Electric vehicle drive motor bearing grease for preventing electrocorrosion and method for preparing the same

Abstract

The application belongs to the technical field of grease preparation, and provides an anti-electric corrosion grease for electric vehicle drive motor bearings and a preparation method thereof. The grease uses poly-alpha olefin and synthetic ester as a compound base oil, and uses in-situ generated modified polyurea as a thickening system. The modified polyurea has 2-ureido-4[1H]-pyrimidinone units covalently grafted on the molecular skeleton, and can realize structure reorganization and recovery through reversible bonding. The grease further contains overbased calcium petroleum sulfonate, oil-soluble anti-rust agent, antioxidant, ash-free anti-wear agent and metal passivator, and introduces water-triggered release type self-repairing microcapsules. After water infiltration, in-situ curing and condensation reaction occur, forming a continuous and dense barrier film layer on the metal surface, realizing interface self-repairing and defect covering. The preparation method includes dehydration and degassing of the base oil, thickening reaction and grafting modification, mixing of the functional additives in sequence, low-temperature dispersion of the microcapsules, and vacuum degassing and curing to obtain the finished product.

Description

Technical Field

[0001] This invention belongs to the field of grease preparation technology, and relates to an anti-electrostatic corrosion grease for electric vehicle drive motor bearings and its preparation method. Background Technology

[0002] Electric vehicle drive motors operate under high speeds, frequent start-stop cycles, and wide temperature ranges, requiring bearings, as critical support components, to undergo long-term, stable lubrication and protection. Compared to traditional gasoline vehicles, the electromagnetic environment of electric drive systems is more complex, making bearing cavities more susceptible to condensation or external moisture intrusion. Simultaneously, the lubricating medium is more prone to structural degradation under high shear, temperature rise, and oxidation conditions. Moisture, water, and corrosive ions entering the bearing contact area reduce oil film continuity and induce metal surface corrosion, further leading to abrasive grain formation, increased noise and vibration, and accelerated friction pair failure. Therefore, lubricating materials for electric vehicle drive motor bearings not only need excellent load-bearing, anti-wear, and anti-oxidation properties but also require continuous suppression of corrosion risks after moisture intrusion.

[0003] In existing technologies, bearing greases typically use mineral oil or synthetic oil as the base oil, combined with thickeners such as soap base or polyurea to form a semi-solid lubrication system. Comprehensive performance is further enhanced by adding rust inhibitors, metal passivators, antioxidants, and anti-wear agents. While this approach can meet basic lubrication needs under normal conditions, in situations where moisture is present for extended periods or intermittently enters, rust inhibitors are easily consumed or migrate over time, making it difficult for the protective film at localized defects to remain intact, leading to a decline in protective performance. Simultaneously, the thickening network of the grease may undergo structural damage after repeated shearing and thermo-oxidative aging, manifesting as decreased consistency, increased oil separation, or deteriorated mechanical stability, further destabilizing the lubrication and protective effects. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide an anti-electrochemical corrosion grease for electric vehicle drive motor bearings and its preparation method. This grease uses a compounded base oil as a carrier and employs an in-situ generated modified polyurea thickening system. Ureidinone structural units are covalently introduced into the polyurea backbone to form a reversibly associated network structure. Simultaneously, water-triggered release self-healing microcapsules are introduced, with the core containing organoalkoxysilane active film-forming components and rust-preventing components. These components solidify in situ under the action of moisture, achieving spontaneous coverage and repair of interface defects, thereby meeting the needs of actual production.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides an anti-electro-corrosion grease for the bearings of electric vehicle drive motors, wherein the grease comprises, by weight percentage: A) 70-85 wt.% base oil; B) 10-18 wt.% polyurea thickener; C) 2-10 wt.% functional additives; and the sum of the weight percentages of A), B), and C) is 100 wt.%.

[0007] The polyurea thickener is a modified polyurea thickener grafted with 2-ureido-4[1H]-pyrimidinone, wherein the 2-ureido-4[1H]-pyrimidinone is covalently linked to the molecular backbone of the polyurea thickener; the functional additives, based on the total mass of the grease, include at least: 0.5-4 wt.% of super-alkalized petroleum sulfonate, 0.2-2 wt.% of oil-soluble rust inhibitor, 0.2-1.5 wt.% of antioxidant, 0.1-2 wt.% of ashless anti-wear agent, 0.01-0.3 wt.% of metal passivator, and 0.3-3 wt.% of self-healing microcapsules.

[0008] Preferably, the base oil comprises PAO and synthetic ester oil, wherein PAO accounts for 60-90 wt.% of the base oil mass and synthetic ester oil accounts for 10-40 wt.% of the base oil mass.

[0009] Preferably, the modified polyurea thickener is generated by in-situ reaction of diisocyanate, diamine and monoamine in base oil, wherein the diisocyanate is one or more of diphenylmethane diisocyanate and isophorone diisocyanate; the diamine is one or more of 4,4′-methylenebis(cyclohexylamine), hexamethylenediamine and ethylenediamine; and the monoamine is a C6-C18 fatty amine.

[0010] Preferably, the 2-ureido-4[1H]-pyrimidinone is introduced as follows: 0.1-3.0 wt.% of the monoamine is replaced by an amino-terminated 2-ureido-4[1H]-pyrimidinone derivative in the diisocyanate reaction, thereby covalently introducing the 2-ureido-4[1H]-pyrimidinone into the polyurea thickener backbone via chain end capping and / or side attachment; the amino-terminated 2-ureido-4[1H]-pyrimidinone derivative is a monofunctional amine. The 2-ureido-4[1H]-pyrimidinone derivative contains only one amino functional group in its molecule that can react with isocyanate, and the amino functional group is a primary amino group with the structure -NH2, or a monosubstituted secondary amino group with the structure -NHR, wherein R in -NHR is a C1-C12 alkyl or benzyl, and the amount of the 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization is 0.1-3.0 wt. of the total mass of amines participating in the reaction in the polyurea thickening reaction.

[0011] Preferably, the preparation method of the amino-terminated 2-ureido-4[1H]-pyrimidinone derivative is as follows: 20.0g of 2-amino-4-hydroxy-6-methylpyrimidin is weighed and mixed with 150mL of anhydrous N,N-dimethylformamide under nitrogen protection. 30.0g of diphenylmethane diisocyanate and 20.0g of n-octylamine are added sequentially. The mixture is reacted at 25-30℃ for 4h. The reaction solution is poured into deionized water to precipitate the solid. The solid is then filtered, washed, and dried to obtain the amino-terminated 2-ureido-4[1H]-pyrimidinone derivative.

[0012] Preferably, the self-healing microcapsules have an average particle size of 1-15 μm and a D90 ≤ 30 μm; the capsule wall material is polyurea or urea-formaldehyde resin, and the capsule wall thickness is 0.05-0.80 μm.

[0013] Preferably, the core of the self-healing microcapsule comprises at least the following components by weight: b) 20-95 parts of an organoalkoxysilane film-forming component; c) 5-40 parts of an oil-soluble rust inhibitor, wherein the organoalkoxysilane film-forming component is an organosilicon compound containing at least one silane alkoxy bond Si-OR, and the R in the silane alkoxy bond Si-OR is a C1-C4 alkyl group.

[0014] Preferably, the core further comprises, by weight, 10-60 parts of a terminal isocyanate-group reactive prepolymer.

[0015] Preferably, the total base number (TBN) of the superalkalized calcium petroleum sulfonate is 200-400 mg KOH / g.

[0016] Preferably, the oil-soluble rust inhibitor is one or more of succinic acid half-ester amine salt, imidazoline salt, and fatty acid amine salt; the antioxidant is a compound system of hindered phenolic antioxidant and amine antioxidant.

[0017] The thickened structure of polyurea is formed by the addition reaction of isocyanate and amine in the base oil phase to generate urea bonds. Diamines participate in chain extension, increasing the length of the polyurea segments, while the monoamine reacts with isocyanate to achieve end-capping, altering the number of end groups and the distribution of urea sites that can form associations. The urea groups in the polyurea segments are highly polar, forming multi-point associations through hydrogen bonds and dipole interactions. These association points are spatially connected, forming a network that binds the base oil, resulting in the thickened structure of the grease. The amine-functionalized 2-ureo-4[1H]-pyrimidinone derivative participates in the same addition reaction pathway as a monofunctional amine, and the 2-ureo-4[1H]-pyrimidinone structure is covalently introduced into the ends or sides of the polyurea segments. This structural unit contains multiple sets of hydrogen bond donor and acceptor sites, which can form reversible hydrogen bond associations with similar sites or urea sites on adjacent segments, thereby increasing the number of associative connection points and altering their lifetime. Under shear stress, some association points break; after the shear stress weakens, hydrogen bond association points reform under thermal motion, thus rebuilding the network connection.

[0018] Over-alkalized petroleum sulfonate calcium exists in dispersion form. The sulfonate groups and calcium ions form an ionic structure, and the internal alkaline components can neutralize acidic oxidation products, reducing the accumulation of acidic substances at the metal interface. Oil-soluble rust inhibitors contain polar groups and oleophobic segments. The polar groups adsorb onto the metal surface and occupy some surface-active sites, while the oleophobic segments align towards the oil phase, altering the effective contact conditions between water and dissolved oxygen at the interface. Metal passivators reduce the availability of metal ions for subsequent reactions by forming coordination complexes with metal surfaces or dissolved metal ions. Hindered phenolic and amine antioxidants inhibit the chain oxidation of base oils through hydrogen donation termination and free radical capture, respectively, reducing the formation rate of peroxides and acidic byproducts. Ashless anti-wear agents preferentially adsorb in the friction contact area and undergo chemical transformation under local energy input, forming a boundary film with heteroatom bonding characteristics, altering the reaction conditions at the friction interface.

[0019] The self-healing microcapsules have walls made of polyurea or urea-formaldehyde resin, providing microscopic channels for water molecule permeation. After water enters the core, organoalkoxysilanes hydrolyze to form silanols, which then condense to form a siloxane network. These silanols condense with the metal oxide layer or surface hydroxyl sites to form siloxane-metal bonds, chemically connecting the siloxane network to the metal surface. The oil-soluble rust-inhibiting components released from the core are simultaneously adsorbed onto the metal surface, forming an interfacial coating layer together with the siloxane network. When the core contains a reactive prepolymer with terminal isocyanate groups, the terminal isocyanate groups react with water to generate amines and release carbon dioxide. The generated amines further add to the remaining isocyanate groups to form urea bonds, causing the prepolymer to form a cross-linked polyurea network at the interface. This polyurea network and the siloxane network are generated in parallel and interpenetrate each other in the same region, forming a coating structure where organic and inorganic phases coexist. Water participates in the reaction and becomes part of the network structure, making it difficult to maintain a continuous aqueous phase at the interface and restricting ion migration pathways, thus weakening the establishment of electrochemical corrosion conditions.

[0020] Secondly, the present invention provides a method for preparing an anti-electrolytic corrosion grease for electric vehicle drive motor bearings, specifically including:

[0021] S1, Base oil dehydration and degassing: The base oil is vacuum dehydrated and degassed at 80-100℃ and cooled under nitrogen protection;

[0022] S2, In-situ thickening and modification: Diisocyanate is added to the base oil and stirred to dissolve, then diamine is added for chain extension reaction, and finally a mixture of monoamine and 2-ureido-4[1H]-pyrimidinone derivatives with terminal amino functionalization is added for end-capping reaction;

[0023] S3, add functional additives, cool down to below 80℃, and add antioxidant, ashless anti-wear agent, metal passivator, over-alkalized petroleum sulfonate calcium and oil-soluble rust inhibitor in sequence and mix evenly.

[0024] S4, add self-healing microcapsules, cool to below 60℃ and add self-healing microcapsules, then vacuum degas and let stand to mature to obtain anti-electro-corrosion lubricating grease for electric vehicle drive motor bearings.

[0025] Preferably, the mass ratio of base oil, diisocyanate, diamine and monoamine in S2 is 100:(8-15):(5-12):(3-10).

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: The lubricating grease of the present invention adopts a modified polyurea thickening system generated in situ in the base oil, and introduces the 2-ureido-4[1H]-pyrimidinone structural unit into the polyurea molecular skeleton in a covalent manner, so that the thickening network has both hydrogen bond association of polyurea segments and reversible association of 2-ureido-4[1H]-pyrimidinone units. Under shear and start-stop conditions, the network connection can break and regenerate, thereby maintaining consistency stability and inhibiting structural decay; After the introduction of water-triggered release self-healing microcapsules, water penetration can trigger the silane hydrolysis and condensation reaction of the capsule core and form a silicon-oxygen bond network coating layer on the metal surface. At the same time, the released oil-soluble rust inhibitor and metal passivator jointly occupy the interfacial active sites, reducing the probability of water and ions forming continuous electrolyte channels on the metal surface; When the capsule core contains a reactive prepolymer with terminal isocyanate groups, a polyurea network can be further generated at the interface and coexist with the silicon-oxygen network, improving the continuity and adhesion stability of the coating layer. Attached Figure Description

[0027] Figure 1 The FTIR spectra of the modified polyurea thickener of Example 1 and the ungrafted polyurea thickener of Comparative Example 1 are shown in the present invention. Detailed Implementation

[0028] The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary, and should not be construed as limiting the implementation methods or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0029] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone any further purification treatment.

[0030] Example 1

[0031] This embodiment provides an anti-electrolytic corrosion grease for electric vehicle drive motor bearings and its preparation method, specifically including:

[0032] This electric vehicle drive motor bearing anti-electrolytic corrosion grease, by weight percentage, comprises: A) 72 wt.% base oil; B) 18 wt.% polyurea thickener; C) 10 wt.% functional additives.

[0033] The base oil comprises PAO and pentaerythritol tetraoctanoate, with PAO accounting for 90 wt.% of the base oil mass and synthetic ester oil accounting for 10 wt.% of the base oil mass; the polyurea thickener is a modified polyurea thickener grafted with 2-ureido-4[1H]-pyrimidinone, which is generated by in-situ reaction of diphenylmethane diisocyanate, 4,4′-methylenebis(cyclohexylamine) and octadecylamine in the base oil, wherein the 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization replaces part of the monoamine in the reaction, and the mass ratio of octadecylamine to the 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization is 99.9:0.1;

[0034] The preparation method of the amino-terminated 2-ureido-4[1H]-pyrimidinone derivative is as follows: 20.0g of 2-amino-4-hydroxy-6-methylpyrimidin is weighed and mixed with 150mL of anhydrous N,N-dimethylformamide. Under nitrogen protection, 30.0g of diphenylmethane diisocyanate and 20.0g of n-octylamine are added at 28℃ and reacted for 4h. The reaction solution is poured into deionized water to precipitate solids. The solids are filtered, washed, and dried to obtain the amino-terminated 2-ureido-4[1H]-pyrimidinone derivative.

[0035] The functional additives include: 4 wt.% of superalkalized petroleum sulfonate calcium with a total base number (TBN) of 200 mg KOH / g, 2 wt.% of succinate half-ester amine salt, 1.5 wt.% of antioxidant (antioxidant 1010 and dioctyl diphenylamine in a mass ratio of 1:1), 2 wt.% of ashless anti-wear agent, 0.2 wt.% of metal passivator, and 0.3 wt.% of self-healing microcapsules;

[0036] The self-healing microcapsules have an average particle size of 15 μm and a D90 ≤ 30 μm; the capsule wall material is polyurea with a capsule wall thickness of 0.2 μm; the capsule core includes, by weight: b) 95 parts of organoalkoxysilane film-forming component; c) 5 parts of oil-soluble rust inhibitor; a) 10 parts of terminal isocyanate-based reactive prepolymer.

[0037] The preparation method of anti-electrolytic corrosion grease for electric vehicle drive motor bearings includes:

[0038] S1, Base oil dehydration and degassing: The base oil is dehydrated and degassed under vacuum at 80°C and cooled under nitrogen protection;

[0039] S2, In-situ thickening and modification: Diphenylmethane diisocyanate is added to the base oil and stirred to dissolve. Then, diamine is added to carry out chain extension reaction. Finally, a mixture of monoamine and 2-ureido-4[1H]-pyrimidinone derivatives with terminal amino functionalization is added to carry out end-capping reaction. The mass ratio of the base oil, diisocyanate, diamine and monoamine is 100:8:5:3.

[0040] S3, add functional additives, cool down to below 80℃, add antioxidant, tri(2-ethylhexyl) phosphate, methyltriazole, superalkalized petroleum sulfonate calcium and oil-soluble rust inhibitor in sequence and mix evenly. The oil-soluble rust inhibitor was purchased from Shanghai Yucheng Chemical Co., Ltd., product model is HOESC L12.

[0041] S4, add self-healing microcapsules, cool to below 60℃ and add self-healing microcapsules, then vacuum degas and let stand to mature to obtain anti-electro-corrosion lubricating grease for electric vehicle drive motor bearings.

[0042] Example 2

[0043] This embodiment provides an anti-electrolytic corrosion grease for electric vehicle drive motor bearings and its preparation method, specifically including:

[0044] The anti-electrostatic corrosion grease for electric vehicle drive motor bearings comprises, by weight percentage: A) 85 wt.% base oil; B) 13 wt.% polyurea thickener; C) 2 wt.% functional additives.

[0045] The base oil comprises PAO and pentaerythritol tetraoctanoate, with PAO accounting for 60 wt.% of the base oil mass and synthetic ester oil accounting for 40 wt.% of the base oil mass; the polyurea thickener is a modified polyurea thickener grafted with 2-ureido-4[1H]-pyrimidinone, which is generated by the in-situ reaction of isophorone diisocyanate, hexamethylenediamine and dodecylamine in the base oil, wherein the 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization replaces part of the monoamine in the reaction, and the mass ratio of dodecylamine to the 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization is 97:3;

[0046] The preparation method of the amino-terminated 2-ureido-4[1H]-pyrimidinone derivative is as follows: 20.0g of 2-amino-4-hydroxy-6-methylpyrimidin is weighed and mixed with 150mL of anhydrous N,N-dimethylformamide. Under nitrogen protection, 30.0g of diphenylmethane diisocyanate and 20.0g of n-octylamine are added at 26℃ and reacted for 4h. The reaction solution is poured into deionized water to precipitate solids. The solids are filtered, washed, and dried to obtain the amino-terminated 2-ureido-4[1H]-pyrimidinone derivative.

[0047] The functional additives include: 0.5 wt.% of superalkalized petroleum sulfonate calcium with a total base number (TBN) of 400 mg KOH / g, 0.5 wt.% of imidazoline salt, 0.2 wt.% of antioxidant (antioxidant 1010 and dioctyl diphenylamine in a mass ratio of 1:1), 0.49 wt.% of ashless anti-wear agent, 0.01 wt.% of metal passivator, and 0.3 wt.% of self-healing microcapsules; the average particle size of the self-healing microcapsules is 1 μm, and D90 ≤ 30 μm; the capsule wall material is urea-formaldehyde resin, and the capsule wall thickness is 0.80 μm; the capsule core includes, by mass,: b) 20 parts of organoalkoxysilane film-forming component; c) 40 parts of oil-soluble rust inhibitor; a) 60 parts of terminal isocyanate-terminated reactive prepolymer;

[0048] The preparation method of anti-electrolytic corrosion grease for electric vehicle drive motor bearings includes:

[0049] S1, Base oil dehydration and degassing: The base oil is dehydrated and degassed under vacuum at 100°C and cooled under nitrogen protection;

[0050] S2, In-situ thickening and modification: Isophorone diisocyanate is added to the base oil and stirred to dissolve. Then, diamine is added for chain extension reaction. Finally, a mixture of monoamine and 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization is added for end-capping reaction. The mass ratio of base oil, diisocyanate, diamine and monoamine is 100:15:12:10.

[0051] S3, add functional additives, cool down to below 80℃, add antioxidant, tri(2-ethylhexyl) phosphate, methyltriazole, superalkalized petroleum sulfonate calcium and oil-soluble rust inhibitor in sequence and mix evenly. The oil-soluble rust inhibitor was purchased from Shanghai Yucheng Chemical Co., Ltd., product model is HOESC L12.

[0052] S4, add self-healing microcapsules, cool to below 60℃ and add self-healing microcapsules, then vacuum degas and let stand to mature to obtain anti-electro-corrosion lubricating grease for electric vehicle drive motor bearings.

[0053] Example 3

[0054] This embodiment provides an anti-electrolytic corrosion grease for electric vehicle drive motor bearings and its preparation method, specifically including:

[0055] This electric vehicle drive motor bearing anti-electrolytic corrosion grease, by weight percentage, comprises: A) base oil 84 wt.%; B) polyurea thickener 10 wt.%; C) functional additives 6 wt.%.

[0056] The base oil comprises PAO and pentaerythritol tetraoctanoate, with PAO accounting for 80 wt.% of the base oil mass and synthetic ester oil accounting for 20 wt.% of the base oil mass; the polyurea thickener is a modified polyurea thickener grafted with 2-ureido-4[1H]-pyrimidinone, which is generated by in-situ reaction of a mixture of diphenylmethane diisocyanate and isophorone diisocyanate, ethylenediamine and hexadecylamine in the base oil, wherein the 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization replaces part of the monoamine in the reaction, and the mass ratio of hexadecylamine to the 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization is 98.5:1.5;

[0057] The preparation method of the amino-terminated 2-ureido-4[1H]-pyrimidinone derivative is as follows: 20.0g of 2-amino-4-hydroxy-6-methylpyrimidin is weighed and mixed with 150mL of anhydrous N,N-dimethylformamide. Under nitrogen protection, 30.0g of diphenylmethane diisocyanate and 20.0g of n-octylamine are added at 30℃ and reacted for 4h. The reaction solution is poured into deionized water to precipitate solids. The solids are filtered, washed, and dried to obtain the amino-terminated 2-ureido-4[1H]-pyrimidinone derivative.

[0058] The functional additives include: 2.0 wt.% of superalkalized petroleum sulfonate calcium with a total base number (TBN) of 300 mg KOH / g, 1.0 wt.% of fatty acid amine salt, 1.0 wt.% of antioxidant (antioxidant 1010 and dioctyl diphenylamine in a mass ratio of 1:1), 1.0 wt.% of ashless anti-wear agent, 0.1 wt.% of metal passivator, and 0.9 wt.% of self-healing microcapsules; the self-healing microcapsules have an average particle size of 8 μm and a D90 ≤ 30 μm; the capsule wall material is polyurea with a capsule wall thickness of 0.40 μm; the capsule core includes, by mass,: b) 50 parts of organoalkoxysilane film-forming component; c) 20 parts of oil-soluble rust inhibitor; a) 30 parts of terminal isocyanate-terminated reactive prepolymer;

[0059] The preparation method of anti-electrolytic corrosion grease for electric vehicle drive motor bearings includes:

[0060] S1, Base oil dehydration and degassing: The base oil is dehydrated and degassed under vacuum at 90°C and cooled under nitrogen protection;

[0061] S2, In-situ thickening and modification: Diphenylmethane diisocyanate is added to the base oil and stirred to dissolve. Then, diamine is added to carry out chain extension reaction. Finally, a mixture of monoamine and 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization is added to carry out end-capping reaction. The mass ratio of base oil, diisocyanate, diamine and monoamine is 100:9:8:5.

[0062] S3, add functional additives, cool down to below 80℃, add antioxidant, tri(2-ethylhexyl) phosphate, methyltriazole, superalkalized petroleum sulfonate calcium and oil-soluble rust inhibitor in sequence and mix evenly. The oil-soluble rust inhibitor was purchased from Shanghai Yucheng Chemical Co., Ltd., product model is HOESC L12.

[0063] S4, add self-healing microcapsules, cool to below 60℃ and add self-healing microcapsules, then vacuum degas and let stand to mature to obtain anti-electro-corrosion lubricating grease for electric vehicle drive motor bearings.

[0064] Example 4

[0065] This embodiment provides an anti-electrolytic corrosion grease for electric vehicle drive motor bearings and its preparation method, specifically including:

[0066] This electric vehicle drive motor bearing anti-electrolytic corrosion grease, by weight percentage, comprises: A) 78 wt.% base oil; B) 15 wt.% polyurea thickener; C) 7 wt.% functional additives.

[0067] The base oil comprises PAO and pentaerythritol tetraoctanoate, with PAO accounting for 70 wt.% of the base oil mass and synthetic ester oil accounting for 30 wt.% of the base oil mass; the polyurea thickener is a modified polyurea thickener grafted with 2-ureido-4[1H]-pyrimidinone, which is generated in situ from a mixture of diphenylmethane diisocyanate, 4,4′-methylenebis(cyclohexylamine) and hexamethylenediamine, and n-tetradecaneamine in the base oil, wherein the 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization replaces a portion of the monoamine in the reaction, and the mass ratio of n-tetradecaneamine to the 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization is 98:2;

[0068] The preparation method of the amino-terminated 2-ureido-4[1H]-pyrimidinone derivative is as follows: 20.0g of 2-amino-4-hydroxy-6-methylpyrimidin is weighed and mixed with 150mL of anhydrous N,N-dimethylformamide. Under nitrogen protection, 30.0g of diphenylmethane diisocyanate and 20.0g of n-octylamine are added at 25℃ and reacted for 4h. The reaction solution is poured into deionized water to precipitate solids. The solids are filtered, washed, and dried to obtain the amino-terminated 2-ureido-4[1H]-pyrimidinone derivative.

[0069] The functional additives include: 2.5 wt.% of superalkalized petroleum sulfonate calcium with a total base number (TBN) of 350 mg KOH / g, 1.5 wt.% of a mixture of succinate half-ester amine salt and imidazoline salt, 1.2 wt.% of antioxidant (antioxidant 1010 and dioctyl diphenylamine in a mass ratio of 1:1), 1.2 wt.% of ashless anti-wear agent, 0.1 wt.% of metal passivator, and 0.5 wt.% of self-healing microcapsules; the self-healing microcapsules have an average particle size of 10 μm and a D90 ≤ 30 μm; the capsule wall material is urea-formaldehyde resin with a capsule wall thickness of 0.60 μm; the capsule core includes, by mass,: b) 40 parts of organoalkoxysilane film-forming component; c) 30 parts of oil-soluble rust inhibitor; a) 40 parts of terminal isocyanate-terminated reactive prepolymer;

[0070] The preparation method of anti-electrolytic corrosion grease for electric vehicle drive motor bearings includes:

[0071] S1, Base oil dehydration and degassing: The base oil is dehydrated and degassed under vacuum at 95°C and cooled under nitrogen protection;

[0072] S2, In-situ thickening and modification: Isophorone diisocyanate is added to the base oil and stirred to dissolve. Then, diamine is added for chain extension reaction. Finally, a mixture of monoamine and 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization is added for end-capping reaction. The mass ratio of base oil, diisocyanate, diamine and monoamine is 100:12:11:7.

[0073] S3, add functional additives, cool down to below 80℃, add antioxidant, tri(2-ethylhexyl) phosphate, methyltriazole, superalkalized petroleum sulfonate calcium and oil-soluble rust inhibitor in sequence and mix evenly. The oil-soluble rust inhibitor was purchased from Shanghai Yucheng Chemical Co., Ltd., product model is HOESC L12.

[0074] S4, add self-healing microcapsules, cool to below 60℃ and add self-healing microcapsules, then vacuum degas and let stand to mature to obtain anti-electro-corrosion lubricating grease for electric vehicle drive motor bearings.

[0075] Comparative Example 1

[0076] This embodiment provides an anti-electrolytic corrosion grease for electric vehicle drive motor bearings and its preparation method. The difference between this embodiment and Example 1 is that the polyurea thickener does not introduce 2-ureido-4[1H]-pyrimidinone structural units, that is, no 2-ureido-4[1H]-pyrimidinone derivatives with terminal amino functionalization are added in the in-situ thickening reaction, and all monoamines are octadecylamine. Other process parameters and operating conditions are exactly the same as in Example 1.

[0077] Figure 1The above are comparative FTIR spectra of the modified polyurea thickener from Example 1 and the ungrafted polyurea thickener from this comparative example. Both spectra are at approximately 3320 cm⁻¹. -1 A broad peak of NH stretching appears at 2925-2855 cm⁻¹. -1 A -CH2- stretching vibration peak appears at approximately 1670 cm⁻¹. -1 A urea C=O stretching peak appears at approximately 1540 cm⁻¹. -1 An amide II band appears at approximately 1260 cm. -1 CN-related absorption was observed at approximately 1705, 1610, 1510, and 1030 cm⁻¹, indicating the formation of a polyurea backbone. Compared to Comparative Example 1, Example 1 showed better absorption at approximately 1705, 1610, 1510, and 1030 cm⁻¹. -1 The presence of new or enhanced absorption at the site indicates that the 2-ureido-4[1H]-pyrimidinone structural unit has been introduced and altered the local interaction environment between the carbonyl group and the nitrogen-containing group.

[0078] Comparative Example 2

[0079] This embodiment provides an anti-electrolytic corrosion grease for electric vehicle drive motor bearings and its preparation method. The difference between this embodiment and Embodiment 1 is that the self-healing microcapsule has a dense capsule wall, and the capsule wall material is polyurea or urea-formaldehyde resin. The capsule wall is made impermeable to water molecules by increasing the degree of crosslinking. Other process parameters and operating conditions are exactly the same as in Embodiment 1.

[0080] Comparative Example 3

[0081] This embodiment provides an anti-electrolytic corrosion grease for electric vehicle drive motor bearings and its preparation method. The difference between this embodiment and Embodiment 1 is that the self-healing microcapsule core does not contain terminal isocyanate-based reactive prepolymers, and the core only contains organic alkoxysilane film-forming components and oil-soluble anti-rust components. Other process parameters and operating conditions are exactly the same as in Embodiment 1.

[0082] The anti-electro-corrosion greases for electric vehicle drive motor bearings prepared in Examples 1-4 and Comparative Examples 1-3 were tested.

[0083] The test method for bearing rust resistance is ISO 11007-1 (0 for no corrosion, 5 for severe corrosion).

[0084] The test method for water erosion retention is ASTM D1264;

[0085] Consistency and mechanical stability tests were conducted according to ASTM D1831: The grease to be tested was loaded into the specified rolling stability test apparatus and subjected to rolling shear treatment according to standard requirements under specified temperature conditions; samples were taken before and after the rolling shear treatment, and the working cone penetration was measured according to ASTM D217; the difference in working cone penetration before and after the rolling shear treatment was used as the mechanical stability evaluation index, and the working cone penetration values ​​before and after the rolling shear treatment were recorded for consistency characterization.

[0086] The test results are shown in Table 1.

[0087] Table 1. Test results of anti-electrolytic corrosion greases in Examples 1-4 and Comparative Examples 1-3

[0088]

[0089] As shown in Table 1, compared with Example 1, Comparative Example 1 has a weakened rust prevention level, an increased water washing loss rate, an increased working cone penetration, and a larger change in cone penetration after rolling shear; Comparative Example 2 has a weakened rust prevention level, an increased water washing loss rate, an increased working cone penetration, and a larger change in cone penetration after rolling shear; Comparative Example 3 has a weakened rust prevention level, an increased water washing loss rate, no change in working cone penetration, and a larger change in cone penetration after rolling shear.

[0090] This is because, in Comparative Example 1, the removal of the covalently introduced 2-ureido-4[1H]-pyrimidinone reduced the number of reversible hydrogen bond association points, making the thickened network more easily destroyed under rolling shear. The increased cone penetration after rolling shear reduced structural integrity, leading to a slight increase in water wash loss and a weakened dynamic wet corrosion rust prevention level. In Comparative Example 2, when the microcapsule wall was dense and impermeable to water, the organic alkoxysilanes and rust-preventive components in the capsule core were difficult to release under aqueous conditions and form an in-situ film on the metal surface. Insufficient interfacial coverage resulted in a weakened dynamic wet corrosion rust prevention level. In Comparative Example 3, when the capsule core did not contain the terminal isocyanate-based reactive prepolymer, the main network formed under aqueous conditions was the siloxane network obtained from silane hydrolysis and condensation. The lack of a simultaneously generated polyurea network reduced the continuity and adhesion stability of the interfacial film, further weakening the dynamic wet corrosion rust prevention level.

[0091] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. An anti-electrolytic corrosion grease for the bearings of electric vehicle drive motors, characterized in that, The grease comprises, by weight percentage: A) 70-85 wt.% base oil; B) 10-18 wt.% polyurea thickener; C) 2-10 wt.% functional additives; and the sum of the weight percentages of A), B), and C) is 100 wt.%. The polyurea thickener is a modified polyurea thickener grafted with 2-ureido-4[1H]-pyrimidinone, wherein the 2-ureido-4[1H]-pyrimidinone is covalently linked to the molecular backbone of the polyurea thickener. The functional additives, based on the total mass of the lubricating grease, include at least: 0.5-4 wt.% superalkalized calcium petroleum sulfonate, 0.2-2 wt.% oil-soluble rust inhibitor, 0.2-1.5 wt.% antioxidant, 0.1-2 wt.% ashless anti-wear agent, 0.01-0.3 wt.% metal passivator, and 0.3-3 wt.% self-healing microcapsules; The modified polyurea thickener is generated by in-situ reaction of diisocyanate, diamine, and monoamine in base oil. The diisocyanate is one or more of diphenylmethane diisocyanate and isophorone diisocyanate; the diamine is one or more of 4,4′-methylenebis(cyclohexylamine), hexamethylenediamine, and ethylenediamine; and the monoamine is a C6-C18 aliphatic amine. The 2-ureido-4[1H]-pyrimidinone is introduced as follows: 0.1-3.0 wt.% of the monoamine is replaced by a 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization to participate in the reaction of diisocyanate, so that 2-ureido-4[1H]-pyrimidinone is covalently introduced into the polyurea thickener skeleton in a chain-end capping and / or side-hanging manner; the 2-ureido-4[1H]-pyrimidinone derivative with terminal amino functionalization is a monofunctional amination derivative, which contains only one amino functional group that can react with isocyanate, and the amino functional group is a primary amino group with the structure -NH2, or a monosubstituted secondary amino group with the structure -NHR, where R in -NHR is C1-C12 alkyl or benzyl.

2. The anti-electrolytic corrosion grease for electric vehicle drive motor bearings according to claim 1, characterized in that, The base oil includes PAO and synthetic ester oil, with PAO accounting for 60-90 wt.% of the base oil mass and synthetic ester oil accounting for 10-40 wt.% of the base oil mass.

3. The anti-electrolytic corrosion grease for electric vehicle drive motor bearings according to claim 1, characterized in that, The self-healing microcapsules have an average particle size of 1-15 μm and a D90 ≤ 30 μm; the capsule wall material is polyurea or urea-formaldehyde resin, and the capsule wall thickness is 0.2-0.80 μm.

4. The anti-electrolytic corrosion grease for electric vehicle drive motor bearings according to claim 1 or 3, characterized in that, The core of the self-healing microcapsule comprises, by weight, at least: b) 20-95 parts of an organoalkoxysilane film-forming component; c) 5-40 parts of an oil-soluble rust inhibitor, wherein the organoalkoxysilane film-forming component is an organosilicon compound containing at least one silane alkoxy bond Si-OR, and the R in the silane alkoxy bond Si-OR is a C1-C4 alkyl group.

5. The anti-electrolytic corrosion grease for electric vehicle drive motor bearings according to claim 4, characterized in that, The core further comprises, by weight, 10-60 parts of a terminal isocyanate-group reactive prepolymer.

6. The anti-electrolytic corrosion grease for electric vehicle drive motor bearings according to claim 1, characterized in that, The total base number (TBN) of the peralkalized calcium petroleum sulfonate is 200-400 mg KOH / g.

7. The anti-electrolytic corrosion grease for electric vehicle drive motor bearings according to claim 1, characterized in that, The oil-soluble rust inhibitor is one or more of succinic acid half-ester amine salt, imidazoline salt, and fatty acid amine salt; the antioxidant is a compound system of hindered phenolic antioxidant and amine antioxidant.

8. A method for preparing an anti-electro-corrosion grease for electric vehicle drive motor bearings, used to prepare the anti-electro-corrosion grease for electric vehicle drive motor bearings as described in claim 1, characterized in that, Includes the following steps: S1, Base oil dehydration and degassing: The base oil is vacuum dehydrated and degassed at 80-100℃ and cooled under nitrogen protection; S2, In-situ thickening and modification: Diisocyanate is added to the base oil and stirred to dissolve, then diamine is added for chain extension reaction, and finally a mixture of monoamine and 2-ureido-4[1H]-pyrimidinone derivatives with terminal amino functionalization is added for end-capping reaction; S3, add functional additives, cool down to below 80℃, and add antioxidant, ashless anti-wear agent, metal passivator, over-alkalized petroleum sulfonate calcium and oil-soluble rust inhibitor in sequence and mix evenly. S4, add self-healing microcapsules, cool to below 60℃ and add self-healing microcapsules, then vacuum degas and let stand to mature to obtain anti-electro-corrosion lubricating grease for electric vehicle drive motor bearings.

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