Medium-resistant high-elasticity rubber material for sealing element and preparation method of medium-resistant high-elasticity rubber material

Abstract

The invention relates to a medium-resistant high-elasticity rubber material for a sealing element and a preparation method of the medium-resistant high-elasticity rubber material, and belongs to the technical field of rubber materials for sealing elements. The rubber material is prepared from 50 to 70 parts of thermoplastic polyester elastomer, 20 to 40 parts of hydrogenated butadiene-acrylonitrile rubber, 3 to 8 parts of nano modified montmorillonite, 2 to 5 parts of maleic anhydride grafted TPEE compatilizer, 1 to 3 parts of vulcanizing agent, 1 to 2 parts of anti-aging agent, 0.5 to 2 parts of lubricating agent and 0.5 to 1.5 parts of crosslinking accelerant. The material is endowed with good elasticity and high-temperature resistance through the elastic characteristic of the thermoplastic polyester elastomer and the three-dimensional network structure of the vulcanized hydrogenated butadiene-acrylonitrile rubber, and meanwhile, the interfacial compatibility of the TPEE and the HNBR is effectively improved through the synergistic effect of the vulcanizing agent and the maleic anhydride grafted TPEE compatilizer, so that the high-temperature resistance of the material is improved. The introduction of the nano-modified montmorillonite improves the oil resistance and thermal stability of the material through the lamellar barrier effect, so that the material keeps good performance stability in a medium.

Description

Technical Field

[0001] The present invention belongs to the technical field of rubber materials for seals, and more specifically, relates to a medium-resistant and highly elastic rubber material for seals and a preparation method thereof. Background Art

[0002] Engine seals are key components for ensuring proper engine operation and play a vital role in numerous fields, including automotive, aerospace, and engineering machinery. In engine sealing applications, materials must simultaneously meet the following key performance requirements: ① Oil resistance: Ability to operate stably and long-term in engine lubricants, fuels, and various chemical media; ② High-temperature resistance: Ability to maintain elasticity and sealing performance in sustained high-temperature environments of 150-200°C; ③ High elasticity: Demonstrating excellent compression set and elastic recovery; ④ Cost control: Material costs must be within a manageable range.

[0003] Modern engine seals face increasingly demanding operating environments, particularly those characterized by high temperatures and oil contamination. Traditional sealing materials are increasingly limited in their resistance to media and high temperatures, making them unable to withstand the erosion of various media and the test of high temperatures for extended periods. While currently commonly used engine sealing materials such as nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), and fluororubber (FKM) can partially meet these requirements, each has its limitations: NBR offers good oil resistance but insufficient high-temperature resistance; FKM offers excellent high-temperature resistance but is expensive; and HNBR, while offering superior overall performance, remains relatively expensive.

[0004] Therefore, the industry needs to develop a new type of elastomeric material that has excellent oil resistance, high temperature resistance, high elasticity, and controllable costs. Summary of the Invention

[0005] The object of the present invention is to provide a medium-resistant and highly elastic rubber material for sealing parts and a preparation method thereof, which has the characteristics of excellent oil resistance and elasticity.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A medium-resistant and highly elastic rubber material for a seal, comprising the following components in parts by weight: 50-70 parts of thermoplastic polyester elastomer; 20-40 parts of hydrogenated nitrile rubber; 3-8 parts of nano-modified montmorillonite; 2-5 parts of maleic anhydride grafted TPEE compatibilizer; 1-3 parts of vulcanizing agent; 1-2 parts of antioxidant; Lubricant: 0.5-2 parts; and Cross-linking accelerator 0.5-1.5 parts.

[0007] As a preferred technical solution of the present invention, the Shore hardness of the thermoplastic polyester elastomer is 60-85D.

[0008] Thermoplastic polyester elastomer (TPEE) has excellent mechanical properties and elasticity, which can guarantee the basic performance of the material to a certain extent. At the same time, it has good oil resistance and low temperature resistance, laying the foundation for the application of the material in complex working conditions.

[0009] More preferably, the Shore hardness of the thermoplastic polyester elastomer is 70-80 D. This hardness range can balance the elasticity and rigidity of the material.

[0010] Preferably, the melt index of the thermoplastic polyester elastomer is 8-15 g / 10 min (190°C / 2.16 kg) Furthermore, the acrylonitrile content of the hydrogenated nitrile rubber is 30-40%, more preferably 33-38%.

[0011] Hydrogenated nitrile rubber (HNBR) has excellent resistance to high temperatures, ozone and chemicals. Its addition can significantly improve the material's media resistance and high-temperature resistance, enabling the material to adapt to the high temperature and complex media environment faced by engine seals.

[0012] Preferably, the Mooney viscosity of the hydrogenated nitrile rubber is 60-80 (ML1+4100°C).

[0013] As a preferred technical solution of the present invention, the nano-modified montmorillonite is montmorillonite modified by a silane coupling agent, and has a particle size of 50-100 nm.

[0014] Nano-modified montmorillonite undergoes silane modification, enhancing its interfacial bonding with the TPEE / HNBR matrix. This results in a high specific surface area and excellent dispersibility, enhancing the material's mechanical properties while also forming a "maze-like" shielding structure that effectively blocks oil and chemical penetration, reducing leakage risks. This creates an effective reinforced network within the material system, further improving its mechanical properties and media resistance, while also enhancing its high-temperature resistance.

[0015] Furthermore, the interlayer spacing of the nano-modified montmorillonite is 30-50 nm, which can significantly improve the thermal stability and oil resistance of the material. As a preferred technical solution of the present invention, the grafting rate of the maleic anhydride grafted TPEE compatibilizer is 0.5-2%.

[0016] More preferably, the grafting rate of the maleic anhydride grafted TPEE compatibilizer is 0.8-1.5%.

[0017] Maleic anhydride-grafted TPEE compatibilizer reduces the interfacial tension between thermoplastic polyester elastomer and hydrogenated nitrile rubber through chemical bonds or physical entanglement, promoting mutual penetration and entanglement between the two materials at the molecular level, forming a stable interpenetrating network structure. This effectively improves the compatibility between thermoplastic polyester elastomer and hydrogenated nitrile rubber, allowing them to better combine and enhance the overall performance of the material. The material maintains good elasticity at high temperatures and has excellent sealing properties in oil media, avoiding problems such as phase separation and ensuring the material's performance stability.

[0018] As a preferred technical solution of the present invention, the vulcanizing agent is dicumyl peroxide and / or 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0019] More preferably, the vulcanizing agent is a composite vulcanizing agent composed of dicumyl peroxide (DCP) and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane in a mass ratio of 1:1.

[0020] Preferably, the particle size of the vulcanizing agent is 1-3 microns.

[0021] Vulcanizing agents can cause hydrogenated nitrile rubber to undergo a cross-linking reaction to form a stable three-dimensional network structure, thereby improving the elasticity and medium resistance of the material, and also have a positive effect on the high temperature resistance of the material.

[0022] As a preferred technical solution of the present invention, it also includes a heat stabilizer, and the heat stabilizer is at least one of polycarbodiimide and calcium zinc composite stabilizer.

[0023] Thermal stabilizers can effectively inhibit the thermal degradation reaction of materials in high temperature environments, improve the thermal stability of materials, extend the service life of materials, and ensure that engine seals can work stably under high temperature conditions.

[0024] As a preferred technical solution of the present invention, the lubricant is at least one of zinc stearate, calcium stearate, and pentaerythritol stearate.

[0025] Lubricants can improve the processing performance of materials, reduce the friction coefficient of materials during processing, prevent problems such as adhesion and deformation of materials during processing, and ensure that the materials can be smoothly made into the required seal shape.

[0026] As a preferred technical solution of the present invention, the antioxidant is N-phenyl-α-naphthylamine and / or 2,2,4-trimethyl-1,2-dihydroquinoline polymer.

[0027] More preferably, the antioxidant is a composite antioxidant composed of N-phenyl-α-naphthylamine and 2,2,4-trimethyl-1,2-dihydroquinoline polymer in a mass ratio of 2:1.

[0028] As a preferred technical solution of the present invention, the cross-linking accelerator is zinc oxide, magnesium oxide or a sulfenamide accelerator.

[0029] The method for preparing the medium-resistant and highly elastic rubber material for the seal as described above comprises the following steps: S1. Premixing: adding a thermoplastic polyester elastomer, a heat stabilizer and a lubricant into a high-speed mixer and mixing to obtain a premix; S2, internal mixing: transfer the premix to an internal mixer, add hydrogenated nitrile rubber, nano-modified montmorillonite and maleic anhydride grafted TPEE compatibilizer, and internal mix for 5-10 minutes at 120-130°C and a rotation speed of 40-50 rpm; S3. Dynamic vulcanization: Add vulcanizing agent and crosslinking accelerator to the internal mixer, and continue mixing at 50-60 rpm and 160-175 ° C for 8-12 minutes; S4. Extrusion granulation: The mixed material is made into sealing products through extrusion molding or direct injection molding. Preferably, in step S1, the mixing temperature is 80-90°C for 3-10 minutes; in step S3, the dynamic vulcanization stage is performed at a gradient vulcanization temperature of 160-165°C, 165-170°C, and 170-175°C, with each gradient maintained for 3-4 minutes. In step S4, the extrusion molding temperature is 170-190°C and the rotation speed is 80-120 rpm.

[0030] Further preferably, in step S4, the temperature distribution of each zone of the extrusion molding is: 170-180°C in the feeding section, 180-190°C in the plasticizing section, and 185-190°C in the homogenizing section.

[0031] During the dynamic vulcanization process of the present invention, at 160-165°C, the crosslinking of HNBR is preferentially promoted to form an initial crosslinking network, thereby preventing over-vulcanization of the rubber phase. At 165-170°C, the compatibility of TPEE and HNBR is balanced, promoting interfacial bonding and forming an interpenetrating network structure. At 170-175°C, the compatibility of TPEE and HNBR is balanced, promoting interfacial bonding and forming an interpenetrating network structure. In the above process, by controlling the heating temperature and speed of the dynamic vulcanization process, HNBR forms a uniformly dispersed micron-sized rubber phase in the TPEE matrix, while maintaining the thermoplastic processing properties of TPEE.

[0032] An engine seal is prepared from the above-mentioned medium-resistant and highly elastic rubber material by the above-mentioned process.

[0033] Specifically, the engine seal is a crankshaft oil seal, a valve cover gasket, an oil pan gasket or a turbocharger seal.

[0034] The application of the above-mentioned medium-resistant and highly elastic rubber material in the preparation of oil-resistant medium engine seals.

[0035] Beneficial effects of the present invention: (1) The present invention effectively improves the high temperature resistance of the material by adding hydrogenated nitrile rubber. The elastic properties of the thermoplastic polyester elastomer and the three-dimensional network structure of the hydrogenated nitrile rubber after vulcanization give the material good elasticity. At the same time, the synergistic effect of the vulcanizer and the maleic anhydride grafted TPEE compatibilizer effectively improves the interfacial compatibility between TPEE and HNBR, solving the problem of two-phase separation. The introduction of nano-modified montmorillonite improves the oil resistance and thermal stability of the material through the barrier effect of the layer, and improves the interfacial bonding force, so that the material can maintain good performance stability in various common engine media such as engine oil, coolant, fuel, etc., and is not prone to swelling, deformation and performance degradation, thereby extending the service life of the seal.

[0036] (2) The present invention adopts TPEE and HNBR dynamic vulcanization compounding, which not only retains the low cost and processability of TPEE, but also utilizes the oil resistance and high temperature stability of HNBR; using a vulcanizing agent and a temperature gradient vulcanization process, HNBR forms a uniformly dispersed micron-sized rubber phase in the TPEE matrix, achieving performance synergy, thereby greatly improving production efficiency and material utilization. DETAILED DESCRIPTION

[0037] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0038] Example 1 A medium-resistant and highly elastic rubber material for a seal, comprising the following components in parts by weight: The preparation process of the medium-resistant and highly elastic rubber material for the above-mentioned seal is as follows: S1. Premixing: Add thermoplastic polyester elastomer, heat stabilizer and lubricant into a high-speed mixer and mix at 85° C. for 4 minutes to obtain a premix; S2, internal mixing: transfer the premix to an internal mixer, add hydrogenated nitrile rubber, nano-modified montmorillonite and maleic anhydride grafted TPEE compatibilizer, and internally mix at 125°C and 45 rpm for 6 minutes; S3. Dynamic vulcanization: Add vulcanizing agent and crosslinking accelerator to the internal mixer, and perform gradient vulcanization at 160℃→165℃→170℃ at a speed of 55 rpm, with each gradient vulcanization time of 4 minutes. S4. Extrusion granulation: The mixed material is extruded into granules through a twin-screw extruder. The temperature distribution of each zone of the extrusion molding is as follows: 170-180°C in the feeding section, 180-190°C in the plasticizing section, and 185-190°C in the homogenizing section.

[0039] S5. Injection molding: The pellets were injected into standard specimens in an injection molding machine at 180° C., wherein the injection pressure was 80-100 MPa, the holding time was 15 seconds, and the cooling time was 30 seconds.

[0040] Example 2 A medium-resistant and highly elastic rubber material for a seal, comprising the following components in parts by weight: The preparation process of the medium-resistant and highly elastic rubber material used for the above-mentioned sealing member is the same as that of Example 1.

[0041] Example 3 A medium-resistant and highly elastic rubber material for a seal, comprising the following components in parts by weight: The preparation process of the medium-resistant and highly elastic rubber material used for the above-mentioned sealing member is the same as that of Example 1.

[0042] Comparative Example 1 The difference between this comparative example and Example 1 is that the amount of thermoplastic polyester elastomer added in this comparative example is 0, while the weight portion of hydrogenated nitrile rubber is 100, and the remaining components, preparation steps and parameters are the same.

[0043] Comparative Example 2 The difference between this comparative example and Example 1 is that the nano-modified montmorillonite is replaced by ordinary montmorillonite in this comparative example.

[0044] Comparative Example 3 The difference between this comparative example and Example 1 is that the addition amount of maleic anhydride grafted TPEE in this comparative example is 0, and the other components, preparation steps and parameters are the same.

[0045] Comparative Example 4 The difference between this comparative example and Example 1 is that the operation of step S3 of this comparative example is as follows: S1, drying the thermoplastic polyester elastomer in a blower at 80°C for 4 hours, and plasticizing the hydrogenated nitrile rubber on an open mill for 5 minutes in advance to break the rubber macromolecular chain to reduce the Mooney viscosity; S2, adding all components into an internal mixer at one time, and mixing for 10 minutes at 145°C and a speed of 45 rpm; S3, transferring the blend to a twin-screw extruder for extrusion granulation, wherein the temperature distribution of each zone of extrusion molding is: 170-180°C for the feeding section, 180-190°C for the plasticizing section, and 185-190°C for the homogenizing section; S4, injection molding the granules into standard specimens in an injection molding machine at 180°C, wherein the injection pressure is 80-100 MPa, the holding time is 15 seconds, and the cooling time is 30 seconds.

[0046] The following performance tests were performed on Examples 1-3 and Comparative Examples 1-4 respectively: (1) Oil resistance test According to ISO1817 standard, the samples were cut into cylindrical shapes with a diameter of 15±0.5 mm and a thickness of 2±0.2 mm. Six parallel samples were prepared for each group, of which three were used to measure volume change and three were used to measure mass change.

[0047] Before the test, the diameter and thickness of the sample were measured with a vernier caliper with an accuracy of 0.01 mm and the volume was calculated; the mass of the sample was weighed with an electronic balance with an accuracy of 0.1 mg.

[0048] Use IRM903 standard oil, preheat it to a constant temperature at 150±2℃, then immerse the sample completely in IRM903 oil with the liquid level at least 20mm above the sample, and soak it at 150±2℃ for 72 hours.

[0049] After the test, remove the sample, dry the oil stains on the sample surface with filter paper, and place it in an environment of 23±2℃ for 30 minutes. Measure the volume and mass of the sample again, calculate the volume change rate and mass change rate before and after the test, and take the average value.

[0050] (2) Compression set test According to ISO815 standard, the specimens were cut into cylindrical shapes with a diameter of 29±0.5 mm and a thickness of 12.5±0.5 mm. Three parallel specimens were prepared for each group.

[0051] The thickness of the sample was measured at three different locations using a thickness gauge with an accuracy of 0.01 mm, and the average value was taken as the initial thickness h0.

[0052] The sample was placed in a compression device and compressed to 25% of its original thickness using a stopper, i.e., a compressed thickness of approximately 9.4 mm, ensuring uniform compression of the sample. The compression device and sample were then placed in a heat aging test chamber at 150 ± 2°C for 70 hours each.

[0053] After the test, remove the compression device, loosen the sample, and place it in an environment at 23±2°C for 30 minutes. Measure the thickness h1 of the sample after recovery, calculate the compression set, and take the average value. Compression set = (h0-h1) / (h0×0.25)×100%.

[0054] The test results are shown in Table 1.

[0055] Table 1 As can be seen from the test results in Table 1, compared with Comparative Examples 1-4, the volume change rate, mass change rate and compression set rate of Examples 1-3 are all lower than those of Comparative Examples 1-4, indicating that the rubber material of the present invention has excellent oil-resistant medium performance and elastic properties under high temperature environment. In addition, in combination with the test results of the embodiment and Comparative Example 4, it can be seen that the rubber material performance obtained by the dynamic vulcanization process of the present invention is more excellent. This may be due to the lack of a vulcanization stage controlled by a temperature gradient, which causes the hydrogenated nitrile rubber to be unable to form a cross-linked network, and the weak interfacial bonding force between the thermoplastic polyester elastomer phase and the hydrogenated nitrile rubber phase, which is prone to phase separation under stress or high temperature conditions, resulting in performance degradation.

[0056] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A medium-resistant and highly elastic rubber material for a seal, characterized in that: The following components are included in parts by weight: 50-70 parts of thermoplastic polyester elastomer; 20-40 parts of hydrogenated nitrile rubber; 3-8 parts of nano-modified montmorillonite; 2-5 parts of maleic anhydride grafted TPEE compatibilizer; 1-3 parts of vulcanizing agent; 1-2 parts of antioxidant; Lubricant: 0.5-2 parts; and Cross-linking accelerator 0.5-1.5 parts.

2. The medium-resistant and highly elastic rubber material for a seal according to claim 1, characterized in that: The Shore hardness of the thermoplastic polyester elastomer is 60-85D; the acrylonitrile content of the hydrogenated nitrile rubber is 30-40%.

3. The medium-resistant and highly elastic rubber material for a seal according to claim 1, characterized in that: The nano-modified montmorillonite is montmorillonite modified by a silane coupling agent, and has a particle size of 50-100 nm.

4. The medium-resistant and highly elastic rubber material for a seal according to claim 1, characterized in that: The grafting rate of the maleic anhydride grafted TPEE compatibilizer is 0.5-2%.

5. The medium-resistant and highly elastic rubber material for a seal according to claim 1, characterized in that: The vulcanizing agent is dicumyl peroxide and / or 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

6. The medium-resistant and highly elastic rubber material for a seal according to claim 1, characterized in that: The lubricant is at least one of zinc stearate, calcium stearate, and pentaerythritol stearate.

7. The medium-resistant and highly elastic rubber material for a seal according to claim 1, characterized in that: The antioxidant is N-phenyl-α-naphthylamine and / or 2,2,4-trimethyl-1,2-dihydroquinoline polymer.

8. A method for preparing a medium-resistant and highly elastic rubber material for a seal according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: S1. Premixing: adding a thermoplastic polyester elastomer, a heat stabilizer and a lubricant into a high-speed mixer and mixing to obtain a premix; S2, internal mixing: transfer the premix to an internal mixer, add hydrogenated nitrile rubber, nano-modified montmorillonite and maleic anhydride grafted TPEE compatibilizer, and internal mix for 5-10 minutes at 120-130°C and a rotation speed of 40-50 rpm; S3. Dynamic vulcanization: Add vulcanizing agent and crosslinking accelerator to the internal mixer, and continue mixing at 50-60 rpm and 160-175 ° C for 8-12 minutes; S4. Extrusion granulation: The mixed material is made into sealing products through extrusion molding or direct injection molding.

9. The preparation method according to claim 8, characterized in that In step S1, the mixing temperature is 80-90° C. and the mixing time is 3-10 minutes; in step S3, the dynamic vulcanization stage is carried out at a gradient vulcanization temperature of 160-165° C., 165-170° C., and 170-175° C., and each gradient is maintained for 3-4 minutes; in step S4, the extrusion molding temperature is 170-190° C. and the rotation speed is 80-120 rpm.

10. An engine seal, prepared from the medium-resistant and highly elastic rubber material according to claims 1-7 by the process according to claims 8-9.

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