Heat-resistant and oil-resistant sealing gasket for engine and preparation method

Abstract

The invention relates to the field of sealing materials, in particular to a heat-resistant and oil-resistant sealing gasket for an engine and a preparation method of the heat-resistant and oil-resistant sealing gasket. The liquid silicone rubber is prepared from the following raw materials in percentage by weight: 60-80% of a liquid silicone rubber base material, 15-28% of an oil-resistant heat-resistant base material, 0.1-3% of a cross-linking agent, 0.1-0.6% of a catalyst and the balance of a processing aid, the oil-resistant and heat-resistant base material is prepared from an inorganic filler, aramid pulp, polyhedral oligomeric silsesquioxane-alcoholic hydroxyl group, an activation dispersant and a double-active-group-epoxy silane coupling agent; the activation dispersant is a trihydroxymethyl caprolactone cross-linked polymer and / or bis (pinacol) borate; and the inorganic filler is composed of a plurality of components selected from fumed silica powder, nano-scale ceramic powder and zinc borate nano-powder. The oil-resistant and heat-resistant base material obtained by the scheme interacts with the silicone rubber base material, so that the prepared heat-resistant and oil-resistant sealing gasket for the engine has better comprehensive performance.

Description

Technical Field

[0001] This application relates to the field of sealing materials, and more specifically, it relates to an engine heat-resistant and oil-resistant gasket and a method for its preparation. Background Technology

[0002] In the engine field, the performance of seals has a significant impact on the normal operation and reliability of the engine. With the continuous advancement of engine technology, its application scenarios are becoming increasingly diverse and complex. Whether it's a high-performance engine operating at high temperatures and speeds, or a special engine operating in harsh environments, higher standards are being placed on the performance of seals. High-quality seals ensure the normal circulation of gases and fluids inside the engine, reducing energy loss, improving combustion efficiency, and thus enhancing engine power output and fuel economy. Furthermore, good sealing can reduce engine noise and vibration, improve driving comfort, extend engine life, and reduce maintenance costs. Therefore, improving the performance of seals has always been a key aspect of engine technology development.

[0003] Engine seals are mostly made of rubber materials, such as nitrile rubber and fluororubber. When addressing engine sealing issues, these rubber materials primarily rely on their own elasticity to fill the gaps between components to achieve a seal. Simultaneously, the rubber's inherent flexibility adapts to the minute deformations of engine components, maintaining the sealing effect. Furthermore, the smooth surface of the rubber material reduces friction with other components, lowering wear and extending service life. In addition, to enhance the performance of rubber seals, they undergo physical or chemical modification treatments, such as adding certain additives to improve the rubber's strength and wear resistance.

[0004] However, rubber materials have significant performance limitations. Their heat resistance is poor, making them prone to thermal aging in the high-temperature operating environment of an engine. This leads to a decline in physical properties, such as increased hardness, decreased elasticity, and poorer sealing performance. This can cause problems like loosening of the engine structure, severely impacting engine performance and lifespan. Furthermore, rubber materials have insufficient oil resistance. Engine oil, fuel, and other fluids can corrode the rubber, causing it to swell, soften, and lose its sealing properties. Prolonged contact with oil can also lead to cracking and peeling, further reducing sealing performance and affecting normal engine operation. Summary of the Invention

[0005] The purpose of this application is to overcome the above-mentioned technical problems and provide an engine heat-resistant and oil-resistant sealing gasket and its preparation method. In a first aspect, an engine heat-resistant and oil-resistant sealing gasket is made from the following raw materials in weight percentages: 60-80% liquid silicone rubber base material; 15-28% oil-resistant and heat-resistant base material; 0.1-3% crosslinking agent; 0.1-0.6% catalyst; the balance being processing aids; wherein the oil-resistant and heat-resistant base material is composed of inorganic filler, aramid pulp, cage-type polysilsesquioxane-ol hydroxyl group, activating dispersant, and dual-active group-epoxysilane coupling agent in a weight ratio of 10:(1-3):(0.5-2):(0.5-1):(0.3-0.7); wherein the activating dispersant is trimethylolcaprolactone crosslinked polymer and / or pinacol diborate; wherein the inorganic filler is a combination of fumed silica powder, nano-sized ceramic powder, and zinc borate nanoparticles.

[0006] By adopting the above technical solution, the activating dispersant and the dual-active group-epoxysilane coupling agent in the oil-resistant and heat-resistant base material work synergistically to improve the compatibility and dispersibility between inorganic fillers, aramid pulp, cage-type polysilsesquioxane-alcohol hydroxyl groups and silicone rubber base material; inorganic fillers, aramid pulp, and cage-type polysilsesquioxane-alcohol hydroxyl groups synergistically enhance heat resistance, oil resistance and physical properties; in terms of heat resistance, cage-type polysilsesquioxane-alcohol hydroxyl groups and nano-scale ceramic powder can enhance thermal stability. Therefore, inorganic fillers, aramid pulp, and epoxysilane coupling agents work synergistically to improve the compatibility and dispersibility between inorganic fillers, aramid pulp, and silicone rubber base material. Hydroxypropyl POSS enhances heat resistance, oil resistance, and physical properties through a synergistic physical-chemical network. Therefore, the resulting oil- and heat-resistant base material, when combined with liquid silicone rubber, oil- and heat-resistant base materials, crosslinking agents, catalysts, and processing aids, interacts with each other and forms a crosslinked network structure that imparts elasticity and strength to the gasket. This results in a gasket with excellent comprehensive performance, maintaining stability at high temperatures, resisting oil erosion, delaying aging, improving durability and compression set performance, and meeting the demands of complex engine operating conditions.

[0007] Furthermore, the inorganic filler is composed of various elements including fumed silica powder, nano-sized ceramic powder, and zinc borate nano-powder, with fumed silica powder being one of them. This fumed silica powder, in combination with the nano-sized ceramic powder, achieves superior performance, further improving the overall performance of the engine's heat-resistant and oil-resistant sealing gaskets.

[0008] Preferably, the activating dispersant is composed of trimethylolcaprolactone crosspolymer and pinacol diborate.

[0009] By adopting the above technical solution, when trimethylolcaprolactone crosslinked polymer and pinacol diboron ester are combined in a weight ratio of 1:(1-5) to form an activating dispersant, it can better synergize with the dual-active group-epoxysilane coupling agent, further improving the compatibility and dispersibility between inorganic fillers, aramid pulp, cage-type polysilsesquioxane-ol hydroxyl groups and silicone rubber matrix, making the raw materials more evenly distributed in the silicone rubber matrix, avoiding local agglomeration, and laying a more solid foundation for improving the heat resistance, oil resistance and physical properties of the sealing gasket.

[0010] Preferably, the dual-active group-epoxysilane coupling agent is γ-epoxypropoxy-γ-methacryloxypropyltrimethoxysilane and / or N-anilinemethyl-γ-epoxypropoxypropyltrimethoxysilane.

[0011] Furthermore, the dual-active group-epoxysilane coupling agent is composed of γ-epoxypropoxy-γ-methacryloxypropyltrimethoxysilane and N-anilinemethyl-γ-epoxypropoxypropyltrimethoxysilane in a weight ratio of 3:(0.5-3).

[0012] By adopting the above technical solution, it is determined that the dual-active group-epoxysilane coupling agent is γ-epoxypropoxy-γ-methacryloxypropyltrimethoxysilane and / or N-anilinemethyl-γ-epoxypropoxypropyltrimethoxysilane, which can play a key role as a "chemical bridge". One of its active groups reacts with the relevant groups on the surface of inorganic fillers, aramid pulp, and cage-type polysilsesquioxane-alcohol hydroxyl groups to form strong chemical bonds. The other end of the epoxy group reacts with the active sites of silicone rubber base material in a ring-opening addition reaction. Together with the activating dispersant, it significantly improves the compatibility and dispersibility between inorganic fillers, aramid pulp, cage-type polysilsesquioxane-alcohol hydroxyl groups and silicone rubber base material, avoids local agglomeration, and lays the foundation for improving the heat resistance, oil resistance and physical properties of the sealing gasket. In terms of heat resistance, it helps cage-type polysilsesquioxane-ol hydroxyl groups to form stable chemical bonds with nano-scale ceramic powder, enhancing thermal stability; in terms of oil resistance, it works with other components to improve the material's oil resistance; in terms of physical properties, it is beneficial to optimize the physical properties of the gasket with fumed silica powder, aramid pulp, etc., and finally, together with liquid silicone rubber base material, crosslinking agent, catalyst, and processing aids, it endows the gasket with excellent comprehensive performance.

[0013] Preferably, the inorganic filler is composed of fumed silica powder, nano-sized ceramic powder, and zinc borate nanoparticles.

[0014] By adopting the above technical solution, the inorganic filler composed of fumed silica powder, nano-sized ceramic powder, and zinc borate nanopowder works synergistically with aramid pulp and cage-type polysilsesquioxane-ol hydroxyl groups to enhance the heat resistance of the gasket, enabling it to maintain stable performance for a long time under high temperature conditions; it can also improve oil resistance, effectively resisting the erosion of oily substances; and it can also optimize physical properties, significantly improving the performance of the gasket in terms of hardness, strength, toughness, and tear resistance.

[0015] Preferably, the inorganic filler is composed of fumed silica powder, nano-sized ceramic powder, and zinc borate nano-powder in a weight ratio of 8:(0.5-2):(1-3).

[0016] By adopting the above technical solution, an inorganic filler composed of fumed silica powder, nano-sized ceramic powder, and zinc borate nanoparticles in a specific weight ratio is used. This filler works synergistically with aramid pulp and cage-type polysilsesquioxane-ol hydroxyl groups to form a three-dimensional network structure in the silicone rubber matrix, enhancing hardness and strength. The nano-sized ceramic powder and cage-type polysilsesquioxane-ol hydroxyl groups synergistically improve thermal stability. The zinc borate nanoparticles form an oleophobic protective film, which, together with the aramid pulp and cage-type polysilsesquioxane-ol hydroxyl groups, enhances oil resistance. This optimizes the physical properties of the gasket from different perspectives, improving heat resistance, oil resistance, hardness, strength, toughness, tear resistance, and other physical properties. Furthermore, the gasket interacts with liquid silicone rubber base material, crosslinking agent, catalyst, and processing aids. The crosslinking agent, under the action of the catalyst, initiates crosslinking of the silicone rubber to form a three-dimensional network structure, imparting elasticity and strength. The processing aids regulate processing performance, ultimately giving the gasket excellent comprehensive performance, reducing heat damage, aging in oily environments, permanent deformation, and breakage, and improving durability and compression set performance.

[0017] Preferably, the aramid pulp has a diameter of 1-10 micrometers and a length of 30-50 micrometers.

[0018] By adopting the above technical solution, the aramid pulp has been specified to have a wire diameter of 1-10 micrometers and a length of 30-50 micrometers. This is combined with a technique for fabricating a gasket from a liquid silicone rubber base material, a specific proportion of oil- and heat-resistant base material, a crosslinking agent, a catalyst, and processing aids. The oil- and heat-resistant base material includes inorganic fillers, aramid pulp, cage-type polysilsesquioxane-ol hydroxyl groups, activating dispersants, and dual-active-group epoxy silane coupling agents. The activating dispersant is trimethylolcaprolactone crosslinked polymer and / or pinacol diborate. The inorganic fillers are various components of fumed silica powder, nano-sized ceramic powder, and zinc borate nanoparticles. This allows the gasket to maintain its structural integrity when exposed to oily substances, thanks to the specific characteristics of the aramid pulp, preventing material performance degradation due to oil swelling. Simultaneously, when the material is subjected to external forces, energy is absorbed through intermolecular slippage and orientation, enhancing the gasket's toughness and tear resistance, preventing breakage due to mechanical stress during use, and improving the overall physical properties and oil resistance of the gasket.

[0019] Preferably, the particle size of the cage-shaped polysilsesquioxane-hydroxyl group is 1-10 micrometers.

[0020] By adopting the above technical solution, the cage-like polysilsesquioxane-ol hydroxyl group can synergistically act with other raw materials within a suitable particle size range. On the one hand, its cage-like structure can effectively disperse and absorb heat, and the surface hydroxyl group can form stable chemical bonds with the nano-sized ceramic powder to enhance thermal stability and synergistically improve the heat resistance of the sealing gasket with the nano-sized ceramic powder. On the other hand, its cage-like structure can adsorb some oil molecules and synergistically enhance the oil resistance of the sealing gasket with zinc borate nanoparticles and aramid pulp. At the same time, it helps to optimize the physical properties of the sealing gasket together with inorganic fillers and aramid pulp.

[0021] Preferably, the crosslinking agent is one or more of the following: hydrogen-containing silicone oil, terminal hydrogen silicone oil, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, and vinyltrioxime silane.

[0022] By adopting the above technical solution, the crosslinking agent can initiate the crosslinking reaction between silicone rubber molecular chains under the action of a catalyst to form a three-dimensional network structure, giving the sealing gasket a certain elasticity and strength. Furthermore, by selecting one or more combinations of hydrogen-containing silicone oil, terminal hydrogen silicone oil, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, and vinyltrioxime silane as the crosslinking agent, the above crosslinking reaction can be better realized, ensuring that the sealing gasket has good elasticity and strength.

[0023] Preferably, the catalyst is one or a combination of platinum catalyst, Karstedt catalyst, Ashby catalyst, and DBTL.

[0024] By adopting the above technical solution, using one or more of platinum catalysts, Karstedt catalysts, Ashby catalysts, and DBTL as catalysts, a cross-linking reaction between silicone rubber molecular chains can be initiated, enabling the sealing gasket to form a three-dimensional network structure with certain elasticity and strength. At the same time, it can be combined with liquid silicone rubber base material, oil-resistant and heat-resistant base material, cross-linking agent, and processing aid to give the sealing gasket good heat resistance, oil resistance, and physical properties.

[0025] Secondly, a method for preparing a heat-resistant and oil-resistant engine gasket includes the following steps: Oil- and heat-resistant base material: Weigh out inorganic filler, aramid pulp, cage-type polysilsesquioxane-alcohol hydroxyl group, activating dispersant, and dual-active group-epoxysilane coupling agent according to the weight parts, mix them evenly to obtain the oil- and heat-resistant base material; Weigh out liquid silicone rubber base material, oil-resistant and heat-resistant base material, crosslinking agent, catalyst, and processing aids by weight percentage, mix them evenly to obtain a rubber compound, put the rubber compound into a mold, and then perform crosslinking and vulcanization molding to obtain a sealing gasket.

[0026] By adopting the above technical solution, the uniform mixing of various raw materials enables complex interactions between the oil-resistant and heat-resistant base material, the liquid silicone rubber base material, the crosslinking agent, the catalyst, and the processing aids. Under the action of the catalyst, the crosslinking agent initiates the crosslinking reaction of the silicone rubber molecular chains to form a three-dimensional network structure, giving the gasket a certain degree of elasticity and strength. The processing aids adjust the processing performance of the material, making its molding smoother and reducing the generation of defects. The various raw materials in the oil-resistant and heat-resistant base material, together with other components, form stable chemical bonds and physical crosslinking structures, giving the gasket excellent comprehensive performance, making it heat-resistant, oil-resistant, waterproof, and dustproof, and exhibiting good performance in terms of physical properties such as hardness, strength, toughness, and tear resistance. At the same time, it improves the compression set performance, meeting the requirements of complex engine operating conditions.

[0027] In summary, this application includes at least one of the following beneficial technical effects: 1. The synergistic effect of the activating dispersant and the dual-active group-epoxy silane coupling agent improves the compatibility and dispersibility between inorganic fillers, aramid pulp, cage-type polysilsesquioxane-alcohol hydroxyl groups and silicone rubber base material, avoids local agglomeration, and lays the foundation for performance improvement; 2. The synergistic effect of cage-type polysilsesquioxane-alcohol hydroxyl groups and nano-sized ceramic powder enables the sealing gasket to maintain stable performance at high temperatures for a long time, significantly improving heat resistance and solving the problem of poor heat resistance of rubber seals; 3. The synergistic effect of zinc borate nanoparticles, aramid pulp, and cage-type polysilsesquioxane-ol hydroxyl groups enhances the oil resistance of the gasket, effectively resists oil erosion, delays aging, and solves the problem of insufficient oil resistance of rubber seals. Detailed Implementation

[0028] The present application will be further described in detail below with reference to the embodiments.

[0029] The liquid silicone rubber base material is vinyl-terminated polydimethylsiloxane, with a molecular weight of 5-200,000 Da. Appearance: colorless or pale yellow transparent liquid; viscosity (25℃, mm / s): 1000~5000; vinyl content: 0.05-0.1%; volatile matter (150℃, 2h): ≤2%. The cage-type polysilsesquioxane-ol hydroxyl group is in powder form, and its molecular structure is as follows; Trimethylolcaprolactone crosslinked polymers are mainly obtained by crosslinking HDI (hexamethylene diisocyanate) with trimethylolcaprolactone. Their molecular weight is 1000-2000 Da and their degree of polymerization is 2-10. Pinacol diboronic acid ester, CAS No. 73183-34-3; Hydrogen-containing silicone oil has a hydrogen content of 0.1-1.6% and a viscosity (25℃) of 5-300 mm. 2 / s; Aramid pulp, manufactured by Dingxing County Xuanyue Technology New Material Co., Ltd., para 1414 type, pulp fiber moisture content: <4%; fiber diameter: 4.5 micrometers, length: 0.3-0.5 mm; specific surface area: 14 m² / g; modified coating agent: silane; decomposition temperature: 560℃; initial carbonization temperature of fiber: 450℃. Platinum catalyst CAS number: 68478-92-2; Fumed silica powder has a particle size of 10-100 nm; The main component of nano-sized ceramic powder is silicon nitride, with a particle size of 10-100 nm; The main component of zinc borate nanopowder is zinc borate, with a particle size of 10-100 nm. Example

[0030] Example 1 An engine heat-resistant and oil-resistant gasket is prepared by the following method: Oil- and heat-resistant base material: Weigh inorganic filler, aramid pulp, cage-type polysilsesquioxane-alcohol hydroxyl group, activating dispersant, and dual-active group-epoxysilane coupling agent in a weight ratio of 10:1:2:1:0.3 and mix them evenly to obtain the oil- and heat-resistant base material; The activating dispersant is a trimethylolcaprolactone crosslinked polymer; the inorganic filler is composed of fumed silica powder, nano-sized ceramic powder, and zinc borate nanoparticles in a weight ratio of 8:1:1; the dual-active group-epoxysilane coupling agent is γ-epoxypropoxy-γ-methacryloyloxypropyltrimethoxysilane; the aramid pulp has a wire diameter of 1-10 micrometers and a length of 30-500 micrometers; in this embodiment, the aramid pulp has a fiber diameter of 4.5 micrometers and a length of 0.3 mm; the cage-type polysilsesquioxane-hydroxyl group has a particle size of 1-10 micrometers; in this embodiment, a particle size of 3 micrometers is selected.

[0031] Weigh out 60% liquid silicone rubber base material, 28% oil-resistant and heat-resistant base material, 3% crosslinking agent, 0.6% catalyst, and 8.4% processing aid by weight percentage, mix them evenly to obtain a rubber compound; place the rubber compound into a mold, cure it at 150℃ for 1 minute, and then place it in an oven at 80℃ for 30 minutes to mature. Demold the mixture to obtain a sealing gasket. The catalyst is a platinum catalyst, the crosslinking agent is hydrogen-containing silicone oil, and the processing aids are an inhibitor (1-ethynylcyclohexanol), an antioxidant (BASF Irganox 1010 hindered phenol), and a diluent (dimethyl silicone oil) in a weight ratio of 1:3:6.

[0032] Example 2 The difference between Example 2 and Example 1 lies in the amount of raw materials used, as detailed below: Inorganic filler, aramid pulp, cage-type polysilsesquioxane-alcohol hydroxyl group, activating dispersant, and dual-active group-epoxysilane coupling agent were weighed in a weight ratio of 10:2:1:1:0.5 and mixed evenly to obtain an oil-resistant and heat-resistant base material. Weigh out 70% liquid silicone rubber base material, 20% oil-resistant and heat-resistant base material, 2% crosslinking agent, 0.5% catalyst, and 7.5% processing aid by weight percentage, mix them evenly to obtain the rubber compound.

[0033] Example 3 The difference between Example 3 and Example 1 lies in the amount of raw materials used, as detailed below: Weigh out inorganic filler, aramid pulp, cage-type polysilsesquioxane-alcohol hydroxyl group, activating dispersant, and dual-active group-epoxysilane coupling agent in a weight ratio of 10:3:0.5:0.5:0.7 and mix them evenly to obtain an oil-resistant and heat-resistant base material. Weigh out 80% liquid silicone rubber base material, 15% oil-resistant and heat-resistant base material, 1% crosslinking agent, 0.1% catalyst, and 3.9% processing aid by weight percentage, mix them evenly to obtain the rubber compound.

[0034] Example 4 The difference between Example 4 and Example 2 is that the activating dispersant is pinacol diboronate.

[0035] Example 5 The difference between Example 5 and Example 2 is that the activating dispersant is composed of trimethylolcaprolactone crosspolymer and pinacol diborate in a weight ratio of 1:4.

[0036] Example 6 The difference between Example 6 and Example 5 is that the dual-active group-epoxysilane coupling agent is N-anilinemethyl-γ-epoxypropoxypropyltrimethoxysilane.

[0037] Example 7 The difference between Example 7 and Example 5 is that the dual-active group-epoxysilane coupling agent is composed of γ-epoxypropoxy-γ-methacryloxypropyltrimethoxysilane and N-anilinemethyl-γ-epoxypropoxypropyltrimethoxysilane in a weight ratio of 3:1.

[0038] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the aramid pulp was replaced with an inorganic filler in equal amounts.

[0039] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the cage-type polysilsesquioxane-alcohol hydroxyl groups are replaced with inorganic fillers in equal amounts.

[0040] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the inorganic filler is nano-sized ceramic powder.

[0041] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the activating dispersant is replaced in equal amounts with a dual-active group-epoxysilane coupling agent.

[0042] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the dual-active group-epoxysilane coupling agent is replaced by an equal amount of γ-aminopropyltriethoxysilane.

[0043] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that the dual-active group-epoxysilane coupling agent is replaced by an activating dispersant in equal amounts.

[0044] Performance testing The adhesives obtained in Examples 1-7 and Comparative Examples 1-6 were placed in molds and cured at a temperature of 150°C for 1 minute. They were then placed in an oven at 80°C for 30 minutes and cooled to 25°C at room temperature. The molds were then removed to obtain samples for the following experiments.

[0045] Detection methods / test methods (1) Physical properties 1-1. Compression Set Test: GB / T 7759.1-2015 "Determination of Compression Set of Vulcanized Rubber or Thermoplastic Rubber - Part 1: Under Normal and High Temperature Conditions" Method: The sample was placed in a compression device and compressed by 25% at a specified temperature of 150℃. After 70 hours, the residual deformation was measured to obtain the compression permanent deformation rate. The obtained compression permanent deformation rate is the 0-day compression permanent deformation rate.

[0046] 1-2. Tensile and elongation at break: GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", prepare dumbbell-shaped specimens, tensile speed 500 mm / min, when the elongation at break is ≥350% and the tensile strength is ≥10 MPa, it is qualified.

[0047] (2) Heat resistance and oil resistance test conditions: base oil is machine oil, temperature is 150℃; immersion time is 7 days, 14 days and 21 days respectively; Calculate the change in compressive permanent deformation (equal to 0-day compressive permanent deformation - 7-day / 14-day / 21-day compressive permanent deformation).

[0048] The levels of change are shown in Table 1; Table 1. Levels of Change grade Change Level 1 <1.00 Level 2 1.00～2.00 Level 3 2.01～3.00 Level 4 3.01～5.00 Level 5 >5.00 The specific experimental data are shown in Table 2. Table 2. Experimental data of Examples 1-7 and Comparative Examples 1-6 Based on Example 1 and Comparative Examples 1-2 and Table 2, it can be seen that the compression set of Comparative Examples 1-2 and 6 is above 20%, Comparative Example 5 is 18.58%, and Example 1 is only 15.22%. Furthermore, the fracture strength and tensile strength of Example 1 are both within the acceptable range (elongation at break ≥350%, tensile strength ≥10MPa), while Comparative Examples 1-2 and 6 are not within the acceptable range. Furthermore, with the increase in heat resistance and oil resistance tests, the change levels of comparative examples 1-2 and 5-6 are more obvious, even reaching level five (>5.00), while the change level of example 1 is not obvious, reaching only level two (1.00~2.00) at 21 days. This indicates that the present application is successful. The inorganic filler, aramid pulp, and octahydroxypropyl POSS play a synergistic role. Under the action of the activating dispersant and the dual-active group-epoxysilane coupling agent, the oil-resistant and heat-resistant base material obtained is used in the raw material system of the sealing gasket, which further improves the heat resistance, oil resistance, and physical properties of the sealing gasket, making it more durable when used in engines.

[0049] Combining Example 1 and Comparative Example 3 with Table 2, it can be seen that the compression set rate of Comparative Example 3 is higher than that of Example 1. Furthermore, as the heat resistance and oil resistance test time reaches 21 days, Comparative Example 3 reaches level 5 (>5.00), while Example 1 only reaches level 2 (1.00~2.00). This indicates that the inorganic filler used in this application, consisting of multiple components such as fumed silica powder, nano-sized ceramic powder, and zinc borate nanoparticles, has a better synergistic effect, further improving the overall performance of the sealing gasket.

[0050] Combining Example 1 and Comparative Example 4 with Example 2, it can be seen that the compression set of Comparative Example 4 is higher than that of Example 1. Furthermore, as the heat resistance and oil resistance test time reaches 21 days, Comparative Example 4 reaches level four (3.01~5.00), while Example 1 only reaches level two (1.00~2.00). This demonstrates that the use of a dual-active group-epoxy silane coupling agent in this application, combined with the raw material system of this application, results in a sealing gasket with better overall performance.

[0051] Combining Examples 2 and 5 with reference to 2, it can be seen that the compression set rate of Example 2 is higher than that of Example 5. This indicates that the activating dispersant, consisting of trimethylolcaprolactone crosslinked polymer and pinacol diborate, plays a synergistic role. Combined with the raw material system of this application, the sealing gasket has better overall performance.

[0052] Combining Examples 5 and 7 with reference to 2, it can be seen that the compression set rate of Example 2 is higher than that of Example 7. This indicates that the dual-active group-epoxysilane coupling agent, consisting of γ-epoxypropoxy-γ-methacryloxypropyltrimethoxysilane and N-anilinemethyl-γ-epoxypropoxypropyltrimethoxysilane, plays a synergistic role. Combined with the raw material system of this application, the sealing gasket has better overall performance.

[0053] 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 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. A heat-resistant and oil-resistant sealing gasket for engines, characterized in that, It is made from the following raw materials by weight percentage: Liquid silicone rubber base material 60-80% Oil-resistant and heat-resistant base material 15-28% Crosslinking agent 0.1-3% Catalyst 0.1-0.6% The remainder is processing aids; The oil-resistant and heat-resistant base material is composed of inorganic fillers, aramid pulp, cage-type polysilsesquioxane-ol hydroxyl groups, activating dispersants, and dual-active group-epoxysilane coupling agents in a weight ratio of 10:(1-3):(0.5-2):(0.5-1):(0.3-0.7); the activating dispersant is trimethylolcaprolactone crosslinked polymer and / or pinacol diborate; the inorganic fillers are a variety of fumed silica powder, nano-sized ceramic powder, and zinc borate nanoparticles.

2. The engine heat-resistant and oil-resistant sealing gasket according to claim 1, characterized in that: The activating dispersant is composed of trimethylolcaprolactone crosspolymer and pinacol diborate.

3. The engine heat-resistant and oil-resistant sealing gasket according to claim 1, characterized in that: The dual-active group-epoxysilane coupling agent is γ-epoxypropoxy-γ-methacryloxypropyltrimethoxysilane and / or N-anilinemethyl-γ-epoxypropoxypropyltrimethoxysilane.

4. The engine heat-resistant and oil-resistant sealing gasket according to claim 1, characterized in that: The inorganic filler is composed of fumed silica powder, nano-sized ceramic powder, and zinc borate nanoparticles.

5. The engine heat-resistant and oil-resistant sealing gasket according to claim 1, characterized in that: The aramid pulp has a diameter of 1-10 micrometers and a length of 30-500 micrometers.

6. The engine heat-resistant and oil-resistant sealing gasket according to claim 1, characterized in that: The particle size of the cage-shaped polysilsesquioxane-hydroxyl group is 1-10 micrometers.

7. The engine heat-resistant and oil-resistant sealing gasket according to claim 1, characterized in that: The crosslinking agent is one or more of the following: hydrogen-containing silicone oil, terminal hydrogen silicone oil, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, and vinyltrioxime silane.

8. The engine heat-resistant and oil-resistant sealing gasket according to claim 1, characterized in that: The catalyst is one or a combination of platinum catalyst, Karstedt catalyst, Ashby catalyst, and DBTL.

9. The engine heat-resistant and oil-resistant sealing gasket according to claim 1, characterized in that: The processing aid is one or more of the following: colorant, inhibitor, release agent, antioxidant, diluent, and thickener.

10. The method for preparing the engine heat-resistant and oil-resistant sealing gasket according to claim 1, characterized in that, Includes the following steps: Oil- and heat-resistant base material: Weigh out inorganic filler, aramid pulp, cage-type polysilsesquioxane-alcohol hydroxyl group, activating dispersant, and dual-active group-epoxysilane coupling agent according to the weight parts, mix them evenly to obtain the oil- and heat-resistant base material; Weigh out liquid silicone rubber base material, oil-resistant and heat-resistant base material, crosslinking agent, catalyst, and processing aids by weight percentage, mix them evenly to obtain a rubber compound, put the rubber compound into a mold, and then perform crosslinking and vulcanization molding to obtain a sealing gasket.

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