Engine lubricating oil of hybrid electric vehicle and preparation method of engine lubricating oil

Abstract

The invention relates to the technical field of lubricating oil, in particular to engine lubricating oil for a hybrid vehicle and a preparation method thereof. The method comprises the following steps: mixing graphene oxide, nano cellulose, a first coupling agent and an antioxidant to obtain a first additive; mixing a first additive with hydroxylated poly-alpha-olefin to obtain a first mixture; nano copper powder and a second coupling agent are mixed to obtain a second additive; adding the purification dispersant, the defoaming agent and the viscosity index improver into the second additive one by one, and uniformly mixing to obtain a composite additive; uniformly mixing a composite additive methylcyclopentane to obtain a second mixture; and adding the first mixture into the second mixture, and uniformly mixing to obtain the engine lubricating oil of the hybrid vehicle. The base oil is composed of a small amount of total synthetic oil and a large amount of mineral oil, the cost of the lubricating oil is greatly reduced, and meanwhile, the mixing sequence of the anti-wear agent, the additive and the base oil is adjusted, so that the lubricating oil system is uniform, and the compatibility of the base oil and the additive is good.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricating oils, and particularly to an engine lubricating oil for hybrid vehicles and a preparation method thereof. Background Art

[0002] Hybrid electric vehicles (HEVs) combine a dual power system of an internal combustion engine (ICE) and an electric motor. Their unique operating mode poses higher requirements for engine lubricating oils. Compared with traditional ICE vehicles, the engines of hybrid electric vehicles switch between frequent start-stop, low-speed electric drive, and high-speed fuel drive, resulting in more complex lubrication conditions. For example, the engine may be in a shutdown state for a long time at low speed or idle speed, and needs to start quickly and provide high-power output at high speed or during rapid acceleration. This intermittent operating mode makes the lubricating oil face more serious problems such as low-temperature starting wear, risk of oil film rupture, and high-temperature oxidation. In addition, the extreme pursuit of energy efficiency in the hybrid system requires the lubricating oil to have a lower friction coefficient and higher thermal stability to reduce energy loss and extend the engine life. These special requirements make it difficult for traditional lubricating oil formulations to meet the needs of hybrid vehicle engines, so it is necessary to develop high-performance lubricating oils specifically for hybrid systems.

[0003] In the prior art, in order to improve the low-temperature fluidity of the engine lubricating oil for hybrid vehicles, a large amount of fully synthetic oil is added as the base oil, which significantly increases the cost of the lubricating oil. However, this approach leads to a substantial increase in the cost of the lubricating oil, which is not conducive to the popularization and promotion of hybrid vehicles. At the same time, single-performance friction improvers and anti-wear agents are difficult to simultaneously meet the requirements of low-temperature fluidity and low-temperature starting wear protection. This performance contradiction makes it difficult for existing lubricating oils to maintain stable performance under the complex working conditions of hybrid vehicles. In view of this, it is necessary to provide an engine lubricant for hybrid vehicles that has both high low-temperature fluidity and low-temperature starting wear resistance. Summary of the Invention

[0004] The purpose of the present invention is to provide an engine lubricating oil for hybrid vehicles and a preparation method thereof, which use a small amount of fully synthetic oil and a large amount of mineral oil to form the base oil, significantly reducing the cost of the lubricating oil. At the same time, the mixing order of each anti-wear agent, additive, and base oil is adjusted to make the lubricating oil system uniform and the compatibility between the base oil and the additive good.

[0005] To achieve this purpose, the present invention adopts the following technical solutions: A preparation method of an engine lubricating oil for hybrid vehicles, comprising the following steps: (1) Mix and grind graphene oxide, nanocellulose, a first coupling agent, and an antioxidant, and then perform ultrasonic treatment to obtain a first additive; (2) Mix the first additive and the hydroxylated poly-α-olefin evenly to obtain a first mixture; (3) Mix and grind the nano copper powder and the second coupling agent, and perform ultrasonic treatment to obtain a second additive; (4) Add a detergent-dispersant, an antifoaming agent, and a viscosity index improver to the second additive one by one, and mix evenly to obtain a composite additive; (5) Mix the composite additive and methylcyclopentane evenly to obtain a second mixture; (6) Add the first mixture to the second mixture and mix evenly to obtain the engine lubricating oil for the hybrid vehicle, and the mass ratio of the hydroxylated poly-α-olefin to methylcyclopentane is 1:(2 - 3).

[0006] Further, in the step (1), the mass ratio of graphene oxide, nanocellulose, the first coupling agent, and the antioxidant is (1 - 4):(1 - 3):(0.5 - 2):1.

[0007] Further, the first coupling agent is selected from one of titanate, silane coupling agent, and phosphate ester; The antioxidant is a compound of dilauryl thiodipropionate and nonyl diphenylamine with a mass ratio of 1:2.

[0008] Further, first mix the first coupling agent and the antioxidant evenly at room temperature, then add graphene oxide and mix evenly at 80 °C. When the heating is stopped, add nanocellulose and mix and grind, and then perform ultrasonic treatment on the first additive.

[0009] Further, in the step (2), the mass ratio of the first additive to the hydroxylated poly-α-olefin is (0.1 - 0.6):5.

[0010] Further, in the step (3), the mass ratio of the nano copper powder to the second coupling agent is (1 - 2):1, and the nano copper powder and the second coupling agent are mixed at 60 °C; The second coupling agent is selected from one of titanate, silane coupling agent, and phosphate ester, and the components selected for the first coupling agent and the second coupling agent are different.

[0011] Further, in the step (4), the mass ratio of the detergent-dispersant, the antifoaming agent, the viscosity index improver, and the second additive is (8 - 12):(0.5 - 1):(3 - 5):12.

[0012] Further, the detergent-dispersant is selected from two of polyisobutylene succinimide, polyisobutylene succinate, and alkyl salicylate; The viscosity index improver is a combination of perfluorohexyl polymethacrylate and polymethacrylate.

[0013] Further, the mass ratio of the composite additive to the methyl cyclopentane is (0.4~0.6):10.

[0014] An engine lubricating oil for a hybrid vehicle is prepared by using the preparation method of the engine lubricating oil for a hybrid vehicle as described above.

[0015] The technical solution provided by the present invention may include the following beneficial effects: In the present invention, graphene oxide and nanocellulose are connected by a first coupling agent, so that the lubricating oil has excellent anti-wear performance; nano copper powder and a second coupling agent are combined to further enhance the anti-wear effect and repair effect of the lubricating oil; the first coupling agent and the second coupling agent are not only beneficial to the dispersion of graphene oxide, nanocellulose and nano copper powder, but also can improve the toughness of the oil film and prevent the oil film from breaking; the selection and ratio of hydroxylated poly-α-olefin and methyl cyclopentane improve the fluidity and stability of the lubricating oil under low-temperature and high-temperature conditions; the setting of the mixing step in the present invention makes the lubricating oil system more uniform and ensures the low-temperature start-up and anti-wear performance of the lubricating oil. Specific embodiments

[0016] The present invention will be further clarified below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0017] A preparation method of an engine lubricating oil for a hybrid vehicle according to an embodiment of the present invention includes the following steps: A preparation method of an engine lubricating oil for a hybrid vehicle includes the following steps: (1) Graphene oxide, nanocellulose, a first coupling agent and an antioxidant are mixed and ground, and then subjected to ultrasonic treatment to obtain a first additive; (2) The first additive and hydroxylated poly-α-olefin are mixed evenly to obtain a first mixture; (3) Nano copper powder and a second coupling agent are mixed and ground, and then subjected to ultrasonic treatment to obtain a second additive; (4) A detergent-dispersant, an antifoaming agent and a viscosity index improver are added to the second additive one by one and mixed evenly to obtain a composite additive; (5) The composite additive and methyl cyclopentane are mixed evenly to obtain a second mixture; (6) The first mixture is added to the second mixture and mixed evenly to obtain the engine lubricating oil for a hybrid vehicle, and the mass ratio of the hydroxylated poly-α-olefin to the methyl cyclopentane is 1:(2-3).

[0018] The present invention enhances the performance of lubricating oil under the complex working conditions of hybrid vehicles through the combination of various additives and treatment methods. Specifically, graphene oxide, nanocellulose, a first coupling agent, and an antioxidant are mixed, ground, and ultrasonically treated to form a first additive. The first coupling agent connects graphene oxide and nanocellulose, enabling the lubricating oil to have excellent anti-wear performance and facilitating the uniform dispersion of graphene oxide and nanocellulose. At this time, the added antioxidant not only improves the antioxidant performance of the lubricating oil but also contributes to the uniformity of the system mixture and captures or decomposes oxy radicals or peroxides generated during the mixing process.

[0019] The combination of nano-copper powder and a second coupling agent further enhances the anti-wear effect and repair effect of the lubricating oil, and the second coupling agent is conducive to the dispersion of nano-copper powder in the lubricating oil system. In the present invention, the first additive is first mixed with hydroxylated poly-α-olefin, and the composite additive is mixed with methylcyclopentane, and then the two mixtures are added together to obtain the lubricating oil. Due to the presence of coupling agents in both mixtures, not only are graphene oxide, nanocellulose, and nano-copper evenly dispersed in the lubricating oil, but also the two base oils have good compatibility and are easy to mix.

[0020] The selection and ratio of the base oil ensure the fluidity and stability of the lubricating oil under low-temperature and high-temperature conditions. By using hydroxylated poly-α-olefin and methylcyclopentane with a mass ratio of 1:(2 - 3) as the base oil, the dosage of the fully synthetic oil poly-α-olefin is reduced, achieving a reduction in the cost of the lubricating oil for hybrid vehicle engines. At the same time, graphene oxide, nanocellulose, and nano-copper work together to provide anti-wear performance, enabling the lubricating oil to meet the performance requirements of low-temperature starting and wear resistance. In addition, the addition of dispersants, ashless detergents, defoamers, and viscosity index improvers improves the stability and cleaning performance of the lubricating oil.

[0021] In the present invention, the first coupling agent connects graphene oxide and nanocellulose, enabling the lubricating oil to have excellent anti-wear performance; the combination of nano-copper powder and the second coupling agent further enhances the anti-wear effect and repair effect of the lubricating oil; the first coupling agent and the second coupling agent not only facilitate the dispersion of graphene oxide, nanocellulose, and nano-copper powder but also improve the toughness of the oil film and prevent the oil film from breaking; the selection and ratio of hydroxylated poly-α-olefin and methylcyclopentane improve the fluidity and stability of the lubricating oil under low-temperature and high-temperature conditions; the setting of the mixing steps in the present invention makes the lubricating oil system more uniform and ensures the low-temperature starting and wear-resistant performance of the lubricating oil.

[0022] Further, in the step (1), the mass ratio of graphene oxide, nanocellulose, the first coupling agent, and the antioxidant is (1-4):(1-3):(0.5-2):1. By specifying the mass ratio of graphene oxide, nanocellulose, the first coupling agent, and the antioxidant, the first coupling agent can achieve the effect of connecting graphene oxide and nanocellulose with less dosage. This ratio can optimize the performance of the lubricating oil. Especially under the complex working conditions of a hybrid vehicle engine, the low-temperature fluidity and anti-wear performance of the lubricating oil can be effectively improved by controlling the dosage of the coupling agent.

[0023] As a nanomaterial, graphene oxide has excellent lubricating performance and anti-wear performance. Due to its high strength and good dispersibility, nanocellulose, and the first coupling agent tightly connects graphene oxide and nanocellulose through chemical bonding or physical adsorption, which can enhance the dispersion uniformity of graphene oxide in the lubricating oil.

[0024] Further, the first coupling agent is selected from one of titanate, silane coupling agent, and phosphate ester; the antioxidant is a compound of dilauryl thiodipropionate and nonyl diphenylamine with a mass ratio of 1:2.

[0025] Titanate can provide strong chemical bonding force, the silane coupling agent has excellent hydrolysis stability, while the phosphate ester can provide good heat resistance and antioxidant performance. Titanate, silane coupling agent, and phosphate ester can not only connect graphene oxide and nanocellulose but also enhance the adhesion between the lubricating oil and the metal surface in the lubricating oil system, thereby improving the toughness of the oil film. Dilauryl thiodipropionate mainly plays a role in capturing free radicals, while nonyl diphenylamine can inhibit the oxidation chain reaction. The antioxidant is a compound of dilauryl thiodipropionate and nonyl diphenylamine with a mass ratio of 1:2 to exert the synergistic effect of the two. This compound antioxidant can significantly improve the antioxidant performance of the lubricating oil and extend the service life of the lubricating oil.

[0026] Further, in step (1), first, the first coupling agent and the antioxidant are mixed evenly at room temperature, then graphene oxide is added and mixed evenly at 80 °C. When the heating is stopped, nanocellulose is added and mixed and ground, and then the first additive is obtained by ultrasonic treatment.

[0027] In this technical solution, the first coupling agent and the antioxidant are mixed evenly at room temperature to ensure the uniformity of the basic mixture; graphene oxide is added and mixed evenly at 80 °C, so that graphene oxide can be fully connected with the first coupling agent; after stopping heating, nanocellulose is added and mixed and ground to avoid the destruction of nanocellulose by high temperature and ensure its connection with the first coupling agent; finally, through ultrasonic treatment, the uniformity and stability of the first additive are further ensured.

[0028] Furthermore, in step (2), the mass ratio of the first additive to the hydroxylated polyalphaolefin is (0.1-0.6):5. By limiting the mass ratio of the first additive to the hydroxylated polyalphaolefin of the base oil, the amount of the first additive in the lubricant is further limited. The anti-wear performance and fluidity of the lubricant are ensured within the above-mentioned limited range.

[0029] Furthermore, in the step (3), the mass ratio of the nano copper powder to the second coupling agent is (1-2):1, and the nano copper powder and the second coupling agent are mixed at 60° C.; the nano copper powder and the second coupling agent are mixed at a mass ratio of (1-2):1, so that the nano copper powder and the second coupling agent have a better connection effect, and the nano copper powder and the second coupling agent are mixed at 60° C. to ensure that the nano copper powder and the second coupling agent are fully connected to form a stable composite structure, thereby preventing free nano copper from affecting the fluidity of the lubricating oil.

[0030] The second coupling agent is selected from one of titanate, silane coupling agent, and phosphate, and the first coupling agent and the second coupling agent are selected from different components. The first coupling agent and the second coupling agent have different components, so that they can respectively play the role of improving lubrication performance and enhancing anti-wear performance in lubricating oil. For example, titanate coupling agent can provide excellent heat resistance and oxidation resistance, while silane coupling agent can improve the adhesion and hydrolysis resistance of lubricating oil. In this way, the combination of coupling agents can be flexibly selected according to actual needs to achieve the purpose of optimizing the performance of lubricating oil. Under the complex working conditions of hybrid vehicle engines, it can effectively reduce the problem of low-temperature starting wear and improve the overall performance and service life of lubricating oil.

[0031] Furthermore, in step (3), the mass ratio of the detergent dispersant, the defoamer, the viscosity index improver, and the second additive is (8-12): (0.5-1): (3-5): 12. The detergent dispersant helps to keep the engine clean, the defoamer can reduce the formation of foam, and the viscosity index improver can improve the viscosity characteristics of the lubricating oil. By limiting the mass ratio range of the detergent dispersant, the defoamer, the viscosity index improver, and the second additive, the stability and reliability of the lubricating oil under different working conditions can be ensured while ensuring that each component exerts its best effect.

[0032] Further, the detergent dispersant is selected from two of polyisobutylene succinimide, polyisobutylene succinate and alkyl salicylate; The viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

[0033] Polyisobutylene succinimide can prevent sludge and carbon deposition, keeping the engine clean; polyisobutylene succinate has dispersion and rust prevention functions, preventing sediment formation and protecting the metal surface; alkyl salicylate neutralizes acidic substances, reduces oxidation products, and prevents deposition. Selecting two of the above as compound detergents can significantly improve the service life of lubricating oil.

[0034] Perfluorohexyl polymethacrylate has excellent high-temperature resistance (>200 °C), oxidation resistance and chemical inertness due to its fluorine-containing groups. The combination of perfluorohexyl polymethacrylate and polymethacrylate as a viscosity index improver can improve the compatibility of two base oils and enhance the low-temperature high fluidity of lubricating oil.

[0035] Correspondingly, the embodiment of the present invention also provides an engine lubricating oil for a hybrid vehicle, which is prepared by using the preparation method of the engine lubricating oil for a hybrid vehicle as described above.

[0036] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The experimental methods without specific conditions in the following embodiments are usually carried out according to conventional methods and conditions or selected according to the product specifications. The reagents, unless otherwise specified, can be obtained from commercial sources; and the performance of products from different sources has no significant impact.

[0037] Example 1

[0038] The preparation method of the engine lubricating oil for a hybrid vehicle in this example has the following steps: (1) Mix the titanate and antioxidant evenly at room temperature, then add graphene oxide and mix evenly at 80 °C. When the heating is stopped, add nanocellulose and mix and grind, and then obtain the first additive by ultrasonic treatment; The mass ratio of graphene oxide, nanocellulose, titanate and antioxidant is 1:1:0.5:1; the antioxidant is a compound of dilauryl thiodipropionate and nonyl diphenylamine in a mass ratio of 1:2; (2) Mix the first additive and hydroxylated poly-α-olefin evenly at a mass ratio of 0.1:5 to obtain a first mixture; (3) Mix and grind nanocopper powder and silane coupling agent at a mass ratio of 1:1 at 60 °C, and obtain the second additive by ultrasonic treatment; (4) Add the detergent-dispersant, defoamer and viscosity index improver to the second additive one by one and mix evenly to obtain a composite additive; the mass ratio of the detergent-dispersant, defoamer, viscosity index improver and the second additive is 8:0.5:3:12; the viscosity index improver is a combination of perfluorohexyl polymethacrylate and polymethacrylate, and the detergent-dispersant is selected from polyisobutylene succinimide and polyisobutylene succinate; (5) Mix the composite additive and methylcyclopentane evenly at a mass ratio of 0.4:10 to obtain a second mixture; (6) Add the first mixture to the second mixture and mix evenly to obtain the engine lubricating oil for the hybrid vehicle. The mixing ratio of the first mixture added to the second mixture makes the mass ratio of hydroxylated polyalphaolefin and methylcyclopentane 1:2.

[0039] Example 2

[0040] The preparation method of the engine lubricating oil for the hybrid vehicle in this example has the following steps: (1) Mix the silane coupling agent and antioxidant evenly at room temperature, then add graphene oxide and mix evenly at 80 °C. Add nanocellulose and mix and grind when the heating is stopped, and then obtain the first additive through ultrasonic treatment; The mass ratio of graphene oxide, nanocellulose, silane coupling agent and antioxidant is 1:2:1:1; the antioxidant is a compound of dilauryl thiodipropionate and nonyl diphenylamine with a mass ratio of 1:2; (2) Mix the first additive and hydroxylated polyalphaolefin evenly at a mass ratio of 0.6:5 to obtain a first mixture; (3) Mix and grind nanocopper powder and phosphate ester at a mass ratio of 2:1 at 60 °C and perform ultrasonic treatment to obtain a second additive; (4) Add the detergent-dispersant, defoamer and viscosity index improver to the second additive one by one and mix evenly to obtain a composite additive; the mass ratio of the dispersant, ashless detergent, defoamer, viscosity index improver and the second additive is 10:0.5:4:12; the viscosity index improver is a combination of perfluorohexyl polymethacrylate and polymethacrylate, and the detergent-dispersant is composed of polyisobutylene succinate and alkyl salicylate; (5) Mix the composite additive and methylcyclopentane evenly at a mass ratio of 0.6:10 to obtain a second mixture; (6) Add the first mixture to the second mixture and mix evenly to obtain the engine lubricating oil for the hybrid vehicle. The mixing ratio of the first mixture added to the second mixture makes the mass ratio of hydroxylated polyalphaolefin and methylcyclopentane 1:2.3.

[0041] Example 3

[0042] The preparation method of the engine lubricating oil for the hybrid vehicle in this example has the following steps: (1) Mix the phosphate ester and antioxidant evenly at room temperature, then add graphene oxide and mix evenly at 80 °C. Add nanocellulose and mix and grind when the heating is stopped, and then obtain the first additive through ultrasonic treatment; Graphene oxide, nanocellulose, phosphate ester and antioxidant are in a mass ratio of 4:3:2:1; the antioxidant is a compound of dilauryl thiodipropionate and nonyl diphenylamine in a mass ratio of 1:2; (2) Mix the first additive and hydroxylated poly-α-olefin evenly at a mass ratio of 0.3:5 to obtain a first mixture; (3) Mix and grind nanocopper powder and the second coupling agent titanate at a mass ratio of 1.5:1 at 60 °C, and then perform ultrasonic treatment to obtain a second additive; (4) Add ashless detergent-dispersant, defoamer and viscosity index improver to the second additive one by one, and mix evenly to obtain a composite additive; the mass ratio of the dispersant, ashless detergent, defoamer, viscosity index improver and the second additive is 12:1:5:12; the viscosity index improver is a combination of perfluorohexyl methacrylate and polymethacrylate, and the detergent-dispersant is composed of polyisobutylene succinate and alkyl salicylate; (5) Mix the composite additive and methylcyclopentane evenly at a mass ratio of 0.5:10 to obtain a second mixture; (6) Add the first mixture to the second mixture and mix evenly to obtain the engine lubricating oil for the hybrid vehicle. The mixing ratio of the first mixture added to the second mixture makes the mass ratio of hydroxylated poly-α-olefin and methylcyclopentane 1:3.

[0043] Example 4

[0044] The preparation method of the engine lubricating oil for the hybrid vehicle in this example has the following steps: (1) Mix the silane coupling agent and the antioxidant evenly at room temperature, then add graphene oxide and mix evenly at 80 °C. When the heating is stopped, add nanocellulose and mix and grind, and then perform ultrasonic treatment to obtain a first additive; Graphene oxide, nanocellulose, silane coupling agent and antioxidant are in a mass ratio of 1:2:1:1; the antioxidant is a compound of dilauryl thiodipropionate and nonyl diphenylamine in a mass ratio of 1:2; (2) Mix the first additive and hydroxylated poly-α-olefin evenly at a mass ratio of 0.6:5 to obtain a first mixture; (3) Mix and grind nanocopper powder and phosphate ester at a mass ratio of 1:1 at 60 °C, and then perform ultrasonic treatment to obtain a second additive; (4) Add the detergent-dispersant, defoamer and viscosity index improver to the second additive one by one, and mix evenly to obtain a composite additive; the mass ratio of the dispersant, ashless detergent, defoamer, viscosity index improver and the second additive is 10:0.5:4:12; the viscosity index improver is a combination of perfluorohexyl methacrylate and polymethacrylate, and the detergent-dispersant is composed of polyisobutylene succinate and alkyl salicylate; (5) Mix the composite additive and methylcyclopentane evenly at a mass ratio of 0.6:10 to obtain a second mixture; (6) Add the first mixture to the second mixture and mix evenly to obtain the engine lubricating oil for the hybrid vehicle. The mixing ratio of the first mixture added to the second mixture makes the mass ratio of hydroxylated polyalphaolefin and methylcyclopentane 1:2.3.

[0045] Example 5

[0046] The preparation method of the engine lubricating oil for the hybrid vehicle in this example has the following steps: (1) Mix the silane coupling agent and the antioxidant evenly at room temperature, then add graphene oxide and mix evenly at 80°C. When the heating is stopped, add nanocellulose and mix and grind, and then obtain the first additive through ultrasonic treatment; The mass ratio of graphene oxide, nanocellulose, silane coupling agent and antioxidant is 1:2:1:1; the antioxidant is a compound of dilauryl thiodipropionate and nonyl diphenylamine in a mass ratio of 1:2; (2) Mix the first additive and hydroxylated polyalphaolefin evenly at a mass ratio of 0.6:5 to obtain a first mixture; (3) Mix and grind nanocopper powder and phosphate ester at a mass ratio of 2:1 at 60°C and perform ultrasonic treatment to obtain a second additive; (4) Add the detergent-dispersant, antifoaming agent and viscosity index improver to the second additive one by one and mix evenly to obtain a composite additive; the mass ratio of the dispersant, ashless detergent, antifoaming agent, viscosity index improver and the second additive is 10:0.5:4:12; the viscosity index improver is a combination of perfluorohexyl polymethacrylate and polymethacrylate, and the detergent-dispersant is composed of polyisobutylene succinate and alkyl salicylate; (5) Mix the composite additive and methylcyclopentane evenly at a mass ratio of 0.6:10 to obtain a second mixture; (6) Add the first mixture to the second mixture and mix evenly to obtain the engine lubricating oil for the hybrid vehicle. The mixing ratio of the first mixture added to the second mixture makes the mass ratio of hydroxylated polyalphaolefin and methylcyclopentane 1:3.

[0047] Example 6

[0048] The preparation method of the engine lubricating oil for the hybrid vehicle in this example has the following steps: (1) Mix the silane coupling agent and the antioxidant evenly at room temperature, then add graphene oxide and mix evenly at 80°C. When the heating is stopped, add nanocellulose and mix and grind, and then obtain the first additive through ultrasonic treatment; Graphene oxide, nanocellulose, silane coupling agent and antioxidant are in a mass ratio of 4:3:0.5:1; the antioxidant is a compound of dilauryl thiodipropionate and nonyl diphenylamine in a mass ratio of 1:2; (2) Mix the first additive and hydroxylated poly-α-olefin evenly at a mass ratio of 0.6:5 to obtain a first mixture; (3) Mix and grind nanocopper powder and phosphate ester at a mass ratio of 2:1 at 60 °C, and perform ultrasonic treatment to obtain a second additive; (4) Add a detergent-dispersant, an antifoaming agent and a viscosity index improver to the second additive one by one, and mix evenly to obtain a composite additive; the mass ratio of the dispersant, ashless detergent, antifoaming agent, viscosity index improver and the second additive is 10:0.5:4:12; the viscosity index improver is a combination of perfluorohexyl methacrylate and polymethacrylate, and the detergent-dispersant is composed of polyisobutylene succinate and alkyl salicylate; (5) Mix the composite additive and methylcyclopentane evenly at a mass ratio of 0.6:10 to obtain a second mixture; (6) Add the first mixture to the second mixture and mix evenly to obtain the engine lubricating oil for the hybrid vehicle. The mixing ratio of the first mixture added to the second mixture makes the mass ratio of hydroxylated poly-α-olefin and methylcyclopentane 1:2.3.

[0049] Example 7

[0050] The preparation method of the engine lubricating oil for the hybrid vehicle in this example has the following steps: (1) Mix the silane coupling agent and the antioxidant evenly at room temperature, then add graphene oxide and mix evenly at 80 °C. When the heating is stopped, add nanocellulose and mix and grind, and then perform ultrasonic treatment to obtain a first additive; Graphene oxide, nanocellulose, silane coupling agent and antioxidant are in a mass ratio of 1:2:1:1; the antioxidant is a compound of dilauryl thiodipropionate and nonyl diphenylamine in a mass ratio of 1:2; (2) Mix the first additive and hydroxylated poly-α-olefin evenly at a mass ratio of 0.6:5 to obtain a first mixture; (3) Mix and grind nanocopper powder and phosphate ester at a mass ratio of 2:1 at 60 °C, and perform ultrasonic treatment to obtain a second additive; (4) Add a detergent-dispersant, an antifoaming agent and a viscosity index improver to the second additive one by one, and mix evenly to obtain a composite additive; the mass ratio of the dispersant, ashless detergent, antifoaming agent, viscosity index improver and the second additive is 8:0.5:3:12; the viscosity index improver is a combination of perfluorohexyl methacrylate and polymethacrylate, and the detergent-dispersant is composed of polyisobutylene succinate and alkyl salicylate; (5) Mix the composite additive and methylcyclopentane evenly at a mass ratio of 0.6:10 to obtain a second mixture; (6) Add the first mixture to the second mixture and mix evenly to obtain the engine lubricating oil for the hybrid vehicle. The mixing ratio of the first mixture added to the second mixture is such that the mass ratio of hydroxylated polyalphaolefin to methylcyclopentane is 1:2.3.

[0051] Comparative Example 1 The lubricating oil components and ratios in this comparative example are the same as those in Example 2, except for the preparation steps, as follows: (1) Mix and grind graphene oxide, nanocellulose, silane coupling agent, and antioxidant at room temperature, and then obtain the first additive through ultrasonic treatment; (2) Mix and grind rice copper powder and phosphate ester at 60 °C, and perform ultrasonic treatment to obtain the second additive; (3) Mix the first additive, the second additive, detergent-dispersant, defoamer, and viscosity index improver evenly to obtain a composite additive; (5) Mix the composite additive, methylcyclopentane, and hydroxylated polyalphaolefin evenly to obtain the lubricating oil.

[0052] Comparative Example 2 The lubricating oil components and ratios in this comparative example are the same as those in Example 2, except that both the first coupling agent and the second coupling agent are silane coupling agents.

[0053] Test the lubricating oils obtained in Examples 1-7 and Comparative Examples 1-2. Refer to GB / T 265 to test the kinematic viscosity of the lubricating oil, and use the four-ball machine method to test the anti-wear performance of the lubricating oil. The results are shown in the following table.

[0054]

[0055] For other components and operations of the engine lubricating oil for a hybrid vehicle and its preparation method according to the embodiments of the present invention, those are known to those of ordinary skill in the art and will not be described in detail here. When the embodiments give a numerical range, it should be understood that unless otherwise specified in the present invention, any value between the two endpoints of each numerical range and any value between the two endpoints can be selected. The performance described can be achieved within the mixing ratio range of the present invention. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0056] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing engine lubricating oil for a hybrid vehicle, characterized in that: The following steps are involved: (1) mixing and grinding graphene oxide, nanocellulose, a first coupling agent and an antioxidant, and then subjecting the mixture to ultrasonic treatment to obtain a first additive; (2) uniformly mixing the first additive and the hydroxylated poly-alpha-olefin to obtain a first mixture; (3) mixing and grinding the nano copper powder and the second coupling agent, and subjecting the mixture to ultrasonic treatment to obtain a second additive; (4) Adding the detergent dispersant, defoaming agent and viscosity index improver into the second additive one by one and mixing them evenly to obtain a composite additive; (5) mixing the composite additive methylcyclopentane uniformly to obtain a second mixture; (6) The first mixture is added to the second mixture and mixed evenly to obtain the engine lubricating oil for the hybrid vehicle, wherein the mass ratio of the hydroxylated poly-alpha olefin to methyl cyclopentane is 1:(2-3).

2. The method for preparing engine lubricating oil for a hybrid vehicle according to claim 1, characterized in that: In the step (1), the mass ratio of graphene oxide, nanocellulose, first coupling agent and antioxidant is (1-4):(1-3):(0.5-2):

1.

3. The method for preparing engine lubricating oil for hybrid vehicles according to claim 2, characterized in that: The first coupling agent is selected from one of titanate, silane coupling agent and phosphate; The antioxidant is a compound of dilauryl thiodipropionate and nonyl diphenylamine in a mass ratio of 1:

2.

4. The method for preparing engine lubricating oil for a hybrid vehicle according to claim 3, characterized in that: Firstly, the first coupling agent and the antioxidant are mixed evenly at room temperature, and then graphene oxide is added and mixed evenly at 80° C. When the heating is stopped, nanocellulose is added and mixed and ground, and then the first additive is subjected to ultrasonic treatment.

5. The method for preparing engine lubricating oil for hybrid vehicles according to claim 3, characterized in that: In the step (2), the mass ratio of the first additive to the hydroxylated poly-alpha-olefin is (0.1-0.6):

5.

6. The method for preparing engine lubricating oil for a hybrid vehicle according to claim 5, characterized in that: In the step (3), the mass ratio of the nano copper powder and the second coupling agent is (1-2):1, and the nano copper powder and the second coupling agent are mixed at 60° C.; The second coupling agent is selected from titanate, silane coupling agent and phosphate ester, and the first coupling agent and the second coupling agent are made of different components.

7. The method for preparing engine lubricating oil for a hybrid vehicle according to claim 2, characterized in that: In the step (4), the mass ratio of the detergent dispersant, the defoamer, the viscosity index improver and the second additive is (4-6): (4-6): (0.5-1): (3-5):

12.

8. The method for preparing engine lubricating oil for a hybrid vehicle according to claim 7, characterized in that: The detergent dispersant is selected from two of polyisobutylene succinimide, polyisobutylene succinate and alkyl salicylate; The viscosity index improver is a combination of polyperfluorohexyl methacrylate and polymethacrylate.

9. The method for preparing engine lubricating oil for a hybrid vehicle according to claim 7, characterized in that: The mass ratio of the composite additive to the methylcyclopentane is (0.4-0.6):

10.

10. An engine lubricating oil for a hybrid vehicle, characterized in that: The lubricant is prepared by the method for preparing the engine lubricant oil for a hybrid vehicle according to any one of claims 1 to 9.

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