Engine crankshaft rear oil seal and preparation method thereof

Abstract

The invention relates to the technical field of sealing materials, and particularly discloses an engine crankshaft rear oil seal and a preparation method thereof. The engine crankshaft rear oil seal is prepared from fluororubber, modified filler, toner, a processing aid, a stabilizer, a vulcanizing agent and a vulcanizing aid. The modified filler is prepared from the following raw materials: silica, amino silane, allyl-2, 3-epoxypropyl ether and a fluorine-containing olefin monomer, and the mass ratio of the silica to the amino silane to the allyl-2, 3-epoxypropyl ether to the fluorine-containing olefin monomer is 1 to (0.1 to 0.2) to (0.3 to 0.5) to (0.2 to 0.3). The wide-temperature stability of the crankshaft rear oil seal can be effectively improved, it is ensured that the crankshaft rear oil seal keeps a stable sealing effect under complex working conditions, and the sealing life of the crankshaft rear oil seal is prolonged.

Description

Technical Field

[0001] This invention relates to the field of sealing materials technology, and in particular to the rear oil seal of an engine crankshaft and its preparation method. Background Technology

[0002] With the rapid development of the automotive industry, engines are constantly iterating towards higher power density, higher speed, and longer lifespan, and the performance requirements for their various components are becoming increasingly stringent. Among them, the crankshaft rear oil seal is a crucial component in the engine sealing system, and its performance directly affects the engine's reliability, emissions levels, and service life.

[0003] The crankshaft rear oil seal is mainly made of fluororubber. Fluororubber has excellent properties such as high temperature resistance, oil resistance and chemical media resistance. Sealing materials based on fluororubber can adapt to the needs of different working conditions to a large extent.

[0004] However, due to the strong attraction between fluorine atoms in its main chain or side chain, fluororubber restricts bond rotation, resulting in high rigidity of the molecular chain. When fluororubber is in a low-temperature environment, it is prone to becoming brittle and cracking. When fluororubber is exposed to a high-temperature environment for a long time, it will also age and harden, lose its elasticity, and cause the crankshaft rear oil seal to lose its original sealing performance. Summary of the Invention

[0005] To address the issue of insufficient heat and cold resistance of fluororubber and improve the sealing performance of the crankshaft rear oil seal, this application provides an engine crankshaft rear oil seal and its preparation method.

[0006] Firstly, the engine crankshaft rear oil seal provided in this application adopts the following technical solution: The engine crankshaft rear oil seal, by weight, is made from the following raw materials: Fluororubber 80-100 parts, modified filler 14-16 parts, colorant 7-9 parts, processing aid 1.8-2.8 parts, stabilizer 7-10 parts, vulcanizing agent 1.7-2.3 parts, vulcanizing aid 2-4 parts; The raw materials for preparing the modified filler include silica, aminosilane, allyl-2,3-epoxypropyl ether and fluorinated olefin monomers, and the mass ratio of silica, aminosilane, allyl-2,3-epoxypropyl ether and fluorinated olefin monomers is 1:(0.1-0.2):(0.3-0.5):(0.2-0.3).

[0007] By adopting the above technical solution, the CF bond energy in fluororubber is relatively high, and the fluorine atoms have a strong shielding effect on the polymer backbone, thus endowing the material with good heat resistance, oil resistance, and chemical resistance. This application introduces a specific ratio of modified filler. After silica is surface-modified with aminosilane, its surface amino groups can react with the epoxy groups of allyl-2,3-epoxypropyl ether, further grafting fluorinated olefin monomers. This gives the modified filler surface fluorinated groups, enhancing its interfacial compatibility with the fluororubber matrix and enabling the formation of physical or chemical crosslinking points between the filler and the fluororubber molecular chains under vulcanization. Meanwhile, the high bond angle and rotational freedom of the ether bonds in allyl-2,3-epoxypropylene ether can reduce the interaction forces between the modified filler and the fluororubber molecular chains, effectively suppressing excessive rigidity of the molecular chains and reducing the tendency for brittle fracture at low temperatures. In low-temperature environments, the dispersed phase of the modified filler can play a toughening role. Under high-temperature conditions, the fluorinated groups in the modified filler synergistically enhance thermal stability with the fluororubber matrix, delaying the aging and hardening process, thereby significantly improving the wide-temperature stability of the crankshaft rear oil seal and extending its sealing life. Furthermore, the synergistic effect of the vulcanizing agent and vulcanization accelerator further optimizes the processing performance of the rubber compound and the vulcanization system, ensuring that the oil seal maintains a stable sealing effect under complex operating conditions.

[0008] Preferably, the method for preparing the modified filler includes the following steps: A first solvent and aminosilane were added to silica, and the mixture was heated and stirred to react. The filtrate was removed by filtration, and the mixture was washed and dried to obtain the surface-modified filler. A second solvent and allyl-2,3-epoxypropyl ether were added to the surface-modified filler, and the mixture was stirred to react. After the reaction was completed, the filtrate was removed by filtration, washed, and dried to obtain the intermediate modified filler. The intermediate modified filler and the third solvent were added into a reaction vessel, vacuumed, heated, and fluorinated olefin monomers and initiators were pumped in. The mixture was stirred and reacted. After the reaction was completed, post-treatment was performed to obtain the modified filler.

[0009] By adopting the above technical solution, the first step involves surface modification of silica using aminosilanes, grafting amino functional groups onto the silica surface to effectively enhance its interfacial bonding with the organic matrix. The second step introduces allyl-2,3-epoxypropyl ether, whose epoxy groups undergo a ring-opening reaction with the amino groups on the silica surface, further grafting flexible segments containing allyl and ether bonds. The third step involves grafting fluorinated olefin monomers onto the modified filler surface via free radical polymerization, giving the filler surface both fluorinated and ether bond structures. This enhances compatibility with the fluororubber matrix and alleviates the rigidity of the fluororubber molecular chains through ether bonds, improving low-temperature brittleness. Simultaneously, the synergistic effect of the fluorinated segments and fluororubber improves the material's high-temperature resistance, effectively delaying high-temperature aging. The multi-step modified filler can be uniformly dispersed in the fluororubber matrix, forming a stable reinforcing network, thereby significantly improving the wide-temperature sealing performance and service life of the crankshaft rear oil seal.

[0010] Preferably, the fluorinated olefin monomer includes one or both of perfluorobutylethylene and hexafluoropropylene.

[0011] By adopting the above technical solution, both perfluorobutylethylene and hexafluoropropylene are rich in fluorine atoms, and their molecular structures are similar to those of the fluororubber matrix. They can form a tight compatibility interface with the fluororubber molecular chains, significantly improving the dispersion uniformity of the modified filler in the matrix. When used alone or in combination, both can synergistically enhance the oil and chemical resistance of the oil seal with the fluororubber matrix, effectively preventing oil penetration.

[0012] Preferably, the aminosilane includes one or both of 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane.

[0013] By adopting the above technical solution, the aminosilane molecule structure contains an active amino functional group and a hydrolyzable alkoxy group. The alkoxy group can undergo a dehydration condensation reaction with the hydroxyl group on the silica surface, so that the aminosilane is firmly grafted onto the silica surface and forms a stable chemical bond. The amino functional group can undergo a ring-opening addition reaction with the epoxy group of allyl-2,3-epoxypropyl ether in the subsequent steps, providing reaction sites for the grafting of flexible segments and fluorine-containing monomers.

[0014] Preferably, the fluororubber includes FEPM type fluororubber and perfluoroether rubber in a mass ratio of 1:(0.15-0.25).

[0015] By adopting the above technical solution, FEPM-type fluororubber exhibits excellent oil resistance and processing fluidity, ensuring the molding and processing performance and basic sealing ability of the rubber compound as a matrix material. Perfluoroether rubber, with its ether bonds in its molecular structure and relatively high molecular chain flexibility, helps improve the low-temperature flexibility of the material. The two are compounded at a mass ratio of 1:(0.15-0.25) to achieve complementary performance. Simultaneously, this compound system exhibits good compatibility and synergy with the fluorinated groups and ether bond structure on the surface of the modified filler, further improving the elasticity and sealing performance of the oil seal material over a wide temperature range, effectively adapting to temperature fluctuations during engine start-up, operation, and shutdown.

[0016] Preferably, the vulcanizing agent includes one or more of vulcanizing agents DCP, DHBP, and BIBP.

[0017] Preferably, the vulcanizing aid includes one or both of triallyl isocyanurate and triallyl cyanurate.

[0018] By employing the above technical solution, peroxide-based vulcanizing agents can decompose under high-temperature conditions to generate free radicals, initiating cross-linking reactions between fluororubber molecular chains to form a stable three-dimensional network structure. This significantly improves the tensile strength, tear strength, and thermal stability of the rubber material. Furthermore, vulcanizing auxiliaries can work synergistically with peroxide vulcanizing agents; their multiple allyl functional groups can participate in the cross-linking reaction, increasing the cross-linking density and further enhancing the elasticity and resistance to compression set of the rubber compound.

[0019] Preferably, the processing aids include one or more of polyethylene wax, carnauba wax, WS-280, and Rheinland Aflux 25.

[0020] By adopting the above technical solutions, processing aids help improve the flowability and processing performance of fluororubber during the mixing process, enabling fluororubber to be mixed more evenly with other raw materials, improving mixing efficiency and quality, and helping to produce engine crankshaft rear oil seals with stable performance and good quality.

[0021] Preferably, the stabilizer comprises magnesium oxide and calcium hydroxide in a mass ratio of 1:(0.7-0.9).

[0022] By adopting the above technical solution and using magnesium oxide combined with calcium hydroxide as stabilizers, acidic byproducts generated during the vulcanization of fluororubber can be efficiently captured, effectively inhibiting the damage of the acidic environment to the rubber molecular chain, thereby improving processing stability and ensuring process consistency and the reliability of the final product in terms of strength, heat resistance, etc.

[0023] Secondly, the method for preparing the engine crankshaft rear oil seal provided in this application adopts the following technical solution: The method for preparing the rear oil seal of an engine crankshaft includes the following steps: (1) Add fluororubber to a mixer and mix for 3-6 minutes. The initial temperature is 70-80℃. Then add processing aids, stabilizers, modified fillers and color powder in sequence. Heat to 100-120℃ and mix thoroughly for 6-10 minutes. Discharge the rubber to obtain the compound. (2) Sheet the rubber compound on the open mill, cool the rubber sheet to 50-60℃, add vulcanizing agent and vulcanizing aid, make triangular wraps 3-5 times, thin pass 5-8 times, roll, and sheet to obtain rubber compound for later use. (3) The rubber material is pre-formed in a precision pre-forming machine to obtain rubber strips or rubber rings; (4) After the skeleton is surface treated, it is dipped in adhesive, pre-cured, and then heat-cured and bonded to the rubber strip or rubber ring to obtain the engine crankshaft rear oil seal.

[0024] By adopting the above technical solution, the synergistic effect of each step ensures uniform dispersion of the rubber compound components, excellent processing performance of the rubber compound, high dimensional accuracy of the preformed product, and strong adhesion between the skeleton and the rubber compound. The resulting engine crankshaft rear oil seal exhibits excellent high-temperature resistance, oil resistance, and aging resistance, with stable and durable sealing performance. It can effectively adapt to the complex working conditions of the engine crankshaft, extend the service life of the oil seal, and ensure the normal operation of the engine.

[0025] This application has the following beneficial effects: The fluororubber of this application exhibits high CF bond energy, and the fluorine atoms provide strong shielding for the polymer backbone, thus endowing the material with excellent heat resistance, oil resistance, and chemical resistance. This application introduces a specific ratio of modified filler. After surface modification of silica with aminosilane, the surface amino groups can react with the epoxy groups of allyl-2,3-epoxypropyl ether, further grafting fluorinated olefin monomers. This gives the modified filler surface fluorinated groups, enhancing its interfacial compatibility with the fluororubber matrix and enabling the formation of physical or chemical crosslinking points between the filler and the fluororubber molecular chains during vulcanization. Meanwhile, the high bond angle and rotational freedom of the ether bonds in allyl-2,3-epoxypropylene ether can reduce the interaction forces between the modified filler and the fluororubber molecular chains, effectively suppressing excessive rigidity of the molecular chains and reducing the tendency for brittle fracture at low temperatures. In low-temperature environments, the dispersed phase of the modified filler can play a toughening role. Under high-temperature conditions, the fluorinated groups in the modified filler synergistically enhance thermal stability with the fluororubber matrix, delaying the aging and hardening process, thereby significantly improving the wide-temperature stability of the crankshaft rear oil seal and extending its sealing life. Furthermore, the synergistic effect of the vulcanizing agent and vulcanization accelerator further optimizes the processing performance of the rubber compound and the vulcanization system, ensuring that the oil seal maintains a stable sealing effect under complex operating conditions. Detailed Implementation

[0026] The present application will be further described in detail below with reference to the embodiments.

[0027] Preparation Example 1 The preparation method of the modified filler includes the following steps: Weigh silica, aminosilane, allyl-2,3-epoxypropyl ether, and fluorinated olefin monomers in a mass ratio of 1:0.1:0.3:0.2. Weigh out the first solvent, specifically an ethanol solution (water: anhydrous ethanol = 3:7), at 15 times the mass of silica. Weigh out the second solvent, specifically acetone, at 15 times the mass of silica. Weigh out the third solvent, specifically acetone, at 20 times the mass of silica. The aminosilane is 3-aminopropyltrimethoxysilane. The fluorinated olefin monomer is perfluorobutylethylene. Weigh out the initiator, specifically azobisisobutyronitrile, at 1% of the mass of silica. Weigh out the acetone, specifically azobisisobutyronitrile, at 10 times the mass of azobisisobutyronitrile. Dissolve the azobisisobutyronitrile in acetone to obtain the initiator solution.

[0028] A. Add ethanol solution and 3-aminopropyltrimethoxysilane to silica, heat to 70°C, stir for 5 hours, filter to remove filtrate, wash, and dry to obtain surface-modified filler. B. Add acetone and allyl-2,3-epoxypropyl ether to the surface-modified filler, stir and react for 2 hours. After the reaction is complete, filter to remove the filtrate, wash and dry to obtain the intermediate modified filler. C. Add the intermediate modified filler and acetone into the reactor, evacuate, heat to 85°C, pump in perfluorobutylethylene and initiator solution, stir and react for 3 hours. After the reaction is complete, wash thoroughly and dry under forced air at 60°C for 24 hours to obtain the modified filler.

[0029] Preparation Example 2 The preparation method of the modified filler includes the following steps: Weigh silica, aminosilane, allyl-2,3-epoxypropyl ether, and fluorinated olefin monomers in a mass ratio of 1:0.15:0.4:0.25. Weigh a first solvent, specifically an ethanol solution (water: anhydrous ethanol = 3:7), at 15 times the mass of silica. Weigh a second solvent, specifically acetone, at 15 times the mass of silica. Weigh a third solvent, specifically acetone, at 20 times the mass of silica. The aminosilane is 3-aminopropyltriethoxysilane. The fluorinated olefin monomer is hexafluoropropylene. Weigh an initiator, specifically azobisisobutyronitrile (AIBN), at 1.5% of the mass of silica. Weigh acetone at 10 times the mass of AIBN and dissolve the AIBN in acetone to obtain the initiator solution.

[0030] A. Add ethanol solution and 3-aminopropyltriethoxysilane to silica, heat to 73°C, stir for 5 hours, filter to remove filtrate, wash, and dry to obtain surface-modified filler. B. Add acetone and allyl-2,3-epoxypropyl ether to the surface-modified filler, stir and react for 2 hours. After the reaction is complete, filter to remove the filtrate, wash and dry to obtain the intermediate modified filler. C. Add the intermediate modified filler and acetone into the reactor, evacuate, heat to 90°C, pump in hexafluoropropylene and initiator solution, stir and react for 3 hours. After the reaction is complete, wash thoroughly and dry under forced air at 60°C for 24 hours to obtain the modified filler.

[0031] Preparation Example 3 The preparation method of the modified filler includes the following steps: Weigh silica, aminosilane, allyl-2,3-epoxypropyl ether, and fluorinated olefin monomers in a mass ratio of 1:0.2:0.5:0.3. Weigh 15 times the mass of silica into a first solvent, specifically an ethanol solution (water: anhydrous ethanol = 3:7). Weigh 15 times the mass of silica into a second solvent, specifically acetone. Weigh 20 times the mass of silica into a third solvent, specifically acetone. The aminosilane is 3-aminopropyltriethoxysilane. The fluorinated olefin monomer is perfluorobutylethylene. Weigh 2% of the silica into an initiator, specifically azobisisobutyronitrile (AIBN). Weigh 10 times the mass of AIBN into acetone and dissolve AIBN in acetone to obtain an initiator solution.

[0032] A. Add ethanol solution and 3-aminopropyltriethoxysilane to silica, heat to 75°C, stir for 5 hours, filter to remove filtrate, wash, and dry to obtain surface-modified filler. B. Add acetone and allyl-2,3-epoxypropyl ether to the surface-modified filler, stir and react for 2 hours. After the reaction is complete, filter to remove the filtrate, wash and dry to obtain the intermediate modified filler. C. Add the intermediate modified filler and acetone into the reactor, evacuate, heat to 90°C, pump in perfluorobutylethylene and initiator solution, stir and react for 3 hours. After the reaction is complete, wash thoroughly and dry under forced air at 60°C for 24 hours to obtain the modified filler.

[0033] Preparation Example 4 The difference between this preparation example and preparation example 3 is that perfluorobutylethylene is replaced by n-hexene by mass.

[0034] Preparation Example 5 The difference between this preparation example and preparation example 3 is that allyl-2,3-epoxypropyl ether is replaced by 2,3-epoxypropyl isopropyl ether by mass.

[0035] Example 1 The preparation method of the engine crankshaft rear oil seal includes the following steps: Raw materials were weighed according to the following proportions by weight: 80 parts fluororubber, 14 parts modified filler, 7 parts colorant, 1.8 parts processing aid, 7 parts stabilizer, 1.7 parts vulcanizing agent, and 2 parts vulcanizing auxiliaries. The fluororubber included FEPM type fluororubber and perfluoroether rubber in a mass ratio of 1:0.15. FEPM type fluororubber: AFLAS 150P; perfluoroether rubber: AGC PM-1100. The modified filler was prepared by Preparation Example 1. The processing aid was Rheinland Aflux 25. The stabilizer was a mixture of magnesium oxide and calcium hydroxide in a mass ratio of 1:0.7. The vulcanizing agent was BIBP. The vulcanizing auxiliaries were triallyl cyanurate.

[0036] (1) Add FEPM type fluororubber and perfluoroether rubber to a mixer and mix for 4 minutes. The initial temperature is 70°C. Then add Rhein Aflux25, magnesium oxide and calcium hydroxide, modified filler and color powder in sequence. Heat to 100°C and mix thoroughly for 6 minutes. Discharge the rubber to obtain the compound. (2) Sheet the rubber compound on the open mill, cool the rubber sheet to 50°C, add vulcanizing agent BIBP and triallyl cyanurate, make three triangular wraps, pass through five thin passes, roll up, and sheet to obtain the rubber compound for later use. (3) The rubber material is pre-formed in a precision pre-forming machine to obtain rubber strips or rubber rings; (4) After the skeleton is surface treated, it is dipped in adhesive, pre-cured, and then heat-cured and bonded to the rubber strip or rubber ring to obtain the engine crankshaft rear oil seal.

[0037] The specific steps of hot vulcanization bonding are as follows: place the rubber strip or ring and the skeleton coated with adhesive into a mold at 170°C, push it into a vacuum vulcanizing machine at 170°C and vulcanize under pressure for 15 minutes. After opening the mold and taking out the part, put it into a constant temperature box for secondary vulcanization. The conditions are 220°C and 4 hours. After secondary vulcanization, the vulcanized semi-finished product is cooled and left to stand for 8 hours. The lip is cut and the rubber edge is trimmed to obtain the engine crankshaft rear oil seal.

[0038] Example 2 The preparation method of the engine crankshaft rear oil seal includes the following steps: Raw materials were weighed according to the following proportions by weight: 90 parts fluororubber, 15 parts modified filler, 8 parts colorant, 2.3 parts processing aid, 8 parts stabilizer, 2 parts vulcanizing agent, and 3 parts vulcanizing auxiliaries. The fluororubber included FEPM type fluororubber and perfluoroether rubber in a mass ratio of 1:0.2. FEPM type fluororubber: AFLAS 150P; perfluoroether rubber: AGC PM-1100; the modified filler was prepared by Preparation Example 2; the processing aid was WS-280; the stabilizer was magnesium oxide and calcium hydroxide compounded in a mass ratio of 1:0.8; the vulcanizing agent was DHBP; and the vulcanizing auxiliaries were triallyl isocyanurate.

[0039] (1) Add FEPM type fluororubber and perfluoroether rubber to a mixer and mix for 5 minutes. The initial temperature is 75℃. Then add WS-280, magnesium oxide and calcium hydroxide, modified filler and color powder in sequence. Heat to 110℃ and mix thoroughly for 8 minutes. Discharge the rubber to obtain the compound. (2) Sheet the rubber compound on a two-roll mill, cool the rubber sheet to 55°C, add vulcanizing agent DHBP and triallyl isocyanate, roll it into a triangular shape 4 times, pass it through a thin mill 7 times, roll it up, and sheet it to obtain the rubber compound for later use. (3) The rubber material is pre-formed in a precision pre-forming machine to obtain rubber strips or rubber rings; (4) After the skeleton is surface treated, it is dipped in adhesive, pre-cured, and then heat-cured and bonded to the rubber strip or rubber ring to obtain the engine crankshaft rear oil seal.

[0040] The specific steps of hot vulcanization bonding are as follows: place the rubber strip or ring and the skeleton coated with adhesive into a mold at 170°C, push it into a vacuum vulcanizing machine at 170°C and vulcanize under pressure for 17 minutes. After opening the mold and taking out the part, put it into a constant temperature box for secondary vulcanization. The conditions are temperature 230°C and time 6 hours. After secondary vulcanization, the vulcanized semi-finished product is cooled and left to stand for 8 hours. The lip is cut and the rubber edge is trimmed to obtain the engine crankshaft rear oil seal.

[0041] Example 3 The preparation method of the engine crankshaft rear oil seal includes the following steps: Raw materials were weighed according to the following proportions by weight: 100 parts fluororubber, 16 parts modified filler, 9 parts colorant, 2.8 parts processing aid, 10 parts stabilizer, 2.3 parts vulcanizing agent, and 4 parts vulcanizing auxiliaries. The fluororubber included FEPM type fluororubber and perfluoroether rubber in a mass ratio of 1:0.25. FEPM type fluororubber: AFLAS 150P; perfluoroether rubber: AGC PM-1100. The modified filler was prepared by Preparation Example 3. The processing aid was specifically polyethylene wax. The stabilizer was specifically a compound of magnesium oxide and calcium hydroxide in a mass ratio of 1:0.9. The vulcanizing agent was specifically vulcanizing agent DCP. The vulcanizing auxiliaries were specifically triallyl isocyanurate.

[0042] (1) Add FEPM type fluororubber and perfluoroether rubber to a mixer and mix for 6 minutes. The initial temperature is 75°C. Then add polyethylene wax, magnesium oxide and calcium hydroxide, modified filler and color powder in sequence. Heat to 120°C and mix thoroughly for 10 minutes. Discharge the rubber to obtain the compound. (2) Sheet the rubber compound on a two-roll mill, cool the rubber sheet to 60°C, add vulcanizing agent DCP and triallyl isocyanate, roll it into a triangular shape 5 times, pass it through a thin tube 8 times, roll it up, and sheet it to obtain the rubber compound for later use. (3) The rubber material is pre-formed in a precision pre-forming machine to obtain rubber strips or rubber rings; (4) After the skeleton is surface treated, it is dipped in adhesive, pre-cured, and then heat-cured and bonded to the rubber strip or rubber ring to obtain the engine crankshaft rear oil seal.

[0043] The specific steps of hot vulcanization bonding are as follows: place the rubber strip or rubber ring and the skeleton coated with adhesive into a mold at 170°C, push it into a vacuum vulcanizing machine at 170°C and vulcanize under pressure for 20 minutes. After opening the mold and taking out the part, put it into a constant temperature box for secondary vulcanization. The conditions are temperature 240°C and time 8 hours. After secondary vulcanization, the vulcanized semi-finished product is cooled and left to stand for 8 hours. The lip is cut and the rubber edge is trimmed to obtain the engine crankshaft rear oil seal.

[0044] Example 4 The difference between this embodiment and Embodiment 3 is that the fluororubber specifically refers to FEPM-type fluororubber and perfluoroether rubber. The mass ratio of FEPM-type fluororubber to perfluoroether rubber is 1:0.5.

[0045] Example 5 The difference between this embodiment and Embodiment 3 is that the fluororubber is specifically FEPM type fluororubber.

[0046] Comparative Example 1 The method for preparing the engine crankshaft rear oil seal differs from that in Example 3 in that the modified filler obtained in Preparation Example 4 is used.

[0047] Comparative Example 2 The method for preparing the engine crankshaft rear oil seal differs from that in Example 3 in that the modified filler obtained in Preparation Example 5 is used.

[0048] Comparative Example 3 The method for preparing the engine crankshaft rear oil seal differs from that in Example 3 in that the modified filler is replaced with silica.

[0049] Comparative Example 4 The method for preparing the engine crankshaft rear oil seal differs from that in Example 3 in that no modified filler is added. Performance testing

[0050] According to GB / T 531.1-2008 standard, the hardness (Shore A type) of the engine crankshaft rear oil seals prepared in Examples 1-5 and Comparative Examples 1-4 was tested, and the results are recorded in Table 1.

[0051] According to GB / T 528-2009 standard, the tensile strength, 100% tensile strength at a constant elongation, and elongation at break of the engine crankshaft rear oil seals prepared in Examples 1-5 and Comparative Examples 1-4 were tested, and the results are recorded in Table 1.

[0052] According to GB / T 529-2009 standard, the tear strength of the engine crankshaft rear oil seals prepared in Examples 1-5 and Comparative Examples 1-4 was tested, and the results are recorded in Table 1.

[0053] According to GB / T 7759.1-2015 standard, the compression set properties of the engine crankshaft rear oil seals prepared in Examples 1-5 and Comparative Examples 1-4 were tested under the conditions of 200℃ and 70 hours. The results are recorded in Table 1.

[0054] According to GB / T 1682-2014 standard, the brittle temperature of the engine crankshaft rear oil seals prepared in Examples 1-5 and Comparative Examples 1-4 was tested, and the results are recorded in Table 2.

[0055] According to GB / T 1690-2010 standard, the oil resistance of the engine crankshaft rear oil seals prepared in Examples 1-5 and Comparative Examples 1-4 was tested. The samples were immersed in IRM903 test oil at 150°C for 70 hours. After the test, the samples were removed and wiped clean. The weight and volume change rate were measured within 30 minutes. The results are recorded in Table 2.

[0056] Table 1

[0057] Table 2

[0058] Based on the comparison of Examples 3 and 4, and the data in Tables 1 and 2, it can be seen that when the mass ratio of FEPM-type fluororubber to perfluoroether rubber is adjusted from 1:0.25 to 1:0.5, the brittle temperature of the engine crankshaft rear oil seal decreases, and the low-temperature resistance is improved. However, due to the introduction of more ether bonds replacing the -CF2- groups, the intermolecular forces are weakened, resulting in a decrease in mechanical properties. This indicates that increasing the proportion of perfluoroether rubber helps optimize the low-temperature performance and flexibility of the oil seal, but it will have a certain impact on some mechanical properties and compression recovery properties. The optimal mass ratio of FEPM-type fluororubber to perfluoroether rubber is 1:0.25.

[0059] Based on the comparison between Examples 3 and 5, and the data in Tables 1 and 2, it can be seen that when only FEPM-type fluororubber is used, without the addition of perfluoroether rubber, the brittle temperature of the engine crankshaft rear oil seal increases, and its low-temperature resistance decreases. This is because perfluoroether rubber has superior low-temperature elasticity and flexibility, and its introduction can effectively improve the low-temperature performance and deformation capability of the oil seal. While using FEPM-type fluororubber alone slightly increases the hardness, its low-temperature adaptability and flexibility are insufficient. This indicates that the combined use of FEPM-type fluororubber and perfluoroether rubber can optimize the low-temperature resistance and flexibility of the oil seal while ensuring a certain level of hardness. Using FEPM-type fluororubber alone cannot achieve these properties simultaneously.

[0060] Based on the comparison between Example 3 and Comparative Example 1, and the data in Tables 1 and 2, it can be seen that when perfluorobutylethylene is replaced by an equal mass of n-hexene during the preparation of the modified filler, the non-fluorinated olefin significantly deteriorates the hardness and oil resistance of the oil seal. However, the fluorinated groups in the perfluorobutylethylene of Example 3 of this application can form good compatibility and synergy with the fluororubber matrix, enhancing the interfacial bonding force between the modified filler and the rubber, which is beneficial to improving the overall structural stability. Furthermore, the fluorinated groups have extremely low surface energy and chemical inertness; after grafting onto the filler surface, they can form an oleophobic barrier layer, effectively preventing oil penetration and swelling.

[0061] Based on the comparison between Example 3 and Comparative Example 2, and the data in Tables 1 and 2, it can be seen that when allyl-2,3-epoxypropyl ether is replaced by 2,3-epoxypropyl isopropyl ether in the preparation process of the modified filler, the isopropyl group in 2,3-epoxypropyl isopropyl ether is a saturated structure with no reactive double bond, and cannot form an effective bond with the fluorinated olefin monomer. This results in a weakening of the interfacial bonding force between the filler and the matrix. The weakening of the interfacial bonding not only reduces the mechanical properties and compression resilience of the material, but also makes it easier for the oil to penetrate through the interfacial defects, exacerbating the swelling of the oil. In Example 3 of this application, the allyl double bond in allyl-2,3-epoxypropylene ether can form a strong chemical bond with the double bond in fluorinated olefins. Grafting fluorinated olefins onto the filler surface is beneficial to improving the dispersion uniformity of silica in the fluororubber matrix and effectively reducing the generation of interfacial voids and defects. This not only enhances the mechanical properties of the oil seal, such as tensile strength and tear strength, but also reduces the probability of oil penetration through interfacial defects, thereby reducing the volume and mass changes caused by oil swelling and maintaining good sealing performance and structural stability of the oil seal.

[0062] Based on the comparison of Example 3 with Comparative Examples 3 and 4 and the data in the table, it can be seen that when the modified filler is replaced by an equal mass of silica or not added at all, the various properties of the oil seal deteriorate significantly. The silica surface, without modification, has poor dispersion ability, leading to agglomeration and stress concentration, which in turn causes a decrease in mechanical properties. Without the addition of modified filler, the rubber matrix lacks reinforcing phase support, resulting in poor structural stability, significantly increased compression set, and a marked decrease in oil resistance. This indicates that the modified filler prepared in this application can comprehensively improve the mechanical properties, oil resistance, and compression set resistance of the oil seal through synergistic effects with the fluororubber matrix, making it a key component for achieving high-performance oil seals.

[0063] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An engine crankshaft rear oil seal, characterized in that, It is prepared from the following raw materials in parts by weight: Fluororubber 80-100 parts, modified filler 14-16 parts, colorant 7-9 parts, processing aid 1.8-2.8 parts, stabilizer 7-10 parts, vulcanizing agent 1.7-2.3 parts, vulcanizing aid 2-4 parts; The raw materials for preparing the modified filler include silica, aminosilane, allyl-2,3-epoxypropyl ether and fluorinated olefin monomers, and the mass ratio of silica, aminosilane, allyl-2,3-epoxypropyl ether and fluorinated olefin monomers is 1:(0.1-0.2):(0.3-0.5):(0.2-0.3).

2. The engine crankshaft rear oil seal according to claim 1, characterized in that, The method for preparing the modified filler includes the following steps: The first solvent and aminosilane were added to silica, and the mixture was heated and stirred to react. The filtrate was removed by filtration, washed, and dried to obtain the surface-modified filler. A second solvent and allyl-2,3-epoxypropyl ether were added to the surface-modified filler, and the mixture was stirred to react. After the reaction was completed, the filtrate was removed by filtration, washed, and dried to obtain the intermediate modified filler. The intermediate modified filler and the third solvent were added into the reactor, vacuumed, heated, and fluorinated olefin monomers and initiators were pumped in. The mixture was stirred and reacted. After the reaction was completed, post-treatment was performed to obtain the modified filler.

3. The engine crankshaft rear oil seal according to claim 1, characterized in that, The fluorinated olefin monomers include one or both of perfluorobutylethylene and hexafluoropropylene.

4. The engine crankshaft rear oil seal according to claim 1, characterized in that, The aminosilane includes one or both of 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane.

5. The engine crankshaft rear oil seal according to claim 1, characterized in that, The fluororubber includes FEPM type fluororubber and perfluoroether rubber in a mass ratio of 1:(0.15-0.25).

6. The engine crankshaft rear oil seal according to claim 1, characterized in that, The vulcanizing agent includes one or more of vulcanizing agents DCP, DHBP, and BIBP.

7. The engine crankshaft rear oil seal according to claim 1, characterized in that, The vulcanization aid includes one or both of triallyl isocyanurate and triallyl cyanurate.

8. The engine crankshaft rear oil seal according to claim 1, characterized in that, The processing aids include one or more of polyethylene wax, palm wax, WS-280, and Rheinland Aflux 25.

9. The engine crankshaft rear oil seal according to claim 1, characterized in that, The stabilizer comprises magnesium oxide and calcium hydroxide in a mass ratio of 1:(0.7-0.9).

10. A method for preparing the engine crankshaft rear oil seal according to any one of claims 1-9, characterized in that, Includes the following steps: (1) Add fluororubber to a mixer and mix for 3-6 minutes. The initial temperature is 70-80℃. Then add processing aids, stabilizers, modified fillers and color powder in sequence. Heat to 100-120℃ and mix thoroughly for 6-10 minutes. Discharge the rubber to obtain the compound. (2) Sheet the rubber compound on the open mill, cool the rubber sheet to 50-60℃, add vulcanizing agent and vulcanizing aid, make triangular wraps 3-5 times, thin pass 5-8 times, roll, and sheet to obtain rubber compound for later use. (3) The rubber material is pre-formed in a precision pre-forming machine to obtain rubber strips or rubber rings; (4) After the skeleton is surface treated, it is dipped in adhesive, pre-cured, and then heat-cured and bonded to the rubber strip or rubber ring to obtain the engine crankshaft rear oil seal.

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