Low temperature resistant rubber sealing material and preparation method thereof

Abstract

The application discloses a low-temperature-resistant rubber sealing material and a preparation method thereof, and belongs to the technical field of rubber sealing materials.The low-temperature-resistant rubber sealing material comprises the following raw materials: fluorine rubber, silicon rubber and a nano compatibilizer; the mass ratio of the fluorine rubber and the silicon rubber is 70-90:10-30; the addition amount of the nano compatibilizer is 15%-20% of the total amount of the fluorine rubber and the silicon rubber; and the nano compatibilizer is a long-chain alkyl modified graphene oxide aminated UiO-66 composite material.Through a ternary synergistic strategy of fluorine-silicon rubber blending matrix, nano compatibilizer interface regulation and end-vinyl functional silicone oil internal plasticization, the technical problems of large low-temperature brittleness and insufficient low-temperature elastic recovery capability of the fluorine rubber material are solved, and the comprehensive goal of significantly improving the low-temperature ductility and impact resistance of the composite material while keeping high mechanical strength is achieved.

Description

Technical Field

[0001] This invention belongs to the technical field of rubber sealing materials, specifically relating to a low-temperature resistant rubber sealing material and its preparation method. Background Technology

[0002] Rubber, as one of the three major polymer materials, plays an irreplaceable role in engineering components such as seals, shock absorbers, and tires in aerospace, automotive, and oil extraction fields due to its comprehensive properties including high elasticity, wear resistance, oil resistance, weather resistance, and tear resistance. In sealing applications, the sealing performance of a material depends on its ability to recover after tensile and compressive deformation at a certain temperature. However, as the temperature decreases, the thermal motion of rubber molecular chain segments gradually weakens, flexibility decreases, and deformation recovery becomes extremely slow. The material successively undergoes a leather-like state and eventually transforms into a glassy state, exhibiting hard and brittle characteristics. This glass transition behavior severely restricts the reliability of rubber sealants in low-temperature environments.

[0003] Fluororubber exhibits irreplaceable advantages in high-temperature, high-pressure, and highly corrosive environments due to its excellent heat resistance, weather resistance, oil resistance, and chemical corrosion resistance. However, while the high fluorine content in its molecular chain endows the material with outstanding chemical and thermal stability, it also significantly increases the rigidity of the molecular chain and reduces the rotational freedom within the chain segments. This leads to a sharp decrease in elasticity at low temperatures and a significant deterioration in impact brittleness, making it difficult to meet the performance requirements of elastic sealing materials under extreme low-temperature conditions.

[0004] To improve the low-temperature performance of fluororubber, at the molecular structure level, flexible segments or ether bonds can be introduced into the fluororubber backbone through copolymerization or grafting modification to reduce the regularity and rigidity of the molecular chain, thereby enhancing the mobility of the chain segments at low temperatures. Although such methods can significantly reduce the glass transition temperature of the material, their synthesis process is complex and large-scale industrial production is difficult. At the formulation design level, adding low-temperature resistant plasticizers can weaken the interaction forces between molecular chains, increase free volume, and thus improve the slippage ability of the molecular chains. However, small molecule plasticizers have weak bonding forces with the rubber matrix and are prone to migration and volatilization under long-term use or high-temperature environments, leading to a gradual deterioration of the material's performance.

[0005] In the modification of dissimilar rubber blends, blending fluororubber with silicone rubber, which exhibits excellent low-temperature performance, is another important approach to improving low-temperature resistance. The silicon-oxygen bonds in the silicone rubber backbone have large bond lengths and bond angles, giving the molecular chains extremely high flexibility, allowing them to maintain good elasticity even at extremely low temperatures. However, fluororubber and silicone rubber are thermodynamically incompatible due to their significant polarity differences, leading to macroscopic phase separation in the blend system, weak interfacial bonding, and deterioration of overall performance. Using polymeric compatibilizers is a common method to improve compatibility, but the compatibilizing effect has significant limitations: on the one hand, compatibilizers tend to form micelle structures in one phase rather than migrate directionally to the interface, reducing compatibilization efficiency; on the other hand, even if they reach the interface, the limited degree of chain entanglement makes it difficult to achieve long-term stable bonding, and the interface is prone to separation again under dynamic loading or thermal cycling. Furthermore, the complex and costly preparation process of polymeric compatibilizers hinders their industrial application.

[0006] In summary, how to improve the low-temperature performance of fluororubber while maintaining its mechanical strength and service stability remains a core challenge in current research. Summary of the Invention

[0007] The purpose of this invention is to provide a low-temperature resistant rubber sealing material and its preparation method, so as to solve the problem of poor low-temperature resistance of rubber sealing materials.

[0008] The objective of this invention can be achieved through the following technical solutions: This invention provides a low-temperature resistant rubber sealing material, comprising the following raw materials: fluororubber, silicone rubber, nano-compensator, and vinyl-terminated silicone oil; wherein the mass ratio of fluororubber to silicone rubber is 70-90:10-30; and the fluororubber and silicone rubber constitute the rubber matrix. The amount of nano-compensator added is 15%-20% of the total amount of rubber matrix; the amount of vinyl-terminated silicone oil is 0.2%-0.8% of the mass of rubber matrix; the nano-compensator is a long-chain alkyl-modified graphene oxide aminated UiO-66 composite material.

[0009] This invention employs a blend of fluororubber and silicone rubber in a specific ratio. Utilizing the intrinsic high flexibility resulting from the long Si-O bond length and large bond angle in the silicone rubber molecular backbone, the activation energy of molecular chain motion in the blend system is effectively reduced. Under low-temperature conditions, the flexible segments of silicone rubber can act as molecular chain motion units to maintain chain mobility, avoiding the low-temperature embrittlement caused by excessive rigidity of the fluororubber molecular chains. Compared to pure fluororubber systems, the fluorosilicone blend matrix achieves a qualitative improvement in low-temperature elongation at break. Furthermore, by controlling the blending ratio, a flexible balance can be established between low-temperature toughness and tensile strength to adapt to the differentiated performance requirements of materials in various service environments.

[0010] In some possible implementations, the nanocompatibility agent is prepared through the following steps: Ammoniated graphene oxide (UiO-66) composite material was dispersed in ethanol, ultrasonically dispersed, and then aliphatic aldehyde and acetic acid were added. The mixture was refluxed at 70-78℃. After the reaction, the mixture was centrifuged, washed, and dried to obtain a nano-composite agent. The low polarity of the long alkyl chain after modification with aliphatic aldehyde improved the compatibility between the aminated graphene oxide (UiO-66) composite material and the fluororubber matrix.

[0011] In some possible implementations, the aliphatic aldehyde is one of dodecanal, undecanoal, 9-undecenal, and n-decanal. The aminated UiO-66 / graphene oxide composite nanocompensator used in this invention, after modification with aliphatic aldehydes, possesses a porous structure, abundant reactive sites, and a long-chain alkyl / alkenyl modification layer, enabling it to simultaneously exert a dual function of physical anchoring and chemical bonding at the interface between fluororubber and silicone rubber. Specifically, when using unsaturated aliphatic aldehydes containing carbon-carbon double bonds (such as 9-undecenal) for modification, the allyl or alkenyl structures introduced at the ends of the compatibilizer molecular chains, which can participate in the peroxide vulcanization reaction, firmly anchor the nanocompensator to the rubber crosslinking network via covalent bonds, significantly enhancing the filler-matrix interface bonding strength and stress transfer efficiency. The construction of this chemically bonded interface effectively solves the problem of low-temperature mechanical property degradation caused by interfacial slippage and stress concentration in traditional physical blending systems.

[0012] In some possible implementations, the ratio of graphene oxide aminated UiO-66 composite material to aliphatic aldehyde is 1 g: 0.002-0.0003 mol.

[0013] In some possible implementations, the graphene oxide-aminated UiO-66 composite material is prepared via the following steps: 2-Amino-1,4-dicarboxylic acid, zirconium tetrachloride, acetic acid, and graphene oxide were added to N,N-dimethylformamide and ultrasonically dispersed. The reaction was carried out at a temperature of 100-140℃ for 16-24 hours. After the reaction was completed, the mixture was cooled to room temperature, and after solid-liquid separation, washing and drying, the graphene oxide-aminated UiO-66 composite material was obtained.

[0014] The graphene oxide-aminated UiO-66 composite material was prepared by mixing the aminated UiO-66 precursor and GO through a hydrothermal reaction using an in-situ growth method.

[0015] UiO-66 is a Zr-based MOF, and its metal clusters contain open sites (defect sites) with coordination unsaturation. These sites can coordinate with other oxygen-containing functional groups in the base material (such as -COOH and -OH, which originate from fillers or from thermal-oxidative aging during processing or storage, resulting in main chain breakage). This is equivalent to establishing a chemical anchor between the filler and the rubber, rather than relying solely on the physical compatibility of alkyl long chains. Simultaneously, the high structural stability of UiO-66 ensures its integrity during high-temperature vulcanization, continuously providing interfacial reinforcement. This stronger interfacial bonding can more effectively transfer stress, improving tensile strength and resistance to compressive settling.

[0016] In some possible implementations, the ratio of 2-amino-1,4-dicarboxylic acid, zirconium tetrachloride, and acetic acid is 0.37-0.39 g : 0.44-0.46 g : 11.5-12 g; and the mass ratio of 2-amino-1,4-dicarboxylic acid to graphene oxide is 1 : 2-3.

[0017] In some possible implementations, the raw materials of the low-temperature resistant rubber sealing material further include: acid absorbent, lubricant, vinyl-terminated silicone oil, vulcanizing agent, and crosslinking agent. Fluororubber and silicone rubber constitute the rubber matrix.

[0018] The amount of acid absorbent used is 4%–5% of the mass of the rubber matrix; The amount of lubricant used is 1%–2% of the mass of the rubber matrix; The amount of vulcanizing agent used is 1%–1.5% of the mass of the rubber matrix; The amount of crosslinking agent used is 2%–3% of the mass of the rubber matrix.

[0019] In some possible implementations, the vinyl-terminated silicone oil includes at least one of vinyl-terminated boron-containing silicone oil and vinyl-terminated fluorine-containing silicone oil. The vinyl-terminated silicone oil has vinyl functional groups capped, allowing the vinyl groups to participate in the vulcanization reaction during the vulcanization process.

[0020] In some possible implementations, the mass ratio of vinyl-terminated borosilicate silicone oil to vinyl-terminated fluorinated silicone oil is 1:2-3. This invention introduces vinyl-terminated functional silicone oils (fluorinated silicone oil and / or borosilicate silicone oil) into the blend system. Through the participation of their vinyl end groups in the peroxide vulcanization reaction, flexible siloxane segments are permanently integrated into the crosslinking network via chemical bonds, achieving an internal plasticizing effect at the molecular scale and avoiding the performance degradation caused by the migration and precipitation of traditional small-molecule plasticizers. The vinyl-terminated fluorinated silicone oil, with its strong polarity of carbon-fluorine bonds, enhances the interfacial affinity with the fluororubber matrix, while simultaneously improving the composite material's resistance to media. The vinyl-terminated borosilicate silicone oil, utilizing the dynamic coordination characteristics of boron-oxygen bonds (B—O), effectively dissipates external stress as a reversible physical crosslinking point under low-temperature conditions, significantly improving low-temperature ductility. The combined use of these two components allows the fluorinated silicone oil to provide interfacial bonding strength and thermal stability, while the borosilicate silicone oil imparts low-temperature toughness and stress dissipation capability, achieving simultaneous optimization of low-temperature tensile strength and elongation at break. The overall effect is significantly better than either single component.

[0021] In some possible implementations, the vinyl-terminated borosilicate oil is synthesized using a hydrolysis-condensation method with diphenyldimethoxysilane and phenylboronic acid as raw materials and tetramethyldivinyldisiloxane as the end-capping agent. Deionized water, cyclohexane, and trifluoromethanesulfonic acid were mixed and stirred until homogeneous. Diphenyldimethoxysilane and phenylboronic acid were then added. Hydrolysis was carried out at 45-50℃ for 45-50 min, followed by reaction at 75-80℃ for 4.5-5 h. Tetramethyldivinyldisiloxane was then added, and the reaction continued for 3-4 h. The reaction solution was separated, washed with water until neutral, and the organic layer was distilled under reduced pressure and dried under vacuum at 150℃ for 3 h. The crude product was dissolved in cyclohexane, washed with water, and then distilled under reduced pressure and dried under vacuum at 150℃ for 3 h to obtain vinyl-terminated borosilicate oil.

[0022] The viscosity of the vinyl-terminated fluorinated silicone oil is 300 cSt ± 30.

[0023] This invention provides a method for preparing a low-temperature resistant rubber sealing material, comprising the following steps: Pretreatment and plasticizing of fluororubber: Raw fluororubber is fed into a two-roll mill and passed through it 3 to 5 times. It is rolled until it evenly covers the rollers and the surface is flat and smooth. Then it is sheeted and cooled to obtain fluororubber sheets. Pretreatment and plasticizing of silicone rubber: Raw silicone rubber is fed into a two-roll mill. After it wraps around the rollers, vinyl-terminated silicone oil is slowly added according to the proportions in the formula table below. The mixture is repeatedly pounded until the vinyl-terminated silicone oil is completely absorbed by the silicone rubber, yielding silicone rubber sheets. Basic mixing of fluororubber and silicone rubber: Fluororubber film and silicone rubber film are mixed and repeatedly passed through thin layers and formed into triangular folds 5-6 times to obtain a uniformly dispersed blend base rubber; Add functional additives and nano-compensators: Adjust the roller gap to 2-3 mm. Add nano-compensators, acid absorbers, and lubricants. After all the additives are added, mix thoroughly in a triangular bag 3-4 times. Add peroxide vulcanization system: Lower the roller temperature and stabilize it at 40~50 ℃, add bis(tert-butylperoxyisopropyl)benzene as vulcanizing agent and triallyl isocyanurate as crosslinking agent. After adding, mix 5~6 times by alternating between rolling and triangular wrapping (this stage is controlled within 3~4 minutes). Film output, storage and resting: Adjust the roller gap to 4~5 mm for film output. Cover the film with a release film and let it rest at room temperature (25 ℃ and below) for 2~4 hours to relax the mixing stress; Vulcanization molding: The prepared rubber compound is vulcanized on a flat vulcanizing machine for the first stage (vulcanization temperature 160-180℃, vulcanization pressure 10-15 MPa, vulcanization time 1.2-1.5 times that of the normal vulcanization time (T90)). Then it is placed in a forced-air drying oven for the second stage vulcanization (200-230℃, 4-10 h) to obtain the low-temperature resistant rubber sealing material.

[0024] By employing a stepwise strategy of pre-treating and plasticizing fluororubber and silicone rubber separately before blending, the problem of uneven dispersion caused by excessive viscosity differences between the two rubbers is effectively avoided, ensuring the uniform distribution of the nano-compensator and vulcanization system in each phase. Simultaneously, the process design of adding the peroxide vulcanization system in the later stages of mixing and strictly controlling the roller temperature effectively avoids the risk of early scorching of the rubber compound, guaranteeing the optimal construction of the vulcanization crosslinking network.

[0025] The beneficial effects of this invention are: This invention provides a low-temperature resistant rubber sealing material and its preparation method. The invention employs a scheme that utilizes a fluorosilicone rubber blend matrix to impart low-temperature toughness, a nano-compensator to establish chemical bonding and anchoring at the interface to enhance stress transfer, and a vinyl-terminated functional silicone oil to synergistically regulate the molecular chain segment movement through intramolecular plasticization and dynamic crosslinking. This approach achieves, for the first time in fluororubber composites, the synergistic optimization of low-temperature elongation at break and tensile strength, effectively overcoming the technical bottleneck of high low-temperature brittleness and insufficient toughness in traditional fluororubber materials. The organic combination of chemical bonding and physical synergy among the functional components forms a low-temperature toughening mechanism from molecular chain segment movement to macroscopic interfacial stress transfer, enabling the composite material to maintain good elasticity and mechanical stability even at low temperatures. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] The following is a detailed description of a low-temperature resistant rubber sealing material and its preparation method according to an embodiment of this application.

[0028] The following is a detailed description with reference to specific examples.

[0029] Preparation Example 1 Preparation of nanocomposite agents: 2-Amino-1,4-dicarboxylic acid, zirconium tetrachloride, acetic acid, and graphene oxide were added to N,N-dimethylformamide and ultrasonically dispersed. The reaction was carried out at 120℃ for 20 h. After the reaction was completed, the mixture was cooled to room temperature, and after solid-liquid separation, washing and drying, graphene oxide aminated UiO-66 composite material was obtained. The ratio of 2-amino-1,4-dicarboxylic acid, zirconium tetrachloride, and acetic acid was 0.38 g: 0.45 g: 12 g; the mass ratio of 2-amino-1,4-dicarboxylic acid, graphene oxide, and N,N-dimethylformamide was 1:2:50.

[0030] The graphene oxide-aminated UiO-66 composite material was dispersed in ethanol, ultrasonically dispersed, and then aliphatic aldehyde and acetic acid were added. The mixture was refluxed at 78°C. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain a nano-composite agent. The aliphatic aldehyde was dodecaldehyde. The ratio of the graphene oxide-aminated UiO-66 composite material to the aliphatic aldehyde was 1 g: 0.002 mol. The ratio of the acetic acid to the aliphatic aldehyde was 0.02 g: 0.002 mol.

[0031] Preparation Example 2 Preparation of nanocomposite agent: The difference between this preparation example and Preparation Example 1 is that the mass ratio of 2-amino-1,4-dicarboxylic acid to graphene oxide is 1:3. The remaining raw materials and preparation process are the same as in Preparation Example 1.

[0032] Preparation Example 3 Preparation of nanocomposite agent: The difference between this preparation example and Preparation Example 1 is that the aliphatic aldehyde is undecylaldehyde. The remaining raw materials and preparation process are the same as in Preparation Example 1.

[0033] Preparation Example 4 Preparation of nanocomposite agent: The difference between this preparation example and Preparation Example 1 is that the fatty aldehyde is 9-undecenal. The remaining raw materials and preparation process are the same as in Preparation Example 1.

[0034] Preparation Example 5 Preparation of nanocomposite agent: The difference between this preparation example and Preparation Example 1 is that the fatty aldehyde is n-decanal. The remaining raw materials and preparation process are the same as in Preparation Example 1.

[0035] Preparation Example 6 Preparation of vinyl-terminated boron-containing silicone oil: Deionized water, cyclohexane, and trifluoromethanesulfonic acid were mixed and stirred until homogeneous. Diphenyldimethoxysilane and phenylboronic acid (diluted with ethanol) were then added. Hydrolysis was carried out at 50°C for 45 min, followed by a reaction at 80°C for 4.5 h. Tetramethyldivinyldisiloxane was then added, and the reaction continued for 3 h. The reaction solution was separated, washed with water until neutral, and the organic layer was distilled under reduced pressure and dried under vacuum at 150°C for 3 h. The crude product was dissolved in cyclohexane, washed with water, and then distilled under reduced pressure and dried under vacuum at 150°C for 3 h to obtain vinyl-terminated borosilicate oil.

[0036] Example 1 This embodiment provides a low-temperature resistant rubber sealing material, comprising the following raw materials: fluororubber, silicone rubber, nano-compensator prepared in Preparation Example 1, acid absorbent, lubricant, vinyl-terminated silicone oil, vulcanizing agent, and crosslinking agent. Fluororubber and silicone rubber constitute the rubber matrix. The mass ratio of fluororubber to silicone rubber is 80:20; the amount of nano-compensator added is 18% of the total amount of the rubber matrix. The composition of the rubber matrix is ​​as follows: acid scavenger (magnesium oxide) accounts for 4% of the rubber matrix mass; lubricant (carnauba wax) accounts for 1% of the rubber matrix mass; vinyl-terminated silicone oil accounts for 0.5% of the rubber matrix mass; vulcanizing agent (bis(tert-butylperoxyisopropyl)benzene) accounts for 1% of the rubber matrix mass; and co-crosslinking agent (tracelyl isocyanurate) accounts for 2% of the rubber matrix mass. The vinyl-terminated silicone oil is a vinyl-terminated fluorinated silicone oil.

[0037] The preparation method includes the following steps: Pretreatment and plasticizing of fluororubber: Raw fluororubber is fed into a two-roll mill, passed through three times, and rolled until it evenly covers the rollers and the surface is flat and smooth. Then it is sheeted and cooled to obtain fluororubber sheets. Pretreatment and plasticizing of silicone rubber: Raw silicone rubber is fed into a two-roll mill. After it wraps around the rollers, vinyl-terminated silicone oil is slowly added according to the proportions in the formula table below. The mixture is repeatedly pounded until the vinyl-terminated silicone oil is completely absorbed by the silicone rubber, yielding silicone rubber sheets. Basic mixing of fluororubber and silicone rubber: Fluororubber film and silicone rubber film are mixed and repeatedly thin-passed and triangularly wrapped 5 times to obtain a uniformly dispersed blend base rubber; Add functional additives and nano-compensators: Adjust the roller gap to 3 mm. Add the nano-compensator, magnesium oxide, and carnauba wax. After adding all the ingredients, mix thoroughly in three triangular batches. Add peroxide vulcanization system: Lower the roller temperature and stabilize it at 40℃ and add bis(tert-butylperoxyisopropyl)benzene and allyl isocyanurate. After adding, mix 6 times by alternating between rolling and triangular wrapping. Film output, storage and resting: Adjust the roller gap to 5 mm before outputting the film. Cover the film with a release film and let it rest at room temperature for 3 hours to relax the mixing stress; Vulcanization molding: The prepared rubber compound is vulcanized on a flat vulcanizing machine for the first stage (vulcanization temperature 160℃, vulcanization pressure 15MPa, vulcanization time 1.5 times the normal vulcanization time (T90)), and then placed in a forced-air drying oven for the second stage vulcanization (230℃, 4h) to obtain the low-temperature resistant rubber sealing material.

[0038] Example 2 The difference between this embodiment and Example 1 is that fluororubber and silicone rubber constitute the rubber matrix. The mass ratio of fluororubber to silicone rubber is 70:30. All other raw materials and preparation processes remain the same as in Example 1.

[0039] Example 3 The difference between this embodiment and Example 1 is that fluororubber and silicone rubber constitute the rubber matrix. The mass ratio of fluororubber to silicone rubber is 90:10. All other raw materials and preparation processes remain the same as in Example 1.

[0040] Example 4 The difference between this embodiment and Example 1 is that the amount of nano-compensator added is 15% of the total amount of rubber matrix; the remaining raw materials and preparation process are the same as in Example 1.

[0041] Example 5 The difference between this embodiment and Example 1 is that the amount of nano-compensator added is 20% of the total amount of rubber matrix; the remaining raw materials and preparation process are the same as in Example 1.

[0042] Example 6 The difference between this embodiment and Example 1 is that the nanocompensator was prepared in Example 2; the other raw materials and preparation process are the same as in Example 1.

[0043] Example 7 The difference between this embodiment and Example 1 is that the nanocompensator was prepared in Example 3; the other raw materials and preparation process are the same as in Example 1.

[0044] Example 8 The difference between this embodiment and Example 1 is that the nanocompensator was prepared in Example 4; the other raw materials and preparation process are the same as in Example 1.

[0045] Example 9 The difference between this embodiment and Example 1 is that the nanocompensator was prepared in Example 5; the other raw materials and preparation process are the same as in Example 1.

[0046] Example 10 The difference between this embodiment and Example 1 is that the vinyl-terminated silicone oil is a vinyl-terminated boron-containing silicone oil; the other raw materials and preparation process are the same as in Example 1.

[0047] Example 11 The difference between this embodiment and Embodiment 1 is that the vinyl-terminated silicone oil includes vinyl-terminated boron-containing silicone oil and vinyl-terminated fluorine-containing silicone oil, and the mass ratio of vinyl-terminated boron-containing silicone oil to vinyl-terminated fluorine-containing silicone oil is 1:2.

[0048] Comparative Example 1 Compared with Example 1, this comparative example does not add silicone rubber, but uses fluororubber to make up the amount. The other raw materials and preparation process are the same as in Example 1.

[0049] Comparative Example 2 The difference between this comparative example and Example 1 is that the nanocompensator was replaced with silane coupling agent-treated graphene oxide: Graphene oxide was dispersed in a mixed solution of anhydrous ethanol and deionized water (volume ratio 4:1) and ultrasonically dispersed. Tridecafluorooctyltriethoxysilane was added, and the pH of the mixed solution was adjusted to 3. The reaction was carried out at 70°C for 4 hours. After the reaction, the mixture was separated and dried to obtain silane coupling agent-treated graphene oxide. All other raw materials and preparation processes remained the same as in Example 1.

[0050] Comparative Example 3 The difference between this comparative example and Example 1 is that no terminal vinyl silicone oil was added. All other raw materials and preparation processes remained the same as in Comparative Example 1.

[0051] Comparative Example 4 This comparative example is based on Comparative Example 1 without the addition of terminal vinyl silicone oil. All other raw materials and preparation processes remain the same as in Comparative Example 1.

[0052] Test Example 1 According to the national standard GB / T 528-2009, "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber," dumbbell-shaped specimens with dimensions of 115 mm × 6 mm × 2 mm (length × width × thickness) were used. Tensile tests were conducted at room temperature with a tensile rate of 500 mm / min and a gauge length of 25 mm. Low-temperature tests were conducted at a tensile rate of 100 mm / min. The tensile strength and elongation at break of the specimens were tested.

[0053] Performance tests were conducted on Examples 1-11 and Comparative Examples 1-4, and the results are shown in Table 1: Table 1

[0054] Test Example 2 Hot air aging test The fluororubber composite material was placed in an aging chamber and aged at 250 °C for 70 h. After aging, the sample was removed and placed in a stress-free laboratory environment for no less than 16 h and no more than 6 days. Tensile properties were then tested at room temperature according to standard tensile test requirements. Table 2

[0055] Based on Tables 1-2 and a comparison of Examples 1-11 and Comparative Examples 1-4, it can be seen that the present invention solves the technical problems of high low-temperature brittleness and insufficient low-temperature elastic recovery of fluororubber materials through a ternary synergistic strategy of fluorosilicone rubber blend matrix, interface regulation of nano-compensator, and internal plasticizing of vinyl-terminated functional silicone oil. This achieves the comprehensive goal of significantly improving the low-temperature ductility and impact resistance of the composite material while maintaining high mechanical strength, and also possesses certain anti-aging properties.

[0056] Comparing Example 1 and Comparative Examples 1-4, it can be seen that Comparative Example 1 exhibits higher strength at room temperature, but shows significant brittle fracture at low temperatures, with a significantly lower elongation at break than Example 1, indicating that the introduction of silicone rubber effectively inhibits low-temperature embrittlement. The fluorosiloxane-treated graphene oxide in Comparative Example 2 only has an affinity for the fluororubber phase, but lacks bridging ability for the silicone rubber phase, resulting in insufficient interface modification (the perfluorinated chain of tridecafluorooctyltriethoxysilane in Comparative Example 2 is highly rigid, creating a certain degree of structural incompatibility with the flexibility of the siloxane backbone), and its low-temperature mechanical properties are significantly inferior to those of the compatibilizer (containing UiO-66) in Example 1. Comparative Example 3 lacks the intramolecular plasticizing effect of flexible silicone oil, resulting in hindered molecular chain segment movement at low temperatures and a significantly reduced elongation at break, indicating that the chemical bonding plasticizing effect of terminal vinyl silicone oil is indispensable for low-temperature toughness. Comparative Example 4, lacking both silicone rubber and terminal vinyl silicone oil, exhibits the most severe low-temperature brittleness. The synergistic use of the two in Example 1 achieved optimal low-temperature mechanical properties, demonstrating the effectiveness of the synergistic strategy of flexible second phase and internal plasticization.

[0057] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-temperature resistant rubber sealing material, characterized in that, The product includes the following raw materials: fluororubber, silicone rubber, nano-compensator, and terminal vinyl silicone oil; wherein the mass ratio of fluororubber to silicone rubber is 70-90:10-30; fluororubber and silicone rubber constitute the rubber matrix; the amount of nano-compensator added is 15%-20% of the total amount of rubber matrix; the amount of terminal vinyl silicone oil is 0.2%-0.8% of the mass of rubber matrix; the nano-compensator is a long-chain alkyl-modified graphene oxide aminated UiO-66 composite material.

2. The low-temperature resistant rubber sealing material according to claim 1, characterized in that, The nanocompatibility agent is prepared through the following steps: The graphene oxide aminated UiO-66 composite material was dispersed in ethanol, ultrasonically dispersed, and then aliphatic aldehyde and acetic acid were added. The mixture was refluxed at 70-78℃. After the reaction was completed, the nanocomposite was obtained by centrifugation, washing and drying.

3. The low-temperature resistant rubber sealing material according to claim 2, characterized in that, The fatty aldehyde is one of dodecaldehyde, undecaldehyde, 9-undecenaldehyde, and n-decanaldehyde.

4. The low-temperature resistant rubber sealing material according to claim 2, characterized in that, The ratio of the amount of graphene oxide aminated UiO-66 composite material to aliphatic aldehyde is 1g:0.002-0.0003mol.

5. The low-temperature resistant rubber sealing material according to claim 2, characterized in that, The graphene oxide aminated UiO-66 composite material was prepared by in-situ growth method, which involves mixing aminated UiO-66 precursor and GO and then reacting them via hydrothermal reaction.

6. The low-temperature resistant rubber sealing material according to claim 1, characterized in that, The raw materials for the low-temperature resistant rubber sealing material also include: acid absorbent, lubricant, vulcanizing agent and crosslinking agent; The amount of acid absorbent used is 4%–5% of the mass of the rubber matrix; The amount of lubricant used is 1%–2% of the mass of the rubber matrix; The amount of vulcanizing agent used is 1%–1.5% of the mass of the rubber matrix; The amount of crosslinking agent used is 2%–3% of the mass of the rubber matrix.

7. The low-temperature resistant rubber sealing material according to claim 1, characterized in that, The terminal vinyl silicone oil includes at least one of terminal vinyl boron-containing silicone oil and terminal vinyl fluorine-containing silicone oil.

8. The low-temperature resistant rubber sealing material according to claim 7, characterized in that, The mass ratio of the terminal vinyl boron-containing silicone oil to the terminal vinyl fluorine-containing silicone oil is 1:2-3.

9. The low-temperature resistant rubber sealing material according to claim 7, characterized in that, The terminated vinyl boron-containing silicone oil is synthesized using diphenyldimethoxysilane and phenylboronic acid as raw materials, and tetramethyldivinyldisiloxane as the end-capping agent, via a hydrolysis-condensation method.

10. A method for preparing a low-temperature resistant rubber sealing material, used to prepare the low-temperature resistant rubber sealing material according to any one of claims 1-9, characterized in that, The process includes the following steps: pre-treating, plasticizing, and plasticizing fluororubber and silicone rubber respectively, then blending them, and finally vulcanizing them.

Images