Low-viscosity high-conductivity lubricating oil special for plug-in hybrid electric vehicle and preparation method thereof

Abstract

The application relates to the field of lubricating oil, and more particularly to a low-viscosity high-conductivity lubricating oil special for plug-in hybrid electric vehicles and a preparation method thereof. The lubricating oil comprises, in mass parts, 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. The final lubricating oil can keep low viscosity, comprehensively consider other performances of the lubricating oil, especially simultaneously have excellent conductivity and electric corrosion resistance, and can greatly meet the diversified performance requirements of the existing plug-in hybrid electric vehicles for the lubricating oil.

Description

TECHNICAL FIELD

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

[0002] With the increasing global concern for environmental protection and energy efficiency, the rapid development of new energy vehicles, especially plug-in hybrid electric vehicles (PHEV), has become an important trend in the automotive industry. Such vehicles combine the advantages of traditional internal combustion engines and electric motors, providing longer driving ranges and lower emissions. However, this combination also presents new challenges, particularly in the selection of lubricating oils for vehicles.

[0003] PHEVs achieve high energy utilization efficiency and low emissions through the coordinated work of internal combustion engines and electric motors. The powertrain system frequently switches between pure electric drive, hybrid drive, and kinetic energy recovery modes, resulting in complex working conditions for transmission components such as gearboxes, bearings, and motor shafts, which face high-speed rotation, transient impact loads, and the superposition of electrification environments.

[0004] To reduce powertrain transmission losses, modern PHEVs tend to use ultra-low viscosity lubricating oils (such as SAE 0W-16). Low viscosity oils can reduce stirring resistance and friction power consumption, improving fuel economy and pure electric driving range. However, existing low viscosity oil base oils have short molecular chains, and the oil film formed is insufficient in strength, which can easily cause boundary lubrication failure under high motor speed (>15,000 rpm) and start-stop impact, leading to increased wear of gears and bearings. Moreover, high-frequency pulse voltages (up to 800V) are generated during the operation of PHEV motors, which are coupled between transmission components through parasitic capacitance to form shaft voltages. When the voltage accumulates to the breakdown threshold (usually >30V), micro-current discharge (EDM corrosion) occurs between the bearing raceway and the ball, causing local melting of the metal surface and generating pits and fish scales (see Figure 1 ). Traditional lubricating oils have extremely low conductivity (<100 pS / m), which cannot form a charge discharge path, further exacerbating the corrosion damage. At the same time, trace amounts of copper ions from the copper coils of the motor migrate to the surface of the friction pair under the action of the electric field, and react with the lubricating oil additives to form an insulating organic film (such as copper complexes), which further exacerbates the accumulation of electric charge, forming a vicious cycle. SUMMARY

[0005] Therefore, how to provide a plug-in hybrid vehicle special lubricating oil capable of maintaining good other comprehensive performance at low viscosity has become the focus of the technical field personnel to study. And the applicant finally proposes a plug-in hybrid vehicle special low viscosity high conductivity lubricating oil through in-depth research in this field, which can comprehensively consider other properties of the lubricating oil under the premise of maintaining low viscosity, especially at the same time has excellent conductivity and corrosion resistance, which can greatly meet the diversified performance requirements of existing plug-in hybrid vehicles for lubricating oil.

[0006] A plug-in hybrid vehicle special low viscosity high conductivity lubricating oil, the raw materials at least include: 85~105 parts of lipid base oil, 8~16 parts of functional resin, 3~12 parts of functional composition, 1~2 parts of viscosity improver.

[0007] In a preferred embodiment, the lipid base oil is a combination of pentaerythritol tetraoctanoate, bis-pentaerythritol mixed ester and diisodecyl adipate.

[0008] In a preferred embodiment, the mass ratio of pentaerythritol tetraoctanoate, bis-pentaerythritol 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 and stirring dodecyl dimethyl benzyl ammonium chloride with an organic solvent, and then mixing it with an organic solvent containing hydrogenated styrene-isoprene copolymer to obtain a mixture; S2: warming and stirring the mixture under nitrogen protection, then adding benzotriazole, hydroxyethyl methacrylate and benzoyl peroxide, twice warming and normal pressure reaction; S3: after the reaction is completed, warm down to stirring and maturation, vacuum devolatilization and filtration, and then the product is obtained.

[0012] Preferably, the method for preparing the functional resin comprises the following steps: S1: mixing dodecyl dimethyl benzyl 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, and then adding benzotriazole, hydroxyethyl methacrylate and benzoyl peroxide, controlling the temperature to 115-120°C, and reacting under 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 for aging, and then filtering after vacuum devolatilization to obtain the functional resin.

[0013] Preferably, the mass ratio of dodecyl dimethyl benzyl 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] Preferably, the mass ratio of dodecyl dimethyl benzyl 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] Preferably, the organic solvent is diisodecyl phthalate.

[0016] Preferably, the functional composition is a combination of molybdenum amine complex, 1-butyl-3-methyl imidazole hexafluorophosphate and polyisobutylene succinimide.

[0017] Preferably, the mass ratio of molybdenum amine complex, 1-butyl-3-methyl imidazole hexafluorophosphate and polyisobutylene succinimide is (3-4):(5-6):(1-2).

[0018] Preferably, the mass ratio of molybdenum amine complex, 1-butyl-3-methyl imidazole hexafluorophosphate and polyisobutylene succinimide is (3.5-4):(5-5.5):(1-1.5).

[0019] Preferably, the number average molecular weight of the polyisobutylene succinimide is 900-1100 Da.

[0020] Preferably, the nitrogen content of the polyisobutylene succinimide is 1.8-2.2 wt%.

[0021] Preferably, the viscosity improver is at least one of olefin copolymers.

[0022] In a preferred embodiment, the low-viscosity high-conductivity lubricating oil for plug-in hybrid vehicles further comprises, in parts by mass, 0.5-1.2 parts of an antioxidant, 0.3-0.8 parts of a metal deactivator, 1-1.5 parts of an anti-wear agent, and 0.05-0.2 parts of an antifoaming agent.

[0023] In a preferred embodiment, the antioxidant is at least one of alkyl diphenylamine, thio-bis(3,5-di-tert-butyl-4-hydroxybenzyl), octyl butyl 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 methyl benzotriazole, 5,6-dimethyl benzimidazole, and toluene triazole diethylamine.

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

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

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

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

[0030] A method for preparing a low-viscosity high-conductivity lubricating oil for plug-in hybrid vehicles, specifically comprising the following steps: S1: adding a lipid base oil into a reaction kettle and heating to 60-65°C, vacuum stirring to remove water for 1.5-2h, then adding a functional resin, a functional composition, and a viscosity improver, and shearing and dispersing at 400-500rpm for 30-40min; S2: adding the remaining raw materials, maintaining the temperature at 70-75°C, and stirring at 200-300rpm for 1-1.5h; S3: slowly defoaming at 35-40°C, then filtering through a 4.5-5μm polytetrafluoroethylene filter membrane, and completing the preparation of the lubricating oil.

[0031] The present application has practical significance and beneficial effects:

[0032] 1. The lubricating oil prepared by the present application can, while maintaining low viscosity, comprehensively consider other properties of the lubricating oil, especially simultaneously having excellent conductivity and corrosion resistance, and can greatly meet the diversified performance requirements of existing plug-in hybrid vehicles for lubricating oil.

[0033] 2、The lubricating oil prepared by the application has excellent reliability, can still provide maximum engine cleaning function in severe driving conditions, protects the vehicle engine, and can effectively avoid the generation of carbon deposition, waste emissions and loss of engine power.

[0034] 3、The lubricating oil prepared by the application has excellent dynamic adhesion performance, forms a strong and elastic oil film through controllable polarity, tightly adsorbs to the moving metal surface, effectively reduces friction, and improves fuel economy. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The detection report result graph of the low-viscosity high-conductivity lubricating oil specially used for plug-in hybrid electric vehicles prepared by Example 1 of the application. DETAILED DESCRIPTION

[0036] Example 1

[0037] The low-viscosity high-conductivity lubricating oil specially used for plug-in hybrid electric vehicles, in terms of mass parts, includes: 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 deactivator, 1.3 parts of anti-wear agent, and 0.12 parts of defoaming agent.

[0038] The lipid base oil is a composition of pentaerythritol tetraoctanoate, di-pentaerythritol mixed ester and diisodecyl adipate, 5:3:2.

[0039] The preparation method of the functional resin, in terms of mass parts, specifically includes the following steps: S1: mixing 2.1 parts of dodecyl dimethyl benzyl ammonium chloride with 10 parts of diisodecyl phthalate, stirring at 250 rpm for 25 min, and then mixing it with diisodecyl phthalate containing 8 parts of hydrogenated styrene-isoprene copolymer (total 30 parts) to obtain a mixture; S2: heating the mixture to 105℃ under nitrogen protection, stirring at 1200 rpm for 35 min, then adding 1 part of benzotriazole, 0.7 part of hydroxyethyl methacrylate and 0.08 part of benzoyl peroxide, controlling the temperature to 115℃, and reacting under normal pressure for 3h; S3: after the reaction is completed, cooling to 80℃, stirring at 150 rpm for 2h for curing, and then filtering after vacuum devolatilization at 5μm to obtain the product.

[0040] The hydrogenated styrene-isoprene copolymer has a number average molecular weight of 80000 Da and is from Hubei Shenneng Chemical Technology Co., Ltd., China.

[0041] The functional composition is a composition of molybdenum amine complex, 1-butyl-3-methyl imidazole hexafluorophosphate and polyisobutylene succinimide, with a mass ratio of 3.8:5:1.2.

[0042] The number average molecular weight of the polyisobutylene succinimide is 950 Da, and the nitrogen content is 2.1 wt%, from Shandong Guohua Chemical Co., Ltd., China.

[0043] The molybdenum amine complex is a sulfur-free type molybdenum amine complex, model RL-349, from BASF, Germany.

[0044] The viscosity improver is an ethylene-propylene copolymer GM 615 from Jin Fenghong Lun Technology Co., Ltd.

[0045] The antioxidant is an alkyl diphenylamine; the metal deactivator is a methyl benzotriazole sodium; the anti-wear agent is a tritolyl phosphate; and the defoaming agent is an organic silicon defoaming agent BYK-066N.

[0046] The preparation method of the low-viscosity high-conductivity lubricating oil special for plug-in hybrid electric vehicles specifically comprises the following steps: S1: add the lipid base oil into the reaction kettle and heat to 62℃, then extract to vacuum stirring and dehydrate for 2h, then add the functional resin, functional composition and viscosity improver, and disperse at a high speed of 450rpm for 30min; S2: add the remaining raw materials, maintain the temperature at 70℃, and stir at 250rpm for 1.5h; S3: slowly defoam at a temperature of 40℃, then press filter through a 5μm polytetrafluoroethylene filter membrane, and complete the light-keeping to obtain the product.

[0047] Example 2

[0048] The embodiment and example 1 only differ in that the low-viscosity high-conductivity lubricating oil special for plug-in hybrid electric vehicles comprises, by mass fraction: lipid base oil 90 parts, functional resin 13 parts, functional composition 6 parts, viscosity improver 1.8 parts, antioxidant 0.6 parts, metal deactivator 0.5 parts, anti-wear agent 1.3 parts, and defoaming agent 0.12 parts.

[0049] The other embodiments are the same.

[0050] Example 3

[0051] The embodiment and example 1 only differ in that the low-viscosity high-conductivity lubricating oil special for plug-in hybrid electric vehicles comprises, by mass fraction: lipid base oil 100 parts, functional resin 9 parts, functional composition 10 parts, viscosity improver 1.8 parts, antioxidant 0.6 parts, metal deactivator 0.5 parts, anti-wear agent 1.3 parts, and defoaming agent 0.12 parts.

[0052] The other embodiments are the same.

[0053] Comparative Example 1

[0054] The comparative example 1 and the example 1 are different only in that the raw materials for the low viscosity and high conductivity lubricating oil for a plug-in hybrid vehicle include, in mass parts, 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 part of an antioxidant, 0.5 part of a metal deactivator, 1.3 parts of an anti-wear agent, and 0.12 part of an antifoaming agent.

[0055] The other embodiments are the same.

[0056] Comparative example 2

[0057] The comparative example 2 and the example 1 are different only in that the raw materials for the low viscosity and high conductivity lubricating oil for a plug-in hybrid vehicle include, in mass parts, 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 part of an antioxidant, 0.5 part of a metal deactivator, 1.3 parts of an anti-wear agent, and 0.12 part of an antifoaming agent.

[0058] The other embodiments are the same.

[0059] Comparative example 3

[0060] The comparative example 3 and the example 1 are different only in that the functional composition is a combination of a molybdenum amine complex, 1-butyl-3-methylimidazolium hexafluorophosphate, and polyisobutylene succinimide at a mass ratio of 5:2:0.5.

[0061] The other embodiments are the same.

[0062] Comparative example 4

[0063] The comparative example 4 and the example 1 are different only in that the functional composition is a combination of a molybdenum amine complex, 1-butyl-3-methylimidazolium hexafluorophosphate, and polyisobutylene succinimide at a mass ratio of 1:8:1.

[0064] The other embodiments are the same.

[0065] Comparative example 5

[0066] The comparative example 1 and example 1 only exist in the following differences: the preparation method of functional resin, in mass parts, specifically comprising the following steps: S1: 18 parts of bisphenol A epoxy resin is added to 15 parts of ethylene glycol ethyl ether acetate in a reaction kettle, heated to 105°C to melt, mechanically stirred at 400 rpm for 35 min, then 0.5 parts of DOPO is added to 5 parts of ethylene glycol ethyl ether acetate, and added dropwise into the reaction kettle, the dropwise time is 35 min, then heated to 110°C and reacted for 1.5 h; S2: cooled to 65°C, 1.5 parts of 3-hexylthiophene and 0.08 parts of benzoyl peroxide are added, ultrasonic dispersion for 12 min, then heated to 75°C, and reacted for 2 h; S3: 3.3 parts of methylhexahydrophthalic anhydride is added, heated to 110°C, constant temperature stirring for 2 h, then vacuum devolatilization at 140°C for 2 h, then the obtained material is cooled to room temperature, and crushed to 15 μm, to obtain the product.

[0067] The other embodiments are the same.

[0068] Comparative example 6

[0069] The comparative example 1 and example 1 only exist in the following differences: the preparation method of functional resin, in mass parts, specifically comprising the following steps: S1: 18 parts of bisphenol A epoxy resin is added to 15 parts of ethylene glycol ethyl ether acetate in a reaction kettle, heated to 105°C to melt, mechanically stirred at 400 rpm for 35 min, then 0.5 parts of DOPO is added to 5 parts of ethylene glycol ethyl ether acetate, and added dropwise into the reaction kettle, the dropwise time is 35 min, then heated to 110°C and reacted for 1.5 h; S2: cooled to 65°C, 1.5 parts of 3-hexylthiophene and 0.08 parts of benzoyl peroxide are added, ultrasonic dispersion for 12 min, then heated to 75°C, and reacted for 2 h; S3: 3.3 parts of methylhexahydrophthalic anhydride is added, heated to 110°C, constant temperature stirring for 2 h, then vacuum devolatilization at 140°C for 2 h, then the obtained material is cooled to room temperature, and crushed to 15 μm, to obtain the product.

[0070] The other embodiments are the same.

[0071] Performance test

[0072] 1. Viscosity test: the viscosity of the lubricating oil prepared in the examples and comparative examples is tested according to the standard ASTM-D445, the kinematic viscosity at 40°C and 100°C is respectively tested, and the average value of 10 tests is recorded in table 1.

[0073] 2. Conductivity test: reference standard ASTM D2624-2023, electric field strength: 10 V / mm (DC stabilized power supply); electrode material platinum parallel plate (diameter 25 mm); applied voltage: step voltage 0-100 V, step 10 V; test after vacuum dehydration of oil sample, obtain current value under constant voltage mode, and calculate final volume resistance, the result is the average of 10 tests.

[0074] 3. Electrochemical corrosion resistance test: electrochemical corrosion simulation bench, load: radial force 1.8 kN, electrical parameters: pulse voltage: ±180 V (square wave, frequency 2 kHz), current density: 15 A / cm²; temperature: 120℃ oil temperature cycle (30 min per cycle), termination condition: cumulative running 100 h, characterized by electrochemical corrosion pit density, the result is the average of 10 tests.

[0075] Table 1 Performance test result table

[0076]

[0077] From the final performance test results of the examples and comparative examples, comparative examples 1-2 did not use the raw material ratio scheme defined in the application as examples 1-3, which directly led to the lubricating oil products prepared by comparative examples 1-2 failing to realize good mutual action of raw materials, so as to obtain higher performance advantage.

[0078] And comparative examples 3-6 did not use suitable functional composition and functional resin raw material, respectively, which directly led to their failure to play the best performance in the lubricating oil system, and finally made their performance appear different degrees of decline.

Claims

1. A low viscosity high conductivity lubricating oil for plug-in hybrid vehicles, characterized by: The raw materials include, in mass parts, 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 modifier; The lipid base oil is a combination of pentaerythritol tetraoctanoate, bis-pentaerythritol mixed ester, and diisodecyl adipate, with a mass ratio of (4-5):(2-3):(2-3); The preparation method of the functional resin comprises: S1: mixing dodecyl dimethyl benzyl ammonium chloride with an organic solvent and stirring, and then mixing the mixture with an organic solvent containing hydrogenated styrene-isoprene copolymer to obtain a mixture; S2: stirring the mixture under nitrogen protection and heating, and then adding benzotriazole, hydroxyethyl methacrylate, and benzoyl peroxide, and reacting under heating and normal pressure; S3: after the reaction is completed, cooling to room temperature, stirring, aging, vacuum devolatilization, and then filtering to obtain the functional resin. The mass ratio of the dodecyl dimethyl benzyl ammonium chloride, the hydrogenated styrene-isoprene copolymer, the benzotriazole, and the hydroxyethyl methacrylate is (1.5-3):(7.5-10):(0.5-1.5):(0.5-1.5). 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). The functional composition is a combination of molybdenum amine complex, 1-butyl-3-methyl imidazole hexafluorophosphate, and polyisobutylene succinimide, with a mass ratio of (3-4):(5-6):(1-2).

2. The low viscosity high conductivity lubricating oil for plug-in hybrid vehicles according to claim 1, characterized by: The number average molecular weight of the polyisobutylene succinimide is 900-1100 Da, and the nitrogen content is 1.8-2.2 wt%.

3. The low viscosity high conductivity lubricating oil for plug-in hybrid vehicles according to claim 2, characterized by: The viscosity modifier is at least one of olefin copolymers.

4. The low viscosity high conductivity lubricating oil for plug-in hybrid vehicles according to claim 3, characterized by: The low-viscosity high-conductivity lubricating oil for plug-in hybrid vehicles further includes, in mass parts, 0.5-1.2 parts of an antioxidant, 0.3-0.8 parts of a metal deactivator, 1-1.5 parts of an anti-wear agent, and 0.05-0.2 parts of an antifoaming agent.

5. The low viscosity high conductivity lubricating oil for plug-in hybrid vehicles according to claim 4, characterized by: The antioxidant is at least one of alkyl diphenylamine, thio-bis(3,5-di-tert-butyl-4-hydroxybenzyl), octyl butyl diphenylamine, and dinonyl diphenylamine.

6. The low viscosity high conductivity lubricating oil for plug-in hybrid vehicles according to claim 5, characterized by: The metal deactivator is at least one of benzotriazole, sodium methyl benzotriazole, 5,6-dimethyl benzimidazole, and toluene triazole diethylamine.

7. The low viscosity high conductivity lubricating oil for plug-in hybrid vehicles according to claim 6, characterized by: The anti-wear agent is at least one of calcium sulfonate, tri-methylphenyl phosphate, sulfided isobutylene, and molybdenum dialkyldithiocarbamate.

8. A process for the preparation of a low viscosity high conductivity lubricating oil for plug-in hybrid electric vehicles according to any one of claims 4 to 7, characterized by: S1: adding the lipid base oil into a reaction kettle, heating to 60-65℃, and stirring under vacuum for 1.5-2 h to remove water, and then adding the functional resin, the functional composition, and the viscosity modifier, and shearing at 400-500 rpm for 30-40 min; S2: adding the remaining raw materials, maintaining the temperature at 70-75℃, and stirring at 200-300 rpm for 1-1.5 h; S3: slowly defoaming after cooling to 35-40℃, and then filtering through a 4.5-5 μm polytetrafluoroethylene filter membrane, and completing the light-avoiding preservation to obtain the low-viscosity high-conductivity lubricating oil for plug-in hybrid vehicles.

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