A heavy-duty open-gear graphene grease and its preparation method

Abstract

The present invention relates to the technical field of lubrication, and specifically relates to a heavy-duty open-gear graphene grease and a preparation method thereof. In the present invention, octadecylamine and ionic liquid are grafted onto the surface of graphene, and after reacting with modified Jatropha curcas oil, modified graphene is obtained. Then, PAO, alkylnaphthalene oil, fumed silica and additives are added to obtain the heavy-duty open-gear graphene grease. By modifying graphene and cooperating with nano tungsten disulfide, the grease has good lubrication and wear resistance; by synthesizing anionic salts to modify graphene, the obtained grease has good extreme pressure performance; by modifying Jatropha curcas oil to obtain graphene oxide, further controlling the specific surface area of fumed silica and the pH of the system, finally the grease can meet the actual high-temperature use requirements; by changing the dosage of each component raw material and adding the raw materials in batches, the obtained grease has good low-temperature resistance and oxidation stability, low bleeding rate and small evaporation loss.

Description

Technical Field

[0001] The present invention relates to the technical field of lubrication, and specifically to a heavy-duty open-gear graphene grease and a preparation method thereof. Background Art

[0002] In the process of industrial processing and production, heavy-duty open gears are a common transmission method. Open gears are widely used in various types of large equipment such as granulators, drum pulpers, and tube mills. During actual operation, due to the high surface roughness of the tooth surface, high or low working temperatures, and high operating loads, friction and wear are extremely likely to occur. Gear wear not only affects the progress of the working process but also causes huge economic losses. Therefore, in order to meet harsh usage conditions, reduce mechanical friction and wear, and extend the service life of machinery, it is necessary to reasonably use grease and prepare suitable grease to meet actual usage requirements.

[0003] Graphene is often used as a component of grease. Graphene is an atomically thick planar sheet with a hexagonal lattice structure arranged by carbon atoms. Since its invention in 2004, it has become the most promising material. Graphene has high electrical and thermal conductivity, excellent mechanical strength, and a large specific surface area, and can be used to improve the wear resistance of grease and reduce the friction force on the contact surface of gear operation. However, due to the easy aggregation and poor dispersibility of graphene during the preparation of grease, the lubrication and wear resistance of the final grease are poor. Therefore, a large number of methods for modifying graphene have emerged. Patent CN202110423727.0 discloses a preparation method of a super-regular graphene-based grease. Through the processes of oxidizing graphite powder and high-temperature reduction, and using the method of dissolution-evaporation-macroscopic dispersion-microscopic homogenization, super-regular graphene sheets are used in the grease. The friction coefficient of the grease is small, and the friction coefficient tends to be stable as the friction time increases.

[0004] Patent CN202010819805.4 discloses a method for preparing graphene using composite ionic liquids. The ground and pretreated graphite powder is mixed with the composite ionic liquid, and carbon dioxide is used as a protective gas for the reaction. The dispersion of graphene is stabilized through the Coulomb interaction between anions and cations, and the dispersibility of graphene is good. However, as an organic salt, the anti-wear performance and extreme pressure performance of ionic liquids are poor when used alone. Therefore, they need to be used in combination with nanomaterials or solid films.

[0005] Patent 202211692907.X discloses a grease for harmonic reducers and a preparation method thereof. The adhesion is improved by polyhydrogenated styrene / isoprene type improvers and polyisobutylene type structure improvers in the grease, and the extreme pressure performance of the grease is improved by using organic molybdenum, zinc salts, and thiadiazoles.

[0006] During the preparation of grease, in addition to considering its anti-friction property and the problem of coping with high pressure use, the service life of the grease also needs to be considered. One important evaluation index is the dropping point and the working penetration of the grease. Patent CN201410026925.3 discloses a composition of a food-grade grease and its preparation method. A combined grease is prepared from raw materials such as base oil, benzoic acid, aluminum isopropoxide trimer, rust inhibitor, and silicone oil. The working penetration of the grease is 270 - 280 (0.1mm), and the dropping point is in the range of 298 - 305 °C.

[0007] As an important evaluation index, a high bleeding rate and high evaporation loss of the grease will directly affect the normal use of the grease. Patent CN201310084582.1 discloses a high-performance complex calcium sulfonate grease and its preparation method. The complex calcium sulfonate grease prepared from overbased calcium sulfonate, base oil, lauric acid, low molecular alcohol, high-purity water, boric acid, calcium hydroxide, antioxidant, and HL-functional agent has the advantages of low bleeding rate, high temperature resistance, and extreme pressure and anti-wear properties.

[0008] If the oxidation stability of the grease is good, the actual service time is long and the properties of the grease are stable. Patent 201911307265.5 discloses a preparation method of a graphene composite grease. Using base oil, graphene, high molecular acid, calcium hydroxide, low molecular acid, lithium hydroxide, etc. as raw materials, the raw materials are added in batches to prepare a lithium-based grease. The obtained grease has good colloidal stability, high dropping point, anti-friction performance and antioxidant property, and extends the service life of the grease.

[0009] Although certain progress has been made in the research of grease, during the preparation of heavy-duty open-gear graphene grease, the lubrication and wear resistance, extreme pressure property, dropping point, penetration, bleeding rate, evaporation loss, and oxidation stability of the grease and other aspects of performance need to be comprehensively considered.

[0010] Therefore, a heavy-duty open-gear graphene grease and its preparation method are proposed. Summary of the Invention

[0011] The purpose of the present invention is to provide a heavy-duty open-gear graphene grease and its preparation method. By modifying graphene oxide, the obtained modified graphene synergistically acts with nano tungsten disulfide in the additive. The average wear scar diameter of the obtained heavy-duty open-gear graphene grease is 0.296 - 0.491 mm, and the friction coefficient is 0.02 - 0.09; by synthesizing anionic salt and connecting it to the surface of graphene oxide through chemical bonds to obtain modified graphene, and synergistically acting with molybdenum dioctyl dithiocarbamate and 2-mercapto-1,3,4-thiadiazole in the additive, the heavy-duty open-gear graphene grease P Bwith values of 1236 N and 1569 N, P D with values of 6080 N and 7846 N; epoxidized Jatropha curcas oil is obtained by oxidizing Jatropha curcas oil, the epoxidized Jatropha curcas oil is ring-opened and reacted with the carboxyl groups in the NH2-PEG-COOH solution, and the unreacted amino groups in the NH2-PEG-COOH are further covalently bonded with phytic acid to prepare modified graphene and heavy-duty open-gear graphene grease; fumed silica is used as a thickening agent for synthesizing the grease, and by controlling the amounts of phytic acid and 2-hydroxy-3-naphthoic acid, the specific surface area of fumed silica, and the pH of the system, the obtained heavy-duty open-gear graphene grease has a penetration of 355 - 430 (0.1 mm) and a dropping point of 220 - 329 °C; a grease is prepared from modified graphene, PAO, alkyl naphthalene base oil, fumed silica, and additives, and by changing the addition amounts of PAO, alkyl naphthalene base oil, fumed silica, and modified graphene, the obtained heavy-duty open-gear graphene grease has an initial oxidation temperature of 280 °C - 295 °C and a low-temperature apparent viscosity of 796 - 980 Pa·s at -40 °C; by changing the preparation method of the ionic liquid in the modified graphene, changing the mass ratios of the surfactant to the modified graphene intermediate II and the modified Jatropha curcas oil, and by adding the PAO reaction raw materials in portions, the addition amount of the first raw material is lower than that of the second raw material. Finally, the obtained grease has a steel wire mesh oil separation of 0.13% - 0.27% and an evaporation loss of 0.08% - 0.33%.

[0012] To achieve the above object, the present invention provides the following technical solutions:

[0013] On the one hand, the present invention provides a preparation method of a heavy-duty open-gear graphene grease, characterized by comprising the following steps:

[0014] Graphite powder is oxidized to obtain graphene oxide; 0.16 - 0.38 parts of octadecylamine, 1-hydroxybenzotriazole, 4-dimethylaminopyridine, 0.09 - 0.22 parts of trimethylchlorosilane, DMF, and hydrochloric acid are added to the mixed solution of the graphene oxide and water to obtain a modified graphene precursor; 0 - 0.21 parts of 1-methylimidazole is added to the modified graphene precursor, and a modified graphene intermediate I is obtained by reaction; 0 - 1.35 parts of an anion salt is added to the modified graphene intermediate I, and refluxing is carried out to obtain a modified graphene intermediate II;

[0015] NH2-PEG-COOH solution is added to the epoxidized Jatropha curcas oil, and an NH2-PEG-COOH-JCOE solution is obtained by reaction; the addition amount of the NH2-PEG-COOH solution is 10.9 - 28.2 parts; after heating, 594 - 627 parts of a phytic acid solution is added, and after reaction, distillation under reduced pressure is carried out to obtain modified Jatropha curcas oil;

[0016] Sodium dodecylbenzenesulfonate, Tween 80, the modified graphene intermediate II, and the modified Jatropha curcas oil with a mass ratio of 0.01 - 0.03:0.01 - 0.02:1:0.3 are placed in a ball milling tank and ground to obtain modified graphene;

[0017] PAO and a mixture containing 0 - 83 parts of alkylnaphthalene oil are used to obtain a mixed base oil; the PAO accounts for 1 / 20 - 4 / 5 of the total mass of the PAO added; after heating and reacting, the modified graphene, 7.21 - 9.01 parts of a thickening agent with a specific surface area of 100 - 300 m 2 / g are added, the pH of the system is 3.0 - 5.0, and after heating and reacting, a heavy-duty open-gear graphene grease precursor is obtained; the PAO, stearic acid, and modified graphene are added in a supplementary manner, heated and reacted, cooled, additives are added, and ground to obtain the heavy-duty open-gear graphene grease; the total addition amount of the modified graphene is 0.05 - 0.40 parts; the total addition amount of the PAO is 0 - 83.0 parts; the grinding speed is 250 - 400 rpm, and the grinding time is 1.5 - 3.5 h.

[0018] Preferably, the preparation method of the graphene oxide is as follows: concentrated sulfuric acid and concentrated nitric acid are mixed at a volume ratio of 4:1 to obtain a mixed acid solution; 10.5 parts of the graphite powder and 8.0 parts of sodium nitrate are added to 0.7 L of the mixed acid solution, and ultrasonic reaction is carried out for 2 h to obtain a graphene oxide solution; the graphene oxide solution is centrifuged to obtain an insoluble substance; the insoluble substance is washed with a 30% volume fraction of hydrogen peroxide solution and a 5% volume fraction of hydrochloric acid solution, and then repeatedly washed with deionized water and dried to obtain graphene oxide.

[0019] Preferably, the anionic salt is one of potassium hexafluorophosphate and 2-hydroxy-3-naphthoic acid borate; the preparation method of the 2-hydroxy-3-naphthoic acid borate includes the following steps:

[0020] 0.76 - 1.15 parts of 2-hydroxy-3-naphthoic acid are dispersed in 20 parts of DMF to obtain a 2-hydroxy-3-naphthoic acid solution; 0.30 parts of boric acid are dispersed in 10 parts of DMF to obtain an inorganic acid solution; the inorganic acid solution is added to the 2-hydroxy-3-naphthoic acid solution, and then 0.02 parts of lithium carbonate are added, and the temperature is slowly raised to 30 - 60 °C, and reflux reaction is carried out until the pH value of the system is stable to obtain a product; the product is centrifuged, washed, and dried to obtain the 2-hydroxy-3-naphthoic acid borate.

[0021] Preferably, the preparation method of the modified Jatropha curcas oil is as follows: Add Jatropha curcas oil into a three-necked flask, add glacial acetic acid and concentrated sulfuric acid thereto under rapid stirring, and after mixing evenly, heat up to 30 °C to obtain the Jatropha curcas oil to be oxidized; Dropwise add hydrogen peroxide with a mass fraction of 35% into the Jatropha curcas oil to be oxidized at a speed of 2 drops per second, heat up to 65 °C and react for 4.5 h, and obtain the epoxidized Jatropha curcas oil after liquid separation and washing; Add 1 / 3 part of the NH2-PEG-COOH solution to the epoxidized Jatropha curcas oil, react at a rotation speed of 600 rpm for 6 h, and then continue to add 2 / 3 part of the amino polyethylene glycol carboxyl solution, and obtain an amino polyethylene glycol carboxyl grafted epoxidized Jatropha curcas oil solution (NH2-PEG-COOH-JCOE) after reacting for 15 h; The total addition amount of the amino polyethylene glycol carboxyl solution is 10.9-28.2 parts; Heat up the NH2-PEG-COOH-JCOE solution to 75 °C, slowly add 594-627 parts of phytic acid solution thereto, and obtain a PTE-NH2-PEG-COOH-JCOE solution after reacting for 24 h; The PTE-NH2-PEG-COOH-JCOE solution is distilled under reduced pressure to remove water, and 5 parts of magnesium sulfate are added and dried for 12 h to obtain the modified Jatropha curcas oil.

[0022] Preferably, the preparation method of the heavy-duty open gear graphene grease is as follows: Add the dodecahydroxy stearic acid, the stearic acid and 0-83 parts of the alkylnaphthalene oil to the PAO to obtain a mixed base oil; The first addition amount of the PAO is 1 / 20-4 / 5 of the total addition amount mass of the PAO; Heat up the mixed base oil to 90 °C and maintain it for 1 h, then add 1 / 4 of the modified graphene and 7.21-9.01 parts of the thickener with a specific surface area of 100-300 m 2 / g, adjust the pH of the system to 3.0-5.0, raise the temperature to 120 °C, and react for 2 h to obtain the precursor of the heavy-duty open gear graphene grease; Add the PAO to the precursor of the heavy-duty open gear graphene grease, supplement the stearic acid, then add 3 / 4 of the modified graphene, raise the temperature to 200 °C, stop heating and stirring after reacting for 20 min, and when the temperature drops to 70 °C, add the additive thereto, stir and mix for 1 h, and cool to room temperature to obtain an intermediate of the heavy-duty open gear graphene grease; The second addition amount of the PAO is 1 / 5-19 / 20 of the total addition amount mass of the PAO; Place the intermediate of the heavy-duty open gear graphene grease in a three-roll mill, the grinding rotation speed is 250-400 rpm, and the grinding time is 1.5-3.5 h to obtain the heavy-duty open gear graphene grease; The total addition amount of the PAO is 0-83.0 parts; The total addition amount of the modified graphene is 0.05-0.40 parts; The thickener is fumed silica.

[0023] Preferably, the 1-methylimidazole is 0.05 - 0.10 parts; the anionic salt is 0.55 - 1.35 parts; the alkyl naphthalene base oil is 23 - 30 parts.

[0024] Preferably, the first addition amount of the PAO is 1 / 20 - 2 / 5 of the total addition amount of the PAO by mass; the second addition amount of the PAO is 3 / 5 - 19 / 20 of the total addition amount of the PAO by mass.

[0025] Preferably, the additive includes 0.1 part of nano metal sulfide, 0.01 - 0.03 part of molybdenum dioctyl dithiocarbamate, 0.01 - 0.04 part of 2-mercapto-1,3,4-thiadiazole, 0.03 part of trans-1,2-cyclohexanedicarboxylic acid, and 0.02 part of 2,5-bis(mercapto)-1,3,4-thiadiazole dimer.

[0026] Preferably, the nano metal sulfide is one of nano tungsten disulfide and nano molybdenum disulfide; the particle size of the nano tungsten disulfide is 500 μm; the particle size of the nano molybdenum disulfide is 500 μm.

[0027] On the other hand, the present invention provides a heavy-duty open-gear graphene grease, which is characterized in that: the heavy-duty open-gear graphene grease includes the modified graphene, the PAO, the alkyl naphthalene oil, the 12-hydroxystearic acid, the stearic acid, and the additive; the heavy-duty open-gear graphene grease is prepared by the preparation method described in any one of the above; the average wear scar diameter of the heavy-duty open-gear graphene grease is 0.296 - 0.491 mm, and the friction coefficient is 0.02 - 0.09; the P B value of the heavy-duty open-gear graphene grease is 1236 N and 1569 N, and the P D value is 6080 N and 7846 N; the penetration of the heavy-duty open-gear graphene grease is 355 - 430 (0.1 mm), and the dropping point is 220 - 329 °C; the initial oxidation temperature of the heavy-duty open-gear graphene grease is 280 °C - 295 °C, and the low-temperature apparent viscosity at -40 °C is 796 - 980 Pa·s; the steel wire mesh oil separation amount of the heavy-duty open-gear graphene grease is 0.13% - 0.27%, and the evaporation loss is 0.08% - 0.33%.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. The present invention chemically modifies graphene, grafting octadecylamine and ionic liquid onto the surface of graphene. The carboxyl groups on the graphene surface are covalently connected to the amino groups of octadecylamine through chemical bonds, introducing long-chain alkanes into the system. The long carbon chains provide more intermolecular contact points, increasing the intermolecular friction and enhancing the frictional stress. The carboxyl groups on the graphene surface are first coupled with hydrolyzed trimethylchlorosilane, and then the chlorine element is replaced by 1-methylimidazole to form imidazolium cations and chloride ions. The chloride ions are replaced by potassium hexafluorophosphate, and the imidazole forms an ionic liquid film on the graphene surface through Π-Π conjugation interaction with graphene, and at the same time, a chemical deposition film mainly composed of Fe2O3 and Fe3O4 is also formed. Modified graphene is obtained by controlling the dosage of the modifying substances. The modified graphene has good dispersibility, and the modified graphene and nano tungsten disulfide act synergistically to reduce the friction between heavy-duty open gears. The obtained heavy-duty open gear graphene grease has an average wear scar diameter of 0.296 - 0.491 mm, a friction coefficient of 0.02 - 0.09, and good lubrication and wear resistance performance.

[0030] 2. An anion salt is synthesized from 2-hydroxy-3-naphthoic acid and boric acid as raw materials, used to modify graphene, and finally a grease is prepared. By controlling the dosages of the raw materials, additives, as well as the grinding speed and time of the grease, the obtained grease has P B values of 1236 N and 1569 N, and P D values of 6080 N and 7846 N, showing good extreme pressure performance of the grease. By forming a borate film between the grease and the open gear, and acting together with the additives molybdenum dioctyl dithiocarbamate and 2-mercapto-1,3,4-thiadiazole, the extreme pressure performance of the grease is improved.

[0031] 3. Epoxy Jatropha curcas oil is obtained by oxidizing Jatropha curcas oil. The epoxy Jatropha curcas oil undergoes ring-opening reaction with the carboxyl groups in the amino polyethylene glycol carboxyl solution, and the unreacted amino groups in the amino polyethylene glycol carboxyl are further covalently connected with phytic acid to further prepare modified graphene and grease. By controlling the dosage of phytic acid in the modified Jatropha curcas oil and changing the dosage of 2-hydroxy-3-naphthoic acid in 2-hydroxy-3-naphthoic acid borate, modified graphene is obtained. The modified graphene is then mixed with base oil, fumed silica and additives to obtain grease. The hydroxyl groups on the surface of fumed silica can form intermolecular hydrogen bonds with the hydroxyl groups on the surface of graphene. The specific surface area of fumed silica is controlled in the range of 100 - 300 m 2 / g, and the pH of the system is controlled. The obtained grease has a penetration in the range of 355 - 430 (0.1 mm) and a dropping point in the range of 220 - 329 °C, with good physical and chemical properties of the grease and being able to meet the actual high-temperature use requirements.

[0032] 4. A grease is prepared from modified graphene, PAO, alkyl naphthalene base oil, fumed silica and additives. By changing the addition amounts of PAO, alkyl naphthalene base oil and fumed silica, the starting oxidation temperature of the obtained heavy-duty open-gear graphene grease is 280°C - 295°C, and the low-temperature apparent viscosity at -40°C is 796 - 980 Pa·s. On the one hand, alkyl naphthalene can improve the compatibility between the auxiliary materials and the system, and on the other hand, it has excellent oxidation stability. The electron-rich naphthalene ring in alkyl naphthalene can capture the oxidizing groups generated by the oxidation of hydrocarbon groups, making it difficult to form the entire oxidation chain, thus preventing the oxidation process. In addition, alkyl naphthalene and fumed silica also have good low-temperature resistance effects. Therefore, the grease prepared by the present invention has good low-temperature resistance and oxidation stability.

[0033] 5. By changing the preparation method of the ionic liquid in the modified graphene, changing the mass ratios of the surfactant to the modified graphene intermediate II and the modified Jatropha curcas oil, and by adding the PAO reaction raw materials in portions, the addition amount of the first raw material is lower than that of the second raw material. The final obtained grease has a steel mesh bleeding value of 0.13% - 0.27% and an evaporation loss of 0.08% - 0.33%. The addition of the ionic liquid reduces the evaporation loss of the grease; the two surfactants sodium dodecylbenzenesulfonate and Tween 80 promote the tight connection between the modified graphene intermediate II and the modified Jatropha curcas oil, and at the same time increase the compatibility of the obtained modified graphene with components such as the base oil. Sodium dodecylbenzenesulfonate, as an ionic surfactant, improves the compatibility of imidazole and 2-hydroxy-3-naphthoate borate in the ionic liquid on the surface of the modified graphene with the system. The rational use of the surfactant, modified graphene and base oil reduces the bleeding value of the grease and also reduces the evaporation loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a test result diagram of the average wear scar diameter and friction coefficient of the grease obtained in Example 17 of the present invention;

[0035] Figure 2 It is a test result diagram of the steel mesh bleeding value and evaporation loss of the grease obtained in Example 63 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0037] Please refer to Figures 1 to 2, the present invention provides a heavy-duty open gear graphene grease and a preparation method thereof, and the technical solution is as follows:

[0038] The substance information involved in the present invention is as follows:

[0039] Jatropha curcas oil, industrial grade, purchased from Jiangxi Zhonghuan New Materials Co., Ltd.;

[0040] Amino polyethylene glycol carboxyl purchased from Guangzhou Carbohydrate Technology Co., Ltd.;

[0041] Phytic acid purchased from Laiyang Wanjwei Biotechnology Co., Ltd.;

[0042] 2-Mercapto-1,3,4-thiadiazole purchased from Hangzhou Shi'an Chemical Co., Ltd.;

[0043] SYP grease anti-wear and extreme pressure performance tester purchased from Shanghai Mitong Electromechanical Technology Co., Ltd.;

[0044] Grease penetrometer purchased from Changzhou Dedu Precision Instruments Co., Ltd.;

[0045] SYS-3498 - Grease wide temperature range dropping point tester purchased from Dandong Zhongyi Electronic Equipment Co., Ltd.;

[0046] High-viscosity polyalphaolefin (PAO) and alkylnaphthalene base oils are both purchased from ExxonMobil Corporation;

[0047] Nano tungsten disulfide, 500nm nano; molybdenum disulfide, 500nm, both purchased from Shanghai Xiangtian Nano Materials Co., Ltd.;

[0048] Molybdenum dioctyldithiocarbamate purchased from Hangzhou Shi'an Chemical Co., Ltd.;

[0049] 2-Mercapto-1,3,4-thiadiazole purchased from Hunan Yunbang Biotechnology Co., Ltd.;

[0050] 2,5-2-Mercapto-1,3,4-thiadiazole dimer CAS: 72676-55-2; octadecylamine CAS: 124-30-1; 1-hydroxybenzotriazole CAS: 2592-95-2; 4-dimethylaminopyridine CAS: 1122-58-3; 2-hydroxy-3-naphthoic acid CAS: 202-180-8; trimethylchlorosilane CAS: 75-77-4; 1-methylimidazole CAS: 616-47-7; potassium hexafluorophosphate CAS: 17084-13-8; trans-1,2-cyclohexanedicarboxylic acid CAS: 2305-32-0; dodecahydroxystearic acid CAS: 106-14-9.

[0051] SYS-3498 - Grease wide temperature range dropping point tester purchased from Dandong Zhongyi Electronic Equipment Co., Ltd.

[0052] It should be noted that other chemical reagents, consumables, and instruments in the present invention are all common reagents, consumables, and instruments used in chemical experiments; the purity of the chemical reagents is analytical pure.

[0053] Examples 1 - 12

[0054] Concentrated sulfuric acid and concentrated nitric acid were mixed in a volume ratio of 4:1 to obtain a mixed acid solution; 10.5 parts of graphite powder and 8.0 parts of sodium nitrate were added to 0.7 L of the mixed acid solution, and ultrasonic reaction was carried out for 2 h to obtain a graphene oxide solution; the graphene oxide solution was centrifuged to obtain insoluble substances; the insoluble substances were washed with a 30% by volume hydrogen peroxide solution and a 5% by volume hydrochloric acid solution, and then repeatedly washed with deionized water and dried to obtain graphene oxide;

[0055] The graphene oxide was mixed with 300 parts of deionized water to obtain a graphene mixed solution; 0.19 part of octadecylamine, 0.23 part of 1-hydroxybenzotriazole, 0.19 part of 4-dimethylaminopyridine, 0.20 part of trimethylchlorosilane, 20 parts of DMF, and 5 parts of 30% by volume hydrochloric acid were added to the graphene mixed solution. Under nitrogen protection, reflux reaction was carried out at 120 °C for 12 h to obtain a modified graphene precursor; 0.10 part of 1-methylimidazole was added to the modified graphene precursor, and reflux reaction was continued for 24 h to obtain a first modified graphene intermediate; 1.20 parts of anionic salt potassium hexafluorophosphate was added to the first modified graphene intermediate, and reflux was carried out for 12 h. The obtained precipitate was centrifuged, washed with deionized water, and dried to obtain a second modified graphene intermediate;

[0056] 200 parts of Jatropha curcas oil was added to a three-necked flask. 1 part of glacial acetic acid and 2 parts of concentrated sulfuric acid were added thereto under rapid stirring. After mixing evenly, the temperature was raised to 30 °C to obtain the Jatropha curcas oil to be oxidized; 50 parts of 35% by mass hydrogen peroxide was added dropwise to the Jatropha curcas oil to be oxidized at a rate of 2 drops / s. After the temperature was raised to 65 °C, the reaction was carried out for 4.5 h. After liquid separation and washing, epoxidized Jatropha curcas oil was obtained; 1 / 3 volume of an amino polyethylene glycol carboxyl solution was added to the epoxidized Jatropha curcas oil, and the reaction was carried out at 600 rpm for 6 h. Then, 2 / 3 volume of the amino polyethylene glycol carboxyl solution was added, and after the reaction for 15 h, an amino polyethylene glycol carboxyl grafted epoxidized Jatropha curcas oil solution (NH2-PEG-COOH-JCOE) was obtained; the total addition amount of the amino polyethylene glycol carboxyl solution was 19.1 parts; the NH2-PEG-COOH-JCOE solution was heated to 75 °C, and 605 parts of phytic acid (PTE) solution was slowly added thereto. After the reaction for 24 h, a PTE-NH2-PEG-COOH-JCOE solution was obtained; the PTE-NH2-PEG-COOH-JCOE solution was distilled under reduced pressure to remove water, and 5 parts of magnesium sulfate was added and dried for 12 h to obtain modified Jatropha curcas oil;

[0057] Sodium dodecylbenzenesulfonate, Tween 80, modified graphene intermediate II, and modified Jatropha curcas oil with a mass ratio of 0.01:0.01:1:0.3 were placed in a ball milling tank and ground to obtain modified graphene; the grinding conditions were as follows: the mass ratio of balls to materials was 50:1, the grinding revolution speed was 300 rpm, and it rotated forward and backward for 2 h each;

[0058] 6.5 parts of dodecahydroxystearic acid, 2.1 parts of stearic acid, and 23 parts of alkylnaphthalene base oil were added to 1 / 4 PAO to obtain a mixed base oil; the mixed base oil was heated to 90 °C and maintained for 1 h, and then 1 / 4 modified graphene and 7.51 parts of fumed silica (thickening agent) with a specific surface area of 300 m 2 / g were added. The pH of the system was adjusted to 5.0, the temperature was raised to 120 °C, and the reaction was carried out for 2 h to obtain a heavy-duty open-gear graphene grease precursor; 3 / 4 PAO was added to the heavy-duty open-gear graphene grease precursor as a temperature-raising oil, 0.6 part of stearic acid was added additionally, and then 3 / 4 modified graphene was added. The temperature was raised to 200 °C, and after the reaction for 20 min, the heating and stirring were stopped. When the temperature dropped to 70 °C, additives were added, and the mixture was stirred for 1 h and cooled to room temperature to obtain a heavy-duty open-gear graphene grease intermediate; the heavy-duty open-gear graphene grease intermediate was placed in a three-roll mill, the grinding speed was 300 rpm, and the grinding time was 3 h to obtain a heavy-duty open-gear graphene grease; the total addition amount of PAO was 60 parts; the total addition amount of modified graphene was 0.1 part;

[0059] The additives include 0.1 part of nano tungsten disulfide, 0.03 part of molybdenum dioctyldithiocarbamate, 0.01 part of 2-mercapto-1,3,4-thiadiazole, 0.03 part of trans-1,2-cyclohexanedicarboxylic acid, and 0.02 part of 2,5-2-mercapto-1,3,4-thiadiazole dimer; the total addition amounts of PAO, the alkylnaphthalene base oil, the dodecahydroxystearic acid, the stearic acid, the modified graphene, the thickening agent, and the additives are 100 parts.

[0060] Different from Example 1, the following preparation method was changed, as shown in Table 1 specifically.

[0061] Table 1 Specific changes in the preparation method

[0062]

[0063]

[0064] Comparative Example 4

[0065] Different from Example 3, nano tungsten disulfide was replaced by nano molybdenum disulfide.

[0066] Examples 13 - 16

[0067] Different from Example 3, the addition amounts of the modified graphene are 0.05 part, 0.08 part, 0.13 part, and 0.20 part in sequence.

[0068] Example 17

[0069] The heavy - load open - type gear graphene grease prepared in Examples 1 - 16 and Comparative Examples 1 - 4 was subjected to an anti - wear performance test. The test method was carried out with reference to SH / T 0204 - 1992 "Determination Method for Anti - wear Performance of Grease (Four - Ball Machine Method)", and the test conditions were as follows: test temperature 76 °C, spindle speed 1200 rpm, test load 392 N, test time 60 min. The final test results are shown in Table 2, and the test results of the grease in Examples 1 - 7 are Figure 1 shown.

[0070] Table 2 Anti - wear Performance Test Results of Greases in Examples 1 - 16 and Comparative Examples 1 - 4

[0071]

[0072]

[0073] As shown in Table 2 and Figure 1As shown, the average wear scar diameter of the heavy-duty open gear graphene grease prepared in the embodiments of the present invention is 0.296 - 0.491 mm, and the friction coefficient is 0.02 - 0.09. In Examples 1 - 7, by changing the addition amounts of octadecylamine, trimethylchlorosilane, 1-methylimidazole, and potassium hexafluorophosphate, the average wear scar diameter shows a trend of decreasing, increasing, and then decreasing, and the average friction coefficient reaches the minimum value in Example 3. The surface of graphene oxide is rich in hydroxyl and carboxyl groups. Some carboxyl groups are covalently bonded to the amino groups of octadecylamine through chemical bonds, and long-chain alkanes are introduced into the system. The long carbon chains provide more intermolecular contact points, thus increasing the intermolecular frictional force. When subjected to the force of gear rotation, the direct force between the gears is converted into the frictional force inside the grease, reducing the friction between the gears; some carboxyl groups are first coupled with the hydrolyzed trimethylchlorosilane, and then the chlorine element is replaced by 1-methylimidazole to form imidazolium cations and chloride ions. The chloride ions are replaced by potassium hexafluorophosphate. The imidazole and graphene interact through Π-Π conjugation, and the formed ionic liquid forms a thin film on the surface of graphene. It synergistically interacts with the nano tungsten disulfide under the action of frictional stress with the engineering surface, not only protecting the surface and improving the surface strength, but also reducing friction and promoting the dispersion of modified graphene in the grease. In Comparative Example 1 and Comparative Example 2, octadecylamine and 1-methylimidazole, potassium hexafluorophosphate were not added respectively, so the friction coefficient is larger and the average wear scar diameter is larger compared with the examples. In Comparative Example 4, after replacing nano tungsten disulfide with nano molybdenum disulfide, the lubricating performance and friction resistance of the grease decreased. Comparing the results of Example 3 with those of Examples 8 - 12, as the relative molecular mass of amino polyethylene glycol carboxyl group increases, the wear scar diameter and friction coefficient first reach the optimal values and then increase to varying degrees. As shown in Example 3, when the relative molecular mass of amino polyethylene glycol carboxyl group is 10,000, the friction and abrasion resistance are the best. In Comparative Example 3, when NH2-PEG-COOH-10000 was replaced with PEG200, the final performance decreased. After mechanical grinding, the modified Jatropha curcas oil is distributed inside the lamellar graphene and outside the graphene grafted with octadecylamine and ionic liquid, jointly improving the lubricating performance of the grease.

[0074] Comparing the results of Example 3 with those of Examples 13 - 16, it can be seen that when the addition amount of modified graphene is 0.1 part, that is, 0.1 wt% in the system, the average wear scar diameter and the friction coefficient are the smallest. During the operation of the heavy-duty open gear, the grease forms a chemical deposition film mainly composed of Fe2O3 and Fe3O4 and a physical adsorption film rich in graphene on the friction surface. The layered structure of graphene dissociates along the layers during the friction process and is distributed in the depressions of the gear friction surface. At the same time, the modified Jatropha curcas oil, octadecylamine, and ionic liquid on its surface synergistically act to isolate the friction surface, continuously adsorbing and desorbing during the friction process, and being in a state of dynamic equilibrium. In summary, the grease prepared by the present invention has good lubricity and wear resistance.

[0075] Example 18

[0076] 0.76 parts of 2-hydroxy-3-naphthoic acid was dispersed in 20 parts of DMF to obtain a 2-hydroxy-3-naphthoic acid solution; 0.30 parts of boric acid was dispersed in 10 parts of DMF to obtain a boric acid solution; the boric acid solution was added to the 2-hydroxy-3-naphthoic acid solution, and then 0.02 parts of lithium carbonate was added. The temperature was slowly raised to 50 °C, and the reaction was refluxed until the pH value of the system was stable to obtain a product; the product was centrifuged, washed and dried to obtain an anionic salt, namely 2-hydroxy-3-naphthoic acid borate;

[0077] 1.01 parts of potassium hexafluorophosphate was replaced with the 2-hydroxy-3-naphthoic acid borate, and then the modified graphene was prepared according to the preparation method of Example 3;

[0078] 6.5 parts of dodecahydroxy stearic acid, 2.1 parts of stearic acid and 23 parts of alkyl naphthalene base oil were added to 1 / 4 PAO to obtain a mixed base oil; the mixed base oil was heated to 90 °C and maintained for 1 h, and then 1 / 4 modified graphene and 7.51 parts of specific surface area of 300 m 2 / g of fumed silica (thickening agent) was added, the pH of the system was adjusted to 5.0, the temperature was raised to 120 °C, and the reaction was carried out for 2 h to obtain a heavy-duty open-gear graphene grease precursor; 3 / 4 PAO was added to the heavy-duty open-gear graphene grease precursor as a heating oil, 0.6 parts of stearic acid was added, and then 3 / 4 modified graphene was added. The temperature was raised to 200 °C, and the heating and stirring were stopped after 20 min. When the temperature was lowered to 70 °C, additives were added, and the mixture was stirred for 1 h and cooled to room temperature to obtain a heavy-duty open-gear graphene grease intermediate; the heavy-duty open-gear graphene grease intermediate was placed in a three-roll mill, the grinding speed was 300 rpm, and the grinding time was 3 h to obtain a heavy-duty open-gear graphene grease; the total amount of PAO added was 60 parts; the total amount of modified graphene added was 0.1 part;

[0079] The additives include 0.1 part of nano tungsten disulfide, 0.03 part of molybdenum dioctyl dithiocarbamate, 0.01 part of 2-mercapto-1,3,4-thiadiazole, 0.03 part of trans-1,2-cyclohexanedicarboxylic acid, 0.02 part of 2,5-2-mercapto-1,3,4-thiadiazole dimer; the total amount of PAO, the alkyl naphthalene base oil, the dodecahydroxy stearic acid, the stearic acid, the modified graphene, the thickening agent and the additives added is 100 parts.

[0080] The detailed preparation methods of Examples 19-29 are listed in Table 3.

[0081] Table 3 Preparation methods of greases of Examples 19-29

[0082]

[0083]

[0084] Comparative Example 5

[0085] Different from Example 18, boric acid was replaced by phosphoric acid.

[0086] Comparative Example 6

[0087] Different from Example 18, the temperature was slowly raised to 100 °C

[0088] Example 30

[0089] The extreme pressure properties of the greases prepared in Examples 18 - 29 and Comparative Examples 5 and 6 were tested. The extreme pressure properties of the greases were carried out with reference to SH / T0202 - 92 "Test Method for Extreme Pressure Properties of Greases (Four - Ball Machine Method)", and tested using a SYP grease anti - wear and extreme pressure performance tester; the data of the maximum non - seizure load PB and the welding load PD were recorded in Table 4.

[0090] The grease P prepared in the example B values were 1236 N and 1569 N, and P D values were 6080 N and 7846 N. In Examples 18 - 23, by controlling the addition amount of 2 - hydroxy - 3 - naphthoic acid, the obtained maximum non - seizure load and welding load were high, and the extreme pressure performance was good. Among them, the P D value obtained in Example 21 was the highest, 7846 N. Using 2 - hydroxy - 3 - naphthoic acid and boric acid as raw materials, borate was formed under the action of a catalyst, and then the borate replaced the chloride ions on the surface of graphene to form graphene modified with borate. The borate and imidazole were tightly connected to graphene through conjugation. During the movement of the friction surface, charges were formed, and the charged ionic particles of borate in the grease moved from one side of the surface to the other side, forming a borate film, which improved the extreme pressure of the final grease. When boric acid was replaced by phosphoric acid, as shown in Comparative Example 5, the P B value and P D value both decreased. The results of Example 21 and Examples 24 and 25 showed that when the reaction temperature was controlled in the range of 30 - 60 °C, the extreme pressure performance of the grease was good. The P B value and P DThe values are the lowest compared with those of the examples, being 618 N and 3089 N respectively. When the temperature is too high, before the reaction between 2-hydroxy-3-naphthoic acid and boric acid occurs, DMF has evaporated and the raw materials form a precipitate. The subsequently condensed DMF dissolves some of the raw materials, but this results in incomplete final reaction, so the extreme pressure property of the obtained grease decreases. The results of Examples 21, 26 - 29 show that when the grinding revolution speed is controlled in the range of 250 - 400 rpm, the forward and reverse rotation times are controlled in the range of 2.0 - 3.5 h, and the addition amounts of the extreme pressure and anti-wear agents molybdenum dioctyldithiocarbamate and 2-mercapto-1,3,4-thiadiazole in the additive are controlled in the ranges of 0.01 - 0.03 parts and 0.01 - 0.04 parts respectively, the obtained grease has good extreme pressure performance.

[0091] Table 4 Test results of extreme pressure performance of greases in Examples 18 - 29 and Comparative Examples 5 and 6

[0092] Group <![CDATA[P B (N)]]> <![CDATA[P D (N)]]> Example 18 1236 6080 Example 19 1236 6080 Example 20 1569 6080 Example 21 1569 7846 Example 22 1569 6080 Example 23 1236 6080 Example 24 1236 6080 Example 25 1569 6080 Example 26 1236 6080 Example 27 1569 6080 Example 28 1569 6080 Example 29 1569 6080 Comparative Example 5 981 4904 Comparative Example 6 618 3089

[0093] Example 31

[0094] Graphene oxide was prepared by the method of Example 1;

[0095] The graphene oxide was mixed with 300 parts of deionized water to obtain a graphene mixed solution; 0.24 part of octadecylamine, 0.23 part of 1-hydroxybenzotriazole, 0.19 part of 4-dimethylaminopyridine, 0.17 part of trimethylchlorosilane, 20 parts of DMF and 5 parts of hydrochloric acid with a volume fraction of 30% were added to the graphene mixed solution. Under nitrogen protection, the mixture was refluxed at 120 °C for 12 h to obtain a modified graphene precursor; 0.09 part of 1-methylimidazole was added to the modified graphene precursor, and the reflux reaction was continued for 24 h to obtain a first modified graphene intermediate; 2-hydroxy-3-naphthoic acid borate prepared in Example 18 was added to the first modified graphene intermediate, and the mixture was refluxed for 12 h. The obtained precipitate was centrifuged, washed with deionized water and dried to obtain a second modified graphene intermediate;

[0096] Add 200 parts of Jatropha curcas oil into a three-necked flask. While stirring rapidly, add 1 part of glacial acetic acid and 2 parts of concentrated sulfuric acid into it. After mixing evenly, heat it up to 30 °C to obtain the Jatropha curcas oil to be oxidized. Dropwise add 50 parts of hydrogen peroxide solution with a mass fraction of 35% into the Jatropha curcas oil to be oxidized at a rate of 2 drops per second. After heating up to 65 °C, react for 4.5 h. After liquid separation and washing, epoxidized Jatropha curcas oil is obtained. Add 1 / 3 volume of amino polyethylene glycol carboxyl solution into the epoxidized Jatropha curcas oil. React at a rotation speed of 600 rpm for 6 h, and then continue to add 2 / 3 volume of the amino polyethylene glycol carboxyl solution. After reacting for 15 h, an amino polyethylene glycol carboxyl grafted epoxidized Jatropha curcas oil solution (NH2-PEG-COOH-JCOE) is obtained. The total addition amount of the NH2-PEG-COOH-10000 solution is 19.1 parts. Heat up the NH2-PEG-COOH-JCOE solution to 75 °C, and slowly add 605 parts of phytic acid (PTE) solution into it. After reacting for 24 h, a PTE-NH2-PEG-COOH-JCOE solution is obtained. The PTE-NH2-PEG-COOH-JCOE solution is distilled under reduced pressure to remove water, and 5 parts of magnesium sulfate is added and dried for 12 h to obtain modified Jatropha curcas oil;

[0097] Place sodium dodecylbenzenesulfonate, Tween 80, modified graphene intermediate II, and modified Jatropha curcas oil with a mass ratio of 0.01:0.01:1:0.3 into a ball milling tank and grind to obtain modified graphene;

[0098] Add 6.5 parts of dodecahydroxy stearic acid, 2.1 parts of stearic acid, and 23 parts of alkyl naphthalene base oil into 1 / 4 PAO to obtain a mixed base oil. Heat up the mixed base oil to 90 °C and maintain it for 1 h. Then add 1 / 4 modified graphene and 7.51 parts of fumed silica (thickening agent) with a specific surface area of 100 m 2 / g. Adjust the pH of the system to 5.0, raise the temperature to 120 °C, and react for 2 h to obtain a heavy-duty open gear graphene grease precursor. Add 3 / 4 PAO as the heating oil into the heavy-duty open gear graphene grease precursor, supplement 0.6 part of stearic acid, and then add 3 / 4 modified graphene. Raise the temperature to 200 °C, stop heating and stirring after reacting for 20 min. When the temperature drops to 70 °C, add additives into it, stir and mix for 1 h, and cool to room temperature to obtain a heavy-duty open gear graphene grease intermediate. Place the heavy-duty open gear graphene grease intermediate in a three-roll mill, with a grinding rotation speed of 300 rpm and a grinding time of 3 h, to obtain a heavy-duty open gear graphene grease. The total addition amount of PAO is 60 parts. The total addition amount of the modified graphene is 0.1 part;

[0099] The additive includes 0.1 part of nano tungsten disulfide, 0.03 part of molybdenum dioctyldithiocarbamate, 0.01 part of 2-mercapto-1,3,4-thiadiazole, 0.03 part of trans-1,2-cyclohexanedicarboxylic acid, and 0.02 part of 2,5-bis(mercapto)-1,3,4-thiadiazole dimer; the total addition amount of the PAO, the alkylnaphthalene base oil, the dodecahydroxystearic acid, the stearic acid, the modified graphene, the thickening agent, and the additive is 100 parts.

[0100] Examples 32 - 36

[0101] The 2-hydroxy-3-naphthoic acid borate prepared in Example 18 was respectively replaced with the 2-hydroxy-3-naphthoic acid borates prepared in Examples 19, 20, 21, 22, and 23, and other preparation methods were the same as those in Example 31.

[0102] Examples 37 - 39

[0103] Different from Example 31, the addition amounts of the phytic acid solution were 601 parts, 594 parts, and 627 parts respectively.

[0104] Examples 40, 41

[0105] Different from Example 31, the specific surface areas of the fumed silica were 200 and 300 m 2 / g.

[0106] Examples 42 - 44

[0107] Different from Example 31, after the fumed silica was added to the system, the pH values of the system were adjusted to 3.0, 4.0, and 4.5 respectively.

[0108] Example 45

[0109] The heavy-duty open-gear graphene grease prepared in Examples 31 - 44 was tested for dropping point and penetration. Among them, the penetration test method was carried out with reference to GB / T 269 - 2023 "Determination of Penetration of Lubricating Greases and Petroleum Jellies", the model of the lubricating grease penetration tester was WZ - 269, and the test temperature was 25 °C; the dropping point of the lubricating grease was carried out with reference to GB / T 3498 - 2008 "Determination of Dropping Point of Lubricating Greases over a Wide Temperature Range", and the dropping point of the examples was tested using a SYS - 3498 lubricating grease wide temperature range dropping point tester. The test results are shown in Table 5.

[0110] Table 5 Penetration and dropping point determination results of the graphene grease in Examples 31 - 44.

[0111] Group Penetration (0.1 mm) Drop Point (°C) Example 31 420 220 Example 32 402 245 Example 33 381 263 Example 34 355 296 Example 35 414 311 Example 36 430 318 Example 37 405 323 Example 38 390 326 Example 39 394 329 Example 40 411 304 Example 41 379 309 Example 42 365 279 Example 43 385 260 Example 44 408 323

[0112] The grease obtained by the preparation method of the present invention has a penetration in the range of 355 - 430 (0.1 mm) and a dropping point in the range of 220 - 329 °C. In Examples 31 - 36, as the content of 2-hydroxy-3-naphthoic acid borate introduced onto the surface of graphene increases, the dropping point of the grease shows a gradually increasing trend. The dropping point of the grease in Example 36 is the highest, reaching 318 °C. The naphthalene ring in 2-hydroxy-3-naphthoic acid borate and graphene improve the high-temperature resistance of the grease, endowing it with good high-temperature tolerance. The penetration shows a trend of first decreasing and then increasing. When the 2-hydroxy-3-naphthoic acid borate incorporating graphene is in excess, it leads to a decrease in the hardness of the grease and an increase in fluidity. In Examples 37 - 39, as phytic acid gradually increases, the penetration gradually decreases. When the addition amount of phytic acid in Example 39 is 627 parts, the penetration slightly increases, and the dropping point gradually rises. Phytic acid is connected to jatropha oil through amino polyethylene glycol carboxyl, improving the overall hardness of the grease system. At the same time, phytic acid has high-temperature resistance. When phytic acid decomposes upon heating, inositol phosphate is produced, and the presence of phosphate in the system also improves the high-temperature resistance of the grease, increasing the dropping point of the grease. The results of Examples 31, 40, and 41 show that as the specific surface area of fumed silica increases, the dropping point rises, while the penetration shows a gradually decreasing trend. The silicon-oxygen bonds in fumed silica endow the grease with high-temperature resistance. However, since the mass of fumed silica added in the above examples is the same, the dropping point does not change significantly. As the specific surface area of fumed silica increases, fumed silica is more likely to come into contact with other substances. For example, the hydroxyl groups on the surface of fumed silica can form intermolecular hydrogen bonds with the hydroxyl groups on the surface of graphene. The increased contact specific surface area enhances the intermolecular force, reducing the fluidity of the grease and decreasing the penetration. The results of Examples 31, 42 - 44 show that within the range of pH 3 - 5 of the system, the penetration and dropping point of the grease are good.

[0113] Example 46

[0114] The modified graphene prepared by the method of Example 3 is used to prepare the grease. 6.5 parts of dodecahydroxy stearic acid, 2.1 parts of stearic acid, and 23 parts of alkyl naphthalene base oil are added to 1 / 4 PAO to obtain a mixed base oil; the mixed base oil is heated to 90 °C and maintained for 1 h, and then 1 / 4 modified graphene and 7.51 parts with a specific surface area of 300 m 2 / g of fumed silica (thickener), adjust the pH of the system to 5.0, raise the temperature to 120°C, react for 2h to obtain a heavy-load open gear graphene grease precursor; add 3 / 4 PAO as a heating oil to the heavy-load open gear graphene grease precursor, add 0.6 parts of stearic acid, then add 3 / 4 modified graphene, raise the temperature to 200°C, stop heating and stirring after reacting for 20min, add additives when the temperature drops to 70°C, stir and mix for 1h, and cool to room temperature to obtain a heavy-load open gear graphene grease intermediate; place the heavy-load open gear graphene grease intermediate in a three-roll mill, grind at a speed of 300rpm, and grind for 3h to obtain a heavy-load open gear graphene grease; the total amount of PAO added is 60 parts; the total amount of modified graphene added is 0.1 parts;

[0115] The additives include 0.1 parts of nano tungsten disulfide, 0.03 parts of dibutyl dithiocarbamate oxymolybdenum, 0.01 parts of 2-mercapto-1,3,4-thiadiazole, 0.03 parts of trans-1,2-cyclohexanedicarboxylic acid, and 0.02 parts of 2,5-2-mercapto-1,3,4-thiadiazole dimer; the total addition amount of the PAO, the alkyl naphthalene base oil, the dodecyl stearic acid, the stearic acid, the modified graphene, the thickener and the additives is 100 parts.

[0116] The detailed information of the preparation process of the embodiment is shown in Table 6.

[0117] Table 6 Changes in base oil preparation process and grease performance test results

[0118]

[0119] Embodiment 53

[0120] Different from Example 46, the total amount of modified graphene added is 0.4 parts; the amount of fumed silica added is 7.21 parts.

[0121] Effect Example 1

[0122] The lubricating greases prepared in Examples 46-53 and Comparative Examples 7 and 8 were subjected to comprehensive performance tests to determine the initial oxidation temperature and low-temperature similar viscosity of the lubricating greases. The similar viscosity was determined using a SYP-0048 lubricating grease similar viscosity tester, with reference to the method of SH / T 0048-1991 "Method for Determining Similar Viscosity of Lubricating Greases". The similar viscosity of the lubricating greases measured at -40°C is recorded in Table 6; the PDSC method was used to determine the anti-oxidation performance of the lubricating greases, and the test results were characterized by the initial oxidation temperature. The test results are shown in Table 6.

[0123] The initial oxidation temperature of the grease prepared in the embodiments of the present invention is 280°C - 295°C, and the low-temperature apparent viscosity at -40°C is 796 - 980 Pa·s. In Examples 46 - 49, with the decrease in the addition amount of alkylnaphthalene base oil and the increase in the addition amount of fumed silica, the initial oxidation temperature first decreases and then increases, and the low-temperature apparent viscosity gradually decreases. On the one hand, alkylnaphthalene has the effect of improving the compatibility between the auxiliary materials and the system, and on the other hand, it has excellent oxidation stability. The electron-rich naphthalene ring in alkylnaphthalene can capture the oxidizing groups generated by the oxidation of hydrocarbon groups, making it difficult to form the entire oxidation chain, thus preventing the oxidation process. Therefore, when the content of alkylnaphthalene base oil decreases, the initial oxidation temperature decreases, but as the fumed silica increases accordingly, the antioxidant property of the grease is improved. The increase in fumed silica decreases the apparent viscosity of the grease at -40°C. Fumed silica improves the low-temperature resistance effect of the grease, reduces the resistance of mechanical shearing of the grease in a low-temperature environment, and improves the usability of the grease under low-temperature conditions. Comparing Examples 50 - 52 with Example 46, it can be seen that with the decrease in PAO and the increase in the amounts of alkylnaphthalene base oil and fumed silica, the initial oxidation temperature gradually increases, and the low-temperature apparent viscosity gradually decreases, indicating that the grease prepared by the present invention has stable properties under both high-temperature and low-temperature usage conditions. Comparing Example 53 with Example 46, the addition amount of modified graphene increases and the content of fumed silica decreases, resulting in a decrease in the low-temperature apparent viscosity of the obtained grease and an increase in the initial oxidation temperature. The synergistic effect of modified graphene and fumed silica improves the high-temperature and low-temperature resistance of the grease. In Comparative Example 7, no alkylnaphthalene base oil is added, and the initial oxidation temperature decreases significantly compared with the examples. In Comparative Example 8, no fumed silica is added, the low-temperature apparent viscosity increases, increasing the difficulty of use under low-temperature conditions, the initial oxidation temperature decreases, and the oxidation stability becomes poor.

[0124] Example 54

[0125] Mix concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 4:1 to obtain a mixed acid solution; add 10.5 parts of graphite powder and 8.0 parts of sodium nitrate to 0.7 L of the mixed acid solution, and carry out ultrasonic reaction for 2 h to obtain a graphene oxide solution; the graphene oxide solution is centrifuged to obtain insoluble substances; wash the insoluble substances with a hydrogen peroxide solution with a volume fraction of 30% and a hydrochloric acid solution with a volume fraction of 5%, then wash repeatedly with deionized water, and dry to obtain graphene oxide;

[0126] The graphene oxide is mixed with 300 parts of deionized water to obtain a graphene mixed solution; 0.16 part of octadecylamine, 0.23 part of 1-hydroxybenzotriazole, 0.19 part of 4-dimethylaminopyridine, 0.22 part of trimethylchlorosilane, 20 parts of DMF and 5 parts of hydrochloric acid with a volume fraction of 30% are added to the graphene mixed solution, and under nitrogen protection, the mixture is refluxed at 120 °C for 12 h to obtain a modified graphene precursor; 0.12 part of 1-methylimidazole is added to the modified graphene precursor, and the reflux reaction is continued for 24 h to obtain a first modified graphene intermediate; 1.35 parts of the 2-hydroxy-3-naphthoic acid borate prepared in Example 21 are added to the first modified graphene intermediate, and the mixture is refluxed for 12 h. The obtained precipitate is centrifuged, washed with deionized water, and dried to obtain a second modified graphene intermediate;

[0127] The modified Jatropha curcas oil is prepared according to the method of Example 1;

[0128] Sodium dodecylbenzenesulfonate, Tween 80, the second modified graphene intermediate, and the modified Jatropha curcas oil with a mass ratio of 0.01:0.01:1:0.3 are placed in a ball milling tank for grinding to obtain modified graphene;

[0129] 6.5 parts of dodecahydroxystearic acid, 2.1 parts of stearic acid, and 23 parts of alkylnaphthalene base oil are added to 1 / 4 PAO to obtain a mixed base oil; the mixed base oil is heated to 90 °C and maintained for 1 h, and then 1 / 4 modified graphene and 7.51 parts of fumed silica (thickening agent) with a specific surface area of 300 m 2 / g are added. The pH of the system is adjusted to 5.0, the temperature is raised to 120 °C, and the reaction is carried out for 2 h to obtain a heavy-duty open-gear graphene grease precursor; 3 / 4 PAO is added to the heavy-duty open-gear graphene grease precursor as a temperature-raising oil, 0.6 part of stearic acid is added, and then 3 / 4 modified graphene is added. The temperature is raised to 200 °C, the heating and stirring are stopped after the reaction for 20 min, and when the temperature is lowered to 70 °C, additives are added, and the mixture is stirred and mixed for 1 h, and then cooled to room temperature to obtain a heavy-duty open-gear graphene grease intermediate; the heavy-duty open-gear graphene grease intermediate is placed in a three-roll mill, the grinding speed is 300 rpm, and the grinding time is 3 h to obtain a heavy-duty open-gear graphene grease; the total amount of PAO added is 60 parts; the total amount of modified graphene added is 0.1 part;

[0130] The additive includes 0.1 part of nano tungsten disulfide, 0.03 part of molybdenum dioctyl dithiocarbamate, 0.01 part of 2-mercapto-1,3,4-thiadiazole, 0.03 part of trans-1,2-cyclohexanedicarboxylic acid, and 0.02 part of 2,5-bis(mercapto)-1,3,4-thiadiazole dimer; the total addition amount of the PAO, the alkyl naphthalene base oil, the dodecahydroxystearic acid, the stearic acid, the modified graphene, the thickening agent and the additive is 100 parts.

[0131] Examples 55 and 56

[0132] Different from Example 54, they are respectively replaced with the 2-hydroxy-3-naphthoic acid borate prepared in Examples 22 and 23.

[0133] Examples 57 - 59

[0134] Different from Example 54, the mass ratios of sodium dodecylbenzenesulfonate, Tween 80, modified graphene intermediate II, and modified Jatropha curcas oil are 0.03:0.01:1:0.3, 0.01:0.02:1:0.3, and 0.03:0.02:1:0.3 in sequence.

[0135] Example 60

[0136] Different from Example 54, the first addition amount of PAO is 1 / 20 of its total mass, and the second addition amount of PAO is 19 / 20 of its total mass.

[0137] Example 61

[0138] Different from Example 54, the first addition amount of PAO is 1 / 10 of its total mass, and the second addition amount of PAO is 9 / 10 of its total mass.

[0139] Example 62

[0140] Different from Example 54, the first addition amount of PAO is 2 / 5 of its total mass, and the second addition amount of PAO is 3 / 5 of its total mass.

[0141] Comparative Example 9

[0142] Different from Example 54, the first addition amount of PAO is 4 / 5 of its total mass, and the second addition amount of PAO is 1 / 5 of its total mass.

[0143] Comparative Example 10

[0144] Different from Example 54, the addition amount of 2-hydroxy-3-naphthoic acid borate is 0 part.

[0145] Example 63

[0146] The stability of the heavy-duty open-gear graphene grease prepared in Examples 54 - 62 and Comparative Examples 9 and 10 was tested. The test indicators included the oil separation on a steel mesh and the evaporation loss. The determination of the oil separation on a steel mesh was carried out according to SH / T 0324-92 "Method for Determining Oil Separation from Lubricating Grease on a Steel Mesh (Static Method)", with the test temperature being 30 °C and the holding time being 30 h; the evaporation loss of the lubricating grease was determined according to GB / T 7325-87 "Method for Determining Evaporation Loss of Lubricating Grease and Lubricating Oil", with the constant temperature water bath temperature for the test being 100 °C and the test time being... The test results are as Figure 2 shown.

[0147] According to Figure 2The test results of the grease performance show that the grease obtained in the embodiments of the present invention has a steel mesh oil separation of 0.13%-0.27% and an evaporation loss of 0.08%-0.33%. Among them, in Examples 54-56, as the addition amount of 2-hydroxy-3-naphthoic acid increases, the evaporation loss gradually decreases. In Example 56, a slightly excessive amount of 2-hydroxy-3-naphthoic acid enters the grease with graphene, and the evaporation loss decreases, but the oil separation shows a trend of decreasing and then increasing. The excessive 2-hydroxy-3-naphthoic acid is not covalently connected to the components in the system through chemical bonds, so to a certain extent, it reduces the stability of the grease and increases the oil separation. In Comparative Example 10, without adding 2-hydroxy-3-naphthoic acid borate, the evaporation loss is lower than that of the grease prepared in the examples. By comparing the results of Examples 54, 57-59, by changing the mass ratios of four components, namely sodium dodecylbenzenesulfonate, Tween 80, modified graphene intermediate II, and modified Jatropha curcas oil, the obtained grease has a small steel mesh oil separation and evaporation loss. Among them, the grease prepared in Example 59 has the lowest steel mesh oil separation, which is 0.13%. The two surfactants, sodium dodecylbenzenesulfonate and Tween 80, promote the tight connection between modified graphene intermediate II and modified Jatropha curcas oil, and at the same time promote the compatibility of the obtained modified graphene with components such as base oil. As an ionic surfactant, sodium dodecylbenzenesulfonate improves the compatibility of imidazole and 2-hydroxy-3-naphthoic acid borate in the ionic liquid on the surface of modified graphene with the system, jointly reducing the oil separation of the grease and also reducing the evaporation loss. The results of Examples 54, 60-62 show that when PAO is added in two times to prepare the grease and the addition amount of the first time is controlled in the range of 1 / 20-2 / 5, the obtained grease has less oil separation and small evaporation loss. Among them, the grease in Example 54 has the smallest steel mesh oil separation. In Comparative Example 9, the addition amount of PAO for the first time is 4 / 5 of its total mass, and the obtained grease has higher oil separation and evaporation loss. It may be that the excessive addition of base oil reacts too quickly with the thickener and the groups on the surface of modified graphene, resulting in a large difference in the synthesis rate of the grease. When a small amount of base oil is added later, the grease synthesis is incomplete and the combination of each component is poor, ultimately leading to an increase in oil separation and evaporation loss. In summary, the heavy-duty open-gear graphene grease prepared in the present invention has a low steel mesh oil separation, small evaporation loss, and good stability of the grease.

[0148] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing heavy-load open gear graphene grease, characterized in that: The following steps are involved: Oxidizing graphite powder to obtain graphene oxide; adding 0.16-0.38 parts of octadecylamine, 1-hydroxybenzotriazole, 4-dimethylaminopyridine, 0.09-0.22 parts of trimethylsilyl chloride, DMF and hydrochloric acid to a mixture of the graphene oxide and water to obtain a modified graphene precursor; adding 0-0.21 parts of 1-methylimidazole to the modified graphene precursor to react to obtain a modified graphene intermediate 1; adding 0-1.35 parts of anionic salt to the modified graphene intermediate 1, and refluxing to obtain a modified graphene intermediate 2; the anionic salt is one of potassium hexafluorophosphate and 2-hydroxy-3-naphthoic acid borate; Adding NH2-PEG-COOH solution to epoxidized jatropha oil to obtain NH2-PEG-COOH-JCOE solution; the amount of NH2-PEG-COOH solution added is 10.9-28.2 parts; adding 594-627 parts of phytic acid solution after heating, and performing vacuum distillation after reaction to obtain modified jatropha oil; Sodium dodecylbenzene sulfonate, Tween 80, the modified graphene intermediate 2, and the modified jatropha curcas oil in a mass ratio of 0.01-0.03:0.01-0.02:1:0.3 are placed in a ball mill to grind to obtain modified graphene; Add dodecyl hydroxystearic acid, stearic acid and 0-83 parts of alkyl naphthalene oil to PAO to obtain a mixed base oil; the amount of PAO added is 1 / 20-4 / 5 of the total amount of PAO added; after heating, add the modified graphene and 7.21-9.01 parts of a carbonyl ether with a specific surface area of ​​100-300m 2 / g of thickener, the pH of the system is 3.0-5.0, and the temperature is increased to obtain a heavy-load open gear graphene grease precursor; the PAO, the stearic acid and the modified graphene are added, the temperature is increased to react, the temperature is lowered, the additive is added, and the heavy-load open gear graphene grease is obtained by grinding; The total amount of modified graphene added is 0.05-0.40 parts; the total amount of PAO added is 0-83.0 parts; the grinding speed is 250-400rpm, and the grinding time is 1.5-3.5h; the additives include 0.1 parts of nano-metal sulfide, 0.01-0.03 parts of dibutyl dithiocarbamate oxymolybdenum, 0.01-0.04 parts of 2-mercapto-1,3,4-thiadiazole, 0.03 parts of trans-1,2-cyclohexanedicarboxylic acid, and 0.02 parts of 2,5-2-mercapto-1,3,4-thiadiazole dimer.

2. The method for preparing a heavy-load open gear graphene grease according to claim 1, characterized in that: The preparation method of the graphene oxide is as follows: concentrated sulfuric acid and concentrated nitric acid are mixed in a volume ratio of 4:1 to obtain a mixed acid solution; 10.5 parts of the graphite powder and 8.0 parts of sodium nitrate are added to 0.7L of the mixed acid solution, and ultrasonically reacted for 2h to obtain a graphene oxide solution; the graphene oxide solution is centrifuged to obtain insoluble matter; The insoluble matter was washed with a 30% by volume hydrogen peroxide solution and a 5% by volume hydrochloric acid solution, and then repeatedly washed with deionized water, and dried to obtain graphene oxide.

3. The method for preparing a heavy-load open gear graphene grease according to claim 1, characterized in that: The preparation method of the 2-hydroxy-3-naphthoic acid borate comprises the following steps: Dispersing 0.76-1.15 parts of 2-hydroxy-3-naphthoic acid in 20 parts of DMF to obtain a 2-hydroxy-3-naphthoic acid solution; 0.30 parts of boric acid are dispersed in 10 parts of DMF to obtain an inorganic acid solution; the inorganic acid solution is added to the 2-hydroxy-3-naphthoic acid solution, and then 0.02 parts of lithium carbonate are added, the temperature is slowly increased to 30-60° C., and reflux reaction is performed until the pH value of the system is stable to obtain a product; The product is centrifuged, washed and dried to obtain the 2-hydroxy-3-naphthoic acid borate.

4. The method for preparing a heavy-load open gear graphene grease according to claim 1, characterized in that: The preparation method of the modified jatropha oil is as follows: add jatropha oil into a three-necked flask, add glacial acetic acid and concentrated sulfuric acid thereto under rapid stirring, mix well and heat to 30° C. to obtain jatropha oil to be oxidized; add hydrogen peroxide with a mass fraction of 35% to the jatropha oil to be oxidized at a rate of 2 drops per second, heat to 65° C. and react for 4.5 hours, separate and wash to obtain the epoxidized jatropha oil; add 1 / 3 of the NH2-PEG-COOH solution to the epoxidized jatropha oil, react at a speed of 600 rpm for 6 hours, and then continue to add 2 / 3 parts of the NH2-PEG-COOH solution, react for 15 hours to obtain an amino polyethylene glycol carboxyl grafted epoxidized jatropha oil solution (NH2-PEG-COOH-JCOE); the NH2-PEG-COOH-JCOE solution is heated to 75°C, and the phytic acid solution is slowly added thereto, and the reaction is carried out for 24 hours to obtain a PTE-NH2-PEG-COOH-JCOE solution; the PTE-NH2-PEG-COOH-JCOE solution is distilled under reduced pressure to remove water, and 5 parts of magnesium sulfate are added and dried for 12 hours to obtain the modified jatropha oil.

5. The method for preparing a heavy-load open gear graphene grease according to claim 1, characterized in that: The preparation method of the heavy-duty open gear graphene grease is as follows: the first addition amount of the PAO is 1 / 20-4 / 5 of the total addition amount of the PAO; the mixed base oil is heated to 90° C. and maintained for 1 hour, and then 1 / 4 of the modified graphene and 7.21-9.01 parts of the graphene with a specific surface area of ​​100-300 m 2 / g of the thickener, adjusting the pH of the system to 3.0-5.0, raising the temperature to 120°C, reacting for 2h to obtain the heavy-load open gear graphene grease precursor; adding the PAO to the heavy-load open gear graphene grease precursor, supplementing the stearic acid, and then adding 3 / 4 of the modified graphene, raising the temperature to 200°C, reacting for 20min, stopping heating and stirring, and when the temperature drops to 70°C, adding the additives thereto, stirring and mixing for 1h, and cooling to room temperature to obtain a heavy-load open gear graphene grease precursor; Gear graphene grease intermediate; the second addition amount of the PAO is 1 / 5-19 / 20 of the total addition amount of PAO by mass; the heavy-load open gear graphene grease intermediate is placed in a three-roll grinder, the grinding speed is 250-400rpm, the grinding time is 1.5-3.5h, and the heavy-load open gear graphene grease is obtained; the total addition amount of the PAO is 0-83.0 parts; the total addition amount of the modified graphene is 0.05-0.40 parts; the thickener is fumed silica.

6. The method for preparing a heavy-load open gear graphene grease according to claim 1, characterized in that: The 1-methylimidazole is 0.05-0.10 parts; the anion salt is 0.55-1.35 parts; and the PAO is 23-30 parts.

7. The method for preparing a heavy-load open gear graphene grease according to claim 1, characterized in that: The first addition amount of the PAO is 1 / 20-2 / 5 of the total addition amount of PAO by mass; the second addition amount of the PAO is 3 / 5-19 / 20 of the total addition amount of PAO by mass.

8. The method for preparing a heavy-load open gear graphene grease according to claim 1, characterized in that: The nano-metal sulfide is one of nano-tungsten disulfide and nano-molybdenum disulfide; the particle size of the nano-tungsten disulfide is 500µm; the particle size of the nano-molybdenum disulfide is 500µm.

9. A heavy-load open gear graphene grease, characterized in that: The heavy-load open gear graphene grease comprises the modified graphene, the PAO, the alkyl naphthalene oil, the dodecyl hydroxystearic acid, the stearic acid, and the additive; the heavy-load open gear graphene grease is prepared by the preparation method according to any one of claims 1 to 8; the heavy-load open gear graphene grease has an average wear spot diameter of 0.296-0.491 mm and a friction coefficient of 0.02-0.09; the heavy-load open gear graphene grease P B The values ​​are 1236N and 1569N, P D The values ​​are 6080N and 7846N; the cone penetration of the heavy-load open gear graphene grease is 355-430 (0.1mm), and the dropping point is 220-329°C; the initial oxidation temperature of the heavy-load open gear graphene grease is 280°C-295°C, and the low-temperature similar viscosity at -40°C is 796-980Pa·s; the steel mesh oil separation of the heavy-load open gear graphene grease is 0.13%-0.27%, and the evaporation loss is 0.08%-0.33%.

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