Urea-calcium composite thickened electric vehicle driving motor bearing lubricating grease and preparation method thereof

Abstract

The invention belongs to the technical field of lubricating grease, and particularly relates to urea-calcium composite thickening type electric automobile driving motor bearing lubricating grease and a preparation method thereof. The lubricating grease comprises the following components in parts by weight: 0.5 to 1.5 parts of 12-hydroxy stearic acid; 0.05 to 0.3 part of calcium hydroxide; 0.5 to 1.5 parts of calcium acetate monohydrate; 1 to 3 parts of hydrogenated tallow primary amine; 1 to 3 parts of cyclohexylamine; 1 to 5 parts of MDI (diphenylmethane diisocyanate); 0.3 to 0.6 part of octadecanol; 71 to 88 parts of base oil; 0.5 to 2 parts of an antioxidant; 0.2 to 0.6 part of a metal deactivator; 3.0 to 6.0 parts of an anti-wear reagent at extreme pressure; and 0.3 to 1.0 part of an antirust agent. The lubricating grease provided by the invention is suitable for lubrication of a bearing of a driving motor of an electric vehicle, and has excellent high and low temperature performance, extreme pressure antiwear property, lubricity, mechanical stability and electrical insulativity.

Description

Technical Field

[0001] This invention belongs to the field of lubricating grease technology, and specifically relates to a urea-calcium composite thickened type electric vehicle drive motor bearing lubricating grease and its preparation method. Background Technology

[0002] With the rapid development of the global new energy vehicle industry, electric vehicle drive motors are evolving towards higher power density, higher speed, higher integration, and longer lifespan with maintenance-free operation. This trend makes the operating conditions of motor bearings increasingly demanding, placing higher requirements on the performance of lubricating greases, specifically including: 1. Excellent electrical insulation: It has high resistivity to resist breakdown caused by high-frequency shaft currents from the frequency converter and prevent electro-corrosion; 2. Wide temperature range and high-speed adaptability: Maintains structural stability and long-lasting lubrication capability under a wide temperature range (-40℃ to above 150℃) and high-speed shear conditions; 3. High extreme pressure anti-wear performance: It can cope with frequent start-stop and high torque conditions, and provide reliable boundary lubrication protection; 4. Excellent NVH performance: Effectively suppresses vibration and noise over a wide temperature range and at different speeds, improving the overall vehicle acoustic quality; 5. Long life and reliability: Maintains stable performance and meets lubrication requirements throughout the entire life cycle under harsh environments such as high speed, high temperature and electrochemical corrosion.

[0003] Because electric vehicle motors operate at much higher speeds than traditional gasoline-powered vehicles, their lubricating greases require lower viscosity base oils to reduce high-speed stirring resistance and temperature rise. However, low-viscosity base oils are generally detrimental to maintaining extreme pressure anti-wear performance. Current mainstream lubricating grease systems have certain limitations: polyurea-based greases possess excellent high-temperature resistance, oxidation stability, and high resistivity, but their extreme pressure anti-wear properties and high-speed noise performance are still insufficient; while complex calcium-based greases have excellent extreme pressure anti-wear properties and water resistance, their high-temperature stability and service life are generally inferior to polyurea systems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a urea-calcium composite thickened grease for electric vehicle drive motor bearings, which is suitable for lubrication of electric vehicle drive motor bearings and has excellent high and low temperature performance, extreme pressure anti-wear properties, lubricity, mechanical stability and electrical insulation.

[0005] To achieve the above objectives, the present invention employs the following technical solution: A urea-calcium composite thickened grease for electric vehicle drive motor bearings comprises, by weight, the following components: 12-Hydroxystearic acid: 0.5–1.5 parts; Calcium hydroxide: 0.05–0.3 parts; Calcium acetate monohydrate: 0.5–1.5 parts; Hydrogenated tallow amine: 1-3 parts; Cyclohexylamine: 1-3 parts; MDI: 1-5 parts; Octadecyl alcohol: 0.3–0.6 parts; Base oil: 71-88 parts; Antioxidant: 0.5–2 parts; Metal deactivating agent: 0.2–0.6 parts; Extreme pressure anti-wear agent: 3.0–6.0 parts; Rust inhibitor: 0.3–1.0 parts; The feeding ratio of 12-hydroxystearic acid to calcium acetate monohydrate is 1:1 to 3:1.

[0006] The feeding ratio of cyclohexylamine to hydrogenated tallow amine is 0.5:1 to 1:1.

[0007] The ratio of antioxidant to metal deactivator is 2:1 to 4:1.

[0008] The total weight of the hydrogenated tallow amine, cyclohexylamine, and MDI is 3.5 to 10 times the total weight of 12-hydroxystearic acid, calcium acetate monohydrate, and calcium hydroxide.

[0009] Preferably, the base oil is a mixture of ETO base oil and polyether base oil; the kinematic viscosity at 40°C is 60–80 mmHg. 2 / s; kinematic viscosity at 100℃ is 10~15mm 2 / s; viscosity index not less than 150, pour point not higher than -40℃; flash point ≥220℃.

[0010] Preferably, the antioxidant is a polymer of N-[(1,1,3,3-tetramethylbutyl)phenyl]-1-naphthylamine and 4-octyl-N-(4-octylphenyl)aniline.

[0011] Preferably, the metal deactivator is a metaborate ester.

[0012] Preferably, the extreme pressure anti-wear agent is composed of limonene polysulfide, dialkyl phosphate and boron nitride nanosheets, wherein the weight ratio of limonene polysulfide to dialkyl phosphate is 1.5:1 to 3:1.

[0013] Preferably, the rust inhibitor is a mixture of 1-butyl-3-methylimidazolium hexafluorophosphate and its derivatives with benzotriazole, wherein the weight ratio of 1-butyl-3-methylimidazolium hexafluorophosphate and its derivatives to benzotriazole is 1:2 to 1:4.

[0014] Preferably, the 12-hydroxystearic acid is of industrial purity, with a melting point ≥76℃ and a saponification value of 191~193mgKOH / g.

[0015] Preferably, the calcium hydroxide is of industrial purity with a purity of ≥98%.

[0016] Preferably, the calcium acetate monohydrate has a purity of ≥99% and a pH value of 6.5–8.0.

[0017] Preferably, the hydrogenated tallow amine has the following characteristics: C18 amine content ≥ 95%, C16 amine content ≤ 3%, and total cyanide content ≤ 0.8%.

[0018] Preferably, the cyclohexylamine has a purity of ≥99.5% and cyclohexanol ≤0.1%.

[0019] Preferably, the MDI has a purity of ≥99.8% and hydrolyzable chloride content of ≤0.002%.

[0020] Preferably, the octadecyl alcohol is industrial grade octadecyl alcohol with a purity ≥98.0%, a melting point of 57-60°C, and an acid value not greater than 1.0 mg KOH / g.

[0021] Preferably, the boron nitride nanosheets have a purity of ≥99.5% and an average particle size of 100–500 nm.

[0022] A method for preparing a urea-calcium composite thickened grease for electric vehicle drive motor bearings involves adding 20%–35% base oil to a dissolving tank, then adding all hydrogenated tallow amine, cyclohexylamine, octadecanol, calcium acetate monohydrate, and calcium hydroxide to the tank. The mixture is stirred at 60–80°C for 30 minutes to ensure uniform dispersion. Simultaneously, 40%–55% of the mixed base oil is added to a saponification kettle, and MDI is added to the kettle. The mixture is stirred at 50–70°C for 30 minutes to completely dissolve the MDI. Finally, the entire mixture from the dissolving tank is poured into the saponification kettle. Inside the reactor, maintain the temperature at 70-90℃ for 20 minutes, add 12-hydroxystearic acid, maintain the temperature at 80-100℃ for 50-60 minutes, raise the temperature to 130-140℃, add the remaining base oil as heating oil, raise the temperature to 150-160℃, refine for 10-20 minutes, transfer the reactor to a blending reactor; circulate and filter through a 100-mesh filter for 20-40 minutes, cool down to below 100℃, add the remaining components, circulate and filter through a 100-mesh filter for 20-40 minutes, homogenize under 20-40MPa pressure for 30-50 minutes, and obtain the finished product.

[0023] Compared with existing technologies, the beneficial effects of this invention are: 1. A urea-calcium composite thickener system is used, consisting of hydrogenated tallow-based primary amine, cyclohexylamine (two primary amines), and MDI (diisocyanate). These react via an addition reaction (amine + isocyanate → urea) to generate low-molecular-weight polyurea with terminal amine groups, forming a three-dimensional entangled network. This network has a lower overall modulus, equivalent to a soft network, but higher crystallinity. Furthermore, calcium ions form ionic bonds with carboxyl groups, resulting in a bond energy an order of magnitude higher, classifying it as a hard network. The two fibers interweave in the oil, forming hydrogen bonds and van der Waals interlocks. This dual-network interlocking ensures that during shearing, the "soft" polyurea network slides and absorbs energy first, while the "hard" calcium soap network breaks later. This interlocking allows the grease to both absorb energy and maintain its shape, preventing collapse under high-speed shearing. The dropping point is increased from 175℃ for pure calcium soap to over 285℃, meeting the requirement of preventing leakage from the motor windings at instantaneous temperatures of 180℃.

[0024] The polyurea network itself contains a large number of polar –C=O, –NH–, which can be adsorbed onto metal surfaces to form a low-shear-strength tribopolymer film; the trace amounts of Ca released by calcium soaps 2+ It can form a CaO·Ca(OH)2 repair film with the oxidized surface, which can suppress micro-vibration wear.

[0025] This invention presents a composite thickening system based on polyurea thickener and supplemented by a composite calcium-based thickener. The design aims to achieve complementary performance: the polyurea matrix ensures the overall high resistivity, high-temperature resistance, and long service life of the grease, fundamentally preventing the risk of electro-corrosion; while the introduced composite calcium component effectively compensates for the shortcomings of polyurea in extreme pressure anti-wear properties, enhancing the reliability of bearings under boundary lubrication conditions. The synergistic effect of these two components forms a high-performance grease that combines high electrical safety, excellent high-temperature stability, and strong extreme pressure anti-wear performance, precisely meeting the technological development needs of electric vehicle drive motors.

[0026] 2. The antioxidant and metal deactivator work synergistically. The antioxidant is a polymer of N-[(1,1,3,3-tetramethylbutyl)phenyl]-1-naphthylamine and 4-octyl-N-(4-octylphenyl)aniline; the metal deactivator is a metaborate ester. The metaborate ester is blended with the polymer of N-[(1,1,3,3-tetramethylbutyl)phenyl]-1-naphthylamine and 4-octyl-N-(4-octylphenyl)aniline. The metaborate ester blocks the metal ion source at the front end, and the high molecular weight aromatic amine removes the free radicals that have been generated at the back end, forming a dual antioxidant defense line of source control + process blocking.

[0027] 3. The extreme pressure anti-wear agent consists of limonene polysulfide, dialkyl phosphate, and boron nitride nanosheets. Under high temperature and high pressure boundary lubrication conditions, limonene polysulfide reacts chemically with the metal surface to form a solid reactive film with low shear strength, such as ferrous sulfide (FeS). This film has a layered hexagonal crystal structure and extremely low shear strength, effectively preventing direct contact and cold welding between metal surfaces, thus protecting the bearing. The ferrous sulfide film formed by the chemical reaction is porous or non-dense, providing a substrate for the subsequent adsorption or filling of other components.

[0028] Dialkyl phosphates function as both anti-wear agents and extreme pressure agents. They can form an organophosphorus compound adsorption film on metal surfaces through physical and chemical adsorption. Under high loads, they can further react with the metal to form a phosphate chemical reaction film. This phosphate film has high hardness, a high melting point, and a strong bond with the substrate, effectively resisting abrasive and fatigue wear. It can fill and strengthen porous FeS films, forming a sulfur-phosphorus co-permeation composite reaction layer, making the protective film denser, tougher, and exhibiting excellent anti-wear properties.

[0029] Boron nitride nanosheets are insulating solid lubricants and anti-wear agents. Boron nitride has a layered structure with weak interlayer bonding (van der Waals forces), making it prone to slippage under frictional shear, thus significantly reducing the coefficient of friction.

[0030] Nanoscale boron nitride nanosheets can penetrate and deposit into microscopic scratches and defects in the sulfur-phosphorus chemical reaction film on metal surfaces, acting as a filler and repair agent to make the contact surface smoother. At the same time, some sheets can be rolled into nanospheres, acting as a ball bearing in the contact area, transforming sliding friction into rolling friction.

[0031] In addition to reducing the coefficient of friction, boron nitride nanosheets also have extremely high thermal conductivity and electrical insulation properties. They can quickly dissipate the frictional heat of bearings and the local high temperature generated by the shaft current of motors, block the shaft current path, and prevent electrolytic pitting.

[0032] The extreme pressure anti-wear agent of this invention better meets the stringent requirements of electric vehicle drive systems for insulation and low corrosion.

[0033] 4. The rust inhibitor is a compound of 1-butyl-3-methylimidazolium hexafluorophosphate and its derivatives with benzotriazole. 1-Butyl-3-methylimidazolium hexafluorophosphate or its derivatives is an ionic liquid. The cations of 1-butyl-3-methylimidazolium hexafluorophosphate or its derivatives preferentially adsorb onto negatively charged metal surfaces through electrostatic interactions, forming an ordered ionic liquid pre-adsorption layer that provides anchoring sites for benzotriazole molecules. This pre-adsorption layer enhances the adsorption strength and coverage of benzotriazole on the metal surface. The π-π stacking interaction between the imidazole ring and the aromatic ring of benzotriazole forms a denser composite protective film, promoting the adsorption of benzotriazole molecules and maximizing the coverage area. It can form an ordered adsorption layer on the metal surface. It is non-volatile and has high thermal stability (>300°C).

[0034] 5. No water is added during the grease preparation process. Instead, water is generated through the reaction of calcium acetate monohydrate, calcium hydroxide, 12-hydroxystearic acid, and octadecyl alcohol to promote the saponification reaction. This significantly reduces dehydration time, improves production efficiency, and thus saves production costs. Detailed Implementation

[0035] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. The reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0036] A urea-calcium composite thickened grease for electric vehicle drive motor bearings comprises, by weight, the following components: 12-Hydroxystearic acid: 0.5-1.5 parts; Calcium acetate monohydrate: 0.5-1.5 parts; The feeding ratio of 12-hydroxystearic acid to calcium acetate monohydrate is 1:1 to 3:1.

[0037] Calcium hydroxide: 0.05-0.3 parts.

[0038] Hydrogenated tallow-based primary amine: 1-3 parts; cyclohexylamine: 1-3 parts; the ratio of cyclohexylamine to hydrogenated tallow-based primary amine is 0.5:1 to 1:1.

[0039] MDI: 1 to 5 parts.

[0040] The total weight of hydrogenated tallow amine, cyclohexylamine, and MDI is 3.5 to 10 times the total weight of 12-hydroxystearic acid, calcium acetate monohydrate, and calcium hydroxide.

[0041] Octadecyl alcohol: 0.3-0.6 parts.

[0042] Base oil: 71-88 parts; the base oil is a mixture of ETO base oil and polyether base oil; kinematic viscosity at 40°C is 60-80 mmHg. 2 / s; kinematic viscosity at 100℃ is 10~15mm 2 / s; viscosity index not less than 150, pour point not higher than -40℃; flash point ≥220℃. The base oil uses a combination of ETO base oil and polyether, which has a higher viscosity index, better low-temperature performance and shear resistance compared to traditional PAO. The starting torque at -40℃ is ≤400mN·m, and the working cone penetration is extended, with the difference between the working cone penetration after 100,000 cycles ≤40 (0.1mm).

[0043] Antioxidant: 0.5 to 2 parts; the antioxidant is a polymer of N-[(1,1,3,3-tetramethylbutyl)phenyl]-1-naphthylamine and 4-octyl-N-(4-octylphenyl)aniline.

[0044] Metal deactivator: 0.2-0.6 parts; the metal deactivator is a metaborate ester.

[0045] Extreme pressure anti-wear agent: 3.0 to 6.0 parts; The extreme pressure anti-wear agent is composed of limonene polysulfide, dialkyl phosphate and boron nitride nanosheets, wherein the weight ratio of limonene polysulfide to dialkyl phosphate is 1.5:1 to 3:1.

[0046] Rust inhibitor: 0.3 to 1.0 parts; The rust inhibitor is a mixture of 1-butyl-3-methylimidazolium hexafluorophosphate and its derivatives with benzotriazole, and the weight ratio of 1-butyl-3-methylimidazolium hexafluorophosphate and its derivatives to benzotriazole is 1:2 to 1:4.

[0047] The ratio of antioxidant to metal deactivator is 2:1 to 4:1.

[0048] The 12-hydroxystearic acid is of industrial purity, with a melting point ≥76℃ and a saponification value of 191~193mgKOH / g.

[0049] The calcium hydroxide mentioned is of industrial purity with a purity of ≥98%.

[0050] The calcium acetate monohydrate has a purity of ≥99% and a pH value of 6.5–8.0.

[0051] The hydrogenated tallow amine has the following characteristics: C18 amine content ≥95%, C16 amine content ≤3%, and total cyanide content ≤0.8%.

[0052] The cyclohexylamine has a purity of ≥99.5% and a cyclohexanol content of ≤0.1%.

[0053] The MDI has a purity of ≥99.8% and hydrolyzable chloride content of ≤0.002%.

[0054] The octadecyl alcohol mentioned is industrial grade octadecyl alcohol with a purity ≥98.0%, a melting point of 57-60°C, and an acid value not greater than 1.0 mg KOH / g.

[0055] The boron nitride nanosheets have a purity of ≥99.5% and an average particle size of 100–500 nm.

[0056] A method for preparing a urea-calcium composite thickened electric vehicle drive motor bearing grease involves adding 20%–35% base oil to an amine dissolving tank, then adding all hydrogenated tallow amine, cyclohexylamine, octadecanol, calcium acetate monohydrate, and calcium hydroxide to the tank, and mixing and circulating the mixture at 60–80°C for 30 minutes to ensure uniform dispersion of the materials for later use. Simultaneously, add 40%–55% of the mixed base oil to the saponification kettle, add MDI to the saponification kettle, and circulate and stir at 50–70°C for 30 minutes to completely dissolve the MDI. Pour all the material from the amine melting tank into the saponification kettle, keep it at 70–90°C for 20 minutes, add 12-hydroxystearic acid, keep it at 80–100°C for 50–60 minutes, raise the temperature to 130–140°C, add the remaining base oil as heating oil, raise the temperature to 150–160°C, refine for 10–20 minutes, and transfer the kettle to the blending kettle. Circulate and filter through a 100-mesh filter for 20–40 minutes, cool to below 100°C, add the remaining components, circulate and filter through a 100-mesh filter for 20–40 minutes, and homogenize at 20–40 MPa pressure for 30–50 minutes to obtain the finished product.

[0057] The technical specifications of the urea-calcium composite thickened electric vehicle drive motor bearing grease are shown in Table 1: Table 1: Technical Specifications of Urea-Calcium Composite Thickened Electric Vehicle Drive Motor Bearing Grease To make the objectives, technical solutions, and technical effects of this invention clearer, the technical solutions in the embodiments of this invention are now described clearly and completely. However, the embodiments described below are only some embodiments of this invention, not all embodiments. All other embodiments obtained by those skilled in the art in conjunction with the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0058] Example 1 A urea-calcium composite thickened grease for electric vehicle drive motor bearings, comprising the following components in parts by weight: 12-Hydroxystearic acid: 0.5 parts; Calcium hydroxide: 0.06 parts; Calcium acetate monohydrate: 0.5 parts; Hydrogenated tallow amine: 3.0 parts; Cyclohexylamine: 1.5 parts; MDI: 3.3 parts; Octadecyl alcohol: 0.4 parts; ETO base oil: 70.0 parts; Polyether base oil: 17.2 parts; Polymer of N-[(1,1,3,3-tetramethylbutyl)phenyl]-1-naphthylamine and 4-octyl-N-(4-octylphenyl)aniline: 0.5 parts; Metaboronic acid ester: 0.2 parts; Limonene polysulfide: 1.5 parts; Dialkyl phosphate: 1.0 part; Boron nitride nanosheets: 0.5 parts; 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM]PF6) and its derivatives: 0.1 parts; Benzotriazole: 0.2 parts; The specific preparation process of this embodiment is as follows: The base oils are metered and mixed. 35% of the mixed base oil is added to the amine-dissolving tank, along with all the hydrogenated tallow amine, cyclohexylamine, octadecyl alcohol, calcium acetate monohydrate, and calcium hydroxide. The mixture is stirred at 70°C for 30 minutes to ensure uniform dispersion. Simultaneously, 50% of the mixed base oil is added to the saponification kettle, along with all the MDI. The mixture is stirred at 55°C for 30 minutes to completely dissolve the MDI. All the material from the amine-dissolving tank is poured into the saponification kettle, kept at 80°C for 20 minutes, and then all of the 12-hydroxystearic acid is added. The mixture is kept at 90°C for 50 minutes. The temperature is raised to 130°C, and the remaining mixed base oil is added as a heating oil. The temperature is raised to 155°C and refined for 10 minutes. The mixture is then transferred to a blending kettle. The mixture is filtered through a 100-mesh filter for 20 minutes. The temperature is lowered to below 100°C, and all components are added. The mixture is filtered through a 100-mesh filter for 25 minutes, and then homogenized at 30 MPa pressure for 30 minutes to obtain the finished product.

[0059] Example 2 A urea-calcium composite thickened grease for electric vehicle drive motor bearings, comprising the following components in parts by weight: 12-Hydroxystearic acid: 1.5 parts; Calcium hydroxide: 0.18 parts; Calcium acetate monohydrate: 0.5 parts; Hydrogenated tallow amine: 3.0 parts; Cyclohexylamine: 1.5 parts; MDI: 3.3 parts; Octadecyl alcohol: 0.5 parts; ETO base oil: 70.0 parts; Polyether base oil: 10.4 parts; Polymer of N-[(1,1,3,3-tetramethylbutyl)phenyl]-1-naphthylamine and 4-octyl-N-(4-octylphenyl)aniline: 2.0 parts; Metaboronic acid ester: 0.6 parts; Limonene polysulfide: 3.0 parts; Dialkyl phosphate: 1.0 part; Boron nitride nanosheets: 2.0 parts; 1-Butyl-3-methylimidazolium hexafluorophosphate and its derivatives: 0.2 parts; Benzotriazole: 0.8 parts; The specific preparation process of this embodiment is as follows: The base oils are metered and mixed. 25% of the mixed base oil is added to a dissolving tank, along with all of the hydrogenated tallow amine, cyclohexylamine, octadecyl alcohol, calcium acetate monohydrate, and calcium hydroxide. The mixture is stirred at 65°C for 30 minutes to ensure uniform dispersion. Simultaneously, 55% of the mixed base oil is added to a saponification kettle, along with all of the MDI. The mixture is stirred at 70°C for 30 minutes to ensure complete dissolution of the MDI. All the material from the dissolving tank is poured into the saponification kettle, kept at 80°C for 20 minutes, and then all of the 12-hydroxystearic acid is added. The mixture is kept at 100°C for 60 minutes. The temperature is raised to 140°C, and the remaining mixed base oil is added as a heating oil. The temperature is raised to 155°C, and the mixture is refined for 10 minutes. The mixture is then transferred to a blending kettle. The mixture is filtered through a 100-mesh filter for 30 minutes. The temperature is lowered to below 100°C, and all components are added. The product is obtained by circulating and filtering through a 100-mesh filter for 30 minutes and then homogenizing under 40MPa pressure for 30 minutes.

[0060] Example 3 A urea-calcium composite thickened grease for electric vehicle drive motor bearings, comprising the following components in parts by weight: 12-Hydroxystearic acid: 1.0 part; Calcium hydroxide: 0.12 parts; Calcium acetate monohydrate: 1.0 part; Hydrogenated tallow amine: 3.0 parts; Cyclohexylamine: 1.5 parts; MDI: 3.3 parts; Octadecyl alcohol: 0.6 parts; ETO base oil: 20 parts; Polyether base oil: 64.4 parts; Polymer of N-[(1,1,3,3-tetramethylbutyl)phenyl]-1-naphthylamine and 4-octyl-N-(4-octylphenyl)aniline: 1.0 part; Metaboronic acid ester: 0.3 parts; Limonene polysulfide: 1.5 parts; Dialkyl phosphate: 1.0 part; Boron nitride nanosheets: 1.0 part; 1-Butyl-3-methylimidazolium hexafluorophosphate and its derivatives: 0.2 parts; Benzotriazole: 0.6 parts; The specific preparation process of this embodiment is as follows: The base oils are metered and mixed. 30% of the mixed base oil is added to the amine-dissolving tank, along with all the hydrogenated tallow amine, cyclohexylamine, octadecyl alcohol, calcium acetate monohydrate, and calcium hydroxide. The mixture is stirred at 80°C for 30 minutes to ensure uniform dispersion. Simultaneously, 45% of the mixed base oil is added to the saponification kettle, along with all the MDI. The mixture is stirred at 70°C for 30 minutes to completely dissolve the MDI. All the material from the amine-dissolving tank is poured into the saponification kettle, kept at 80°C for 20 minutes, and then all of the 12-hydroxystearic acid is added. The mixture is kept at 90°C for 60 minutes. The temperature is raised to 135°C, and 15% of the mixed base oil is added as a heating oil. The temperature is raised to 160°C, and the mixture is refined for 15 minutes. The mixture is then transferred to a blending kettle. The mixture is filtered through a 100-mesh filter for 30 minutes. The temperature is lowered to below 100°C, and all components are added. The product is obtained by circulating and filtering through a 100-mesh filter for 25 minutes and then homogenizing under 30MPa pressure for 40 minutes.

[0061] The test results of the urea-calcium composite thickened electric vehicle drive motor bearing grease prepared in Examples 1-3 are shown in Table 2; Table 2 This invention ensures the overall high resistivity, high temperature resistance, and long service life of the lubricating grease, fundamentally preventing the risk of electro-corrosion, while also compensating for the deficiencies of polyurea in extreme pressure anti-wear and shear resistance. It uses a high-index ETO (hyperbranched polyethylene synthetic oil) and polyether base oil as the base oil, resulting in a higher index, better low-temperature performance and shear resistance, and some biodegradability. A compound of limonene polysulfide, dialkyl phosphate, and boron nitride nanosheets is used as the extreme pressure agent, significantly improving extreme pressure anti-wear properties while rapidly dissipating bearing frictional heat and localized high temperatures generated by motor shaft current, blocking the shaft current path and preventing electro-corrosion pitting. A polymer compound of metaboronate, N-[(1,1,3,3-tetramethylbutyl)phenyl]-1-naphthylamine, and 4-octyl-N-(4-octylphenyl)aniline enhances antioxidant properties. A compound of 1-butyl-3-methylimidazolium hexafluorophosphate and its derivatives with benzotriazole enhances rust prevention. The absence of water in the preparation process significantly increases production efficiency.

[0062] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A urea-calcium composite thickened type electric vehicle drive motor bearing grease, characterized in that, The components, by weight, include: 12-Hydroxystearic acid: 0.5–1.5 parts; Calcium hydroxide: 0.05–0.3 parts; Calcium acetate monohydrate: 0.5–1.5 parts; Hydrogenated tallow amine: 1-3 parts; Cyclohexylamine: 1-3 parts; MDI: 1-5 parts; Octadecyl alcohol: 0.3–0.6 parts; Base oil: 71-88 parts; Antioxidant: 0.5–2 parts; Metal deactivating agent: 0.2–0.6 parts; Extreme pressure anti-wear agent: 3.0–6.0 parts; Rust inhibitor: 0.3–1.0 parts; The feeding ratio of 12-hydroxystearic acid to calcium acetate monohydrate is 1:1 to 3:1; The feeding ratio of cyclohexylamine to hydrogenated tallow-based primary amine is 0.5:1 to 1:1; The ratio of antioxidant to metal deactivator is 2:1 to 4:

1. The total weight of the hydrogenated tallow amine, cyclohexylamine, and MDI is 3.5 to 10 times the total weight of 12-hydroxystearic acid, calcium acetate monohydrate, and calcium hydroxide.

2. The urea-calcium composite thickened grease for electric vehicle drive motor bearings according to claim 1, characterized in that, The base oil is a mixture of ETO base oil and polyether base oil; its kinematic viscosity at 40°C is 60–80 mmHg. 2 / s; kinematic viscosity at 100℃ is 10~15mm 2 / s; viscosity index not less than 150, pour point not higher than -40℃; flash point ≥220℃.

3. The urea-calcium composite thickened grease for electric vehicle drive motor bearings according to claim 1, characterized in that, The antioxidant is a polymer of N-[(1,1,3,3-tetramethylbutyl)phenyl]-1-naphthylamine and 4-octyl-N-(4-octylphenyl)aniline.

4. The urea-calcium composite thickened grease for electric vehicle drive motor bearings according to claim 1, characterized in that, The metal deactivator is a metaborate ester.

5. The urea-calcium composite thickened grease for electric vehicle drive motor bearings according to claim 1, characterized in that, The extreme pressure anti-wear agent is composed of limonene polysulfide, dialkyl phosphate and boron nitride nanosheets, wherein the weight ratio of limonene polysulfide to dialkyl phosphate is 1.5:1 to 3:

1.

6. The urea-calcium composite thickened grease for electric vehicle drive motor bearings according to claim 1, characterized in that, The rust inhibitor is a mixture of 1-butyl-3-methylimidazolium hexafluorophosphate and its derivatives with benzotriazole, wherein the weight ratio of 1-butyl-3-methylimidazolium hexafluorophosphate and its derivatives to benzotriazole is 1:2 to 1:

4.

7. The method for preparing a urea-calcium composite thickened grease for electric vehicle drive motor bearings according to claim 1, characterized in that, Add 20%–35% base oil to the dissolving tank, along with all the hydrogenated tallow amine, cyclohexylamine, stearyl alcohol, calcium acetate monohydrate, and calcium hydroxide. Stir at 60–80°C for 30 minutes to ensure even dispersion. Simultaneously, add 40%–55% of the mixed base oil to the saponification kettle, then add MDI. Stir at 50–70°C for 30 minutes to completely dissolve the MDI. Pour all the material from the dissolving tank into the saponification kettle and maintain the temperature at 70–90°C for 20 minutes. Add 12-hydroxystearic acid, keep warm at 80-100℃ for 50-60 minutes, raise the temperature to 130-140℃, add the remaining base oil as heating oil, raise the temperature to 150-160℃, refine for 10-20 minutes, transfer to blending kettle; circulate and filter through a 100-mesh filter for 20-40 minutes, cool to below 100℃, add the remaining components, circulate and filter through a 100-mesh filter for 20-40 minutes, homogenize at 20-40MPa pressure for 30-50 minutes, and obtain the finished product.

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