modified rare earth complex solution. The fluororubber emulsion and modified rare earth complex solution are mixed evenly. The total mass of rare earth elements in the modified rare earth complex solution accounts for 0.5~2% of the dry mass of the fluororubber emulsion. Then, the solid is precipitated by adjusting the pH and adding a coagulant. The solid is washed and dried to obtain the product. The modified rare earth complex solution is prepared by mixing a modified methacrylic acid solution and a rare earth salt solution; The modified methacrylic acid solution is prepared as follows: glycidyl methacrylate, a catalyst, and a polymerization inhibitor are added to methacrylic acid to form mixture A. Under nitrogen protection, mixture A is heated to 85-105°C and stirred continuously at 300-500 rpm for 4-6 hours. After the reaction is completed, the product is subjected to vacuum distillation at 60-80°C and -0.07-0.10 MPa to obtain modified methacrylic acid.
[0008] Furthermore, the fluororubber emulsion is a vinylidene fluoride-hexafluoropropylene copolymer emulsion or a perfluoroether rubber emulsion with a solid content of 20-30%.
[0009] Furthermore, in the preparation of the modified methacrylic acid solution, hydroquinone is used as the polymerization inhibitor and tetrabutylammonium bromide is used as the catalyst.
[0010] Furthermore, the rare earth salt solution is a rare earth nitrate solution, specifically one or more of cerium nitrate, neodymium nitrate, or lanthanum nitrate.
[0011] To better achieve the objectives of this invention, this invention also provides a method for preparing fluororubber resistant to high-temperature water vapor, specifically comprising the following steps: Step 1: Synthesis of Modified Methacrylic Acid Glycidyl methacrylate, hydroquinone, and tetrabutylammonium bromide were added to methacrylic acid to form mixture A. Under nitrogen protection, mixture A was heated to 85-105°C and stirred continuously at 300-500 rpm for 4-6 hours. After the reaction was completed, the product was subjected to vacuum distillation at 60-80°C and -0.07--0.10 MPa to obtain modified methacrylic acid. Step 2: Preparation of modified rare earth complex solution Under mechanical stirring, a rare earth salt solution is added dropwise to a modified methacrylic acid solution. The total mass of rare earth elements in the modified rare earth complex solution accounts for 0.5-2% of the dry mass of the fluororubber latex. The reaction is continued by stirring. After the reaction is completed, the modified rare earth complex solution is obtained. The rare earth salt solution is one or more of cerium nitrate solution, neodymium nitrate solution, or lanthanum nitrate solution; Step 3: Preparation of rare earth hybrid fluororubber raw material The modified rare earth complex solution is added to a fluororubber emulsion with a solid content of 20-30%. After stirring, the solid is precipitated by adjusting the pH and adding a coagulant. The solid is washed and dried to obtain rare earth hybrid fluororubber raw rubber. Step 4: Mixing and Vulcanization Rare earth hybrid fluororubber raw rubber is mixed on a two-roll mill, and after adding additives and vulcanizing, fluororubber resistant to high temperature water vapor is obtained.
[0012] Furthermore, the specific process of step 1 is as follows: Glycidyl methacrylate is added to methacrylic acid at a molar ratio of 1:0.5~1, and 0.5~2% by mass of tetrabutylammonium bromide as a catalyst and 50~200ppm of hydroquinone are added to form mixture A. After the reaction is completed, the mixture is distilled under reduced pressure to obtain modified methacrylic acid.
[0013] Furthermore, the specific process of step 2 is as follows: The modified methacrylic acid was dissolved in ethanol to obtain a modified methacrylic acid solution with a mass concentration of 5-20%. Rare earth nitrates are dissolved in deionized water to obtain a rare earth salt solution of 0.1~0.5 mol / L; Under mechanical stirring at 300-600 rpm, a rare earth salt solution is added dropwise to a modified methacrylic acid solution, such that the molar ratio of rare earth ions in the rare earth salt solution to carboxyl groups in the modified methacrylic acid solution is 1:2-6. After the addition is complete, the mixture is stirred and reacted at 40-60℃ for 95-145 min to obtain a modified rare earth complex solution.
[0014] Furthermore, the specific process of step 3 is as follows: A fluororubber latex with a solid content of 20-30% is preheated to 50-70°C. A modified rare earth complex solution is added to the fluororubber latex while stirring at 300-500 rpm. The total mass of rare earth elements in the modified rare earth complex solution accounts for 0.5-2% of the dry mass of the fluororubber latex. After the addition is complete, a mixture B is obtained. The mixture B is kept at a constant temperature and stirred for 90-120 minutes. Under continuous stirring at 300-400 rpm, 5-15% dilute ammonia solution was added dropwise to the stirred mixture B to adjust the pH of the system to 8.5-10.0. Stirring was then continued for 30-50 minutes. After stirring, 5-15 wt% calcium chloride solution was added as a coagulant, with the amount of calcium chloride solution being 5-15% of the volume of the fluororubber latex. Stirring was continued for 30-90 minutes to allow all solids to co-precipitate. Stirring was then stopped, and the supernatant was discarded after standing for 1-3 hours to obtain rubber particles. The precipitated rubber particles were repeatedly washed with hot deionized water at 60-80℃ until the conductivity of the washing filtrate was <10 μS / cm. The washed rubber particles were dried in a forced-air dryer at 70-90℃ for 24-36 hours to obtain rare earth hybrid fluororubber raw rubber.
[0015] Compared with the prior art, the beneficial effects of this invention are as follows: 1. The core modification steps of this invention are all carried out in solution, the reaction conditions are mild, the post-processing is simple, and the key hybridization process is completed in the aqueous fluororubber emulsion system. By utilizing the advantages of emulsion nanoscale dispersion, the uniform introduction of the modifier is ensured. 2. By complexing rare earth elements with modified methacrylic acid and then blending them with fluororubber emulsion, the resulting fluororubber exhibits excellent mechanical properties, resistance to high-temperature aging, and resistance to high-temperature water vapor. 3. The modification process of methacrylic acid and the proportion of modified rare earth complex solution in the raw rubber of rare earth hybrid fluororubber have a synergistic effect on the three indicators of tensile strength, tensile strength retention rate after heat aging at 250℃ and tensile strength retention rate after steam treatment at 200℃. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.
[0017] Figure 1 This is a process flow diagram for preparing fluororubber resistant to high-temperature water vapor according to the present invention. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0019] Example 1: A method for preparing a fluororubber resistant to high-temperature water vapor, specifically including the following steps: The process flow diagram for preparing high-temperature water vapor resistant fluororubber is as follows: Figure 1 As shown.
[0020] Step 1: Synthesis of Modified Methacrylic Acid Glycidyl methacrylate (GMA) was added to methacrylic acid (MAA) at a molar ratio of 1:0.5, along with 2% by mass of tetrabutylammonium bromide (TBAB) as a catalyst and 50 ppm of hydroquinone to form mixture A. Mixture A was heated to 105°C under nitrogen protection and stirred continuously at 300 rpm for 6 hours. After the reaction was completed, the product was subjected to vacuum distillation at 60°C and -0.10 MPa to remove unreacted monomers and a small amount of water, yielding modified methacrylic acid.
[0021] Step 2: Preparation of modified rare earth complex solution The modified methacrylic acid was dissolved in ethanol to obtain a modified methacrylic acid solution with a mass concentration of 5%.
[0022] Cerium nitrate was dissolved in deionized water to obtain a 0.1 mol / L rare earth salt solution.
[0023] Under mechanical stirring at 300 rpm, a rare earth salt solution was added dropwise to a modified methacrylic acid solution, such that the molar ratio of rare earth ions in the rare earth salt solution to carboxyl groups in the modified methacrylic acid solution was 1:6. After the addition was complete, the mixture was stirred and reacted at 40°C for 145 min to obtain a modified rare earth complex solution.
[0024] Step 3: Preparation of rare earth hybrid fluororubber raw material A fluororubber emulsion with a solid content of 20% was preheated to 70°C. The fluororubber emulsion was a vinylidene fluoride-hexafluoropropylene copolymer emulsion. A modified rare earth complex solution was added to the fluororubber emulsion while stirring at 300 rpm. The total mass of rare earth elements in the modified rare earth complex solution accounted for 2% of the dry mass of the fluororubber emulsion. After the addition was completed, a mixture B was obtained. The mixture B was kept at a constant temperature and stirred for another 90 minutes. Under continuous stirring at 300 rpm, 15% dilute ammonia solution was added dropwise to the stirred mixture B to make the pH of the system 8.5. Then, stirring was continued for 50 minutes. After stirring, 5 wt% calcium chloride solution was added as a coagulant. The amount of calcium chloride solution was 15% of the volume of the fluororubber latex. Stirring was continued for 30 minutes to allow all solids to co-precipitate. Then, stirring was stopped, and after standing for 3 hours, the supernatant was decanted to obtain rubber particles. The precipitated rubber particles were repeatedly washed with hot deionized water at 60°C until the conductivity of the washing filtrate was <10 μS / cm. The washed rubber particles were dried in a forced-air dryer at 90°C for 24 hours to obtain rare earth hybrid fluororubber raw rubber.
[0025] Step 4: Mixing and Vulcanization Rare earth hybrid fluororubber raw rubber is mixed on a two-roll mill, and after adding additives and vulcanizing, fluororubber resistant to high temperature water vapor is obtained.
[0026] Example 2: A method for preparing a fluororubber resistant to high-temperature water vapor, specifically including the following steps: Step 1: Synthesis of Modified Methacrylic Acid GMA was added to MAA at a molar ratio of 1:1, along with 0.5% TBAB (by mass of MAA) and 200 ppm hydroquinone to form mixture A. Mixture A was heated to 85°C under nitrogen protection and stirred continuously at 500 rpm for 4 hours. After the reaction was completed, the product was subjected to vacuum distillation at 80°C and -0.07 MPa to obtain modified methacrylic acid.
[0027] Step 2: Preparation of modified rare earth complex solution The modified methacrylic acid was dissolved in ethanol to obtain a modified methacrylic acid solution with a mass concentration of 20%.
[0028] Cerium nitrate and neodymium nitrate were dissolved in deionized water to obtain a 0.5 mol / L rare earth salt solution, wherein the molar ratio of cerium nitrate to neodymium nitrate was 1:1.
[0029] Rare earth salt solution was added dropwise to modified methacrylic acid solution under mechanical stirring at 600 rpm, so that the molar ratio of rare earth ions in rare earth salt solution to carboxyl groups in modified methacrylic acid solution was 1:2. After the addition was completed, the reaction was continued to be stirred at 60℃ for 95 min to obtain modified rare earth complex solution.
[0030] Step 3: Preparation of rare earth hybrid fluororubber raw material A fluororubber latex with a solid content of 30% was preheated to 50°C. The fluororubber latex was a perfluoroether rubber latex. A modified rare earth complex solution was added to the fluororubber latex while stirring at 500 rpm. The total mass of rare earth elements in the modified rare earth complex solution accounted for 0.5% of the dry rubber mass of the fluororubber latex. After the addition was completed, a mixture B was obtained. The mixture B was kept at a constant temperature and stirred for 120 min. Under continuous stirring at 400 rpm, 5% (w / w) dilute ammonia was added dropwise to the stirred mixture B to make the pH of the system 10.0. Stirring was then continued for 30 minutes. After stirring, 15 wt% calcium chloride solution was added as a coagulant. The amount of calcium chloride solution was 5% of the volume of the fluororubber latex. Stirring was continued for 90 minutes to allow all solids to co-precipitate. Stirring was then stopped, and the supernatant was discarded after standing for 1 hour to obtain rubber particles. The precipitated rubber particles were repeatedly washed with hot deionized water at 80°C until the conductivity of the washing filtrate was <10 μS / cm. The washed rubber particles were dried in a forced-air dryer at 70°C for 36 hours to obtain rare earth hybrid fluororubber raw rubber.
[0031] Step 4: Mixing and Vulcanization Rare earth hybrid fluororubber raw rubber is mixed on a two-roll mill, and after adding additives and vulcanizing, fluororubber resistant to high temperature water vapor is obtained.
[0032] Example 3: A method for preparing a fluororubber resistant to high-temperature water vapor, specifically including the following steps: Step 1: Synthesis of Modified Methacrylic Acid GMA was added to MAA at a molar ratio of 1:0.8, along with 1.5% TBAB (by mass of MAA) and 120 ppm hydroquinone to form mixture A. Mixture A was heated to 90°C under nitrogen protection and stirred continuously at 400 rpm for 5 hours. After the reaction was completed, the product was subjected to vacuum distillation at 65°C and -0.08 MPa to obtain modified methacrylic acid.
[0033] Step 2: Preparation of modified rare earth complex solution The modified methacrylic acid was dissolved in ethanol to obtain a modified methacrylic acid solution with a mass concentration of 10%.
[0034] Cerium nitrate, neodymium nitrate, and lanthanum nitrate were dissolved in deionized water to obtain a 0.25 mol / L rare earth salt solution, wherein the molar ratio of cerium nitrate, neodymium nitrate, and lanthanum nitrate was 1:1:1.
[0035] Rare earth salt solution was added dropwise to modified methacrylic acid solution under mechanical stirring at 450 rpm, so that the molar ratio of rare earth ions in rare earth salt solution to carboxyl groups in modified methacrylic acid solution was 1:4. After the addition was completed, the mixture was stirred and reacted at 50°C for 105 min to obtain modified rare earth complex solution.
[0036] Step 3: Preparation of rare earth hybrid fluororubber raw material A fluororubber latex with a solid content of 25% was preheated to 60°C. The fluororubber latex was a perfluoroether rubber latex. A modified rare earth complex solution was added to the fluororubber latex while stirring at 400 rpm. The total mass of rare earth elements in the modified rare earth complex solution accounted for 1.5% of the dry rubber mass of the fluororubber latex. After the addition was completed, a mixture B was obtained. The mixture B was kept at a constant temperature and stirred for 100 min. Under continuous stirring at 350 rpm, 10% dilute ammonia solution was added dropwise to the stirred mixture B to make the pH of the system 9.0. Then, stirring was continued for 40 minutes. After stirring, 10 wt% calcium chloride solution was added as a coagulant. The amount of calcium chloride solution was 8% of the volume of the fluororubber latex. Stirring was continued for 55 minutes to allow all solids to co-precipitate. Then, stirring was stopped, and after standing for 2 hours, the supernatant was decanted to obtain rubber particles. The precipitated rubber particles were repeatedly washed with hot deionized water at 65°C until the conductivity of the washing filtrate was <10 μS / cm. The washed rubber particles were dried in a forced-air dryer at 80°C for 28 hours to obtain rare earth hybrid fluororubber raw rubber.
[0037] Step 4: Mixing and Vulcanization Rare earth hybrid fluororubber raw rubber is mixed on a two-roll mill, and after adding additives and vulcanizing, fluororubber resistant to high temperature water vapor is obtained.
[0038] Comparative Example 1: Compared with Example 3, the difference is that the methacrylic acid was not modified. Instead, the methacrylic acid solution was directly reacted with the rare earth salt solution to obtain the modified rare earth complex solution. The remaining steps were the same as in Example 3.
[0039] Comparative Example 2: Compared with Example 3, the difference is that the proportion of the modified rare earth complex solution was changed in the preparation process of rare earth hybrid fluororubber raw rubber, so that the total mass of rare earth elements in the modified rare earth complex solution accounted for 4% of the mass of the dry fluororubber emulsion. The remaining steps were the same as in Example 3.
[0040] Comparative Example 3: Compared with Example 3, the difference is that the methacrylic acid is not modified, and the methacrylic acid solution is directly reacted with the rare earth salt solution to obtain the modified rare earth complex solution; at the same time, the proportion of the modified rare earth complex solution is changed in the preparation process of rare earth hybrid fluororubber raw rubber so that the total mass of rare earth elements in the modified rare earth complex solution accounts for 4% of the mass of the fluororubber latex dry rubber, and the remaining steps are the same as in Example 3.
[0041] Experimental Example: The following performance tests were conducted on Examples 1-3 and Comparative Examples 1-3, and the test results are shown in Table 1: Hardness (Shore Hardness): GB / T 531.1-2008; Tensile strength and elongation at break: GB / T 528-2009; Thermal aging performance (high temperature resistance): The sample was aged in hot air at 250℃ for 168 hours, and the retention rate of tensile strength and elongation at break after aging was tested. High-temperature steam resistance: The sample was treated at 200℃ and saturated steam (1.6MPa) for 168 hours, and the tensile strength retention rate and hardness change were tested after treatment.
[0042] Table 1 Performance test results of Examples 1-3 and Comparative Examples 1-3
[0043] As shown in Examples 1-3, the high-temperature steam-resistant fluororubber prepared by this invention has a hardness of 75-80 HS, a tensile strength of 19.6-24.8 MPa, and an elongation at break of 169-180%, exhibiting good basic mechanical properties. Furthermore, after heat aging and high-temperature steam treatment, all samples showed excellent stability, with tensile strength retention rates all above 85% and elongation at break retention rates all above 80%. The hardness change after steam treatment was also controlled within a small range, indicating that the prepared fluororubber has excellent resistance to high-temperature oxidation and high-temperature steam degradation.
[0044] As can be seen from Example 3 and Comparative Example 1, if methacrylic acid is not modified, the prepared fluororubber will have significantly poorer high-temperature water vapor resistance.
[0045] As can be seen from Example 3 and Comparative Example 2, if the proportion of the modified rare earth complex solution is changed during the preparation of rare earth hybrid fluororubber raw rubber, the elongation at break and toughness of the prepared fluororubber will decrease significantly, and the resistance to aging in the medium will also deteriorate.
[0046] As can be seen from Example 3 and Comparative Example 3, the modification process of methacrylic acid and the proportion of modified rare earth complex solution in the raw rubber of rare earth hybrid fluororubber have a synergistic effect on the three indicators of tensile strength, tensile strength retention rate after heat aging at 250°C and tensile strength retention rate after steam treatment at 200°C for the prepared fluororubber.
[0047] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A fluororubber resistant to high-temperature water vapor, characterized in that, It can be obtained by mixing rare earth hybrid fluororubber raw rubber on a two-milling machine, adding additives and vulcanizing; The rare earth hybrid fluororubber raw rubber is prepared from fluororubber emulsion and modified rare earth complex solution. The fluororubber emulsion and modified rare earth complex solution are mixed evenly. The total mass of rare earth elements in the modified rare earth complex solution accounts for 0.5~2% of the dry mass of the fluororubber emulsion. Then, the solid is precipitated by adjusting the pH and adding a coagulant. The solid is washed and dried to obtain the product. The modified rare earth complex solution is prepared by mixing a modified methacrylic acid solution and a rare earth salt solution; The modified methacrylic acid solution is prepared as follows: glycidyl methacrylate, a catalyst, and a polymerization inhibitor are added to methacrylic acid to form mixture A. Under nitrogen protection, mixture A is heated to 85-105°C and stirred continuously at 300-500 rpm for 4-6 hours. After the reaction is completed, the product is subjected to vacuum distillation at 60-80°C and -0.07-0.10 MPa to obtain modified methacrylic acid.
2. The fluororubber resistant to high-temperature water vapor according to claim 1, characterized in that, The fluororubber emulsion is a vinylidene fluoride-hexafluoropropylene copolymer emulsion or a perfluoroether rubber emulsion with a solid content of 20-30%.
3. The fluororubber resistant to high-temperature water vapor according to claim 1, characterized in that, In the preparation of the modified methacrylic acid solution, hydroquinone is used as the polymerization inhibitor and tetrabutylammonium bromide is used as the catalyst.
4. The fluororubber resistant to high-temperature water vapor according to claim 1, characterized in that, The rare earth salt solution is a rare earth nitrate solution, specifically one or more of cerium nitrate, neodymium nitrate, or lanthanum nitrate.
5. A method for preparing a high-temperature water vapor resistant fluororubber according to any one of claims 1-4, characterized in that, Specifically, the following steps are included: Step 1: Synthesis of Modified Methacrylic Acid Glycidyl methacrylate, hydroquinone, and tetrabutylammonium bromide were added to methacrylic acid to form mixture A. Under nitrogen protection, mixture A was heated to 85-105°C and stirred continuously at 300-500 rpm for 4-6 hours. After the reaction was completed, the product was subjected to vacuum distillation at 60-80°C and -0.07--0.10 MPa to obtain modified methacrylic acid. Step 2: Preparation of modified rare earth complex solution Under mechanical stirring, a rare earth salt solution is added dropwise to a modified methacrylic acid solution. The total mass of rare earth elements in the modified rare earth complex solution accounts for 0.5-2% of the dry mass of the fluororubber latex. The reaction is continued by stirring. After the reaction is completed, the modified rare earth complex solution is obtained. The rare earth salt solution is one or more of cerium nitrate solution, neodymium nitrate solution, or lanthanum nitrate solution; Step 3: Preparation of rare earth hybrid fluororubber raw material The modified rare earth complex solution is added to a fluororubber emulsion with a solid content of 20-30%. After stirring, the solid is precipitated by adjusting the pH and adding a coagulant. The solid is washed and dried to obtain rare earth hybrid fluororubber raw rubber. Step 4: Mixing and Vulcanization Rare earth hybrid fluororubber raw rubber is mixed on a two-roll mill, and after adding additives and vulcanizing, fluororubber resistant to high temperature water vapor is obtained.
6. The method for preparing high-temperature water vapor resistant fluororubber according to claim 5, characterized in that, The specific process of step 1 is as follows: Glycidyl methacrylate is added to methacrylic acid at a molar ratio of 1:0.5~1, and 0.5~2% by mass of tetrabutylammonium bromide as a catalyst and 50~200ppm of hydroquinone are added to form mixture A. After the reaction is completed, the mixture is distilled under reduced pressure to obtain modified methacrylic acid.
7. The method for preparing high-temperature water vapor resistant fluororubber according to claim 5, characterized in that, The specific process of step 2 is as follows: The modified methacrylic acid was dissolved in ethanol to obtain a modified methacrylic acid solution with a mass concentration of 5-20%. Rare earth nitrates are dissolved in deionized water to obtain a rare earth salt solution of 0.1~0.5 mol / L; Under mechanical stirring at 300-600 rpm, a rare earth salt solution is added dropwise to a modified methacrylic acid solution, such that the molar ratio of rare earth ions in the rare earth salt solution to carboxyl groups in the modified methacrylic acid solution is 1:2-6. After the addition is complete, the mixture is stirred and reacted at 40-60℃ for 95-145 min to obtain a modified rare earth complex solution.
8. The method for preparing high-temperature water vapor resistant fluororubber according to claim 5, characterized in that, The specific process of step 3 is as follows: A fluororubber latex with a solid content of 20-30% is preheated to 50-70°C. A modified rare earth complex solution is added to the fluororubber latex while stirring at 300-500 rpm. The total mass of rare earth elements in the modified rare earth complex solution accounts for 0.5-2% of the dry mass of the fluororubber latex. After the addition is complete, a mixture B is obtained. The mixture B is kept at a constant temperature and stirred for 90-120 minutes. Under continuous stirring at 300-400 rpm, 5-15% dilute ammonia solution was added dropwise to the stirred mixture B to adjust the pH of the system to 8.5-10.
0. Stirring was then continued for 30-50 minutes. After stirring, 5-15 wt% calcium chloride solution was added as a coagulant, with the amount of calcium chloride solution being 5-15% of the volume of the fluororubber latex. Stirring was continued for 30-90 minutes to allow all solids to co-precipitate. Stirring was then stopped, and the supernatant was discarded after standing for 1-3 hours to obtain rubber particles. The precipitated rubber particles were repeatedly washed with hot deionized water at 60-80℃ until the conductivity of the washing filtrate was <10 μS / cm. The washed rubber particles were dried in a forced-air dryer at 70-90℃ for 24-36 hours to obtain rare earth hybrid fluororubber raw rubber.