Extreme pressure anti-wear self-repairing lubricating oil additive and preparation method and application thereof in lubricating oil

Abstract

The invention provides an extreme pressure anti-wear self-repairing lubricating oil additive as well as a preparation method and application thereof in lubricating oil. The extreme pressure anti-wear self-repairing lubricating oil additive is prepared from the following components in parts by mass: 5 to 15 parts of modified graphene oxide, 30 to 50 parts of an antioxidant, 10 to 30 parts of an anti-wear agent and 10 to 30 parts of an extreme pressure agent, the modified graphene oxide is obtained by reacting carboxylated graphene oxide loaded with nano silicon dioxide with linolenamide borate and then copolymerizing with acrylate. Nano silicon dioxide is grafted on the surface of graphene oxide through in-situ hydrolysis of tetraethoxysilane, then carboxyl active sites are obtained on the surface of RGO-S through carboxylation modification of KH550 and butanedioic anhydride, then the RGO-S is grafted with linoleamide borate, and a composite structure with extreme pressure film forming and self-repairing functions is formed; and a polymer chain is constructed on the surface of the compound through free radical polymerization, so that the component compatibility and the friction film-forming property are enhanced.

Description

Technical Field

[0001] The invention relates to the field of lubricating oil additives, and in particular to an extreme pressure, anti-wear and self-repairing lubricating oil additive, a preparation method thereof and application in lubricating oil. Background Art

[0002] In the context of the rapid development of industrial equipment, lubricating oil is a key medium for reducing mechanical friction and wear, and its performance directly determines the service life and energy efficiency of the equipment. According to statistics, energy consumption caused by friction accounts for about 30% of the world's total energy consumption, and the proportion of mechanical parts scrapped due to wear is as high as 80%. With the prevalence of extreme working conditions (such as high load, high temperature, and high speed), traditional lubricating oils are difficult to meet the needs of continuous lubrication. It is urgent to enhance its extreme pressure and anti-wear properties through additives and give it self-repairing ability to cope with the dynamic repair needs of micro-damage on metal surfaces.

[0003] At present, common extreme pressure and anti-wear self-repairing additives mainly include sulfur-phosphorus compounds (such as zinc dialkyl dithiophosphates), organic borates, nano-metal particles (such as copper and molybdenum compounds) and layered materials (such as molybdenum disulfide, graphite), etc. For example, through the synergistic effect of borates and copper salts, a boron reinforcement layer and a copper repair film can be formed on the friction surface; while the dispersion of nano-sulfides depends on surfactants or mechanical mixing processes. Existing preparation methods mostly use physical mixing of components or high-temperature reactions, such as compounding chlorinated alkanes, dialkyl dithiocarbamates with antioxidants, or dispersing nanoparticles in base oils and improving stability through microwave-ultrasonic treatment. However, these methods often rely on the chemical action of a single active element, or achieve functional superposition through simple compounding of multiple components, and lack systematic synergistic mechanism design.

[0004] The defects of existing technologies are mainly reflected in the limitations of anti-wear and self-repair capabilities. First, although sulfur and phosphorus additives can form extreme pressure films, they are easily consumed under high loads, resulting in a shortened oil life, and sulfides are prone to cause metal corrosion; chlorinated compounds are resistant to high temperatures but have the risk of hydrolysis, which limits their application scenarios. Secondly, nanomaterials (such as MoS 2 ) can enhance wear resistance, but the dispersion stability is poor, and it is easy to agglomerate to form abrasive particles that aggravate wear. In addition, the preparation process is complex and costly. In addition, the self-repair function mostly relies on metal deposition or physical adsorption film. Such film layers have weak bonding with the substrate and are easy to fall off under dynamic shear, making it difficult to achieve continuous repair. For example, the protective film formed by the combination of traditional borate esters and copper salts is prone to oxidation failure at high temperatures, and the phase separation problem caused by poor compatibility between additive components is not solved, further weakening the long-term stability of the lubrication system.

[0005] In summary, it is necessary to develop a new technical solution to solve the problems existing in the prior art. Summary of the invention

[0006] The present invention provides an extreme pressure, anti-wear and self-repairing lubricant additive. The present invention adopts in-situ hydrolysis of tetraethoxysilane to graft nano-silicon dioxide on the surface of graphene oxide, inhibits the agglomeration of graphene sheets through structural support, and exerts a synergistic lubrication effect at the same time; through carboxylation modification of KH550 and succinic anhydride, the surface of RGO-S obtains carboxyl active sites, and then grafts with linoleamide borate to form a composite structure with both extreme pressure film-forming and self-repairing functions; through free radical polymerization, polymer chains are constructed on the surface of the composite to enhance the compatibility of components and friction film-forming performance. In addition, the present invention also compounds the extreme pressure, anti-wear and self-repairing lubricant additive with molybdenum disulfide modified with polyacrylic acid, and significantly improves the friction reduction and anti-wear performance of the lubricant system through the synergistic effect of layered materials and organic molecules.

[0007] One object of the present invention is to provide an extreme pressure, anti-wear and self-repairing lubricating oil additive, wherein the extreme pressure, anti-wear and self-repairing lubricating oil additive is composed of the following components in parts by mass:

[0008]

[0009] in,

[0010] The modified graphene oxide is obtained by reacting carboxylated graphene oxide loaded with nano-silicon dioxide with linoleamide borate and then copolymerizing with acrylic acid ester.

[0011] Furthermore, the antioxidant is selected from one or more of 2,6-di-tert-butyl-p-cresol, 2,4,6-tri-tert-butylphenol or 2,6-di-tert-butyl-4-nonylphenol.

[0012] Furthermore, the anti-wear agent is selected from one or more of phosphate derivatives, organic sulfur-phosphorus compounds, amine phosphates or polyphosphoric acid.

[0013] Furthermore, the extreme pressure agent is selected from one or more of sulphurized olefins, sulphurized fatty acids or sulphurized fatty acid esters.

[0014] Another object of the present invention is to provide a method for preparing the above-mentioned extreme pressure anti-wear self-repairing lubricating oil additive, comprising the following steps:

[0015] S1, mixing graphene oxide and tetraethoxysilane, stirring and reacting under alkaline conditions to obtain graphene oxide loaded with nano-silica; mixing silane coupling agent KH550 and succinic anhydride, stirring and reacting, then adding the graphene oxide loaded with nano-silica, continuing to stir and react, to obtain carboxylated graphene oxide loaded with nano-silica;

[0016] S2, mixing boric acid and diethanolamine, heating and stirring to react, to obtain an intermediate; mixing the intermediate and linoleic acid, adding a catalyst, heating and reacting, to obtain linoleamide borate;

[0017] S3, blending the carboxylated nano-silica-loaded graphene oxide and linoleamide borate, adding a catalyst, heating and reacting to obtain an intermediate product; blending the intermediate product and acrylate, adding an initiator, heating and reacting to obtain modified graphene oxide;

[0018] S4. All components are blended evenly to obtain an extreme pressure, anti-wear and self-repairing lubricant additive.

[0019] Furthermore, in step S1, the mass ratio of the graphene oxide to tetraethoxysilane is 1:(5-15); the mass ratio of the nano-silica loaded graphene oxide, silane coupling agent KH550 and succinic anhydride is 1:(0.01-0.5):(0.01-0.5).

[0020] Furthermore, in step S2, the molar ratio of the boric acid to diethanolamine is 1:(2-3), and the heating temperature is 150-180°C; and the molar ratio of the intermediate to linoleic acid is 1:(0.5-0.9).

[0021] Furthermore, in step S3, the molar ratio of the carboxylated nano-silica-loaded graphene oxide to linoleamide borate is 1:(0.5-1.5); and the molar ratio of the intermediate product to acrylate is 1:(0.1-1).

[0022] Another object of the present invention is to provide the use of the extreme pressure anti-wear self-repairing lubricating oil additive in lubricating oil, wherein the lubricating oil comprises the following components in parts by mass:

[0023] 80-100 parts of base oil

[0024] 5-15 parts of extreme pressure anti-wear self-repairing lubricant additive

[0025] Modified molybdenum disulfide 1-5 parts

[0026] 8-40 parts of additives;

[0027] in,

[0028] The modified molybdenum disulfide is obtained by reacting hydroxylated molybdenum disulfide with polyacrylic acid.

[0029] Furthermore, the base oil is selected from one or more of mineral base oil, synthetic base oil or biological base oil.

[0030] Furthermore, the preparation method of the modified molybdenum disulfide comprises the following steps: blending molybdenum disulfide and mercaptoethanol, ultrasonicating, and then freeze-drying to obtain hydroxylated molybdenum disulfide; blending the hydroxylated molybdenum disulfide and polyacrylic acid, heating for reaction, to obtain polyacrylic acid-modified molybdenum disulfide.

[0031] Furthermore, the auxiliary agent is selected from one or more of a preservative, a rust inhibitor, a dispersant or a defoaming agent.

[0032] Furthermore, the preservative is selected from one or more zinc dialkyl dithiophosphates or zinc dialkyl dithiocarbamates, and the amount is 1-10 parts; the rust inhibitor is selected from one or more sodium carboxylates or sodium sulfonates, and the amount is 5-10 parts; the dispersant is selected from one or more succinates or succinimides, and the amount is 3-8 parts; the defoamer is dimethyl silicone oil, and the amount is 0.1-1 part.

[0033] The present invention has the following beneficial effects:

[0034] (1) The present invention firstly grafts nano-silicon dioxide on the surface of graphene oxide by in-situ hydrolysis of tetraethoxysilane to obtain graphene oxide (RGO-S) loaded with nano-silicon dioxide. Nano-silicon dioxide can support the lamellar structure of graphene oxide, increase the interlayer spacing, effectively reduce the agglomeration of graphene oxide and improve its dispersion stability in lubricating oil additives. During the friction process, RGO-S can enter the friction contact surface to form a film, improve the tribological properties of the material, and at the same time can reduce the friction coefficient through the microscopic rolling effect, improve the load-bearing capacity, and can fill the wear positions such as microcracks and micropits on the surface of the friction pair, playing a role in self-repair. In addition, graphene oxide and nano-silicon dioxide can play a synergistic lubrication role, which is conducive to the retention of RGO-S and enhances the self-repair effect. Subsequently, by reacting KH550 with succinic anhydride, a carboxyl group is grafted at the end of KH550, and by condensing the siloxane group with the hydroxyl group on the surface of RGO-S, a carboxyl group is introduced into RGO-S, and then reacting with linoleamide borate having an amino active site, linoleamide borate is successfully introduced into RGO-S, and linoleamide borate can form a heterogeneous extreme pressure film on the surface of the friction metal, which plays a role in reducing friction and anti-wear, and can protect RGO-S at the same time, reduce its loss, and further enhance the self-repairing effect. In addition, the present invention also performs free radical polymerization on the RGO-S-linoleamide borate (intermediate product) obtained above and acrylate to form a polymer chain on the surface of RGO-S-linoleamide borate. The formation of the polymer chain can enhance the compatibility of RGO-S-linoleamide borate with other components and enhance dispersibility on the one hand, and enhance the film-forming performance of linoleamide borate on the other hand, and further enhance the friction reduction and anti-wear effect and self-repairing effect.

[0035] (2) The present invention also compounds the extreme pressure anti-wear self-repairing lubricant additive with modified molybdenum disulfide and applies them to lubricant products. The modified molybdenum disulfide is grafted with polyacrylic acid segments on its surface, which is beneficial to improve its dispersibility and enhance its film-forming performance, and can synergize with the extreme pressure anti-wear self-repairing lubricant additive to further enhance the anti-wear self-repairing performance of the lubricant product. DETAILED DESCRIPTION

[0036] In order to more clearly illustrate the technical solution of the present invention, the following examples are listed. Unless otherwise stated, the raw materials, reactions and post-treatment methods shown in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0037] The words "preferred", "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that can provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.

[0038] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers indicating, for example, the amounts of ingredients used in the specification and claims should be understood to be modified in all cases by the term "about". Therefore, unless indicated to the contrary, the numerical parameters set forth in the following specification and the appended claims are approximate values ​​that vary depending on the desired properties to be obtained by the present invention.

[0039] The present invention uses the following raw materials:

[0040] Antioxidant: 2,6-di-tert-butyl-p-cresol.

[0041] Antiwear agent: triphenyl phosphate.

[0042] Extreme pressure agent: trichlorophenylthiophosphate.

[0043] Graphene oxide: brand M83920, purchased from Shanghai Myrel Biochemical Technology Co., Ltd.

[0044] Base oil: 500N mineral base oil.

[0045] Preservative: Zinc dialkyl dithiophosphate.

[0046] Rust inhibitor: sodium carboxylate.

[0047] Dispersant: Succinimide.

[0048] Defoaming agent: dimethyl silicone oil.

[0049] The preparation method of modified molybdenum disulfide comprises the following steps:

[0050] Using water as solvent, molybdenum disulfide and mercaptoethanol are mixed (molybdenum disulfide: mercaptoethanol = 1:3, m / m), ultrasonicated for 48 hours, and then freeze-dried at -50°C for 24 hours, washed and dried to obtain hydroxylated molybdenum disulfide; using anhydrous ethanol as solvent, the hydroxylated molybdenum disulfide and polyacrylic acid are mixed (hydroxylated molybdenum disulfide: polyacrylic acid = 1:3, m / m), heated under reflux for 2 hours, cooled, filtered, washed and dried to obtain modified molybdenum disulfide.

[0051] Polyacrylic acid: average molecular weight is 3000, purchased from Beijing Wokai Biotechnology Co., Ltd.

[0052] The water in the present invention is all deionized water.

[0053] The "parts" in the present invention refer to parts by mass.

[0054] Example 1

[0055] An extreme pressure, anti-wear and self-repairing lubricating oil additive, the extreme pressure, anti-wear and self-repairing lubricating oil additive is composed of the following components in parts by mass:

[0056]

[0057] in,

[0058] The modified graphene oxide is obtained by reacting carboxylated graphene oxide loaded with nano-silicon dioxide with linoleamide borate and then copolymerizing with methyl acrylate.

[0059] The preparation method of the extreme pressure anti-wear self-repairing lubricant additive comprises the following steps:

[0060] S1. Add 0.3 parts of graphene oxide to 85 parts of anhydrous ethanol-water mixed solution (anhydrous ethanol: water = 24: 1, v / v), ultrasonically disperse for 30 minutes to form a suspension, then add 6 parts of ammonia solution (25wt%), stir evenly, then add 3 parts of tetraethoxysilane, stir and react for 24 hours at room temperature, filter, wash and dry to obtain nano-silicon dioxide-loaded graphene oxide, disperse it in DMF, prepare a suspension for standby use; use DMF as solvent, blend silane coupling agent KH550 and succinic anhydride, stir and react for 3 hours, then add nano-silicon dioxide-loaded graphene oxide suspension (nano-silicon dioxide-loaded graphene oxide: silane coupling agent KH550: succinic anhydride = 1:0.1:0.1, m / m / m), continue stirring and reacting for 5 hours, wash and dry to obtain carboxylated nano-silicon dioxide-loaded graphene oxide;

[0061] S2, using xylene as solvent, mixing boric acid and diethanolamine (boric acid: diethanolamine = 1:2.5, n / n), stirring and reacting at 160°C, ending the reaction when the water output is close to the theoretical value, rotary evaporation, washing, and obtaining an intermediate; using xylene as solvent, mixing the intermediate and linoleic acid (intermediate: linoleic acid = 1:0.9, n / n), heating under reflux for reaction, ending the reaction when the water output no longer increases, distilling under reduced pressure, washing, and obtaining linoleamide borate;

[0062] S3, using xylene as solvent, blending the carboxylated nano-silica-loaded graphene oxide and linoleamide borate (carboxylated nano-silica-loaded graphene oxide: linoleamide borate = 1:1, n / n), heating and refluxing to react, terminating the reaction when the water output no longer increases, distilling under reduced pressure, washing, and obtaining an intermediate product; using water as solvent, blending the intermediate product and methyl acrylate (intermediate product: methyl acrylate = 1:0.5, n / n), adding 1wt% of sodium persulfate as the reactant, reacting at 80°C for 12h, filtering, washing, and drying to obtain modified graphene oxide;

[0063] S4. Blend all the components uniformly according to the above mass fractions to obtain an extreme pressure, anti-wear and self-repairing lubricant additive.

[0064] Example 2

[0065] An extreme pressure, anti-wear and self-repairing lubricating oil additive, the extreme pressure, anti-wear and self-repairing lubricating oil additive is composed of the following components in parts by mass:

[0066]

[0067] in,

[0068] The modified graphene oxide is obtained by reacting carboxylated graphene oxide loaded with nano-silicon dioxide with linoleamide borate and then copolymerizing with 2-ethyl methacrylate.

[0069] The preparation method of the extreme pressure anti-wear self-repairing lubricating oil additive is the same as that of Example 1.

[0070] Example 3

[0071] An extreme pressure, anti-wear and self-repairing lubricating oil additive, the extreme pressure, anti-wear and self-repairing lubricating oil additive is composed of the following components in parts by mass:

[0072]

[0073] in,

[0074] The modified graphene oxide is obtained by reacting carboxylated graphene oxide loaded with nano-silicon dioxide with linoleamide borate and then copolymerizing with 2-methyl methacrylate.

[0075] The preparation method of the extreme pressure anti-wear self-repairing lubricating oil additive is the same as that of Example 1.

[0076] Comparative Example 1

[0077] An extreme pressure anti-wear self-repairing lubricant additive. The difference between this comparative example and Example 1 is that step S1 is changed to:

[0078] Using DMF as solvent, silane coupling agent KH550 and succinic anhydride were mixed and stirred for 3 hours, and then graphene oxide suspension (graphene oxide: silane coupling agent KH550: succinic anhydride = 1:0.1:0.1, m / m / m) was added, and the stirring reaction was continued for 5 hours, and then washed and dried to obtain carboxylated graphene oxide;

[0079] In step S3, the molar mass of the carboxylated nano-silica-loaded graphene oxide is replaced by carboxylated graphene oxide, and the amounts of other components and the preparation method are the same as those in Example 1.

[0080] Comparative Example 2

[0081] An extreme pressure, anti-wear and self-repairing lubricant additive. The difference between this comparative example and Example 1 is that step S2 is not performed, and in step S3, the linoleamide borate ester is replaced by linoleamide in molar mass, and the amounts of other components and the preparation method are the same as those in Example 1.

[0082] Comparative Example 3

[0083] An extreme pressure, anti-wear and self-repairing lubricant additive. The difference between this comparative example and Example 1 is that in step S3, the intermediate product and methyl acrylate are blended but no copolymerization reaction is carried out, and the amounts of other components and the preparation method are the same as those in Example 1.

[0084] Application Example 1

[0085] A lubricating oil comprising the following components in parts by weight:

[0086]

[0087] in,

[0088] The extreme pressure, anti-wear and self-repairing lubricating oil additive is prepared by Example 1.

[0089] The preparation method of the lubricating oil comprises the following steps:

[0090] According to the above mass fractions, the base oil is heated to 50°C, and the preservative, rust inhibitor and dispersant are added under continuous stirring. After stirring for 30 minutes, it is cooled to 35°C, and the defoaming agent is added. The stirring is continued for 30 minutes, and the lubricating oil is obtained by filtering and packaging.

[0091] Application Example 2

[0092] A lubricating oil comprising the following components in parts by weight:

[0093]

[0094]

[0095] in,

[0096] The extreme pressure, anti-wear and self-repairing lubricating oil additive is prepared by Example 2.

[0097] The preparation method of the above lubricating oil is the same as that of Application Example 1.

[0098] Application Example 3

[0099] A lubricating oil comprising the following components in parts by weight:

[0100]

[0101] in,

[0102] The extreme pressure, anti-wear and self-repairing lubricating oil additive is prepared by Example 3.

[0103] The preparation method of the above lubricating oil is the same as that of Application Example 1.

[0104] Comparative application example 1

[0105] A lubricating oil. The difference between this comparative application example and application example 1 is that the extreme pressure anti-wear self-repairing lubricating oil additive is prepared by comparative example 1, and the amounts of other components and the preparation method are the same as those in application example 1.

[0106] Comparative Application Example 2

[0107] A lubricating oil. The difference between this comparative application example and application example 1 is that the extreme pressure anti-wear self-repairing lubricating oil additive is prepared by comparative example 2, and the amounts of other components and the preparation method are the same as those in application example 1.

[0108] Comparative Application Example 3

[0109] A lubricating oil. The difference between this comparative application example and application example 1 is that the extreme pressure anti-wear self-repairing lubricating oil additive is prepared by comparative example 3, and the amounts of other components and the preparation method are the same as those in application example 1.

[0110] Test Case

[0111] Performance tests are performed on use cases 1-3 and comparative application examples 1-3.

[0112] Test method:

[0113] Load-bearing capacity: Tested in accordance with GB / T 3142-2019;

[0114] Corrosion resistance: Tested in accordance with GB / T 5096-2017;

[0115] Wear spot diameter: refer to SH / T 0189-2017 and test under test condition A.

[0116] The test results are shown in Table 1.

[0117] Table 1 Performance test results

[0118]

[0119] From the above test results, it can be seen that the extreme pressure anti-wear self-repairing lubricant additive prepared by the present invention is applied to lubricating oil, which has excellent load-bearing capacity, good corrosion resistance and small wear spot diameter, indicating that the present invention has excellent extreme pressure anti-wear self-repairing ability. However, comparative example 1 does not load nano-silica, comparative example 2 does not graft boric acid ester, and comparative example 3 does not perform free radical polymerization, resulting in different degrees of decrease in its load-bearing capacity, corrosion resistance, and wear spot diameter.

[0120] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0121] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An extreme pressure, anti-wear and self-repairing lubricant additive, characterized in that: The extreme pressure anti-wear self-repairing lubricating oil additive is composed of the following components in parts by mass: in, The modified graphene oxide is obtained by reacting carboxylated graphene oxide loaded with nano-silicon dioxide with linoleamide borate and then copolymerizing with acrylic acid ester.

2. The extreme pressure anti-wear self-repairing lubricant additive according to claim 1, characterized in that: The antioxidant is selected from one or more of 2,6-di-tert-butyl-p-cresol, 2,4,6-tri-tert-butylphenol or 2,6-di-tert-butyl-4-nonylphenol.

3. The extreme pressure anti-wear self-repairing lubricant additive according to claim 1, characterized in that: The anti-wear agent is selected from one or more of phosphate derivatives, organic sulfur-phosphorus compounds, amine phosphates or polyphosphoric acid.

4. The extreme pressure anti-wear self-repairing lubricant additive according to claim 1, characterized in that: The extreme pressure agent is selected from one or more of sulphurized olefins, sulphurized fatty acids or sulphurized fatty acid esters.

5. The method for preparing the extreme pressure, anti-wear and self-repairing lubricating oil additive according to any one of claims 1 to 4, characterized in that: The steps include: S1, mixing graphene oxide and tetraethoxysilane, stirring and reacting under alkaline conditions to obtain graphene oxide loaded with nano-silica; mixing silane coupling agent KH550 and succinic anhydride, stirring and reacting, then adding the graphene oxide loaded with nano-silica, continuing to stir and react, to obtain carboxylated graphene oxide loaded with nano-silica; S2, mixing boric acid and diethanolamine, heating and stirring to react, to obtain an intermediate; mixing the intermediate and linoleic acid, adding a catalyst, heating and reacting, to obtain linoleamide borate; S3, blending the carboxylated nano-silica-loaded graphene oxide and linoleamide borate, adding a catalyst, heating and reacting to obtain an intermediate product; blending the intermediate product and acrylate, adding an initiator, heating and reacting to obtain modified graphene oxide; S4. All components are blended evenly to obtain an extreme pressure, anti-wear and self-repairing lubricant additive.

6. The method for preparing the extreme pressure, anti-wear and self-repairing lubricating oil additive according to claim 5, characterized in that: In step S1, the mass ratio of the graphene oxide to tetraethoxysilane is 1:(5-15); the mass ratio of the nano-silica-loaded graphene oxide, silane coupling agent KH550 and succinic anhydride is 1:(0.01-0.5):(0.01-0.5).

7. The method for preparing the extreme pressure, anti-wear and self-repairing lubricating oil additive according to claim 5, characterized in that: In step S2, the molar ratio of the boric acid to diethanolamine is 1:(2-3); the molar ratio of the intermediate to linoleic acid is 1:(0.5-0.9).

8. The method for preparing the extreme pressure, anti-wear and self-repairing lubricating oil additive according to claim 5, characterized in that: In step S3, the molar ratio of the carboxylated nano-silica-loaded graphene oxide to linoleamide borate is 1:(0.5-1.5); and the molar ratio of the intermediate product to acrylate is 1:(0.1-1).

9. Use of the extreme pressure anti-wear self-repairing lubricating oil additive according to any one of claims 1 to 4 in lubricating oil, characterized in that: The lubricating oil comprises the following components in parts by weight: in, The modified molybdenum disulfide is obtained by reacting hydroxylated molybdenum disulfide with polyacrylic acid.

10. The use of the extreme pressure anti-wear self-repairing lubricating oil additive in lubricating oil according to claim 9, characterized in that: The preparation method of the modified molybdenum disulfide comprises the following steps: Molybdenum disulfide and mercaptoethanol are mixed, ultrasonicated, and then freeze-dried to obtain hydroxylated molybdenum disulfide; the hydroxylated molybdenum disulfide and polyacrylic acid are mixed, heated for reaction, and polyacrylic acid-modified molybdenum disulfide is obtained.

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