Special low-viscosity and high-conductivity lubricating oil for plug-in hybrid vehicle and preparation method of special low-viscosity and high-conductivity lubricating oil

Abstract

The invention relates to the field of lubricating oil, in particular to special low-viscosity high-conductivity lubricating oil for a plug-in hybrid vehicle and a preparation method of the special low-viscosity high-conductivity lubricating oil. The lubricating oil at least comprises the following raw materials in parts by mass: 85-105 parts of lipid base oil, 8-16 parts of functional resin, 3-12 parts of a functional composition and 1-2 parts of a viscosity improver. The finally prepared lubricating oil can comprehensively consider other properties of the lubricating oil on the premise of keeping low viscosity, especially has excellent conductivity and electric corrosion resistance at the same time, and can greatly meet the diversified performance requirements of existing plug-in hybrid vehicles for lubricating oil.

Description

Technical Field

[0001] The present application relates to the field of lubricating oils, and more specifically to a low-viscosity, high-conductivity lubricating oil specifically for plug-in hybrid electric vehicles and a preparation method thereof. Background Art

[0002] With growing global attention to environmental protection and energy efficiency, the rapid development of the new energy vehicle market, particularly plug-in hybrid electric vehicles (PHEVs), has become a key trend in the automotive industry. These vehicles combine the advantages of traditional internal combustion engines and electric motors, offering extended range and lower emissions. However, this combination also presents new challenges, particularly in the selection of automotive lubricants.

[0003] PHEVs achieve high energy efficiency and low emissions through the coordinated operation of an internal combustion engine and an electric motor. Their powertrain frequently switches between pure electric drive, hybrid drive, and kinetic energy recovery modes, subjecting transmission components (such as the gearbox, bearings, and motor shaft) to complex operating conditions characterized by high-speed rotation, transient impact loads, and the combined effects of an electrified environment.

[0004] In order to reduce the transmission loss of the power system, modern PHEVs tend to use ultra-low viscosity lubricants (such as SAE 0W-16). Low viscosity oil can reduce stirring resistance and friction power consumption, improve fuel economy and pure electric range. However, the existing low-viscosity oil base oil has a short molecular chain, and the oil film formed is not strong enough. It is easy to cause boundary lubrication failure under high motor speed (>15,000 rpm) and start-stop impact, resulting in increased wear of gears and bearings. In addition, the PHEV motor generates high-frequency pulse voltage (up to 800V) when working, and forms shaft voltage between transmission components through parasitic capacitance coupling. When the voltage accumulates to the breakdown threshold (usually >30V), micro-current discharge (EDM electro-erosion) will be formed between the bearing raceway and the ball, causing local melting of the metal surface, generating pits and fish scale patterns (see Figure 1 Conventional lubricants have extremely low electrical conductivity (<100 pS / m), preventing them from forming a charge discharge path, further exacerbating electrolytic corrosion damage. Furthermore, trace copper ions shed from the motor's copper coils migrate to the friction pair surface under the influence of the electric field. There, they react electrochemically with lubricant additives to form insulating organic films (such as copper complexes), exacerbating charge accumulation and creating a vicious cycle. Summary of the Invention

[0005] Therefore, in summary, how to provide a lubricant specifically for plug-in hybrid vehicles that maintains excellent other comprehensive properties at low viscosity has become a key research topic for researchers in this field. Through in-depth research in this field, the applicant has ultimately proposed a low-viscosity, high-conductivity lubricant specifically for plug-in hybrid vehicles. This lubricant comprehensively considers other lubricant properties while maintaining low viscosity, particularly exhibiting excellent conductivity and electrical corrosion resistance, effectively meeting the diverse performance requirements of existing plug-in hybrid vehicles for lubricant oils.

[0006] A low-viscosity, high-conductivity lubricant specially designed for plug-in hybrid electric vehicles. The raw materials comprise, by weight, at least: 85-105 parts of a lipid base oil, 8-16 parts of a functional resin, 3-12 parts of a functional composition, and 1-2 parts of a viscosity improver.

[0007] In a preferred embodiment, the lipid base oil is a composition of pentaerythritol tetraoctanoate, dipentaerythritol mixed esters and diisodecyl adipate.

[0008] In a preferred embodiment, the mass ratio of pentaerythritol tetraoctanoate, dipentaerythritol mixed ester and diisodecyl adipate is (4-5): (2-3): (2-3).

[0009] In a preferred embodiment, the mass ratio of the lipid base oil, the functional resin and the functional composition is (9-10): (0.9-1.4): (0.5-1).

[0010] In a preferred embodiment, the mass ratio of the lipid base oil, the functional resin and the functional composition is (9-9.5): (1-1.2): (0.6-0.8).

[0011] In a preferred embodiment, the preparation method of the functional resin specifically includes the following steps: S1: mixing dodecyldimethylbenzyl ammonium chloride with an organic solvent and stirring, then mixing it with an organic solvent containing hydrogenated styrene-isoprene copolymer to obtain a mixture; S2: heating the mixture and stirring it under nitrogen protection, then adding benzotriazole, hydroxyethyl methacrylate and benzoyl peroxide, heating it a second time and reacting it under normal pressure; S3: after the reaction is completed, cooling it to stirring and maturing, vacuum degassing and filtering to obtain the product.

[0012] In a preferred embodiment, the preparation method of the functional resin specifically includes the following steps: S1: mixing dodecyldimethylbenzyl ammonium chloride with an organic solvent, stirring at 200-300 rpm for 20-30 min, and then mixing it with an organic solvent containing hydrogenated styrene-isoprene copolymer to obtain a mixture; S2: heating the mixture to 100-110°C under nitrogen protection, stirring at 120-150 rpm for 30-40 min, then adding benzotriazole, hydroxyethyl methacrylate and benzoyl peroxide, controlling the temperature to 115-120°C, and reacting at normal pressure for 2.5-3 h; S3: after the reaction is completed, cooling to 75-80°C, stirring at 150-200 rpm for 1-2 h, vacuum devolatilizing, and filtering through 5 μm to obtain the product.

[0013] In a preferred embodiment, the mass ratio of the dodecyldimethylbenzyl ammonium chloride, hydrogenated styrene-isoprene copolymer, benzotriazole and hydroxyethyl methacrylate is (1.5-3): (7.5-10): (0.5-1.5): (0.5-1.5).

[0014] In a preferred embodiment, the mass ratio of the dodecyldimethylbenzyl ammonium chloride, hydrogenated styrene-isoprene copolymer, benzotriazole and hydroxyethyl methacrylate is (1.8-2.4): (8-8.5): (0.8-1.2): (0.6-0.8).

[0015] In a preferred embodiment, the organic solvent is diisodecyl phthalate.

[0016] In a preferred embodiment, the functional composition is a composition of a molybdenum amine complex, 1-butyl-3-methylimidazolium hexafluorophosphate and polyisobutylene succinimide.

[0017] In a preferred embodiment, the mass ratio of the molybdenum amine complex, 1-butyl-3-methylimidazolium hexafluorophosphate and polyisobutylene succinimide is (3-4): (5-6): (1-2).

[0018] In a preferred embodiment, the mass ratio of the molybdenum amine complex, 1-butyl-3-methylimidazolium hexafluorophosphate and polyisobutylene succinimide is (3.5-4): (5-5.5): (1-1.5).

[0019] In a preferred embodiment, the number average molecular weight of the polyisobutylene succinimide is 900-1100 Da.

[0020] In a preferred embodiment, the nitrogen content of the polyisobutylene succinimide is 1.8-2.2 wt %.

[0021] In a preferred embodiment, the viscosity improver is at least one olefin copolymer.

[0022] In a preferred embodiment, the low-viscosity, high-conductivity lubricant for plug-in hybrid vehicles further comprises, by weight, 0.5 to 1.2 parts of an antioxidant, 0.3 to 0.8 parts of a metal passivator, 1 to 1.5 parts of an antiwear agent, and 0.05 to 0.2 parts of a defoaming agent.

[0023] In a preferred embodiment, the antioxidant is at least one of alkyl diphenylamine, thiobis(3,5-di-tert-butyl-4-hydroxybenzyl), octylbutyl diphenylamine and dinonyl diphenylamine.

[0024] In a preferred embodiment, the antioxidant is alkyl diphenylamine.

[0025] In a preferred embodiment, the metal deactivator is at least one of benzotriazole, sodium tolutriazole, 5,6-dimethylbenzimidazole and toluenetriazole diethylamine.

[0026] In a preferred embodiment, the metal deactivator is sodium methylbenzotriazole.

[0027] In a preferred embodiment, the anti-wear agent is at least one of calcium sulfonate, tricresyl phosphate, isobutylene sulfide and molybdenum dialkyldithiocarbamate.

[0028] In a preferred embodiment, the anti-wear agent is tricresyl phosphate.

[0029] In a preferred embodiment, the defoaming agent is at least one of silicone defoaming agents.

[0030] A method for preparing a low-viscosity, high-conductivity lubricant specifically for plug-in hybrid electric vehicles comprises the following steps: S1: adding a lipid base oil to a reactor and heating it to 60-65°C, evacuating it to a vacuum state and stirring for dehydration for 1.5-2 hours; then adding a functional resin, a functional composition, and a viscosity improver, and dispersing them at a high-speed shearing speed of 400-500 rpm for 30-40 minutes; S2: adding the remaining raw materials, maintaining the temperature at 70-75°C, and stirring at 200-300 rpm for 1-1.5 hours; S3: cooling the temperature to 35-40°C and slowly defoaming the mixture, then filtering through a 4.5-5 μm polytetrafluoroethylene filter membrane, and protecting the mixture from light to obtain the lubricant.

[0031] This application has practical significance and beneficial effects: 1. The lubricating oil prepared in the present application can comprehensively consider other properties of the lubricating oil while maintaining low viscosity, especially having excellent conductivity and electrical corrosion resistance, which can greatly meet the diverse performance requirements of existing plug-in hybrid vehicles for lubricating oils.

[0032] 2. The lubricant produced by the present application has excellent reliability and can still provide maximum engine cleaning function under harsh driving conditions, protecting the vehicle engine and effectively avoiding the formation of carbon deposits, waste emissions and loss of engine horsepower.

[0033] 3. The lubricating oil prepared in this application has excellent dynamic adhesion performance. It forms a strong elastic oil film through controllable polarity, which is tightly adsorbed on the moving metal surface, effectively reducing friction and improving fuel economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a graph showing the test report results of the low-viscosity and high-conductivity lubricant specially prepared for plug-in hybrid vehicles in Example 1 of the present application. DETAILED DESCRIPTION

[0035] Example 1 Low-viscosity, high-conductivity lubricant specially designed for plug-in hybrid vehicles, calculated by mass, the raw materials include: 95 parts of lipid base oil, 11 parts of functional resin, 7.5 parts of functional composition, 1.8 parts of viscosity improver, 0.6 parts of antioxidant, 0.5 parts of metal passivator, 1.3 parts of anti-wear agent, and 0.12 parts of defoaming agent.

[0036] The lipid base oil is a composition of pentaerythritol tetraoctanoate, dipentaerythritol mixed esters and diisodecyl adipate in a ratio of 5:3:2.

[0037] The preparation method of the functional resin, calculated by mass, specifically includes the following steps: S1: mixing 2.1 parts of dodecyldimethylbenzyl ammonium chloride with 10 parts of diisodecyl phthalate, stirring at 250 rpm for 25 minutes, and then mixing it with diisodecyl phthalate containing 8 parts of hydrogenated styrene-isoprene copolymer (30 parts in total) to obtain a mixture; S2: heating the mixture to 105°C under nitrogen protection, stirring at 1200 rpm for 35 minutes, then adding 1 part of benzotriazole, 0.7 part of hydroxyethyl methacrylate and 0.08 part of benzoyl peroxide, controlling the temperature to 115°C, and reacting at normal pressure for 3 hours; S3: after the reaction is completed, cooling to 80°C, stirring at 150 rpm for 2 hours, vacuum devolatilizing and filtering at 5μm to obtain the product.

[0038] Hydrogenated styrene-isoprene copolymer with a number average molecular weight of 80,000 Da was obtained from Hubei Shineng Chemical Technology Co., Ltd., China.

[0039] The functional composition is a composition of a molybdenum amine complex, 1-butyl-3-methylimidazole hexafluorophosphate and polyisobutylene succinimide, with a mass ratio of 3.8:5:1.2.

[0040] Polyisobutylene succinimide has a number average molecular weight of 950 Da and a nitrogen content of 2.1 wt %, and was obtained from Shandong Guohua Chemical Co., Ltd., China.

[0041] The molybdenum amine complex is a sulfur-free molybdenum amine complex, model RL-349, from BASF, Germany.

[0042] The viscosity improver is ethylene-propylene copolymer GM 615, which is from Jinfeng Hongrun Technology Co., Ltd.

[0043] The antioxidant is alkyl diphenylamine; the metal passivator is sodium methyl benzotriazole; the anti-wear agent is tricresyl phosphate; and the defoaming agent is silicone defoaming agent BYK-066N.

[0044] The preparation method of low-viscosity and high-conductivity lubricating oil specially used for plug-in hybrid vehicles specifically includes the following steps: S1: adding a lipid base oil to a reactor and heating it to 62°C, evacuating it to a vacuum state and stirring to dehydrate it for 2 hours, then adding a functional resin, a functional composition and a viscosity improver, and dispersing them at a high shear speed of 450 rpm for 30 minutes; S2: adding the remaining raw materials, maintaining the temperature at 70°C, and stirring at 250 rpm for 1.5 hours; S3: cooling to 40°C and slowly defoaming, then filtering through a 5μm polytetrafluoroethylene filter membrane, and keeping it away from light to obtain the product.

[0045] Example 2 This embodiment differs from Example 1 only in the following: The low-viscosity, high-conductivity lubricant specifically for plug-in hybrid vehicles comprises, by weight, 90 parts of a lipid base oil, 13 parts of a functional resin, 6 parts of a functional composition, 1.8 parts of a viscosity improver, 0.6 parts of an antioxidant, 0.5 parts of a metal passivator, 1.3 parts of an antiwear agent, and 0.12 parts of a defoaming agent.

[0046] The other embodiments are the same.

[0047] Example 3 This embodiment differs from Example 1 only in the following: The low-viscosity, high-conductivity lubricant specifically for plug-in hybrid vehicles comprises, by weight, 100 parts of a lipid base oil, 9 parts of a functional resin, 10 parts of a functional composition, 1.8 parts of a viscosity improver, 0.6 parts of an antioxidant, 0.5 parts of a metal passivator, 1.3 parts of an antiwear agent, and 0.12 parts of a defoaming agent.

[0048] The other embodiments are the same.

[0049] Comparative Example 1 This comparative example differs from Example 1 only in the following: The low-viscosity, high-conductivity lubricant specifically for plug-in hybrid vehicles comprises, by mass, 125 parts of a lipid base oil, 3.5 parts of a functional resin, 10 parts of a functional composition, 1.8 parts of a viscosity improver, 0.6 parts of an antioxidant, 0.5 parts of a metal passivator, 1.3 parts of an antiwear agent, and 0.12 parts of a defoaming agent.

[0050] The other embodiments are the same.

[0051] Comparative Example 2 This comparative example differs from Example 1 only in the following: the low-viscosity, high-conductivity lubricant specifically for plug-in hybrid vehicles comprises, by weight, 95 parts of a lipid base oil, 11 parts of a functional resin, 1.5 parts of a functional composition, 1.8 parts of a viscosity improver, 0.6 parts of an antioxidant, 0.5 parts of a metal passivator, 1.3 parts of an antiwear agent, and 0.12 parts of a defoaming agent.

[0052] The other embodiments are the same.

[0053] Comparative Example 3 The only difference between this comparative example and Example 1 is that the functional composition is a composition of molybdenum amine complex, 1-butyl-3-methylimidazolium hexafluorophosphate and polyisobutylene succinimide, with a mass ratio of 5:2:0.5.

[0054] The other embodiments are the same.

[0055] Comparative Example 4 The only difference between this comparative example and Example 1 is that the functional composition is a composition of a molybdenum amine complex, 1-butyl-3-methylimidazolium hexafluorophosphate and polyisobutylene succinimide, with a mass ratio of 1:8:1.

[0056] The other embodiments are the same.

[0057] Comparative Example 5 The only difference between this comparative example and Example 1 is as follows: the preparation method of the functional resin, calculated by mass, specifically comprises the following steps: S1: adding 18 parts of bisphenol A epoxy resin to 15 parts of ethylene glycol ethyl ether acetate in a reactor, heating to 105°C to melt, and mechanically stirring at 400rpm for 35 minutes, then adding 0.5 parts of DOPO to 5 parts of ethylene glycol ethyl ether acetate and dropwise adding to the reactor, the dropping time is 35 minutes, and then heating to 110°C and reacting for 1.5 hours; S2: cooling to 65°C, adding 1.5 parts of 3-hexylthiophene and 0.08 parts of benzoyl peroxide, ultrasonically dispersing for 12 minutes, then heating to 75°C, and keeping warm for 2 hours; S3: adding 3.3 parts of methylhexahydrophthalic anhydride, heating to 110°C, stirring at a constant temperature for 2 hours, then keeping warm at 140°C for 2 hours, and then vacuum devolatilizing. The obtained material is cooled to room temperature and crushed to 15μm.

[0058] The other embodiments are the same.

[0059] Comparative Example 6 The only difference between this comparative example and Example 1 is as follows: the preparation method of the functional resin, calculated in parts by mass, specifically comprises the following steps: S1: adding 10 parts of bisphenol A epoxy resin to 15 parts of ethylene glycol ethyl ether acetate in a reactor, heating to 105°C to melt, and mechanically stirring at 400rpm for 35 minutes, then adding 2.5 parts of DOPO to 5 parts of ethylene glycol ethyl ether acetate and dropwise adding to the reactor, the dropping time is 35 minutes, and then heating to 110°C and reacting for 1.5 hours; S2: cooling to 65°C, adding 0.5 parts of 3-hexylthiophene and 0.08 parts of benzoyl peroxide, ultrasonically dispersing for 12 minutes, then heating to 75°C, and keeping warm for 2 hours; S3: adding 1.5 parts of methylhexahydrophthalic anhydride, heating to 110°C, stirring at a constant temperature for 2 hours, then keeping warm at 140°C for 2 hours, and then vacuum devolatilizing. The obtained material is cooled to room temperature and crushed to 15μm.

[0060] The other embodiments are the same.

[0061] Performance Testing 1. Viscosity Test: The lubricating oils prepared in the Examples and Comparative Examples were subjected to viscosity tests with reference to standard ASTM-D445. The kinematic viscosities at 40°C and 100°C were tested respectively. The results were averaged over 10 tests and recorded in Table 1.

[0062] 2. Conductivity test: Reference standard ASTM D2624-2023, electric field strength: 10 V / mm (DC regulated power supply); electrode material: platinum parallel plate (25 mm diameter); applied voltage: 0-100 V step-by-step, 10 V step; oil sample was vacuum dehydrated and tested, current value was obtained in constant voltage mode, and the final volume resistivity was calculated. The results were averaged from 10 tests and reported in Table 1.

[0063] 3. Electrocorrosion resistance test: Electrocorrosion simulation bench, load: radial force 1.8kN, electrical parameters: pulse voltage: ±180V (square wave, frequency 2kHz), current density: 15A / cm²; temperature: 120℃ oil temperature cycle (each cycle 30min), termination condition: cumulative operation 100h, characterized by electrocorrosion pit density, the results are the average of 10 tests and recorded in Table 1.

[0064] Table 1 Performance test results

[0065] Judging from the final performance test results of the embodiments and comparative examples, Comparative Examples 1-2 did not adopt the raw material ratio scheme specified in this application like Examples 1-3, which directly resulted in the lubricating oil products prepared in Comparative Examples 1-2 being unable to achieve good raw material synergy, and thus unable to obtain higher performance advantages.

[0066] However, Comparative Examples 3 to 6 did not use appropriate functional compositions and functional resin raw materials, which directly led to their inability to perform optimally in the lubricating oil system, and ultimately caused their performance to decline to varying degrees.

Claims

1. A low-viscosity, high-conductivity lubricant specifically for plug-in hybrid electric vehicles, characterized by: The raw materials include at least 85-105 parts of lipid base oil, 8-16 parts of functional resin, 3-12 parts of functional composition, and 1-2 parts of viscosity improver, calculated by mass. The lipid base oil is a composition of pentaerythritol tetraoctanoate, dipentaerythritol mixed ester and diisodecyl adipate in a mass ratio of (4-5): (2-3): (2-3); The preparation method of the functional resin comprises: S1: mixing dodecyldimethylbenzyl ammonium chloride with an organic solvent and stirring, then mixing the mixture with an organic solvent containing a hydrogenated styrene-isoprene copolymer to obtain a mixture; S2: heating the mixture and stirring it under nitrogen protection, then adding benzotriazole, hydroxyethyl methacrylate and benzoyl peroxide, heating it a second time and reacting it under normal pressure; S3: after the reaction is completed, cooling it to stirring and maturing, vacuum degassing it and filtering it to obtain the functional resin; The mass ratio of the dodecyldimethylbenzyl ammonium chloride, hydrogenated styrene-isoprene copolymer, benzotriazole and hydroxyethyl methacrylate is (1.5-3): (7.5-10): (0.5-1.5): (0.5-1.5).

2. The low-viscosity, high-conductivity lubricant for plug-in hybrid electric vehicles according to claim 1, characterized in that: The mass ratio of the lipid base oil, the functional resin and the functional composition is (9-10): (0.9-1.4): (0.5-1).

3. The low-viscosity, high-conductivity lubricant for plug-in hybrid electric vehicles according to claim 2, characterized in that: The functional composition is a composition of a molybdenum amine complex, 1-butyl-3-methylimidazolium hexafluorophosphate and polyisobutylene succinimide, with a mass ratio of (3-4): (5-6): (1-2).

4. The low-viscosity, high-conductivity lubricant for plug-in hybrid electric vehicles according to claim 3, characterized in that: The polyisobutylene succinimide has a number average molecular weight of 900-1100 Da and a nitrogen content of 1.8-2.2 wt %.

5. The low-viscosity, high-conductivity lubricant for plug-in hybrid electric vehicles according to claim 4, characterized in that: The viscosity improver is at least one of olefin copolymers.

6. The low-viscosity, high-conductivity lubricant for plug-in hybrid electric vehicles according to claim 1, characterized in that: The low-viscosity, high-conductivity lubricant specially formulated for plug-in hybrid electric vehicles further comprises, by weight, 0.5 to 1.2 parts of an antioxidant, 0.3 to 0.8 parts of a metal passivator, 1 to 1.5 parts of an antiwear agent, and 0.05 to 0.2 parts of a defoaming agent.

7. The low-viscosity, high-conductivity lubricant for plug-in hybrid electric vehicles according to claim 6, characterized in that: The antioxidant is at least one of alkyl diphenylamine, thiobis(3,5-di-tert-butyl-4-hydroxybenzyl), octylbutyl diphenylamine and dinonyl diphenylamine.

8. The low-viscosity, high-conductivity lubricant for plug-in hybrid electric vehicles according to claim 7, characterized in that: The metal passivator is at least one of benzotriazole, sodium methylbenzotriazole, 5,6-dimethylbenzimidazole and toluenetriazole diethylamine.

9. The low-viscosity, high-conductivity lubricant for plug-in hybrid electric vehicles according to claim 8, characterized in that: The anti-wear agent is at least one of calcium sulfonate, tricresyl phosphate, isobutylene sulfide and molybdenum dialkyldithiocarbamate.

10. A method for preparing the low-viscosity, high-conductivity lubricating oil for plug-in hybrid electric vehicles according to any one of claims 6 to 9, characterized in that: S1: Add the lipid base oil into the reactor and heat it to 60-65° C., evacuate to vacuum and stir to dehydrate for 1.5-2 hours, then add the functional resin, functional composition and viscosity improver, and disperse them at a high shear speed of 400-500 rpm for 30-40 minutes; S2: Add the remaining raw materials, maintain the temperature at 70-75° C., and stir at 200-300 rpm for 1-1.5 hours; S3: Cool to 35-40° C. and slowly defoam, then filter through a 4.5-5 μm polytetrafluoroethylene filter membrane, and keep it away from light to obtain the product.

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