Lubricating grease applied to automobile transmission device and preparation method thereof

Abstract

The invention provides long-period low-carbon running lubricating grease and a preparation method and application thereof.The lubricating grease comprises specific parts of base oil, a thickening agent and an additive, and the additive is limited to comprise specific parts of an antioxidant, an anti-rust agent, a copper corrosion inhibitor and an anti-wear reagent at extreme pressure; through specific selection and matching of the thickening agent, the obtained lubricating grease has excellent anti-shearing performance, through specific selection and matching of the additive, the additive fully enters a ball cage friction pair, the problem of abnormal sound at a large swing angle is effectively solved, good extreme pressure anti-wear performance is shown, and the lubricating grease has good anti-shearing performance. The base oil is specifically selected and matched, so that the lubricating grease has high and low temperature resistance and good compatibility with TPE (thermoplastic elastomer).

Description

Technical Field

[0001] This invention belongs to the field of lubricating grease technology, specifically relating to a lubricating grease, its preparation method and application, and in particular to a lubricating grease with good shear performance and load-bearing capacity, its preparation method and application. Background Technology

[0002] The automotive transmission is the "hub" of the powertrain, and its lubrication is a complex field involving tribology, materials science, chemistry, and mechanical engineering. Here, lubricant is not merely a "grease" to reduce friction, but a functional working fluid that ensures shift quality, transmission efficiency, component lifespan, and overall vehicle reliability. This system transmits the power generated by the engine to the drive wheels in a controllable manner, adapting to driving demands. Its core tasks are: reducing speed and increasing torque, achieving gear changes, allowing differential speeds, and ensuring smooth engagement and disengagement of power.

[0003] The demand for lubricating grease in automotive transmission systems has evolved from simple "rust prevention and lubrication" to a high-performance, multi-functional, and customized "critical engineering material." Choosing the right grease is crucial for ensuring vehicle reliability, durability, safety (such as steering), quietness, and energy efficiency. Greases must possess excellent oxidation stability, mechanical stability, and colloidal stability, with minimal performance degradation throughout their lifespan. They must have a wide operating temperature range, maintaining stable structure and performance from extremely cold starts to the high temperatures generated by braking. Material compatibility is essential; they must be compatible with various rubber / plastic seals, coatings, and alloys without causing aging, corrosion, or swelling. Extreme pressure anti-wear properties are necessary for high-load areas, preventing wear and pitting. Solid lubricants are used for extreme pressure or emergency lubrication (such as molybdenum disulfide and graphite). Rust and corrosion inhibitors are required to combat salt spray and rain. Antioxidants ensure long service life at high temperatures. Precise friction characteristics are crucial; in areas where friction control is needed, the grease's coefficient of friction must remain stable within a specific range.

[0004] CN201510677287.6 discloses a grease specifically for automotive constant velocity joints, comprising the following raw materials: octadecylamine, cyclohexylamine, diphenylmethane-4,4'-diisocyanate, fatty acids, lithium hydroxide, water, base oil A, base oil B, antioxidant A, antioxidant B, extreme pressure anti-wear agent A, extreme pressure anti-wear agent B, extreme pressure anti-wear agent C, oiliness agent, thickener, and rust inhibitor. During preparation, the various raw materials are stirred and reacted in a required order according to different temperature and time parameters, and processed according to relevant process requirements. The grease described in this invention possesses excellent high and low temperature performance, anti-wear properties, oxidation resistance, shear stability, good water resistance, corrosion and rust prevention, colloidal stability, extreme pressure properties, effectively reduces vibration, has good compatibility with sealing materials, and a long service life.

[0005] CN202311408676.X discloses a grease composition for universal joints and its preparation method. The grease composition comprises the following components: base oil, isocyanate, organic amine, friction reducer, extreme pressure agent, and rust inhibitor. This grease composition exhibits excellent extreme pressure and durability properties, as well as excellent high-temperature resistance, with an operating temperature range of -30°C to 180°C, meeting the lubrication requirements of universal joints in medium and heavy-duty commercial vehicles.

[0006] However, none of the above solutions adequately address the issue of abnormal noise during large steering angles in new energy vehicles, nor do they provide a satisfactory solution for environmentally friendly greases. Therefore, finding a suitable replacement for existing products that can further improve performance in automotive transmission greases has become a pressing issue. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a lubricating grease, its preparation method, and its application. This lubricating grease possesses excellent high and low temperature performance while also meeting the requirements of long-term, low-carbon, and environmentally friendly operation. The novel polyurea thickener system, while meeting long-term high-temperature oxidation resistance requirements, exhibits excellent shear resistance, preventing sludge and varnish formation and maintaining viscosity stability. A suitable type and proportion of base oil are combined to achieve a good viscosity-temperature index, forming a hydrodynamic film. Simultaneously, it enhances the compatibilization of additives, making them more easily adsorbed onto metal surfaces, forming a high-strength protective film, and resolving the problem of abnormal noise at large sway angles.

[0008] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a lubricating grease, wherein the components of the lubricating grease, by weight, include: 70-90 parts of base oil, 4-20 parts of thickener and 2-20 parts of additive; The additives, by weight, include: 0.5-5 parts antioxidant, 0.5-3 parts rust inhibitor, 1-2 parts copper corrosion inhibitor and 0.5-10 parts extreme pressure anti-wear agent.

[0009] The base oil has a weight of 70-90 parts, for example, 70 parts, 75 parts, 78 parts, 80 parts, 85 parts or 90 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0010] The thickener is 4-20 parts by weight, for example, 4 parts, 4.5 parts, 5 parts, 7 parts, 9 parts, 14 parts, 16 parts or 20 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0011] The additive is in the range of 2-20 parts by weight, for example, 2 parts, 3.3 parts, 4 parts, 6 parts, 11 parts, 14 parts, 17 parts or 20 parts, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0012] The antioxidant is present in parts by weight of 0.5-5 parts, for example, 0.5 parts, 1 part, 2.5 parts, 3 parts, 4 parts or 5 parts, etc., and specific values ​​between the above-mentioned values ​​are not exhaustively listed in this invention due to space limitations and for the sake of brevity.

[0013] The copper corrosion inhibitor is 1-2 parts by weight, for example, 1 part, 1.2 parts, 1.5 parts, 1.7 parts or 2 parts, etc., and specific values ​​between the above-mentioned values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0014] The rust inhibitor is present in a weight ratio of 0.5-3 parts, for example, 0.5 parts, 1.2 parts, 2 parts or 3 parts, etc., and the specific values ​​between the above-mentioned values ​​are not exhaustively listed in this invention due to space limitations and for the sake of brevity.

[0015] The extreme pressure anti-wear agent is 0.5-10 parts by weight, for example, 0.5 parts, 1.5 parts, 3.7 parts, 5.5 parts, 9 parts or 10 parts, etc., and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0016] In summary, by making the specific selections and combinations of the base oils and additives, the resulting grease possesses excellent extreme pressure anti-wear properties, shear resistance, and oxidation resistance, forming a stable protective film on the metal surface. This satisfies the requirements of long-term low-carbon operation while effectively solving the problem of large sway angles in new energy vehicles.

[0017] Preferably, the base oil includes polyether, ester, and / or synthetic hydrocarbon oils.

[0018] Preferably, the ester oil includes any one or a combination of at least two of polyol esters, diesters, and complex esters, such as a combination of complex esters and polyol esters, a combination of polyol esters and diesters, or a combination of diesters and complex esters, etc., but is not limited to the combinations listed above. Other combinations not listed above are also applicable.

[0019] The combination of the above-mentioned specific base oils can balance high and low temperature performance while enhancing oil film thickness.

[0020] Preferably, the thickener comprises a combination of isocyanate and polyorganic amine.

[0021] Preferably, the mass ratio of the isocyanate to the polyorganic amine is (0.2-4):1, for example, 0.2:1, 1:1, 1.2:1, 1.4:1, 2.4:1, 2.6:1, 3.5:1, 3.7:1 or 3.9:1, etc.

[0022] Preferably, the isocyanate includes diphenylmethane diisocyanate (MDI) and / or polyphenylmethylene polyisocyanate (PAPI).

[0023] Preferably, the polyamine includes any one or a combination of at least two of the following: oleyl primary amine, cyclohexylamine, tetradecyl primary amine, and decanediamine.

[0024] The combination of the above-mentioned specific thickener systems can significantly improve the shear resistance and high-temperature stability of greases.

[0025] Preferably, the antioxidant includes any one or a combination of at least two of phosphite antioxidants, amine antioxidants, and / or phenolic antioxidants.

[0026] Preferably, the additive further includes 0.5-5 parts by weight (e.g., 0.5 parts by weight, 1.4 parts by weight, 2.8 parts by weight, 3.2 parts by weight, 4.6 parts by weight, or 5.0 parts by weight, etc.) of antioxidant.

[0027] The aforementioned combination of antioxidants works synergistically with the thickener system, extending the effective action time of the antioxidants and slowing down their volatilization and migration loss.

[0028] Preferably, the rust inhibitor comprises any one or a combination of at least two of nonenyl succinic anhydride, heptadecanyl hydroxyethyl imidazoline, N-oleoyl sarcosine, dodecenyl succinate half ester, calcium sulfonate, or basic dinonylnaphthalene sulfonate barium.

[0029] Preferably, the additive also includes 0.5-3 parts by weight (e.g., 0.5 parts by weight, 1 part by weight, 1.5 parts by weight, 2 parts by weight or 2.5 parts by weight, etc.) of rust inhibitor.

[0030] Preferably, the copper corrosion inhibitor comprises any one or a combination of at least two of thiadiazole derivatives and / or benzotriazole derivatives.

[0031] Preferably, the extreme pressure anti-wear agent comprises any one or a combination of at least two of the following: molybdenum dialkyldithiocarbamate, borate ester, sulfurized olefin, di-n-butyl phosphite, light calcium carbonate, calcium pyrophosphate, topologically modified nano-carbon, thiadiazole dimer, and ammonium phosphate salt. For example, a combination of molybdenum dialkyldithiocarbamate and borate ester or light calcium carbonate, or a combination of molybdenum dialkyldithiocarbamate and sulfurized olefin or topologically modified nano-carbon, etc., but not limited to the combinations listed above. Other combinations not listed above are also applicable. A combination of borate ester, di-n-butyl dithiocarbamate, sulfurized olefin, and thiadiazole dimer is preferred.

[0032] In a second aspect, the present invention provides a method for preparing the grease as described in the first aspect, the method comprising: reacting a thickener and a base oil, adding additives and mixing to obtain the grease.

[0033] Preferably, the preparation method specifically includes the following steps: (1) Isocyanate and polyorganic amine are dissolved and mixed to obtain thickener A; (2) Thickener A and a portion of base oil are mixed, and then heated and held at a constant temperature to obtain mixture B; (3) Add the remaining base oil, antioxidant, optional extreme pressure anti-wear agent, copper corrosion inhibitor, optional oxidant and optional rust inhibitor to the mixture B obtained in step (2) and mix to obtain the grease.

[0034] Preferably, the mixing temperature in step (1) is 30-50°C, for example, it can be 30°C, 40°C, or 50°C, as well as specific values ​​between the above-mentioned values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0035] Preferably, the mixing time in step (1) is 90-160 min, for example, it can be 90 min, 95 min, 100 min, 120 min or 160 min, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0036] Preferably, the mixing temperature in step (2) is 120-160°C, for example, it can be 120°C, 130°C, 135°C, 140°C or 160°C, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0037] Preferably, the heating rate of the heating process in step (2) is 1~5℃ / min, for example, it can be 1.2℃ / min, 1.5℃ / min, 1.7℃ / min, 4℃ / min or 5℃ / min, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0038] Preferably, the heat preservation time in step (2) is 10-30 min, for example, it can be 10 min, 20 min or 30 min, and the specific point values ​​between the above points are not exhaustively listed in this invention due to space limitations and for the sake of brevity.

[0039] Preferably, the mixing time in step (3) is 60-90 minutes, for example, 60 minutes, 70 minutes or 90 minutes, and specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the range.

[0040] Preferably, the mixing time in step (3) is 60-90 min, for example, it can be 30 min, 40 min, 50 min, 60 min, 80 min or 100 min, and specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values ​​included in the range.

[0041] Preferably, after the mixing in step (3) is completed, a homogenization step is also included.

[0042] As a preferred technical solution, the preparation method specifically includes the following steps: (1) Dissolve and mix isocyanate and polyorganic amine at 30-50℃ for 90-160 min to obtain thickener A; (2) Mix thickener A and part of base oil at 120-160℃, heat and refine at a heating rate of 1~5℃ / min, and hold for 10-30 min to obtain mixture B; (3) Add the remaining base oil, antioxidant, optional extreme pressure anti-wear agent, copper corrosion inhibitor, optional oxidant and optional rust inhibitor to the mixture B obtained in step (2) and mix at 60-100°C for 60-90 min. After grinding, the grease is obtained.

[0043] Thirdly, the present invention provides the application of the lubricating grease as described in the first aspect in an automotive transmission system.

[0044] Compared with the prior art, the present invention has the following beneficial effects: The grease provided by this invention comprises a specific proportion of base oil, thickener, and additives, and the additives are specifically defined as including a specific proportion of antioxidants, rust inhibitors, copper corrosion inhibitors, and extreme pressure anti-wear agents. On one hand, because transmission components generate a large amount of heat during operation, and the design requires no maintenance for life, the dust cover design prevents timely heat dissipation. By combining various antioxidants with non-metallic soap bases, the thickener network structure of the grease is ensured not to degrade under prolonged high-temperature conditions, preventing hardening and oil separation. On the other hand, the grease is repeatedly filled, agitated, and extruded, and the thickener is continuously sheared. Through the combined reaction of isocyanate and poly-organic amines, the prepared thickener structure is structurally stable and shear-resistant. In three aspects, through the combined use of base oil and additives, the non-polar PAO itself has excellent thermal oxidation stability, which greatly reduces the initial driving force of the oxidation reaction. This allows the antioxidant to focus more on protecting the overall system without having to "remedy" the free radicals generated by the rapid oxidation of the base oil. Polar ester oils, as "endogenous" friction reducers, work synergistically with polyethers and extreme pressure anti-wear agents to activate the metal surface, reduce the activation energy required for the extreme pressure anti-wear agent to form a chemical reaction film, and give the grease better load-bearing and anti-wear capabilities. At the same time, the ester oils effectively inhibit the acidic components after the extreme pressure anti-wear agent fails, enabling rapid replenishment of rapid wear, reducing energy consumption, delaying its thermal decomposition, and eliminating abnormal noises at large swing angles. Detailed Implementation

[0045] To further illustrate the technical means and effects of the present invention, the following describes the technical solution of the present invention in conjunction with preferred embodiments. However, those skilled in the art will understand that the embodiments are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0046] Information on some of the materials involved in the specific embodiments of this invention is shown below: (1) Base oils: diester (Synative® ES 2813), polyol ester (Synative® ES 4380), polyol ester (POE 390), saturated complex ester (Synative® ES TMTC), unsaturated complex ester (CD301B), polyether (Synative® EEB 45), PAO10 (SpectraSyn Elite 10), PAO6 (SpectraSyn 6); (2) Thickeners: oil-based primary amine (FENTAMINE® AO V), tetradecyl primary amine (FENTAMINE® A14); (3) Antioxidants: Phosphite esters (Irgafos®168), phenolic antioxidants (Irganox®L135, Irganox®L125), amine antioxidants (VANLUBE® 81 100 FDM, Irganox®L67); (4) Rust inhibitors: dodecenyl succinate half ester (Irgacor® L12), N-oleoyl sarcosine (Sarkosyl® O); (5) Extreme pressure anti-wear agents: molybdenum dialkyl dithiocarbamate (MOLYVAN® A), sulfurized olefin (ADDITIN RC2545), thiadiazole dimer (NA-LUBE® EP-5665), ammonium phosphate salt (Irgalube® 349). Example 1

[0047] This embodiment provides a lubricating grease for use in automotive transmission systems and its preparation method. The components of the lubricating grease, in parts by weight, are shown in the table below:

[0048] The method for preparing the lubricating grease includes the following steps: (1) Add some PAO6 (SpectraSyn 6), diphenylmethane diisocyanate (MDI), oleyl primary amine (FENTAMINE® AO V), tetradecyl primary amine (FENTAMINE® A14), and cyclohexylamine to the reactor, heat to 35°C and mix; then react for 90 min to obtain mixture A; (2) Add polyol ester (Synative® ES 4380) and polyphenyl polymethylene polyisocyanate (PAPI) to mixture A obtained in step (1), then heat to 120°C and keep warm for 20 min to obtain mixture B; (3) Add unsaturated complex ester (CD301B) and polyether (Synative® EEB45) to the mixture B obtained in step (2), cool to 120°C, add amine antioxidant (VANLUBE® 81 100 FDM), cool to 80°C, add molybdenum dialkyl dithiocarbamate (MOLYVAN® A), sulfurized olefin (ADDITIN RC 2545), topologically modified nano carbon, borate ester, N-oleoylsarcosine (Sarkosyl® O), phosphite (Irgafos® 168), and thiadiazole derivative (T561), stir for 90 min, homogenize and discharge from the reactor to obtain the grease. Example 2

[0049] This embodiment provides a lubricating grease and its preparation method. The components of the lubricating grease are shown in the table below by weight:

[0050] The preparation method of the lubricating grease provided in this embodiment is the same as that in Embodiment 1.

[0051] Comparative Example 1 This comparative example provides a lubricating grease, grade JP350.

[0052] Comparative Example 2 This comparative example provides a lubricating grease, designated XBT-1.

[0053] Comparative Example 3 This comparative example provides a lubricating grease that differs from Example 1 only in that no ester base oil is added; other substances, amounts, and preparation methods are the same as in Example 1.

[0054] Comparative Example 4 This comparative example provides a lubricating grease that differs from Example 1 only in that it does not contain polyether base oil; other substances, amounts, and preparation methods are the same as in Example 1.

[0055] Comparative Example 5 This comparative example provides a lubricating grease that differs from Example 1 only in that it does not contain amine antioxidants; other substances, dosages, and preparation methods are the same as in Example 1.

[0056] Comparative Example 6 This comparative example provides a lubricating grease that differs from Example 1 only in that it does not contain extreme pressure anti-wear agents; other substances, dosages, and preparation methods are the same as in Example 1.

[0057] Performance testing: The performance of the greases provided in Examples 1-2 and Comparative Examples 1-6 was tested. The specific methods and test results are shown in the table below:

[0058] From the data in Table 3, we can see that: The greases provided in Examples 1-2 of this invention have excellent extreme pressure anti-wear properties, shear resistance, water resistance, high and low temperature performance, TPE compatibility, and corrosion resistance.

[0059] The two commercially available greases provided in Comparative Examples 1-2 showed a large change in cone penetration over 100,000 cycles, indicating poor shear resistance. In contrast, the polyurea thickener system developed in Examples 1-2 showed a very small change over 100,000 cycles, indicating that its thickener fiber structure cannot be permanently destroyed, exhibiting good thixotropy and excellent shear resistance. This meets the requirements of the grease in this area to resist huge centrifugal shear forces without leakage, and to withstand high-frequency rolling shear at the contact point while maintaining lubrication.

[0060] The greases provided in Comparative Examples 3-4 did not contain both polyether and ester oils. It can be seen that their extreme pressure anti-wear performance was worse than that of Example 5, and their coefficient of friction was larger. The synergistic effect of polyether and ester oils was not brought into play, and they could not maintain sufficient oil film thickness in environments with large temperature changes to achieve long-term low-carbon operation. Leaked grease could not be degraded and absorbed.

[0061] The grease provided in Comparative Example 5 did not contain amine antioxidants, and its high-temperature performance was significantly worse. Comparative Example 2, through the synergistic effect of amine antioxidants with the weakly alkaline thickener system and with diester (Synative® ES 2813), maintained the chemical balance of the system and enhanced the high-temperature antioxidant effect.

[0062] The grease provided in Comparative Example 6, without the addition of extreme pressure anti-wear and antioxidant agents, exhibited better anti-wear properties than those of commercially available Examples 1-2, but worse than Examples 1-2. This indicates that liquid additives such as sulfurized olefins and di-n-butyl phosphite adhere to a thicker chemical reaction film on the metal surface with polyether, allowing it to withstand higher Hertzian contact stress at the contact point between the ball and the track. Solid additives such as molybdenum dialkyl dithiocarbamate, light calcium carbonate, and topologically modified nano-carbon can be solubilized into the grease through specific ester oils, such as TMTC, and then rapidly adsorbed onto the metal surface via diesters. When the hydrodynamic film and boundary chemical reaction film rupture at instantaneous high temperatures, they provide excellent load-bearing and friction-reducing effects, solving the problem of large sway angle noise generated by new energy vehicles under various harsh conditions.

[0063] The applicant declares that this invention illustrates a lubricating grease for automotive transmission systems and its preparation method through the above embodiments, but this invention is not limited to the above embodiments, that is, it does not mean that this invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials of this invention, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A lubricating grease, characterized in that, The components of the grease, by weight, include: 70-90 parts base oil, 4-20 parts thickener and 2-20 parts additive; The additives, by weight, include: 0.1-5 parts antioxidant, 0.1-3 parts rust inhibitor, 1-2 parts copper corrosion inhibitor and 0.5-10 parts extreme pressure anti-wear agent.

2. The lubricating grease according to claim 1, characterized in that, The base oils include polyether, ester, and / or synthetic hydrocarbon oils; Preferably, the ester oil includes any one or a combination of at least two of diesters, complex esters, and polyol esters; Preferably, the mass ratio of the ester oil to the synthetic hydrocarbon oil is (0.1-2.0):

1.

3. The lubricating grease according to claim 1 or 2, characterized in that, The thickener comprises a combination of isocyanate and polyorganic amines; Preferably, the mass ratio of the isocyanate to the polyorganic amine is (0.2-4):1; Preferably, the isocyanate comprises diphenylmethane diisocyanate and / or polyphenylmethylene polyisocyanate; Preferably, the polymeric organic amine includes any one or a combination of at least two of the following: oleyl primary amine, cyclohexylamine, tetradecyl primary amine, and sebacic diamine.

4. The lubricating grease according to any one of claims 1-3, characterized in that, The additive includes 0.5-10 parts by weight of extreme pressure anti-wear agent; Preferably, the extreme pressure anti-wear agent comprises any one or a combination of at least two of the following: molybdenum dialkyl dithiocarbamate, borate ester, sulfurized olefin, di-n-butyl phosphite, light calcium carbonate, calcium pyrophosphate, topologically modified nano-carbon, thiadiazole dimer, and ammonium phosphate salt.

5. The lubricating grease according to any one of claims 1-4, characterized in that, The additive also includes 0.5-3 parts by weight of rust inhibitor; Preferably, the rust inhibitor comprises any one or a combination of at least two of nonenyl succinic anhydride, heptadecanyl hydroxyethyl imidazoline, N-oleoyl sarcosine, dodecenyl succinate half ester, calcium sulfonate, or basic dinonylnaphthalene sulfonate barium.

6. The lubricating grease according to any one of claims 1-5, characterized in that, The additive also includes 0.5-5 parts by weight of antioxidant; Preferably, the antioxidant includes phosphite antioxidants, amine antioxidants, and / or phenolic antioxidants.

7. The lubricating grease according to any one of claims 1-5, characterized in that, The additive also includes 1-2 parts by weight of copper corrosion inhibitor; Preferably, the copper corrosion inhibitor comprises a thiadiazole derivative and / or a benzotriazole derivative.

8. A method for preparing a lubricating grease according to any one of claims 1-7, characterized in that, The preparation method includes: reacting a thickener and a base oil, adding additives and mixing to obtain the grease.

9. The preparation method according to claim 8, characterized in that, The preparation method specifically includes the following steps: (1) Isocyanate and polyorganic amine are dissolved and mixed to obtain thickener A; (2) Thickener A and a portion of base oil are mixed, and then heated and held at a constant temperature to obtain mixture B; (3) Add the remaining base oil, antioxidant, optional extreme pressure anti-wear agent, copper corrosion inhibitor, optional oxidant and optional rust inhibitor to the mixture B obtained in step (2) and mix to obtain the grease.

10. The preparation method according to claim 9, characterized in that, The mixing temperature in step (1) is 30-50℃; Preferably, the mixing time in step (1) is 90-160 min; Preferably, the mixing temperature in step (2) is 120-160°C; Preferably, the heating rate of the heating process in step (2) is 1~5℃ / min; Preferably, the heat preservation time in step (2) is 10-30 min; Preferably, the mixing temperature in step (3) is 60-100℃; Preferably, the mixing time in step (3) is 60-90 min; Preferably, after the mixing in step (3) is completed, a homogenization step is also included.

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