Low-heat-generation self-lubricating oil seal rubber material and preparation method thereof

Abstract

The invention provides a low-heat-generation self-lubricating oil seal rubber material and a preparation method thereof. The rubber material comprises the following components in parts by weight: 100 parts of main rubber, 3-6 parts of zinc oxide, 1-3 parts of an anti-aging agent, 1-3 parts of solid marone indene resin, 3-8 parts of a self-repairing lubricant, 5-25 parts of a reinforcing agent, 70-100 parts of diatomite, 5-15 parts of a plasticizer, 1-5 parts of tetrafluoroethylene, 1-3 parts of stearic acid, 1-3 parts of a flow promoter, 0.2-0.5 part of sulfur and 1-2 parts of an accelerant. The nano silicon dioxide-ionic liquid composite material is added into the oil seal rubber material as a self-repairing lubricant, and the ionic liquid of the composite material can form a lubricating film on a friction interface, so that the friction coefficient is reduced, the self-lubricating effect is realized, and the dynamic temperature rise is reduced; in addition, the ionic liquid can also cover a damaged area and repair microscopic cracks; meanwhile, after the self-repairing lubricant is dispersed, a heat conduction network can be formed, and heat generation is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber materials, in particular to a rubber material for a low-heat-generating self-lubricating oil seal and a preparation method thereof. Background Art

[0002] The rapid development of modern science and technology has driven the development of the machinery industry. The performance of oil seals has a great impact on the overall working efficiency of machinery. With the continuous improvement of the degree of mechanization, the oil seals are exposed to high temperature, high pressure and other working conditions, which leads to a gradually increasing probability of oil seal failure and leakage, thus causing various accidents.

[0003] Currently, rubber oil seals are the most widely used material in the oil seal market both domestically and internationally. The main rubber materials used include nitrile rubber, hydrogenated nitrile rubber, and fluororubber. During operation, the dynamic oil seal's lip grips the crankshaft, generating high-speed friction with the crankshaft, which generates significant heat at the lip. If this heat cannot be dissipated promptly, the oil seal lip will significantly heat up. For rubber materials, the theoretical lifespan is halved for every 10°C increase in operating temperature.

[0004] Therefore, improving the self-lubricating performance of the oil seal and reducing the friction with the crankshaft will help reduce energy consumption and wear and extend the service life of the oil seal. At the same time, improving the thermal conductivity of the oil seal rubber material will transfer the heat generated by the lip to the engine oil in a timely manner, reducing the temperature of the oil seal and also helping to extend the service life of the oil seal. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a rubber material for a low-heating self-lubricating oil seal, which is used to solve the problems of large friction coefficient and poor thermal conductivity of the oil seal rubber material in the prior art. At the same time, the present invention will also provide a method for preparing the rubber material for a low-heating self-lubricating oil seal.

[0006] To achieve the above-mentioned and other related purposes, the present invention provides the following technical solutions:

[0007] The first aspect of the present invention provides a rubber material for a low-heat self-lubricating oil seal, wherein the rubber material comprises the following components in parts by weight: 100 parts of main rubber, 3 to 6 parts of zinc oxide, 1 to 3 parts of an antioxidant, 1 to 3 parts of a solid marone resin, 3 to 8 parts of a self-repairing lubricant, 5 to 25 parts of a reinforcing agent, 70 to 100 parts of diatomaceous earth, 5 to 15 parts of a plasticizer, 1 to 5 parts of tetrafluoroethylene, 1 to 3 parts of stearic acid, 1 to 3 parts of a flow aid, 0.2 to 0.5 parts of sulfur, and 1 to 2 parts of an accelerator.

[0008] As a preferred technical solution, the self-healing lubricant is selected from a nano-silica-ionic liquid composite material. The ionic liquid can seep out during the oil seal friction process, forming a molecular lubricating film on the contact surface, effectively reducing the friction coefficient and achieving a self-lubricating effect. Simultaneously, the polar groups of the ionic liquid can adsorb on the metal dual surface, reducing the adhesion between the rubber material and the metal and avoiding the "stick-slip" phenomenon. Because SiO2 blocks heat transfer and the ionic liquid inhibits free radical chain reactions, the addition of the nano-silica-ionic liquid composite material can improve the heat resistance of the rubber material. The ionic liquid reduces friction within the molecular chain, further reducing the material's heat generation.

[0009] In addition, nano-SiO2, as a reinforcing filler, combines with rubber molecular chains through physical adsorption and hydrogen bonding, improving the material's mechanical properties. The lubricating effect of the ionic liquid reduces filler agglomeration and avoids stress concentration. Furthermore, the addition of the ionic liquid reduces the volume resistivity of the rubber material by a small amount, providing an antistatic effect.

[0010] Furthermore, the nano-silica-ionic liquid composite material is nano-silica grafted with ionic liquid or nano-silica coated with ionic liquid.

[0011] Furthermore, the ionic liquid is selected from 1-butyl-3-methylimidazolium hexafluorophosphate or 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

[0012] Furthermore, the ionic liquid-coated nano-silica is prepared by the following method: nano-SiO2 and ionic liquid are mixed in a solvent at a mass ratio of 1:(0.3-1), ultrasonically dispersed, centrifuged, and dried to obtain the ionic liquid-coated nano-silica. This method is a physical adsorption method, which forms covalent bonds between the exposed hydroxyl groups on the surface of the nano-SiO2 and the ionic liquid to achieve stable loading of the ionic liquid on the SiO2 surface. This method is simple, suitable for large-scale production, and has lower costs.

[0013] Furthermore, the nano-silica grafted with an ionic liquid is obtained by the following preparation method: treating nano-SiO2 with a silane coupling agent to obtain surface-aminated SiO2, activating the carboxyl groups of the ionic liquid, and reacting the carboxyl-activated ionic liquid with the surface-aminated SiO2 to form an amide bond, thereby obtaining the nano-silica grafted with the ionic liquid. This method is a covalent grafting method that can firmly bond the ionic liquid to the SiO2, ensuring that the ionic liquid is stably present in the rubber material in the form of a chemical bond, achieving long-term self-lubrication and low heat generation.

[0014] Furthermore, the mass ratio of the nano-SiO2 to the ionic liquid is 1:(0.3-1).

[0015] Furthermore, a catalyst is added during the reaction process, wherein the catalyst is selected from at least one of dicyclohexylcarbodiimide and 4-dimethylaminopyridine to promote the formation of amide bonds. The mass ratio of the nano-SiO2 to the catalyst is 1:(0.01-0.02).

[0016] Furthermore, the mass ratio of the nano-SiO2 to the silane coupling agent is 1:(0.1-0.3).

[0017] As a preferred technical solution, the main rubber is selected from at least one of nitrile rubber, hydrogenated nitrile rubber, and carboxyl nitrile rubber.

[0018] As a preferred technical solution, the zinc oxide is selected from at least one of NC-234, NC-105, and AZ-12N.

[0019] As a preferred technical solution, the antioxidant is selected from antioxidant RD.

[0020] As a preferred technical solution, the reinforcing agent is selected from at least one of carbon black and white carbon black; preferably, it is a combination of carbon black and white carbon black.

[0021] As a preferred technical solution, the diatomaceous earth is selected from modified diatomaceous earth, and the modified diatomaceous earth is obtained by the following preparation method: preparing a coupling agent solution, adding the coupling agent solution and calcium stearate in sequence while stirring the diatomaceous earth, and then drying and sieving to obtain the modified diatomaceous earth.

[0022] Furthermore, the coupling agent is selected from at least one of Si69 coupling agent, KH-550, and NDZ-201.

[0023] Furthermore, the mass ratio of diatomaceous earth, coupling agent and calcium stearate is 100:(1-5):(0.5-1.5).

[0024] As a preferred technical solution, the plasticizer is selected from plasticizer TOTM.

[0025] As a preferred technical solution, the flow aid is selected from at least one of flow aid WB222 and polyethylene wax.

[0026] As a preferred technical solution, the accelerator is selected from at least one of accelerator TMTD, accelerator CZ, accelerator TDEC, accelerator DM, and accelerator BZ.

[0027] As a preferred technical solution, the rubber material further includes 1 to 2 parts of pigment.

[0028] A second aspect of the present invention provides a method for preparing a rubber material for a low-heat self-lubricating oil seal, comprising the following steps:

[0029] (1) Weigh each raw material in proportion;

[0030] (2) adding the main rubber, zinc oxide, antioxidant and malone resin into an internal mixer for plasticating;

[0031] (3) adding the self-repairing lubricant and the plasticizer into an internal mixer for a first mixing;

[0032] (4) adding a reinforcing agent and diatomaceous earth for a second mixing;

[0033] (5) Continue to add tetrafluoroethylene, stearic acid and flow aid to perform the third mixing;

[0034] (6) Add sulfur and accelerator for final mixing and unload the rubber when the temperature reaches 110-120℃.

[0035] Furthermore, in step (4), cleaning is performed after the first mixing to cool down and protect the rubber material. The cleaning time is 20 to 40 seconds.

[0036] Furthermore, the plasticating time is 50 to 120 seconds;

[0037] The first mixing time is 30 to 90 seconds;

[0038] The second mixing time is 150 to 240 seconds;

[0039] The third mixing time is 60 to 120 seconds;

[0040] The final mixing time is 50 to 90 seconds.

[0041] As described above, the rubber material for a low-heat self-lubricating oil seal and the preparation method thereof of the present invention have the following beneficial effects:

[0042] 1. The present invention adds a nano-silica-ionic liquid composite material as a self-repairing lubricant to the oil seal rubber material. The ionic liquid in the composite material can form a lubricating film at the friction interface, reduce the friction coefficient, achieve a self-lubricating effect, and reduce dynamic temperature rise. Moreover, when the surface of the material is locally damaged due to friction or microcracks, the ionic liquid will seep out to cover the damaged area, and the dynamic bonds of the ionic liquid can break and reorganize under heat or pressure stimulation to repair microcracks. At the same time, after the self-repairing lubricant is dispersed, the nano-silica as a skeleton and the ionic liquid as a bridge can construct a continuous heat-conducting network in the rubber matrix, helping heat diffusion and reducing heat generation of the rubber material.

[0043] 2. The present invention modifies diatomaceous earth to achieve a tighter interface with the rubber material, reduce phonon scattering, and improve thermal conductivity. The modified diatomaceous earth is more evenly dispersed, forming a local heat conduction network, thereby reducing heat generation in the rubber material. Furthermore, the modified diatomaceous earth forms a hydrophobic surface, which can reduce the adhesion friction between the diatomaceous earth and the rubber, further reducing the friction coefficient. DETAILED DESCRIPTION

[0044] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0045] In a first aspect, the present invention provides a nano-silica grafted with an ionic liquid, which is prepared by the following preparation method:

[0046] 10 g of nano-SiO2 (particle size 15-30 nm, purity ≥99%) was added to 100 mL of anhydrous ethanol and ultrasonically dispersed for 30 minutes (power 300 W), then 2 g of silane coupling agent KH-550 was added dropwise, and the mixture was stirred at 60°C for 6 hours (speed 500 rpm), centrifuged (8000 rpm, 10 min), washed with ethanol 3 times, and vacuum dried at 80°C for 12 hours to obtain surface-aminated SiO2;

[0047] 3 g of 1-butyl-3-methylimidazolium hexafluorophosphate was reacted with 1 g of bromoacetic acid at 50 °C for 4 h to obtain a carboxyl-activated ionic liquid;

[0048] 10 g of surface-aminated SiO2, 3 g of carboxyl-activated ionic liquid, 0.1 g of dicyclohexylcarbodiimide and 0.05 g of 4-dimethylaminopyridine were added to 50 mL of anhydrous ethanol and stirred at 70 ° C for 24 h (300 rpm) under nitrogen protection. After the reaction, 5 mL of glacial acetic acid was added for neutralization and centrifuged (8000 rpm, 10 min). The product was washed three times with ethanol and deionized water respectively to remove unreacted ionic liquid and catalyst, and then vacuum dried at 60 ° C for 24 hours to obtain nano-silica grafted with ionic liquid (white powder).

[0049] In a second aspect, the present invention provides a nano-silica coated with an ionic liquid, which is prepared by the following preparation method:

[0050] 10 g of nano-SiO2 (particle size 15-30 nm, purity ≥99%) was added to 200 mL of anhydrous ethanol and magnetically stirred (300 rpm) for 30 minutes. After centrifugation (8000 rpm, 10 minutes), the mixture was vacuum dried at 60°C for 12 hours to obtain loose nano-SiO2 powder with exposed surface hydroxyl groups.

[0051] 5 g of 1-butyl-3-methylimidazolium hexafluorophosphate was dissolved in 50 mL of anhydrous ethanol and stirred magnetically until transparent to obtain a mixed solution. Then, the treated nano-SiO2 powder was slowly added to the mixed solution, stirred in a 40°C water bath for 4 hours (500 rpm), and then allowed to stand at room temperature for 12 hours.

[0052] The product was then centrifuged (8000 rpm, 10 min), washed three times with sewage ethanol, and vacuum dried at 60° C. for 24 hours to obtain nano-silica (white powder) coated with ionic liquid.

[0053] In a third aspect, the present invention provides a modified diatomaceous earth obtained by the following preparation method:

[0054] 100 g of diatomaceous earth was sieved through an 80-mesh sieve and dried at 105°C for 2 h to a moisture content of ≤0.5%. 3 g of Si69 coupling agent was slowly added to an ethanol-water mixture (90 mL of ethanol and 10 mL of water) and stirred at room temperature for 30 min (200 rpm) to obtain a coupling agent solution.

[0055] Place diatomaceous earth in a high-speed mixer, preheat to 80°C and stir at a low speed (500 rpm). While stirring, spray the coupling agent solution evenly onto the diatomaceous earth (spraying rate 10 mL / min), and simultaneously increase the speed to 1500 rpm for 10 minutes. Maintain the temperature at 80°C, add 1 g of calcium stearate, increase the speed to 2000 rpm, and continue stirring for 15 minutes. Then cool to 60°C and maintain stirring at 1000 rpm for 30 minutes to fully graft the Si69 coupling agent.

[0056] The modified diatom

[0057] Example 1

[0058] This embodiment provides a rubber material for a low-heat self-lubricating oil seal, which includes the following components in parts by weight: 100 parts of nitrile rubber, 5 parts of zinc oxide, 1 part of antioxidant RD, 1 part of solid malone resin, 5 parts of the above-prepared nano-silica coated with ionic liquid, 2 parts of carbon black, 15 parts of white carbon black, 93 parts of diatomaceous earth, 8 parts of plasticizer TOTM, 1 part of tetrafluoroethylene, 1 part of stearic acid (1801), 1 part of flow aid WB222, 1.5 parts of polyethylene wax, 0.3 parts of sulfur, 0.5 parts of accelerator TMTD, 0.5 parts of accelerator CZ, and 0.2 parts of accelerator TDEC.

[0059] The rubber material of the low heat buildup self-lubricating oil seal is prepared by the following method:

[0060] (1) Weigh each raw material in proportion;

[0061] (2) Add nitrile rubber, zinc oxide, antioxidant RD and gumarone resin into an internal mixer and plasticize for 60 seconds;

[0062] (3) adding the nano-silica coated with ionic liquid and the plasticizer TOTM into an internal mixer and performing the first mixing for 60 seconds;

[0063] (4) adding carbon black, white carbon black and diatomaceous earth and performing a second mixing for 180 seconds, and cleaning for 30 seconds after the mixing is completed;

[0064] (5) Continue adding tetrafluoroethylene, stearic acid, flow aid WB222 and polyethylene wax and perform a third mixing for 90 seconds;

[0065] (6) Add sulfur and accelerator and carry out final mixing for 60 seconds. Unload the rubber when the rubber temperature reaches 120℃.

[0066] Example 2

[0067] This embodiment provides a rubber material for a low-heat self-lubricating oil seal. Compared with Example 1, the only difference is that the rubber material includes the following components in parts by weight: 100 parts of nitrile rubber, 5 parts of zinc oxide, 1 part of antioxidant RD, 1 part of solid malone resin, 5 parts of the above-prepared nano-silica grafted with ionic liquid, 2 parts of carbon black, 15 parts of white carbon black, 93 parts of diatomaceous earth, 8 parts of plasticizer TOTM, 1 part of tetrafluoroethylene, 1 part of stearic acid (1801), 1 part of flow aid WB222, 1.5 parts of polyethylene wax, 0.3 parts of sulfur, 0.5 parts of accelerator TMTD, 0.5 parts of accelerator CZ, and 0.2 parts of accelerator TDEC.

[0068] Example 3

[0069] This embodiment provides a rubber material for a low-heat self-lubricating oil seal. Compared with Example 2, the only difference is that the rubber material includes the following components in parts by weight: 100 parts of nitrile rubber, 5 parts of zinc oxide, 1 part of antioxidant RD, 1 part of solid malone resin, 5 parts of the above-prepared nano-silica grafted with ionic liquid, 2 parts of carbon black, 15 parts of white carbon black, 93 parts of the above-prepared modified diatomaceous earth, 8 parts of plasticizer TOTM, 1 part of tetrafluoroethylene, 1 part of stearic acid (1801), 1 part of flow aid WB222, 1.5 parts of polyethylene wax, 0.3 parts of sulfur, 0.5 parts of accelerator TMTD, 0.5 parts of accelerator CZ, and 0.2 parts of accelerator TDEC.

[0070] Comparative Example 1

[0071] This comparative example provides a rubber material, which is different from Example 1 only in that: the rubber material includes the following components in parts by weight: 100 parts of nitrile rubber, 5 parts of zinc oxide, 1 part of antioxidant RD, 1 part of solid marone resin, 2 parts of carbon black, 15 parts of white carbon black, 93 parts of diatomaceous earth, 8 parts of plasticizer TOTM, 1 part of tetrafluoroethylene, 1 part of stearic acid (1801), 1 part of flow aid WB2221, 1.5 parts of polyethylene wax, 0.3 parts of sulfur, 0.5 parts of accelerator TMTD, 0.5 parts of accelerator CZ, and 0.2 parts of accelerator TDEC.

[0072] Performance test

[0073] The rubber materials prepared in Examples 1 to 3 and Comparative Example 1 were subjected to performance tests, and the test results are shown in Table 1:

[0074] Table 1. Performance test results of rubber materials of Examples 1 to 3 and Comparative Example 1

[0075]

[0076] In summary, the present invention incorporates a nanosilica-ionic liquid composite material into the oil seal rubber material as a self-healing lubricant. The ionic liquid in the composite forms a lubricating film at the friction interface, reducing the coefficient of friction, achieving a self-lubricating effect, and reducing dynamic temperature rise. Furthermore, the ionic liquid can coat damaged areas and repair microcracks. Furthermore, the self-healing lubricant, once dispersed, forms a heat-conducting network, reducing heat generation. Therefore, the present invention effectively overcomes the shortcomings of existing technologies and has high industrial value.

[0077] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A rubber material for a low heat buildup self-lubricating oil seal, characterized in that: The rubber material includes the following components in parts by weight: 100 parts of main rubber, 3-6 parts of zinc oxide, 1-3 parts of antioxidant, 1-3 parts of solid marone resin, 3-8 parts of self-repairing lubricant, 5-25 parts of reinforcing agent, 70-100 parts of diatomaceous earth, 5-15 parts of plasticizer, 1-5 parts of tetrafluoroethylene, 1-3 parts of stearic acid, 1-3 parts of flow aid, 0.2-0.5 parts of sulfur, and 1-2 parts of accelerator.

2. The rubber material according to claim 1, characterized in that The self-repairing lubricant is selected from nano-silicon dioxide-ionic liquid composite materials, and the nano-silicon dioxide-ionic liquid composite materials are nano-silicon dioxide grafted with ionic liquid or nano-silicon dioxide coated with ionic liquid.

3. The rubber material according to claim 2, characterized in that The ionic liquid is selected from 1-butyl-3-methylimidazolium hexafluorophosphate or 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

4. The rubber material according to claim 2, characterized in that The nano-silicon dioxide coated with ionic liquid is obtained by the following preparation method: nano-SiO2 and ionic liquid are mixed in a solvent at a mass ratio of 1:(0.3-1), ultrasonically dispersed, centrifuged and dried to obtain the nano-silicon dioxide coated with ionic liquid.

5. The rubber material according to claim 2, characterized in that The nano-silica grafted with ionic liquid is obtained by the following preparation method: treating nano-SiO2 with a silane coupling agent to obtain surface-aminated SiO2, activating the ionic liquid by carboxyl groups, reacting the carboxyl-activated ionic liquid with the surface-aminated SiO2 to form an amide bond, and obtaining the nano-silica grafted with ionic liquid.

6. The rubber material according to claim 1, characterized in that The zinc oxide is selected from at least one of NC-234, NC-105, and AZ-12N.

7. The rubber material according to claim 1, characterized in that The reinforcing agent is selected from at least one of carbon black and white carbon black; preferably a combination of carbon black and white carbon black.

8. The rubber material according to claim 1, characterized in that The diatomaceous earth is selected from modified diatomaceous earth, and the modified diatomaceous earth is obtained by the following preparation method: preparing a coupling agent solution, adding the coupling agent solution and calcium stearate in sequence during the stirring process of the diatomaceous earth, and then drying and sieving to obtain the modified diatomaceous earth.

9. The rubber material according to claim 1, characterized in that The accelerator is selected from at least one of accelerator TMTD, accelerator CZ, accelerator TDEC, accelerator DM, and accelerator BZ.

10. The method for preparing a rubber material for a low-heating self-lubricating oil seal according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Weigh each raw material in proportion; (2) adding the main rubber, zinc oxide, antioxidant and malone resin into an internal mixer for plasticating; (3) adding the self-repairing lubricant and the plasticizer into an internal mixer for a first mixing; (4) adding a reinforcing agent and diatomaceous earth for a second mixing; (5) continue to add tetrafluoroethylene, stearic acid and flow aid to perform the third mixing; (6) Add sulfur and accelerator for final mixing and unload the rubber when the temperature reaches 110-120℃.

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