Extreme pressure anti-wear agent for lubricating oil and preparation method thereof

Abstract

The invention discloses an extreme pressure anti-wear agent for lubricating oil and a preparation method thereof, and relates to the field of lubricating oil additives. The present invention first utilizes 2,4-dichlorobenzyl alcohol to react with phosphorus pentasulfide to generate thiophosphoric acid, which contacts with a metal surface to form a lubricating film; then generates molybdenum phosphate with sodium molybdate, introduces molybdenum atoms, and reduces the friction coefficient of oil products; then physically mixes with graphene to obtain composite organic molybdenum, and increases wear resistance; then iodoacetamide is used to modify 3-chlorobenzoyl hydrazide, introduces an amide bond, reduces liquid infiltration, and the hydrazide structure can inhibit the migration of C elements from base oil to the metal surface; then the chlorine group in the hydrazide is combined with the thiol group of 2,5-dithiothiadiazole to obtain a modified anti-wear agent, and the C-S bond formed is easy to generate a reaction film, and thiadiazole is biodegradable, reducing environmental pollution; finally, the two are mixed to obtain an extreme pressure anti-wear agent for lubricating oil, which has the effects of wear resistance, corrosion resistance, and green environmental protection.

Description

Technical Field

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

[0002] With the gradual improvement of national environmental protection, the advancement of automobile engine and transmission system design and the development of mechanical equipment, higher and higher requirements are put forward for the formulation of lubricant industry standards. Lubricant additives are compounds added to base oil at corresponding concentrations. They can be a single compound or the interaction of multiple types of compounds.

[0003] Since traditional lubricant additives represented by zinc dialkyl dithiophosphate (ZDDP) can no longer meet environmental protection requirements, green anti-friction and anti-wear lubricant additives play an increasingly important role. In order to reduce environmental pollution, whether it is possible to find an excellent environmentally friendly lubricant extreme pressure anti-wear additive to replace the most widely used ZDDP has become a hot spot in lubricant research and development. Summary of the invention

[0004] The object of the present invention is to provide an extreme pressure anti-wear agent for lubricating oil and a preparation method thereof, so as to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: an extreme pressure anti-wear agent for lubricating oil, wherein the extreme pressure anti-wear agent for lubricating oil is prepared by mixing composite organic molybdenum and modified anti-wear agent.

[0006] Furthermore, the composite organic molybdenum is prepared from 2,4-dichlorobenzyl alcohol, phosphorus pentasulfide, sodium molybdate and graphene.

[0007] Furthermore, the modified anti-wear agent is prepared from iodoacetamide, 3-chlorobenzoyl hydrazide and 2,5-dimercaptothiadiazole.

[0008] Furthermore, a method for preparing an extreme pressure anti-wear agent for lubricating oil comprises the following preparation steps:

[0009] Dissolve 25-35 parts of 2,4-dichlorobenzyl alcohol in 32-46 parts of toluene, add 18-22 parts of phosphorus pentasulfide at 40-60°C, 600 rpm, under nitrogen protection, raise the temperature to 85-95°C, react for 2-4 hours, and obtain a thiophosphoric acid solution;

[0010] After 21-34 parts of sodium molybdate and 40-50 parts of water are stirred and dissolved, 16-32 parts of dilute sulfuric acid solution are added to adjust to acidity, and then 25-39 parts of thiophosphoric acid solution are added, the temperature is raised to 80-100°C, the reaction is performed for 4-6 hours, the temperature is cooled to 20-30°C, the filter is sucked, and the filter is then rinsed with 57-73 parts of methanol, and the filter is dried at 50-60°C for 2-6 hours to obtain modified organic molybdenum;

[0011] Disperse 16-24 parts of modified organic molybdenum in 98-122 parts of ethanol, stir at 500 rpm for 10-30 min, add 34-56 parts of graphene aqueous solution, ultrasonicate at 40-60° C. and 20-100 kHz for 1-2 h, centrifuge, wash, and dry at 50-60° C. for 2-6 h to obtain composite organic molybdenum;

[0012] Dissolve 7-15 parts of 3-chlorotoluhydrazide and 2-4 parts of potassium hydroxide solid in 56-144 parts of isopropanol, add 18-42 parts of iodoacetamide and 18-46 parts of toluene, react at 80-100°C for 40-50 hours, add 55-141 parts of dichloromethane and 32-68 parts of saturated sodium bicarbonate solution to extract and separate three times after concentration, concentrate the organic phase to obtain composite hydrazide;

[0013] Dissolve 0.8-2.4 parts of potassium iodide and 1.2-1.8 parts of potassium carbonate in 47-63 parts of dimethylformamide, add 7-13 parts of 2,5-dimercaptothiadiazole, stir at 600 rpm for 10-20 min, then add 17-23 parts of composite hydrazide, react at 100-120° C. for 3-6 h, cool naturally to 20-30° C., wash with 38-52 parts of water, filter to obtain the filter cake, rinse with 21-45 parts of acetone, and dry at 50-60° C. for 2-6 h to obtain a modified wear-resistant agent;

[0014] Mix 12-18 parts of composite organic molybdenum, 4-6 parts of modified anti-wear agent, 0.02-0.08 parts of defoamer, and 0.06-0.14 parts of anti-emulsifier to obtain an extreme pressure anti-wear agent for lubricating oil.

[0015] Furthermore, the concentration of the dilute sulfuric acid in step (2) is 35%, and the pH is 1.5-2.0.

[0016] Furthermore, the concentration of the graphene aqueous solution in step (3) is 2 mg / mL.

[0017] Furthermore, in step (3), the centrifugal speed is 1800 rpm, and the centrifugal time is 10-20 min; the washing conditions are: 62-84 parts of deionized water and 62-84 parts of ethanol are alternately rinsed twice.

[0018] Furthermore, the concentration conditions in step (4) are: vacuum degree -0.1MPa~-0.04MPa, and concentration time: 1~3h.

[0019] Furthermore, the defoaming agent in step (6) is one or more of T921, DF667, and FS1265.

[0020] Furthermore, the anti-emulsifier in step (6) is one or more of D114, T1001, and T705.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0022] The invention prepares an extreme pressure anti-wear agent by mixing composite organic molybdenum with a modified anti-wear agent, so as to achieve the effects of wear resistance, corrosion resistance and green environmental protection.

[0023] Firstly, the composite organic molybdenum uses 2,4-dichlorobenzyl alcohol to react with phosphorus pentasulfide to generate di(β-2,4-dichlorobenzyl) dithiophosphoric acid, in which the sulfur, phosphorus and chlorine groups react by adsorption when in contact with the metal surface, initially forming a lubricating film on the surface to reduce wear; then it reacts with sodium molybdate under acidic conditions to generate di(β-2,4-dichlorobenzyl) dithiophosphoric acid molybdenum, introducing molybdenum atoms to reduce the friction coefficient of the oil and improve wear resistance; it is then physically mixed with graphene to make the organic molybdenum evenly adhere to the graphene surface, causing the graphene to be evenly dispersed inside the anti-wear agent in a network structure, and when friction occurs, it enters the secondary surface, fills and repairs the scratches after wear, and forms a stable oil film to increase wear resistance.

[0024] Secondly, the modified anti-wear agent is prepared from iodoacetamide, 3-chlorobenzohydrazide and thiadiazole; the iodine group of iodoacetamide reacts with the hydrazide structure of 3-chlorobenzohydrazide to make it have an amide bond, obtain hydrophobic properties, reduce liquid penetration, and improve the anti-corrosion effect. In addition, the hydrazide structure can effectively inhibit the migration of C elements from the base oil to the metal surface, has better stability and is green and environmentally friendly; then the chlorine group in the hydrazide combines with the thiol group of 2,5-dimercaptothiadiazole to form a CS bond, which is easy to form a reaction film with the metal surface to achieve an anti-wear effect. On this basis, thiadiazole is biodegradable and reduces environmental pollution. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] In order to more clearly illustrate the method provided by the present invention, the following examples are used to describe in detail the various index testing methods of the extreme pressure anti-wear agent for lubricating oil prepared in the following examples are as follows:

[0027] Load-bearing capacity: The composite additives of the embodiment and the comparative example were mixed evenly with the hydraulic oil and tested according to GB / T 3142-1982.

[0028] Corrosion resistance: The composite additives of the embodiment and the comparative example were mixed evenly with the hydraulic oil and tested according to GB / T 5096.

[0029] Biodegradation rate: The composite additives of the embodiments and comparative examples were mixed evenly with hydraulic oil and tested according to GB / T19277.1-2011.

[0030] Example 1

[0031] Dissolve 25 parts of 2,4-dichlorobenzyl alcohol in 32 parts of toluene, add 18 parts of phosphorus pentasulfide at 40°C, 600 rpm, under nitrogen protection, raise the temperature to 85°C, react for 2 hours, and obtain a thiophosphoric acid solution;

[0032] After 21 parts of sodium molybdate and 40 parts of water were stirred and dissolved, 16 parts of 35% dilute sulfuric acid solution were added to adjust the pH to 1.5, and then 25 parts of thiophosphoric acid solution were added, the temperature was raised to 80°C, the reaction was performed for 4 hours, the temperature was cooled to 20°C, the filter was sucked, and the filtrate was rinsed with 57 parts of methanol, and the filtrate was dried at 50°C for 2 hours to obtain modified organic molybdenum;

[0033] Disperse 16 parts of modified organic molybdenum in 98 parts of ethanol, stir at 500 rpm for 10 min, add 34 parts of 2 mg / mL graphene aqueous solution, ultrasonicate at 40°C and 20 kHz for 1 h, centrifuge at 1800 rpm / min for 10 min, wash twice with 62 parts of water and 62 parts of ethanol alternately, and dry at 50°C for 2 h to obtain composite organic molybdenum;

[0034] Dissolve 7 parts of 3-chlorotoluene hydrazide and 2 parts of potassium hydroxide solid in 56 parts of isopropanol, add 18 parts of iodoacetamide and 18 parts of toluene, react at 80°C for 40 hours, concentrate at -0.1 MPa for 1 hour, add 55 parts of dichloromethane and 32 parts of saturated sodium bicarbonate solution to extract and separate three times, concentrate the organic phase at -0.1 MPa for 1 hour to obtain composite hydrazide;

[0035] Dissolve 0.8 parts of potassium iodide and 1.2 parts of potassium carbonate in 47 parts of dimethylformamide, add 7 parts of 2,5-dimercaptothiadiazole, stir at 600 rpm for 10 minutes, then add 17 parts of composite hydrazide, react at 100°C for 3 hours, cool naturally to 20°C, wash with 38 parts of water, filter and take the filter cake, rinse with 21 parts of acetone, and dry at 50°C for 2 hours to obtain a modified wear-resistant agent;

[0036] 12 parts of composite organic molybdenum, 4 parts of modified anti-wear agent, 0.02 parts of T921 and 0.06 parts of D114 were mixed to obtain an extreme pressure anti-wear agent for lubricating oil.

[0037] Example 2

[0038] Dissolve 30 parts of 2,4-dichlorobenzyl alcohol in 39 parts of toluene, add 20 parts of phosphorus pentasulfide at 50°C, 600 rpm, under nitrogen protection, raise the temperature to 90°C, react for 3 hours, and obtain a phosphoric acid solution;

[0039] After 27.5 parts of sodium molybdate and 45 parts of water were stirred and dissolved, 24 parts of 35% dilute sulfuric acid solution were added to adjust the pH to 1.75, and then 32 parts of phosphoric acid solution were added, the temperature was raised to 90°C, the reaction was performed for 5 hours, the temperature was cooled to 25°C, the filter was sucked, and the filtrate was rinsed with 65 parts of methanol, and the filtrate was dried at 55°C for 4 hours to obtain modified organic molybdenum;

[0040] Disperse 20 parts of modified organic molybdenum in 110 parts of ethanol, stir at 500 rpm for 20 min, add 45 parts of 2 mg / mL graphene aqueous solution, ultrasonicate at 50°C and 60 kHz for 1.5 h, centrifuge at 1800 rpm / min for 15 min, wash twice with 73 parts of water and 73 parts of ethanol alternately, and dry at 55°C for 4 h to obtain composite organic molybdenum;

[0041] Dissolve 11 parts of 3-chlorotoluene hydrazide and 3 parts of potassium hydroxide solid in 100 parts of isopropanol, add 30 parts of iodoacetamide and 32 parts of toluene, react at 90°C for 45 hours, concentrate at -0.07 MPa for 2 hours, add 98 parts of dichloromethane and 50 parts of saturated sodium bicarbonate solution, extract and separate three times, concentrate the organic phase at -0.07 MPa for 2 hours to obtain composite hydrazide;

[0042] Dissolve 1.6 parts of potassium iodide and 1.5 parts of potassium carbonate in 55 parts of dimethylformamide, add 10 parts of 2,5-dimercaptothiadiazole, stir at 600 rpm for 15 minutes, then add 20 parts of composite hydrazide, react at 110°C for 4.5 hours, cool naturally to 25°C, wash with 45 parts of water, filter and take the filter cake, rinse with 33 parts of acetone, and dry at 55°C for 4 hours to obtain a modified wear-resistant agent;

[0043] Mix 15 parts of composite organic molybdenum, 5 parts of modified anti-wear agent, 0.05 parts of DF667 and 0.10 parts of T1001 to obtain an extreme pressure anti-wear agent for lubricating oil.

[0044] Example 3

[0045] Dissolve 35 parts of 2,4-dichlorobenzyl alcohol in 46 parts of toluene, add 22 parts of phosphorus pentasulfide at 60°C, 600 rpm, under nitrogen protection, raise the temperature to 95°C, react for 4 hours, and obtain a phosphoric acid solution;

[0046] After 34 parts of sodium molybdate and 50 parts of water were stirred and dissolved, 32 parts of 35% dilute sulfuric acid solution were added to adjust the pH to 2.0, and then 39 parts of phosphoric acid solution were added, the temperature was raised to 100°C, the reaction was performed for 6 hours, the mixture was cooled to 30°C, the mixture was filtered, and then washed with 73 parts of methanol, and dried at 60°C for 6 hours to obtain modified organic molybdenum;

[0047] Disperse 24 parts of modified organic molybdenum in 122 parts of ethanol, stir at 500 rpm for 30 min, add 56 parts of 2 mg / mL graphene aqueous solution, ultrasonicate at 60°C and 100 kHz for 2 h, centrifuge at 1800 rpm / min for 20 min, wash twice with 84 parts of water and 84 parts of ethanol alternately, and dry at 60°C for 6 h to obtain composite organic molybdenum;

[0048] Dissolve 15 parts of 3-chlorotoluene hydrazide and 4 parts of potassium hydroxide solid in 144 parts of isopropanol, add 42 parts of iodoacetamide and 46 parts of toluene, react at 100°C for 50 hours, concentrate at -0.04 MPa for 3 hours, add 141 parts of dichloromethane and 68 parts of saturated sodium bicarbonate solution, extract and separate three times, concentrate the organic phase at -0.04 MPa for 3 hours to obtain composite hydrazide;

[0049] Dissolve 2.4 parts of potassium iodide and 1.8 parts of potassium carbonate in 63 parts of dimethylformamide, add 13 parts of 2,5-dimercaptothiadiazole, stir at 600 rpm for 20 minutes, then add 23 parts of composite hydrazide, react at 120°C for 6 hours, cool naturally to 30°C, wash with 52 parts of water, filter and take the filter cake, rinse with 45 parts of acetone, and dry at 60°C for 6 hours to obtain a modified wear-resistant agent;

[0050] 18 parts of composite organic molybdenum, 6 parts of modified anti-wear agent, 0.08 parts of FS1265 and 0.14 parts of T705 were mixed to obtain an extreme pressure anti-wear agent for lubricating oil.

[0051] Comparative Example 1

[0052] The difference between Comparative Example 1 and Example 2 is that there are no steps (1) and (2), and step (3) is changed to: 20 parts of sodium molybdate are dispersed in 110 parts of ethanol, stirred at 500 rpm for 20 min, 45 parts of 2 mg / mL graphene aqueous solution are added, ultrasonicated at 50° C. and 60 kHz for 1.5 h, centrifuged at 1800 rpm / min for 15 min, washed twice with 73 parts of water and 73 parts of ethanol alternately, and dried at 55° C. for 4 h to obtain composite organic molybdenum. The remaining steps are the same as those in Example 2.

[0053] Comparative Example 2

[0054] The difference between Comparative Example 2 and Example 2 is that there is no step (3). The remaining steps are the same as those in Example 2.

[0055] Comparative Example 3

[0056] The difference between Comparative Example 3 and Example 2 is that there is no step (1), and step (2) is changed to: 27.5 parts of sodium molybdate and 45 parts of water are stirred and dissolved, and then 24 parts of 35% dilute sulfuric acid solution are added to adjust the pH to 1.75, and then 22 parts of phosphorus pentasulfide and 46 parts of toluene are added. The temperature is raised to 90°C, reacted for 5 hours, cooled to 25°C, filtered, and then rinsed with 65 parts of methanol, and dried at 55°C for 4 hours to obtain modified organic molybdenum.

[0057] Comparative Example 4

[0058] The difference between Comparative Example 4 and Example 2 is that there is no step (4), and step (5) is changed to: 1.6 parts of potassium iodide and 1.5 parts of potassium carbonate are dissolved in 55 parts of dimethylformamide, 10 parts of 2,5-dimercaptothiadiazole are added, and stirred at 600 rpm for 15 minutes, followed by adding 20 parts of iodoacetamide, reacting at 110° C. for 4.5 hours, cooling naturally to 25° C., washing with 45 parts of water, filtering to obtain a filter cake, washing with 33 parts of acetone, and drying at 55° C. for 4 hours to obtain a modified anti-wear agent. The remaining steps are the same as those in Example 2.

[0059] Comparative Example 5

[0060] The difference between Comparative Example 5 and Example 2 is that there is no step (4), and step (5) is changed to: 1.6 parts of potassium iodide and 1.5 parts of potassium carbonate are dissolved in 55 parts of dimethylformamide, 10 parts of 2,5-dimercaptothiadiazole are added, and stirred at 600 rpm for 15 minutes, followed by adding 20 parts of 3-chlorotoluohydrazide, reacting at 110° C. for 4.5 hours, cooling naturally to 25° C., washing with 45 parts of water, filtering to obtain a filter cake, washing with 33 parts of acetone, and drying at 55° C. for 4 hours to obtain a modified anti-wear agent. The remaining steps are the same as those in Example 2.

[0061] Comparative Example 6

[0062] The difference between Comparative Example 6 and Example 2 is that there is no step (5). Step (6) is changed to: 15 parts of composite organic molybdenum, 5 parts of composite hydrazide, 0.05 parts of DF667, and 0.10 parts of T1001 are mixed to obtain an extreme pressure and anti-wear agent for lubricating oil. The remaining steps are the same as those of Example 2.

[0063] Effect example

[0064] Table 1 below shows the performance analysis results of the extreme pressure antiwear agents for lubricating oils using Examples 1 to 3 of the present invention and Comparative Examples 1 to 6.

[0065] Table 1 Performance analysis results of extreme pressure antiwear agents for lubricating oils of Examples 1 to 3 and Comparative Examples 1 to 6

[0066]

[0067] From the comparison of the experimental data of Examples 1, 2, and 3 with Comparative Example 1, it can be found that the introduction of sulfur and phosphorus elements by phosphorus pentasulfide can react with the metal surface to form a lubricating film and reduce wear; from the comparison of the experimental data of Examples 1, 2, and 3 with Comparative Example 2, it can be found that by physically mixing with graphene, organic molybdenum is uniformly attached to the graphene network structure, and when friction occurs, it enters the secondary surface to fill and repair the scratches after wear, and forms a stable oil film to increase wear resistance; from the comparison of the experimental data of Examples 1, 2, and 3 with Comparative Example 3, it can be found that the chlorine group in 2,4-dichlorobenzyl alcohol can react when in contact with the metal surface to form a chemical film to enhance wear resistance; from the comparison of the experimental data of Examples 1, 2, and 3 with Comparative Example 3, it can be found that the chlorine group in 2,4-dichlorobenzyl alcohol can react when in contact with the metal surface to form a chemical film to enhance wear resistance; By comparing the experimental data of Examples 1, 2, and 3 with those of Comparative Example 4, it can be found that 3-chlorotoluohydrazide can effectively inhibit the migration of C element from the base oil to the metal surface, has better stability and can increase the biodegradation rate, and is green and environmentally friendly; by comparing the experimental data of Examples 1, 2, and 3 with those of Comparative Example 5, it can be found that the iodine group of iodoacetamide reacts with the hydrazide structure of 3-chlorotoluohydrazide to form an amide bond, has hydrophobic properties, can reduce liquid penetration, and improve the anti-corrosion effect; by comparing the experimental data of Examples 1, 2, and 3 with those of Comparative Example 6, it can be found that thiadiazole has good biodegradability, and at the same time, the thiol group combines with the chlorine group in the hydrazide to form a CS bond, generates a reaction film with the metal, and improves the lubrication effect.

[0068] It is obvious 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 as exemplary and non-restrictive in all respects.

Claims

1. An extreme pressure anti-wear agent for lubricating oil, characterized in that: The extreme pressure anti-wear agent for lubricating oil is prepared by mixing composite organic molybdenum and modified anti-wear agent; The method for preparing the extreme pressure anti-wear agent for lubricating oil comprises the following preparation steps: (1) Dissolve 25-35 parts of 2,4-dichlorobenzyl alcohol in 32-46 parts of toluene, add 18-22 parts of phosphorus pentasulfide at 40-60°C, 600 rpm, under nitrogen protection, raise the temperature to 85-95°C, react for 2-4 hours, and obtain a thiophosphoric acid solution; (2) After 21-34 parts of sodium molybdate and 40-50 parts of water are stirred and dissolved, 16-32 parts of dilute sulfuric acid solution are added to adjust to acidity, followed by addition of 25-39 parts of thiophosphoric acid solution, heating to 80-100°C, reacting for 4-6 hours, cooling to 20-30°C, filtering with suction, and then washing the filtrate with 57-73 parts of methanol, and drying at 50-60°C for 2-6 hours to obtain modified organic molybdenum; (3) Dispersing 16-24 parts of modified organic molybdenum in 98-122 parts of ethanol, stirring at 500 rpm for 10-30 min, adding 34-56 parts of graphene aqueous solution, ultrasonicating at 40-60° C. and 20-100 kHz for 1-2 h, centrifuging, washing, and drying at 50-60° C. for 2-6 h to obtain composite organic molybdenum; (4) Dissolve 7-15 parts of 3-chlorotoluhydrazide and 2-4 parts of potassium hydroxide solid in 56-144 parts of isopropanol, add 18-42 parts of iodoacetamide and 18-46 parts of toluene, react at 80-100°C for 40-50 hours, add 55-141 parts of dichloromethane and 32-68 parts of saturated sodium bicarbonate solution after concentration, extract and separate three times, concentrate the organic phase, and obtain a composite hydrazide; (5) Dissolve 0.8-2.4 parts of potassium iodide and 1.2-1.8 parts of potassium carbonate in 47-63 parts of dimethylformamide, add 7-13 parts of 2,5-dimercaptothiadiazole, stir at 600 rpm for 10-20 min, then add 17-23 parts of composite hydrazide, react at 100-120°C for 3-6 h, cool naturally to 20-30°C, wash with 38-52 parts of water, filter and take the filter cake, rinse with 21-45 parts of acetone, and dry at 50-60°C for 2-6 h to obtain a modified wear-resistant agent; (6) 12 to 18 parts of composite organic molybdenum, 4 to 6 parts of modified anti-wear agent, 0.02 to 0.08 parts of defoaming agent, and 0.06 to 0.14 parts of anti-emulsifier are mixed to obtain an extreme pressure anti-wear agent for lubricating oil.

2. The extreme pressure anti-wear agent for lubricating oil according to claim 1, characterized in that: The concentration of dilute sulfuric acid in step (2) is 35%, and the pH is 1.5-2.

0.

3. The extreme pressure anti-wear agent for lubricating oil according to claim 1, characterized in that: The concentration of the graphene aqueous solution in step (3) is 2 mg / mL.

4. The extreme pressure anti-wear agent for lubricating oil according to claim 1, characterized in that: The centrifugal speed in step (3) is 1800 rpm, and the centrifugal time is 10-20 min; the cleaning conditions are: 62-84 parts of deionized water and 62-84 parts of ethanol are alternately rinsed twice.

5. The extreme pressure anti-wear agent for lubricating oil according to claim 1, characterized in that: The concentration conditions in step (4) are: vacuum degree -0.1MPa~-0.04MPa, and concentration time: 1~3h.

6. The extreme pressure anti-wear agent for lubricating oil according to claim 1, characterized in that: The defoaming agent in step (6) is one or more of T921, DF667, and FS1265.

7. The extreme pressure anti-wear agent for lubricating oil according to claim 1, characterized in that: The anti-emulsifier in step (6) is one or more of D114, T1001, and T705.

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