Anti-cracking perfluoroether rubber as well as preparation method and application thereof

Abstract

The invention provides anti-cracking perfluoroether rubber as well as a preparation method and application thereof, and relates to the technical field of rubber materials. The anti-cracking perfluoroether rubber is prepared from the following materials in parts by weight: 100 parts of perfluoroether rubber, 10 to 20 parts of fluorine-containing nano SiO2, 20 to 30 parts of BN-coated SiO2, 2 to 5 parts of a silane coupling agent, 1 to 3 parts of a peroxide cross-linking agent, 1 to 3 parts of a bisphenol AF cross-linking agent, 1 to 2 parts of an antioxidant, 1 to 2 parts of a heat stabilizer, 0.5 to 1 part of a lubricating agent and 0.5 to 1 part of a dispersing agent. The invention aims to provide the novel anti-cracking perfluoroether rubber aiming at the defects in the prior art, and the overall anti-cracking performance of the material is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber materials, and in particular to a crack-resistant perfluoroether rubber and a preparation method and application thereof. Background Art

[0002] With the rapid development of modern industry, performance requirements for sealing materials are increasing. In high-end fields such as aerospace, petrochemicals, and semiconductor manufacturing, equipment often operates under extreme conditions such as high temperature, high pressure, and severe corrosion. This poses severe challenges to the temperature resistance, chemical resistance, and sealing reliability of sealing materials. Perfluoroelastomer (FFKM), due to its unique molecular structure, offers excellent properties such as high temperature resistance, chemical resistance, and low permeability, making it an indispensable sealing material in these fields. Perfluoroelastomer is a specialized synthetic rubber with fluorine atoms attached to carbon atoms in the main chain or side chains. The strong electronegativity of fluorine atoms imparts high chemical and thermal stability to the FFKM molecular chain, enabling it to exhibit excellent corrosion resistance to most chemicals (including strong acids, strong bases, and organic solvents) within a temperature range of -25°C to 300°C or even higher. FFKM also exhibits low permeability, excellent mechanical properties, and electrical insulation. Due to these outstanding properties, FFKM is widely used in extreme operating conditions such as engine seals in the aerospace industry, pipe and valve seals in the petrochemical industry, and ultra-pure media sealing in semiconductor manufacturing. However, the cracking problem of FFKM products in practical applications limits their full performance and wider application.

[0003] While the fluorine atoms in the perfluoroether rubber (FFKM) molecular chain impart excellent chemical stability, they also reduce its flexibility and increase its rigidity. This rigid structure is particularly pronounced at low temperatures, restricting the movement of the molecular chain. When subjected to external forces, stress concentrations easily occur at weak links in the chain, triggering the initiation and propagation of cracks. Furthermore, defects or impurities in the FFKM molecular chain can also serve as crack initiation points.

[0004] Adding fillers is a common method to improve the performance of rubber. Adding nanofillers such as nanosilica, carbon nanotubes, etc. to FFKM can improve the strength and hardness of the material, but the interface interaction between the filler and the rubber matrix is weak, which easily leads to stress concentration. Under the action of stress, debonding is easily generated between the filler and the matrix, thereby causing cracks. In addition, the dispersibility of the filler is also a problem. If the filler is unevenly dispersed in the rubber, local performance defects will be formed, reducing the material's anti-cracking performance. Based on this, the present invention provides a crack-resistant perfluoroether rubber and its preparation method and application. Summary of the Invention

[0005] The purpose of the present invention is to provide a crack-resistant perfluoroether rubber and its preparation method and application, which improves the problem of poor crack resistance of perfluoroether rubber in low-temperature environments due to high molecular chain rigidity and restricted movement, thereby reducing the initiation and expansion of cracks; improves the interfacial interaction between nanofillers and the perfluoroether rubber matrix, reduces stress concentration and debonding caused by weak interfacial interaction, and thus reduces the generation of cracks; improves the dispersibility of nanofillers in perfluoroether rubber, avoids local performance defects caused by uneven filler dispersion, and improves the overall crack resistance of the material.

[0006] On the one hand, the present invention provides an anti-cracking perfluoroether rubber, comprising the following materials in parts by weight: 100 parts of perfluoroether rubber, 10-20 parts of fluorine-containing nano-SiO2, 20-30 parts of BN@SiO2, 2-5 parts of silane coupling agent, 1-3 parts of peroxide crosslinking agent, 1-3 parts of bisphenol AF crosslinking agent, 1-2 parts of antioxidant, 1-2 parts of thermal stabilizer, 0.5-1 part of lubricant and 0.5-1 part of dispersant.

[0007] Furthermore, the preparation method of the fluorine-containing nano-SiO2 includes: mixing perfluorooctyltriethoxysilane with ethanol, adding ammonia water to adjust the pH to 8-9, and stirring to form a hydrolyzate; adding the nano-SiO2 after drying pretreatment to the hydrolyzate, performing a reflux reaction at 75-85°C for 20-24h, and obtaining the fluorine-containing nano-SiO2 by centrifugation, washing, and drying after the reaction is completed.

[0008] Furthermore, the drying pretreatment temperature is 100-120° C. and the time is 2-3 hours.

[0009] Furthermore, the usage ratio of the dried pre-treated nano-SiO2, perfluorooctyltriethoxysilane and ethanol is 100 g: (10-20) mL: (200-300) mL.

[0010] Furthermore, the preparation method of BN@SiO2 includes: mixing nano-boron nitride with isopropyl alcohol, adding polyvinyl pyrrolidone, ultrasonically treating the mixture, centrifuging the upper dispersion, adding SiO2 particles thereto, stirring and reacting at 700-800 rpm and 55-65°C for 4-5 hours, filtering, drying, and grinding the mixture through a 200-mesh sieve to obtain the obtained product.

[0011] Furthermore, the usage ratio of the nano-boron nitride, isopropyl alcohol, polyvinyl pyrrolidone and SiO2 particles is (18-22) g: (400-500) mL: (4-6) g: (70-90) g.

[0012] Furthermore, the silane coupling agent is γ-mercaptopropyltrimethoxysilane; the peroxide crosslinking agent is di(tert-butylperoxyisopropyl)benzene; the bisphenol AF crosslinking agent is 2,2-bis(4-hydroxyphenyl)hexafluoropropane; the antioxidant is antioxidant 1010; the thermal stabilizer includes magnesium aluminum hydrotalcite and epoxidized soybean oil in a ratio of 1:1 by weight; the lubricant is Kluber HX 83-302; and the dispersant is dispersant FS-20.

[0013] On the other hand, the present invention also provides a method for preparing crack-resistant perfluoroether rubber, comprising the steps of:

[0014] (1) Add perfluoroether rubber, fluorinated nano-SiO2 and BN@SiO2 into an internal mixer and perform preliminary mixing. First, pre-crosslink them at 110-120℃ in the internal mixer for 3-5 minutes, and then mix them at 145-155℃ for 10-12 minutes to ensure that the filler is evenly dispersed.

[0015] (2) Add peroxide crosslinker and bisphenol AF crosslinker to the mixture in proportion and continue to mix for 4-6 minutes; add silane coupling agent, antioxidant, heat stabilizer, lubricant and dispersant and continue to mix for 4-6 minutes;

[0016] (3) The mixture obtained in step (2) is placed in a mold and formed by hot pressing; after forming, it is subjected to vulcanization treatment, and under nitrogen protection, the temperature is raised to 200-240°C within 2-4 hours and maintained for 18-22 hours to obtain the product.

[0017] Furthermore, the molding temperature is 160-170° C., the pressure is 80-100 MPa, and the molding time is 10-20 min.

[0018] The crack-resistant perfluoroether rubber application seal prepared in the present invention includes a semiconductor etching equipment seal ring or an aerospace engine fuel seal.

[0019] The beneficial effects of the present invention are:

[0020] The present invention introduces fluorine atoms onto the surface of nano-SiO2, increasing its fluorine content and enhancing its chemical structural similarity to the perfluoroether rubber matrix. This significantly enhances the interfacial interaction between the nano-SiO2 and the perfluoroether rubber matrix, reducing stress concentration and debonding at the interface. Furthermore, the fluorine-containing nano-SiO2 acts as a reinforcement within the rubber matrix, filling the gaps between the rubber molecular chains and restricting their movement, thereby increasing the rubber's strength and modulus, inhibiting crack initiation and propagation, and improving the perfluoroether rubber's crack resistance in low-temperature environments.

[0021] The nano-boron nitride in the BN@SiO2 prepared by the present invention has a layered structure. Its layers can form a skeleton structure in the rubber matrix, playing a supporting role and improving the rigidity of the material; while the SiO2 particles fill the gaps between the nano-boron nitride layers, forming an interlocking structure. This "skeleton-filling" synergistic reinforcement structure can effectively inhibit the expansion of cracks. When cracks propagate in the rubber matrix, they are blocked and dispersed by the interlocking structure of BN@SiO2, thereby reducing further development of the cracks. At the same time, there is also a good interfacial interaction between BN@SiO2 and the rubber matrix, further improving the overall performance of the material, including crack resistance, tensile strength, and thermal stability.

[0022] The present invention uses γ-mercaptopropyltrimethoxysilane as a silane coupling agent, whose molecular structure contains thiol groups. During the rubber vulcanization process, the thiol groups can chemically react with the unsaturated bonds in the rubber molecular chain to form chemical bonds, thereby tightly connecting the nanofiller to the rubber matrix. This chemical bonding has a stronger binding force than physical adsorption, can significantly increase the interfacial binding energy, and can reduce stress concentration and debonding caused by weak interfacial interactions. Under dynamic loads, the interface containing the sulfide bond network can better transfer stress, prevent the initiation and propagation of cracks, and improve the crack resistance of perfluoroether rubber. In contrast, conventional silane coupling agents (such as KH-550) lack thiol groups and cannot form chemical bonds with rubber molecules. The interfacial binding energy is low, and they are prone to interfacial failure under dynamic loads, resulting in reduced crack resistance.

[0023] This invention utilizes a synergistic crosslinking system combining a peroxide crosslinker (BIPB) and a bisphenol AF crosslinker (2,2-bis(4-hydroxyphenyl)hexafluoropropane). The peroxide crosslinker decomposes at high temperatures to produce free radicals, which initiate crosslinking reactions between rubber molecular chains, forming carbon-carbon crosslinks and enhancing the rubber's strength and modulus. The bisphenol AF crosslinker reacts with active groups within the rubber molecular chains to form ether crosslinks, further increasing the crosslink density. These two crosslinkers operate through different mechanisms, but their synergistic effect creates a more complex and stable crosslinked network. This crosslinked network restricts the movement of rubber molecular chains, enhancing the material's rigidity and strength while also dispersing stress and reducing crack initiation and propagation. Furthermore, compared to traditional dicumyl peroxide (DCP), BIPB offers advantages in environmental friendliness and stability in high-temperature vulcanization systems. Its decomposition products are odorless, and its crosslinking efficiency is higher, resulting in a more uniform crosslinked structure, thereby enhancing the overall performance of perfluoroether rubber.

[0024] The present invention adopts magnesium aluminum hydrotalcite and epoxy soybean oil as thermal stabilizers, and there is a synergistic effect between the two. Magnesium aluminum hydrotalcite has a layered structure and can adsorb acidic substances such as HCl generated by the thermal decomposition of rubber, reducing the damage of acidic substances to the rubber molecular chains, thereby improving the thermal stability of the material. Epoxidized soybean oil can react with the rubber molecular chains to form stable chemical bonds, further enhancing the stability of the rubber molecular chains, while also improving the processing properties of the rubber. The use of magnesium aluminum hydrotalcite alone cannot completely neutralize the acidic substances generated by thermal decomposition, and the improvement in thermal stability is limited; and the use of epoxy soybean oil alone cannot achieve the best adsorption and stabilization effects. The synergistic effect of the two can give full play to their respective advantages, effectively increase the thermal decomposition temperature of perfluoroether rubber, and extend the service life of the material. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of the technical solution 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 perfluoroether rubber in the present invention was purchased from HALOPOLYMER, Russia, model 1000; boron nitride was purchased from Beijing Dekedaojin Technology Co., Ltd. (specification <100 nm, 99.9%); nanosilica, CAS No.: 60676-86-0, item No.: S817567, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; and magnesium aluminum hydrotalcite, item No.: H875612, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0027] Example 1

[0028] This embodiment provides a crack-resistant perfluoroether rubber, comprising the following materials in parts by weight: 100 parts perfluoroether rubber, 15 parts fluorine-containing nano-SiO2, 25 parts BN@SiO2, 3 parts γ-mercaptopropyltrimethoxysilane, 2 parts di(tert-butylperoxyisopropyl)benzene, 2 parts 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1.5 parts antioxidant 1010, 1.5 parts thermal stabilizer, 0.7 parts Kluber HX 83-302, and 0.8 parts dispersant FS-20; wherein the thermal stabilizer comprises magnesium aluminum hydrotalcite and epoxidized soybean oil in a ratio of 1:1 by weight;

[0029] Among them, the preparation method of fluorine-containing nano-SiO2 includes: mixing perfluorooctyltriethoxysilane with ethanol, adding ammonia water to adjust the pH to 8.5, and stirring to form a hydrolyzate; adding nano-SiO2 that has been dried and pretreated at a temperature of 110°C for 2.5 hours to the hydrolyzate, and performing a reflux reaction at 80°C for 22 hours. After the reaction, centrifugation and ethanol washing are performed three times, and vacuum drying is performed at 60°C for 6 hours to obtain the product; the usage ratio of the dried and pretreated nano-SiO2, perfluorooctyltriethoxysilane and ethanol is 100g:15mL:250mL.

[0030] Among them, the preparation method of BN@SiO2 includes: mixing nano-boron nitride with isopropyl alcohol and then adding polyvinyl pyrrolidone, ultrasonically treating at 200w for 24 hours, centrifuging at 4000r / min for 10 minutes, taking the upper dispersion, adding SiO2 particles thereto, stirring and reacting at 750rpm and 60℃ for 4.5 hours, filtering, vacuum drying at 60℃ for 12 hours, and grinding through a 200-mesh sieve to obtain the obtained product; the usage ratio of nano-boron nitride, isopropyl alcohol, polyvinyl pyrrolidone and SiO2 particles is 20g:450mL:5g:80g.

[0031] The preparation method of the crack-resistant perfluoroether rubber comprises the following steps:

[0032] (1) Perfluoroether rubber, fluorinated nano-SiO2, and BN@SiO2 were added to an internal mixer for preliminary mixing. They were first pre-crosslinked at 115°C for 4 min in an internal mixer, and then internally mixed at 150°C for 11 min to ensure uniform dispersion of the filler.

[0033] (2) Add peroxide crosslinker and bisphenol AF crosslinker to the mixture in proportion and continue to mix for 5 minutes; add silane coupling agent, antioxidant, heat stabilizer, lubricant and dispersant and continue to mix for 5 minutes;

[0034] (3) The mixture obtained in step (2) is placed in a mold and hot pressed at a temperature of 165°C and a pressure of 90 MPa for 15 minutes to form the mixture; after forming, a post-vulcanization treatment is performed, and the temperature is raised to 220°C within 3 hours under nitrogen protection and maintained for 20 hours to obtain the obtained product.

[0035] Example 2

[0036] This embodiment provides a crack-resistant perfluoroether rubber, comprising the following materials in parts by weight: 100 parts perfluoroether rubber, 10 parts fluorinated nano-SiO2, 20 parts BN@SiO2, 2 parts γ-mercaptopropyltrimethoxysilane, 1 part di(tert-butylperoxyisopropyl)benzene, 1 part 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1 part antioxidant 1010, 1 part thermal stabilizer, 0.5 parts Kluber HX83-302, and 0.5 parts dispersant FS-20; wherein the thermal stabilizer comprises magnesium aluminum hydrotalcite and epoxidized soybean oil in a ratio of 1:1 by weight;

[0037] Among them, the preparation method of fluorine-containing nano-SiO2 includes: mixing perfluorooctyltriethoxysilane with ethanol, adding ammonia water to adjust the pH to 8, and stirring to form a hydrolyzate; adding nano-SiO2 that has been dried and pretreated at a temperature of 100°C for 2 hours to the hydrolyzate, and performing a reflux reaction at 75°C for 20 hours. After the reaction, centrifugation and ethanol washing are performed three times, and vacuum drying is performed at 60°C for 6 hours to obtain the product; the usage ratio of the dried and pretreated nano-SiO2, perfluorooctyltriethoxysilane and ethanol is 100g:10mL:200mL.

[0038] Among them, the preparation method of BN@SiO2 includes: mixing nano-boron nitride with isopropyl alcohol and then adding polyvinyl pyrrolidone, ultrasonically treating at 200w for 24 hours, centrifuging at 4000r / min for 10 minutes, taking the upper dispersion, adding SiO2 particles thereto, stirring and reacting at 700rpm and 55℃ for 4 hours, filtering, vacuum drying at 60℃ for 12 hours, and grinding through a 200-mesh sieve to obtain the product; the usage ratio of nano-boron nitride, isopropyl alcohol, polyvinyl pyrrolidone and SiO2 particles is 18g:400mL:4g:70g.

[0039] The preparation method of the crack-resistant perfluoroether rubber comprises the following steps:

[0040] (1) Perfluoroether rubber, fluorinated nano-SiO2, and BN@SiO2 were added to an internal mixer for preliminary mixing. They were first pre-crosslinked at 110°C for 3 min in an internal mixer, and then internally mixed at 145°C for 10 min to ensure uniform dispersion of the filler.

[0041] (2) Add peroxide crosslinker and bisphenol AF crosslinker to the mixture in proportion and continue to mix for 4 minutes; add silane coupling agent, antioxidant, heat stabilizer, lubricant and dispersant and continue to mix for 4 minutes;

[0042] (3) The mixture obtained in step (2) is placed in a mold and hot pressed at a temperature of 160°C and a pressure of 80 MPa for 10 minutes to form the mixture; after forming, a post-vulcanization treatment is performed, and the temperature is raised to 200°C within 2 hours under nitrogen protection and maintained for 18 hours to obtain the mixture.

[0043] Example 3

[0044] This embodiment provides a crack-resistant perfluoroether rubber, comprising the following materials in parts by weight: 100 parts perfluoroether rubber, 10 parts fluorinated nano-SiO2, 30 parts BN@SiO2, 2 parts γ-mercaptopropyltrimethoxysilane, 3 parts di(tert-butylperoxyisopropyl)benzene, 1 part 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2 parts antioxidant 1010, 1 part thermal stabilizer, 1 part Kluber HX83-302, and 0.5 part dispersant FS-20; wherein the thermal stabilizer comprises magnesium aluminum hydrotalcite and epoxidized soybean oil in a 1:1 ratio by weight;

[0045] Among them, the preparation method of fluorine-containing nano-SiO2 includes: mixing perfluorooctyltriethoxysilane with ethanol, adding ammonia water to adjust the pH to 8, and stirring to form a hydrolyzate; adding nano-SiO2 that has been dried and pretreated at a temperature of 120°C for 2 hours to the hydrolyzate, and performing a reflux reaction at 75°C for 24 hours. After the reaction, centrifugation and ethanol washing are performed three times, and vacuum drying is performed at 60°C for 6 hours to obtain the product; the usage ratio of the dried and pretreated nano-SiO2, perfluorooctyltriethoxysilane and ethanol is 100g:10mL:300mL.

[0046] Among them, the preparation method of BN@SiO2 includes: mixing nano-boron nitride with isopropyl alcohol and then adding polyvinyl pyrrolidone, ultrasonically treating at 200w for 24 hours, centrifuging at 4000r / min for 10 minutes, taking the upper dispersion, adding SiO2 particles thereto, stirring and reacting at 700rpm and 65℃ for 4 hours, filtering, vacuum drying at 60℃ for 12 hours, and grinding through a 200-mesh sieve to obtain the product; the usage ratio of nano-boron nitride, isopropyl alcohol, polyvinyl pyrrolidone and SiO2 particles is 22g:400mL:6g:70g.

[0047] The preparation method of the crack-resistant perfluoroether rubber comprises the following steps:

[0048] (1) Perfluoroether rubber, fluorinated nano-SiO2, and BN@SiO2 were added to an internal mixer for preliminary mixing. They were first pre-crosslinked at 120°C for 3 min in the internal mixer and then internally mixed at 155°C for 10 min to ensure uniform dispersion of the filler.

[0049] (2) Add peroxide crosslinker and bisphenol AF crosslinker to the mixture in proportion and continue to mix for 6 minutes; add silane coupling agent, antioxidant, heat stabilizer, lubricant and dispersant and continue to mix for 4 minutes;

[0050] (3) The mixture obtained in step (2) is placed in a mold and hot pressed at a temperature of 170°C and a pressure of 80 MPa for 20 minutes to form the mixture; after forming, a post-vulcanization treatment is performed, and the temperature is raised to 240°C within 2 hours under nitrogen protection and maintained for 18 hours to obtain the obtained product.

[0051] Example 4

[0052] This embodiment provides a crack-resistant perfluoroether rubber, comprising the following materials in parts by weight: 100 parts perfluoroether rubber, 20 parts fluorinated nano-SiO2, 20 parts BN@SiO2, 5 parts γ-mercaptopropyltrimethoxysilane, 1 part di(tert-butylperoxyisopropyl)benzene, 3 parts 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1 part antioxidant 1010, 2 parts thermal stabilizer, 0.5 parts Kluber HX83-302, and 1 part dispersant FS-20; wherein the thermal stabilizer comprises magnesium aluminum hydrotalcite and epoxidized soybean oil in a ratio of 1:1 by weight;

[0053] Among them, the preparation method of fluorine-containing nano-SiO2 includes: mixing perfluorooctyltriethoxysilane with ethanol, adding ammonia water to adjust the pH to 9, and stirring to form a hydrolyzate; adding nano-SiO2 that has been dried and pretreated at a temperature of 100°C for 3 hours to the hydrolyzate, and performing a reflux reaction at 85°C for 20 hours. After the reaction, centrifugation and ethanol washing are performed three times, and vacuum drying is performed at 60°C for 6 hours to obtain the product; the usage ratio of the dried and pretreated nano-SiO2, perfluorooctyltriethoxysilane and ethanol is 100g:20mL:200mL.

[0054] Among them, the preparation method of BN@SiO2 includes: mixing nano-boron nitride with isopropyl alcohol and then adding polyvinyl pyrrolidone, ultrasonically treating at 200w for 24 hours, centrifuging at 4000r / min for 10 minutes, taking the upper dispersion, adding SiO2 particles thereto, stirring and reacting at 800rpm and 55℃ for 5 hours, filtering, vacuum drying at 60℃ for 12 hours, and grinding through a 200-mesh sieve to obtain the product; the usage ratio of nano-boron nitride, isopropyl alcohol, polyvinyl pyrrolidone and SiO2 particles is 18g:500mL:4g:90g.

[0055] The preparation method of the crack-resistant perfluoroether rubber comprises the following steps:

[0056] (1) Perfluoroether rubber, fluorinated nano-SiO2, and BN@SiO2 were added to an internal mixer for preliminary mixing. They were first pre-crosslinked at 110°C for 5 min in an internal mixer, and then mixed at 145°C for 12 min to ensure uniform dispersion of the filler.

[0057] (2) Add peroxide crosslinker and bisphenol AF crosslinker to the mixture in proportion and continue to mix for 4 minutes; add silane coupling agent, antioxidant, heat stabilizer, lubricant and dispersant and continue to mix for 6 minutes;

[0058] (3) The mixture obtained in step (2) is placed in a mold and hot pressed at a temperature of 160°C and a pressure of 100 MPa for 10 minutes to form the mixture; after forming, a post-vulcanization treatment is performed, and the temperature is raised to 200°C within 4 hours under nitrogen protection and maintained for 22 hours to obtain the obtained product.

[0059] Comparative Example 1

[0060] In Comparative Example 1, the fluorine-containing nano-SiO2 is replaced by nano-SiO2, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0061] Comparative Example 2

[0062] In Comparative Example 2, no fluorine-containing nano-SiO2 was added, and the rest was the same as in Example 1, and the preparation steps were the same as in Example 1.

[0063] Comparative Example 3

[0064] In Comparative Example 3, BN@SiO2 is replaced by boron nitride, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0065] Comparative Example 4

[0066] In Comparative Example 4, BN@SiO2 is replaced by nano-SiO2, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0067] Comparative Example 5

[0068] In Comparative Example 5, BN@SiO2 was not added, and the rest was the same as in Example 1, and the preparation steps were the same as in Example 1.

[0069] Comparative Example 6

[0070] In Comparative Example 6, γ-mercaptopropyltrimethoxysilane was replaced by KH-550, and the rest was the same as in Example 1, and the preparation steps were the same as in Example 1.

[0071] Comparative Example 7

[0072] In Comparative Example 7, the magnesium-aluminum hydrotalcite and epoxy soybean oil were replaced by single magnesium-aluminum hydrotalcite, and the rest was the same as in Example 1, and the preparation steps were the same as in Example 1.

[0073] Comparative Example 8

[0074] In Comparative Example 8, di(tert-butylperoxyisopropyl)benzene was replaced by diisopropylbenzene peroxide, and the rest was the same as in Example 1, and the preparation steps were the same as in Example 1.

[0075] Test Example: The rubber materials prepared in the above Examples 1-4 and Comparative Examples 1-8 were subjected to the following tests:

[0076] Dynamic flexure test: Rubber samples were cut into uniform sizes (20 mm × 20 mm × 2 mm) and mounted in a flexure test apparatus. The test was stopped at the time of fracture. The samples were observed at each time point, the folding surface was observed, and crack growth was measured. The bending fatigue life and crack growth rate were calculated.

[0077] Tensile strength test: Refer to GB / T 528-2009 standard and use standard dumbbell-shaped specimens for testing.

[0078] Hardness test: Shore hardness tester was used to test in accordance with GB / T 531.1-2008 standard.

[0079] Thermal decomposition temperature test: The test was performed using a thermogravimetric analyzer (TGA) with a heating rate of 10°C / min and a nitrogen atmosphere.

[0080] For each test, 5 samples were taken for testing and the average value was taken. The results are shown in Table 1 below:

[0081] Table 1

[0082] Combined with the above data, it can be seen that in Example 1, the combination of fluorine-containing nano-SiO2 and BN@SiO2 significantly improves the bending fatigue life and tensile strength, which is mainly attributed to the chemical grafting of fluorine-containing nano-SiO2 enhancing the interfacial binding energy and reducing stress concentration; BN@SiO2 forms an interlocking structure by inserting nano-BN sheets into the SiO2 gap, thereby inhibiting crack propagation.

[0083] Comparative Examples 1-5 show that the bending life and tensile strength of unmodified SiO2 or single filler system are significantly reduced, indicating that the synergistic effect of filler modification and compounding is the key.

[0084] In Example 1, the filler was evenly dispersed and had few interface defects due to the internal mixing at 150°C and hot pressing at 90 MPa. In Comparative Example 4, the tensile strength dropped to 8 MPa due to insufficient filler rigidity, indicating that the skeleton support role of BN is irreplaceable.

[0085] Example 1 uses γ-mercaptopropyltrimethoxysilane, which bonds to the rubber molecules through thiol groups, with a hardness of 82HA and a low crack propagation rate; Comparative Example 6 lacks a sulfur bond network, resulting in weak interface bonding and an increase in the crack rate to 2.5 μm / h, verifying the advantages of sulfur-containing coupling agents under dynamic loads.

[0086] Example 1, using BIPB and bisphenol AF crosslinkers in combination with magnesium-aluminum hydrotalcite and epoxidized soybean oil, achieved a thermal decomposition temperature of 320°C, superior to Comparative Examples 8 and 7. The odor and low crosslinking efficiency of DCP in Comparative Example 8 led to decreased thermal stability, demonstrating the advantages of BIPB at extreme temperatures.

[0087] Finally, it should be noted that the above embodiments and comparative examples are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A crack-resistant perfluoroether rubber, characterized in that: The invention comprises the following materials in parts by weight: 100 parts of perfluoroether rubber, 10-20 parts of fluorine-containing nano-SiO2, 20-30 parts of BN@SiO2, 2-5 parts of silane coupling agent, 1-3 parts of peroxide crosslinking agent, 1-3 parts of bisphenol AF crosslinking agent, 1-2 parts of antioxidant, 1-2 parts of thermal stabilizer, 0.5-1 part of lubricant and 0.5-1 part of dispersant.

2. The crack-resistant perfluoroether rubber according to claim 1, characterized in that: The preparation method of the fluorine-containing nano-SiO2 comprises: mixing perfluorooctyltriethoxysilane with ethanol, adding ammonia water to adjust the pH to 8-9, and stirring to form a hydrolyzate; adding the nano-SiO2 after drying pretreatment to the hydrolyzate, performing a reflux reaction at 75-85°C for 20-24 hours, and centrifuging, washing, and drying after the reaction is completed to obtain the fluorine-containing nano-SiO2.

3. The crack-resistant perfluoroether rubber according to claim 2, characterized in that: The drying pretreatment temperature is 100-120° C. and the time is 2-3 hours.

4. The crack-resistant perfluoroether rubber according to claim 2, characterized in that: The usage ratio of the dried pre-treated nano-SiO2, perfluorooctyltriethoxysilane and ethanol is 100 g: (10-20) mL: (200-300) mL.

5. The crack-resistant perfluoroether rubber according to claim 1, characterized in that: The preparation method of BN@SiO2 includes: mixing nano-boron nitride and isopropyl alcohol, adding polyvinyl pyrrolidone, ultrasonically treating, centrifuging, collecting the upper dispersion, adding SiO2 particles thereto, stirring and reacting at 700-800 rpm and 55-65°C for 4-5 hours, filtering, drying, and grinding to pass through a 200-mesh sieve to obtain the BN@SiO2.

6. The crack-resistant perfluoroether rubber according to claim 5, characterized in that: The dosage ratio of the nano boron nitride, isopropyl alcohol, polyvinyl pyrrolidone and SiO2 particles is (18-22) g: (400-500) mL: (4-6) g: (70-90) g.

7. The crack-resistant perfluoroether rubber according to claim 1, characterized in that: The silane coupling agent is γ-mercaptopropyltrimethoxysilane; the peroxide crosslinking agent is di(tert-butylperoxyisopropyl)benzene; the bisphenol AF crosslinking agent is 2,2-bis(4-hydroxyphenyl)hexafluoropropane; the antioxidant is antioxidant 1010; the thermal stabilizer includes magnesium aluminum hydrotalcite and epoxidized soybean oil in a ratio of 1:1 by weight; the lubricant is Kluber HX 83-302; and the dispersant is dispersant FS-20.

8. A method for preparing the crack-resistant perfluoroether rubber according to any one of claims 1 to 7, characterized in that the steps include: (1) Add perfluoroether rubber, fluorinated nano-SiO2 and BN@SiO2 into an internal mixer and perform preliminary mixing. First, pre-crosslink them at 110-120℃ in the internal mixer for 3-5 minutes, and then mix them at 145-155℃ for 10-12 minutes to ensure that the filler is evenly dispersed. (2) Add peroxide crosslinker and bisphenol AF crosslinker to the mixture in proportion and continue to mix for 4-6 minutes; add silane coupling agent, antioxidant, heat stabilizer, lubricant and dispersant and continue to mix for 4-6 minutes; (3) The mixture obtained in step (2) is placed in a mold and formed by hot pressing; after forming, it is subjected to vulcanization treatment, and under nitrogen protection, the temperature is raised to 200-240°C within 2-4 hours and maintained for 18-22 hours to obtain the product.

9. The method for preparing a crack-resistant perfluoroether rubber according to claim 8, characterized in that: The molding temperature is 160-170° C., the pressure is 80-100 MPa, and the molding time is 10-20 minutes.

10. Use of the anti-cracking perfluoroether rubber according to any one of claims 1 to 7 in a seal, characterized in that: The sealing member includes a sealing ring of semiconductor etching equipment or a fuel sealing member of an aerospace engine.

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