Preparation method of wear-resistant antioxidant polyurea lubricant

Abstract

The invention relates to a preparation method of a wear-resistant anti-oxidation polyurea lubricant, and belongs to the technical field of lubricating materials, nickel oxide is loaded on the surfaces of tungsten disulfide and graphene oxide in situ through a hydrothermal synthesis method to form nano composite powder, basic lubrication is provided through the interlayer slippage characteristic of tungsten disulfide, and the wear-resistant anti-oxidation polyurea lubricant is prepared. The lamellar structure of graphene oxide enhances mechanical support, the hard phase characteristic of nickel oxide inhibits abrasive wear, and then ionic liquid modification is carried out, and a structured solvation layer is constructed by means of electrostatic interaction, hydrogen bonds and Van der Waals force, so that the problem that nano composite powder is easy to agglomerate in a polyurea lubricant matrix is solved, and the wear resistance of the lubricant is improved. In addition, microcapsule powder with poly-alpha-olefin as a core material is dynamically released in the friction process and forms a liquid film, and the liquid film is coordinated with solid lubrication of the nano composite powder, so that the lubrication performance and the wear resistance are greatly improved, and the long-term lubrication requirement of heavy-duty machinery is met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lubricating materials, and relates to a preparation method of a wear-resistant and oxidation-resistant polyurea lubricant. BACKGROUND

[0002] As a kind of high polymer material generated by the reaction of isocyanate and amine compound, the polyurea material has excellent mechanical strength, outstanding high and low temperature resistance (can remain stable at minus 50 DEG C to 200 DEG C or even wider temperature range), good chemical inertness and anti-aging performance due to the hydrogen bond formed by the unique urea functional group, and exhibits significant advantages in lubricant modification and preparation.

[0003] By accurately designing the molecular structure of the polyurea, such as adjusting the ratio of soft segment (polyether, polyester, etc.) and hard segment (urea bond, urethane bond, etc.), selecting isocyanate monomers and amine chain extenders with different carbon chain lengths, the elasticity recovery and interface adsorption capacity of the material can be optimized; at the same time, combined with suitable preparation process (such as in-situ polymerization, emulsion polymerization, etc.), and reasonably compounded with anti-wear additives (such as nano metal oxides, sulfides, etc.), antioxidants (such as hindered phenolic antioxidants, amine antioxidants, etc.), the wear resistance and oxidation resistance of the polyurea lubricant can be further improved, so that it can still form a continuous, dense and not easy to break lubricating film under extreme working conditions, effectively resisting oxidation corrosion and friction loss.

[0004] The Chinese invention with the publication number CN108865373B discloses a kind of composite calcium sulfonate polyurea mixed grease and its preparation method, including mineral base oil, urea-based thickener, composite calcium sulfonate and polyisobutylene tackifier, which maintains the basic characteristics of urea-based grease such as high dropping point, easy pumping, oxidation resistance and corrosion resistance, and combines the advantages of composite calcium sulfonate-based lubricant such as good water resistance and strong extreme pressure wear resistance.

[0005] The mineral base oil in the above scheme is a high-pressure hydrogenation series bright oil (i.e. 150BS, 175BS, 250BS, etc.), which is essentially a petroleum distillate. A small amount of unsaturated hydrocarbon bonds remaining in the molecular structure of the mineral base oil are easily attacked by oxygen at high temperatures, leading to a free radical chain oxidation reaction. The transmission system (gears, roller bearings) of steel annealing furnace and other equipment is in a high-temperature environment for a long time and needs to bear heavy load caused by the weight of the kiln body. During the long-term service of the above-mentioned grease, intermediate products such as resin and asphaltene will be gradually generated, and then dehydrated and dehydrogenated to form amorphous carbon. In addition, the chemical reaction between calcium ions in ash and carboxyl groups in carbon precursor will occur in a high-temperature environment, generating metal carboxylate that is insoluble in oil, cross-linking and solidifying loose carbon particles, and finally forming hard and stubborn coke-like substances on the inner wall of the gear box, bearing raceway and pipeline, causing the problem of lubricating grease circulation obstruction. SUMMARY

[0006] The application aims to provide a preparation method of a wear-resistant and oxidation-resistant polyurea lubricant.

[0007] The application can be achieved by the following technical solutions.

[0008] The application provides a preparation method of a wear-resistant and oxidation-resistant polyurea lubricant, which comprises the following steps.

[0009] Step one: synthesizing nickel oxide on tungsten disulfide and graphene oxide by a hydrothermal synthesis method to obtain a nano-composite powder; and then modifying the nano-composite powder by an ionic liquid to obtain an ionic liquid modified nano-composite powder.

[0010] Step two: taking poly-alpha-olefin as a core material, and synthesizing polyurea formaldehyde prepolymer from urea and formaldehyde as monomers, and forming a shell layer through condensation polymerization under the crosslinking action of a crosslinking agent to obtain microcapsule powder.

[0011] Step three: stirring and refining microcapsule powder, organic amine and diisocyanate, and grinding to obtain a polyurea lubricant matrix; and mixing the polyurea lubricant matrix and the ionic liquid modified nano-composite powder to obtain a wear-resistant and oxidation-resistant polyurea lubricant.

[0012] Further, the preparation process of the ionic liquid modified nano-composite powder is as follows.

[0013] The nano-composite powder and anhydrous ethanol are added into a reaction kettle and ultrasonically dispersed for 15-20 min, then the ionic liquid is added dropwise and ultrasonically dispersed for 15-20 min, and then the mixture is ground under a pressure of 10-15 MPa for 5-6 h, and kept at 80-90 DEG C for 12-14 h, and then cooled to room temperature to obtain the ionic liquid modified nano-composite powder.

[0014] Further, the amount ratio of the nano-composite powder, anhydrous ethanol and ionic liquid is 0.5-1.0 g:30-40 mL:0.8-1.2 g.

[0015] Further, the ionic liquid is 1-butyl-3-methyl imidazole tetrafluoroborate.

[0016] Further, the preparation process of the nano-composite powder is as follows.

[0017] The tungsten disulfide powder, graphene oxide powder, polyvinylpyrrolidone, nickel chloride, and distilled water were added into a reaction kettle, ultrasonic treatment was performed for 30-40 min, ammonia water with a concentration of 25-28 wt%, cetyltrimethylammonium chloride, and KH-550 were added, stirring was performed at 20-25 °C for 2-3 h, hydrothermal treatment was performed at 100-110 °C for 16-20 h, centrifugation, filtration, washing, and drying were performed, and a nano-composite powder was obtained.

[0018] Further, the tungsten disulfide powder, graphene oxide powder, polyvinylpyrrolidone, nickel chloride, distilled water, ammonia water, cetyltrimethylammonium chloride, and KH-550 were used in a ratio of 0.5-1.0 g: 0.02-0.04 g: 0.05-0.09 g: 0.24-0.34 g: 50-60 mL: 0.2-0.4 mL: 0.1-0.2 g: 0.1-0.2 g.

[0019] Further, the preparation process of the microcapsule powder is as follows:

[0020] Urea, resorcinol, a glyoxal aqueous solution with a concentration of 40 wt%, ammonium chloride, sodium lignosulfonate with a concentration of 0.2 wt%, and deionized water were added into a reaction kettle, stirring was performed at 500-700 r / min for 10-15 min, poly-alpha-olefin was added, and homogenizing shear emulsification was performed for 5-7 min to obtain a stable oil-in-water emulsion, stirring was performed at 350-450 r / min for 5-7 min, n-octanol was added dropwise, a formaldehyde aqueous solution with a concentration of 37 wt% was added, hydrochloric acid with a concentration of 1 mol / L was used to adjust the pH value to 3-4, the temperature was slowly increased to 35-40 °C, and the temperature was maintained for 30-40 min, then the temperature was increased to 60-65 °C at a rate of 1 °C / min, and the temperature was maintained for 3-4 h, vacuum filtration, washing, and drying were performed, and a microcapsule powder was obtained.

[0021] Further, the urea, resorcinol, glyoxal aqueous solution, ammonium chloride, sodium lignosulfonate, deionized water, poly-alpha-olefin, n-octanol, and formaldehyde aqueous solution were used in a ratio of 25-35 g: 1.2-2.2 g: 5-8 g: 2.5-4.5 g: 2-4 g: 150-200 mL: 75-95 g: 0.8-1.0 mL: 50-70 g.

[0022] Further, the preparation process of the polyurea lubricant matrix is as follows:

[0023] The microcapsule powder is added into a reaction kettle, heated to 80-85 DEG C, then organic amine and diisocyanate are added, and the reaction is carried out at 300-500 r / min for 40-60 min, the temperature is raised to 100-120 DEG C, distilled water is added, and the temperature is kept for 20-30 min, the temperature is raised to 180-190 DEG C, and stirring and refining are carried out for 15-45 min, after the stirring and refining are completed, the temperature is cooled to room temperature, and three-roll grinding machine is used for grinding for 3 times, and the polyurea lubricant matrix is obtained.

[0024] Further, the amount ratio of the microcapsule powder, the organic amine and the diisocyanate is 100-150 g: 6-8 g: 25-35 g.

[0025] Further, the organic amine is one of octadecylamine and cyclohexylamine.

[0026] Further, the diisocyanate is one of hexamethylene diisocyanate, isophorone diisocyanate and dicyclohexyl methane diisocyanate.

[0027] Further, the preparation process of the wear-resistant and oxidation-resistant polyurea lubricant is as follows:

[0028] The polyurea lubricant matrix and the acetone solution are added into a reaction kettle, then the ionic liquid modified nano composite powder and the hindered phenol antioxidant 1010 are added, and ultrasonic is carried out for 2-3 h, and the acetone is removed at 80-85 DEG C and 500-700 r / min, and the wear-resistant and oxidation-resistant polyurea lubricant is obtained.

[0029] Further, the amount ratio of the polyurea lubricant matrix, the acetone solution, the ionic liquid modified nano composite powder and the hindered phenol antioxidant 1010 is 50-70 g: 15-25 mL: 0.5-1.0 g: 0.1-0.2 g.

[0030] The beneficial effects of the present application are as follows:

[0031] 1. In the present application, the nickel oxide is in-situ loaded on the surface of the tungsten disulfide and the graphene oxide by the hydrothermal synthesis method to form a nano composite powder, the interlayer slip characteristics of the tungsten disulfide provide basic lubrication, the sheet structure of the graphene oxide enhances the mechanical support, the hard phase characteristics of the nickel oxide inhibit the abrasive wear, and then the nano composite powder is modified by the ionic liquid to construct a structured solvation layer by means of the electrostatic action, the hydrogen bond and the van der Waals force, not only the problem that the nano composite powder is easy to agglomerate in the polyurea lubricant matrix is solved, but also a chemical adsorption film is formed on the friction interface, in addition, the microcapsule powder with poly-alpha-olefin as a core material is dynamically released and forms a liquid film in the friction process, cooperates with the solid lubrication of the nano composite powder, greatly improves the lubrication performance and the wear resistance, and meets the long-term lubrication demand of heavy machinery.

[0032] 2、The polyurea lubricant has excellent oxidation resistance and wide temperature range adaptability, the ionic liquid can stably inhibit the oxidation chain reaction at high temperature, has high thermal stability, the nickel oxide has catalytic oxygen inhibition effect, the dense sheet structure of the graphene oxide can block the contact of oxygen and the base, slows down the oxidation rate, forms multiple oxidation resistance synergies with the hindered phenol antioxidant 1010, effectively delays the oxidation degradation of the polyurea lubricant base and the poly-alpha-olefin core material, and the dense shell of the microcapsule powder can further prevent the direct contact of oxygen and the poly-alpha-olefin core material, so that the lubricant has good oxidation resistance.

[0033] 3、The shell layer of the microcapsule powder has high compressive strength and a rough surface, and forms an interlocking structure with the polyurea base, and the urea groups of the microcapsule shell layer and the urea groups of the polyurea base form hydrogen bonds, improving the interfacial bonding force between them, and then the three-roll mill is used to disperse a small amount of agglomerates, so that the microcapsule powder is uniformly dispersed in the polyurea lubricant base, and the imidazole cation of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate is combined with the negative potential points on the surface of the tungsten disulfide sheet and the graphene oxide in the nano-composite powder through electrostatic action and van der Waals force, and the tetrafluoroborate anion forms hydrogen bonds with the hydroxyl groups on the surface of the nickel oxide, so that a structured solvation layer can be formed on the surface of the nanoparticles, so that it can be uniformly dispersed in the polyurea lubricant base. DETAILED DESCRIPTION

[0034] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined object, the specific embodiments, features and effects according to the present application are described in detail as follows in combination with the preferred embodiments.

[0035] Example 1: The present embodiment provides a wear-resistant and oxidation-resistant polyurea lubricant, which is prepared by the following steps:

[0036] S1: 0.75g of tungsten disulfide powder (particle size 100nm, purchased from Jiangsu Xianfeng Nanometer Material Technology Co., Ltd.), 0.03g of graphene oxide (purity 99.99%, purchased from Henan Wanying Refractory Material Technology Co., Ltd.), 0.07g of polyvinylpyrrolidone (K85 specification, purchased from Shanghai Aldrin Biochemical Technology Co., Ltd.), 0.29g of nickel chloride (purchased from Jinan Shengda Chemical Co., Ltd.) and 55mL of distilled water are added to a reaction kettle, ultrasonic treatment is performed for 35min, 0.3mL of 26wt% ammonia water, 0.15g of cetyltrimethylammonium chloride and 0.15g of silane coupling agent KH-550 are added, stirring is performed at 22℃ for 2h, hydrothermal treatment is performed at 105℃ for 18h, centrifugation is performed, filtration is performed, the filter cake is washed with distilled water and anhydrous ethanol respectively for 2 times, and drying is performed at 82℃ for 13h, to obtain a nano-composite powder.

[0037] Distilled water as a solvent makes the nickel chloride completely dissolved and ionized into nickel ions, and polyvinylpyrrolidone is combined with the surface of tungsten disulfide by hydrogen bond to form a steric barrier, and forms intermolecular forces with the graphene oxide sheet to jointly build a steric barrier to inhibit the agglomeration of tungsten disulfide, and ammonia water adjusts the pH of the system to 8 to form a stable and moderate complex with nickel ions, and hexadecyl trimethyl ammonium chloride is adsorbed on the surface of tungsten disulfide and graphene oxide by electrostatic adsorption to enhance the dispersion stability, and KH-550 utilizes its amino group to form chemical bonds with the surface hydroxyl groups of tungsten dioxide and graphene oxide and nickel ions to further strengthen the site-oriented effect, and under the hydrothermal condition of 105℃, the complex is decomposed to release nickel ions and hydrolyzed to generate nickel hydroxide, which is in-situ deposited on the surface of tungsten disulfide and graphene oxide, and after 18h of insulation, the nickel hydroxide is dehydrated and decomposed into nickel oxide nanoparticles, which are uniformly grown on the surface and edge of the tungsten disulfide sheet to form a nanocomposite powder.

[0038] S2: 0.75g of nanocomposite powder and 35mL of anhydrous ethanol were added to the reaction kettle, ultrasonic dispersion was performed for 17min, 1.0g of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, purchased from the State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences) was added dropwise, ultrasonic dispersion was performed for 17min, the nanocomposite powder was uniformly dispersed with the ionic liquid, 12MPa pressure was applied for grinding for 5h, and the temperature was kept at 85℃ for 13h, and then the temperature was cooled to room temperature to obtain ionic liquid modified nanocomposite powder.

[0039] The imidazole cation of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate is combined with the negative sites on the surface of the tungsten disulfide sheet and graphene oxide in the nanocomposite powder by electrostatic interaction and van der Waals force, and the tetrafluoroborate anion forms a hydrogen bond with the surface hydroxyl groups of nickel oxide, and meanwhile, the solvent mediation effect of ethanol promotes the formation of a structured solvation layer of the ionic liquid on the surface of the nanoparticles.

[0040] S3: 30g of urea, 1.7g of resorcinol, 6.5g of 40wt% glyoxal aqueous solution, 3.5g of ammonium chloride, 3g of 0.2wt% sodium lignosulfonate, and 175mL of deionized water were added to the reaction kettle, stirring was performed at 600r / min for 12min, 85g of poly-alpha-olefin (PAO40) was added, and homogenizing shearing emulsification was performed at 22℃ and a speed of 5250r / min for 6min to obtain a stable oil-in-water emulsion, stirring was performed at 400r / min for 6min, 0.9mL of n-octanol was added dropwise for defoaming, 60g of 37wt% formaldehyde aqueous solution was added, the pH value was adjusted to 3 with 1mol / L hydrochloric acid, the temperature was slowly increased to 37℃, and the temperature was kept for 35min, then the temperature was increased to 62℃ at a speed of 1℃ / min, and the temperature was kept for 3h, vacuum filtration was performed, the filter cake was washed with deionized water, ethanol, and isopropyl alcohol alternately, and freeze-drying was performed for 25h to obtain a microcapsule powder.

[0041] Sodium lignosulfonate was used as an anionic emulsifier. Its hydrophilic sulfonic acid groups were oriented towards the aqueous phase, while its hydrophobic groups were adsorbed onto the surface of polyalphaolefin (PAO) oil droplets. Combined with high-shear homogenization, PAO was broken into tiny droplets and formed a stable oil-in-water emulsion. Ammonium chloride enhanced the emulsion stability by adjusting the ionic strength of the aqueous phase, laying the foundation for dispersion in subsequent reactions. Next, formaldehyde aqueous solution was added. Under acidic conditions, urea and formaldehyde first underwent a hydroxymethylation reaction to generate a water-soluble polyurea-formaldehyde prepolymer. Resorcinol reacted with the prepolymer through its phenolic hydroxyl groups. The hydroxymethyl group forms an ether bond, while the glyoxal rapidly crosslinks with the amino group of the urea molecule due to its highly active aldehyde group. The two work synergistically to enhance the activity and crosslinking density of the prepolymer. At the same time, the prepolymer is oriented to adsorb onto the oil-water interface by electrostatic attraction. Subsequently, by gradient heating, the prepolymer undergoes rapid polycondensation reaction and continuous deposition and crosslinking, forming a dense and high-strength shell on the surface of the oil droplets. The polyα-olefin is then encapsulated inside the shell to form microcapsules. The addition of n-octanol eliminates bubbles during emulsification and stirring, preventing the formation of pores in the shell.

[0042] S4: Add 125g of microcapsule powder to the reaction vessel and heat to 82℃. Then add 7g of octadecylamine (industrial grade, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and 30g of hexamethylene diisocyanate. React at 400r / min for 50min. After the reaction is complete, raise the temperature to 110℃, add 17mL of distilled water to remove excess hexamethylene diisocyanate, keep warm for 25min, raise the temperature to 185℃, and stir and refine for 30min. After stirring and refining, cool to room temperature and grind three times with a three-roll mill, controlling the grinding pressure at 0.4MPa to obtain the polyurea lubricant matrix.

[0043] The isocyanate group in hexamethylene diisocyanate undergoes an addition reaction with the amino group in octadecylamine to first generate a urea-structured prepolymer, which is then further crosslinked to form a three-dimensional network polyurea structure. The microcapsule powder is tightly encapsulated in the network structure, and its rough surface forms a mechanical interlock with the polyurea to prevent it from falling off during subsequent use, while retaining the self-lubricating function of releasing oil when the microcapsules rupture during friction.

[0044] S5: Add 60g of polyurea lubricant matrix and 20mL of acetone solution to the reactor, then add 0.75g of ionic liquid modified nanocomposite powder and 0.15g of hindered phenolic antioxidant 1010, sonicate for 2h, and volatilize the acetone at 82℃ and 600r / min to obtain wear-resistant and antioxidant polyurea lubricant.

[0045] Example 2: This example provides a wear-resistant and antioxidant polyurea lubricant, which is prepared through the following steps:

[0046] S1: 0.5g tungsten disulfide powder (particle size 100nm, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.), 0.02g graphene oxide, 0.05g polyvinylpyrrolidone, 0.24g nickel chloride and 50mL distilled water were added to a reaction vessel and sonicated for 30min. Then, 0.2mL of 25wt% ammonia water, 0.1g hexadecyltrimethylammonium chloride and 0.1g silane coupling agent KH-550 were added. The mixture was stirred at 20℃ for 2h and hydrothermally treated at 100℃ for 16h. After centrifugation and filtration, the filter cake was washed twice with distilled water and anhydrous ethanol, respectively, and dried at 80℃ for 12h to obtain nanocomposite powder.

[0047] S2: Add 0.5g of nanocomposite powder and 30mL of anhydrous ethanol to the reaction vessel, sonicate for 15min, then add 0.8g of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate), sonicate for 15min to make the nanocomposite powder and ionic liquid evenly dispersed, apply 10MPa pressure to grind for 5h, keep at 80℃ for 12h, cool to room temperature to obtain ionic liquid modified nanocomposite powder.

[0048] S3: Add 25g urea, 1.2g resorcinol, 5g of 40wt% glyoxal aqueous solution, 2.5g ammonium chloride, 2g of 0.2wt% sodium lignosulfonate, and 150mL deionized water to a reactor. Stir at 500r / min for 10min. Add 75g polyα-olefin (PAO40). Homogenize and shear emulsify at 5000r / min for 5min at 20℃ to obtain a stable oil-in-water emulsion. Stir at 350r / min for 5min. Add 0.8mL n-octanol for defoaming. Add 50g of 37wt% formaldehyde aqueous solution. Adjust the pH to 3 with 1mol / L hydrochloric acid. Slowly raise the temperature to 35℃ and hold for 30min. Then raise the temperature to 60℃ at 1℃ / min and hold for 3h. Vacuum filter. Wash the filter cake alternately with deionized water, ethanol, and isopropanol. Freeze-dry for 24h to obtain microcapsule powder.

[0049] S4: Add 100g of microcapsule powder to a reaction vessel and heat to 80℃. Then add 6g of octadecylamine (industrial grade, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and 25g of hexamethylene diisocyanate (analytical grade, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.). React at 300r / min for 40min. After the reaction is complete, raise the temperature to 100℃, add 15mL of distilled water to remove excess hexamethylene diisocyanate, keep warm for 20min, raise the temperature to 180℃, and stir and refine for 15min. After stirring and refining, cool to room temperature and grind three times with a three-roll mill at a pressure of 0.4MPa to obtain the polyurea lubricant matrix.

[0050] S5: Add 50g of polyurea lubricant matrix and 15mL of acetone solution to the reactor, then add 0.5g of ionic liquid modified nanocomposite powder and 0.1g of hindered phenolic antioxidant 1010, sonicate for 2h, and volatilize the acetone at 80℃ and 500r / min to obtain wear-resistant and antioxidant polyurea lubricant.

[0051] Example 3: This example provides a wear-resistant and antioxidant polyurea lubricant, which is prepared through the following steps:

[0052] S1: 1.0 g tungsten disulfide powder (particle size 100 nm, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.), 0.04 g graphene oxide, 0.09 g polyvinylpyrrolidone, 0.34 g nickel chloride and 60 mL distilled water were added to a reaction vessel and ultrasonically treated for 40 min. Then, 0.4 mL of 28 wt% ammonia water, 0.2 g hexadecyltrimethylammonium chloride and 0.2 g silane coupling agent KH-550 were added. The mixture was stirred at 25 °C for 3 h and hydrothermally treated at 110 °C for 20 h. After centrifugation and filtration, the filter cake was washed three times with distilled water and anhydrous ethanol, respectively, and dried at 85 °C for 14 h to obtain nanocomposite powder.

[0053] S2: Add 1.0g of nanocomposite powder and 40mL of anhydrous ethanol to the reaction vessel, sonicate for 20min, then add 1.2g of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate), sonicate for 20min to make the nanocomposite powder and ionic liquid evenly dispersed, apply 15MPa pressure to grind for 6h, keep at 90℃ for 14h, cool to room temperature to obtain ionic liquid modified nanocomposite powder.

[0054] S3: Add 35g urea, 2.2g resorcinol, 8g of 40wt% glyoxal aqueous solution, 4.5g ammonium chloride, 4g of 0.2wt% sodium lignosulfonate, and 200mL deionized water to a reactor. Stir at 700r / min for 15min. Add 95g poly-α-olefin (PAO40). Homogenize and shear emulsify at 5500r / min for 7min at 25℃ to obtain a stable oil-in-water emulsion. Stir at 450r / min for 7min. Add 1.0mL n-octanol for defoaming. Add 70g of 37wt% formaldehyde aqueous solution. Adjust the pH to 4 with 1mol / L hydrochloric acid. Slowly heat to 40℃ and hold for 40min. Then heat to 65℃ at 1℃ / min and hold for 4h. Vacuum filter. Wash the filter cake alternately with deionized water, ethanol, and isopropanol. Freeze-dry for 26h to obtain microcapsule powder.

[0055] S4: Add 150g of microcapsule powder to the reaction vessel, heat to 85℃, then add 8g of octadecylamine and 35g of hexamethylene diisocyanate, react at 500r / min for 60min, after the reaction is complete, raise the temperature to 120℃, add 20mL of distilled water to remove excess hexamethylene diisocyanate, keep warm for 30min, raise the temperature to 190℃, stir and refine for 45min, after stirring and refining is complete, cool to room temperature, and grind 3 times with a three-roll mill, with the grinding pressure controlled at 0.5MPa, to obtain the polyurea lubricant matrix.

[0056] S5: Add 70g of polyurea lubricant matrix and 25mL of acetone solution to the reactor, then add 1.0g of ionic liquid modified nanocomposite powder and 0.2g of hindered phenolic antioxidant 1010, sonicate for 3h, and volatilize the acetone at 85℃ and 700r / min to obtain wear-resistant and antioxidant polyurea lubricant.

[0057] Example 4: This example provides a wear-resistant and antioxidant polyurea lubricant. The difference from Example 1 is that cyclohexylamine (analytical grade, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.) is used instead of octadecylamine in step S4.

[0058] Example 5: This example provides a wear-resistant and antioxidant polyurea lubricant. The difference from Example 1 is that isophorone diisocyanate is used instead of hexamethylene diisocyanate in step S4.

[0059] Example 6: This example provides a wear-resistant and antioxidant polyurea lubricant. The difference from Example 1 is that in step S4, dicyclohexylmethane diisocyanate is used instead of hexamethylene diisocyanate, and the amount is adjusted to 33g.

[0060] Comparative Example 1: This comparative example provides a wear-resistant and antioxidant polyurea lubricant, which differs from Example 1 in that base oil is used instead of microcapsule powder in step S4.

[0061] Comparative Example 2: This comparative example provides a wear-resistant and antioxidant polyurea lubricant, which differs from Example 1 in that the ionic liquid-modified nanocomposite powder is removed in step S5.

[0062] Comparative Example 3: This comparative example provides a wear-resistant and antioxidant polyurea lubricant. The difference from Example 1 is that in step S5, the nanocomposite powder prepared in step S1 is used instead of the ionic liquid-modified nanocomposite powder.

[0063] The wear-resistant and antioxidant polyurea lubricants prepared in Examples 1-6 and Comparative Examples 1-3 were subjected to performance tests:

[0064] Extreme pressure performance: The extreme pressure performance was determined according to SH / T 0202-1992 "Determination of Extreme Pressure Performance of Lubricating Grease (Four-Ball Test Method)". The test procedure was as follows: The sample was placed in a clean ball box containing three clean steel balls, which were then assembled and placed on a ball seat. Another clean steel ball was mounted on the spindle of the testing instrument. The rotational speed was set to 1770 r / min, the load was set and applied slowly, the motor was started, and the test run lasted 10 seconds. After the test, the wear trace diameters of the three balls were measured, P. B The value represents the maximum non-seize load; the higher the value, the better the lubrication performance.

[0065] Anti-wear performance: The anti-wear performance was determined according to SH / T 0202-1992 "Determination of Extreme Pressure Properties of Lubricating Grease (Four-Ball Test Method)". The test procedure is as follows: Fill the ball box with the sample, embed three clean steel balls into the box and assemble them, placing them on the ball seat. Install another clean steel ball on the spindle of the testing instrument. Set the rotation speed to 1200 r / min, the test force to 392 N, the time to 60 min, and the temperature to 75±2℃. Start the test when the set temperature is reached. After the test, measure the wear trace diameter of the three balls and record the coefficient of friction. The lower the value, the better the lubrication performance.

[0066] Antioxidant performance: The oxidation stability was determined according to SH / T 0325-1992 "Determination of Oxidation Stability of Lubricating Grease". The test procedure is as follows: 4.00±0.01g of sample was placed in each of five dishes, ensuring even distribution, and placed on a dish rack. The dish rack was placed in the oxygen bomb and the bolts were tightened to seal it. Oxygen was introduced until the pressure reached 689kPa, then the oxygen was released to remove internal air. This process was repeated four times until the oxygen pressure reached 593kPa at a temperature of 20-23℃. The oxygen bomb was allowed to stand overnight and checked for leaks. The oxygen bomb was placed in an oil bath at 99±0.5℃. When the pressure rose above 785±14kPa, oxygen was intermittently released until the pressure stabilized at 785±14kPa, and this was maintained for at least 2 hours. The oxygen bomb was then immersed in the oil bath, and the time was started, continuously oxidizing until the product specification time period (100h) was reached.

[0067] The test results are shown in the table below:

[0068] Table 1 Performance Test Overview

[0069] Project Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Abrasion diameter (mm) 0.295 0.289 0.291 0.293 0.283 0.292 0.458 0.412 0.385 P B value (N) 627 621 624 625 629 619 482 526 553 Lowest friction coefficient 0.034 0.038 0.031 0.033 0.031 0.032 0.087 0.065 0.052 Oxidation stability (100°C, 100h) Pressure drop (MPa) 0.0045 0.0042 0.0041 0.0047 0.0049 0.0041 0.0148 0.0103 0.0086

[0070] As shown in Table 1, the wear scar diameters of Examples 1-6 are smaller than those of Comparative Examples 1-3, and the maximum non-seize load (P) is smaller. BThe coefficient of friction in Examples 1-6 was higher than that in Comparative Examples 1-3, and the lowest coefficient of friction was lower than that in Comparative Examples 1-3, indicating that the lubrication performance of Examples 1-6 was better. This may be because the microcapsules ruptured during friction, releasing the poly-α-olefin core material to form a dynamic liquid lubricating film that filled the gaps at the friction interface. In the ionic liquid-modified nanocomposite powder, the interlayer slip characteristics of tungsten disulfide, the wear-resistant support of nickel oxide, and the friction-reducing effect of the ionic liquid were superimposed to form a composite lubricating film with physical lubrication, chemical adsorption, and hard phase support, which effectively reduced direct contact between friction surfaces and lowered the wear scar diameter and coefficient of friction. In contrast, Comparative Example 1 used base oil instead of microcapsules, which lacked the dynamic oil release function, and the lubricating film was easily lost. Comparative Example 2 removed the ionic liquid-modified nanocomposite powder, thus losing the multi-dimensional anti-wear synergistic effect. Comparative Example 3 did not use ionic liquid-modified nanocomposite powder, and the nanoparticles were prone to agglomeration, which could not uniformly exert the anti-wear effect, resulting in a decrease in lubrication performance.

[0071] As shown in Table 1, the oxidation stability of Examples 1-6 is higher than that of Comparative Examples 1-3, indicating that Examples 1-6 have better antioxidant performance. This may be because the high thermal stability of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate can inhibit the oxidation reaction, nickel oxide has a catalytic inhibitory effect on the oxidation of polyalphaolefins in the base oil, the sheet structure of graphene oxide can block oxidation diffusion, and the hindered phenolic antioxidant 1010 works synergistically with the above components to further delay the oxidative degradation of the polyurea matrix and polyalphaolefins. In contrast, Comparative Example 1 lacks the protection of the capsule shell, and the base oil is directly exposed and easily oxidized. Comparative Examples 2 and 3 lack the synergistic antioxidant effect of the ionic liquid-modified nanocomposite powder, resulting in significantly worse oxidation stability and a significant increase in pressure drop.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a wear-resistant and antioxidant polyurea lubricant, characterized in that, Includes the following steps: Step 1: Nickel oxide is synthesized on tungsten disulfide and graphene oxide via hydrothermal synthesis to obtain nanocomposite powder; then modified with ionic liquid to obtain ionic liquid-modified nanocomposite powder. Step 2: Using polyα-olefin as the core material and urea and formaldehyde as monomers, polyurea-formaldehyde prepolymer is synthesized. Under the cross-linking action of the cross-linking agent, a shell layer is formed through polycondensation reaction to obtain microcapsule powder. Step 3: Stir and refine the microcapsule powder, organic amine and diisocyanate, and grind them to obtain the polyurea lubricant matrix; mix the polyurea lubricant matrix with the ionic liquid modified nanocomposite powder to obtain the wear-resistant and antioxidant polyurea lubricant.

2. The method for preparing a wear-resistant and antioxidant polyurea lubricant according to claim 1, characterized in that, The preparation process of the ionic liquid-modified nanocomposite powder in step one is as follows: The nanocomposite powder and anhydrous ethanol were added to a reaction vessel and ultrasonically dispersed for 15-20 min. Then, the ionic liquid was added dropwise and ultrasonically dispersed for 15-2 min. The mixture was then ground under a pressure of 10-15 MPa for 5-6 h and kept at 80-90℃ for 12-14 h. After cooling to room temperature, the ionic liquid-modified nanocomposite powder was obtained.

3. The method for preparing a wear-resistant and antioxidant polyurea lubricant according to claim 1, characterized in that, The ratio of the nanocomposite powder, anhydrous ethanol, and ionic liquid is 0.5-1.0g: 30-40mL: 0.8-1.2g; The ionic liquid is 1-butyl-3-methylimidazolium tetrafluoroborate.

4. The method for preparing a wear-resistant and antioxidant polyurea lubricant according to claim 3, characterized in that, The preparation process of the nanocomposite powder is as follows: Tungsten disulfide powder, graphene oxide powder, polyvinylpyrrolidone, nickel chloride, and distilled water were added to a reaction vessel and ultrasonically treated for 30-40 minutes. Then, ammonia water, hexadecyltrimethylammonium chloride, and KH-550 with a concentration of 25-28 wt% were added. The mixture was stirred at 20-25℃ for 2-3 hours and hydrothermally treated at 100-110℃ for 16-20 hours. After centrifugation, filtration, washing, and drying, nanocomposite powder was obtained.

5. The method for preparing a wear-resistant and antioxidant polyurea lubricant according to claim 4, characterized in that, The ratio of tungsten disulfide powder, graphene oxide powder, polyvinylpyrrolidone, nickel chloride, distilled water, ammonia, hexadecyltrimethylammonium chloride, and KH-550 used is 0.5-1.0g: 0.02-0.04g: 0.05-0.09g: 0.24-0.34g: 50-60mL: 0.2-0.4mL: 0.1-0.2g: 0.1-0.2g.

6. The method for preparing a wear-resistant and antioxidant polyurea lubricant according to claim 1, characterized in that, The preparation process of the microcapsule powder in step two is as follows: Urea, resorcinol, a 40wt% glyoxal aqueous solution, ammonium chloride, a 0.2wt% sodium lignosulfonate, and deionized water were added to a reaction vessel and stirred at 500-700 rpm for 10-15 min. Poly-α-olefin was added, and homogenized and sheared emulsified for 5-7 min to obtain a stable oil-in-water emulsion. The mixture was stirred at 350-450 rpm for 5-7 min, and n-octanol was added dropwise. A 37wt% formaldehyde aqueous solution was added, and the pH was adjusted to 3-4 with 1 mol / L hydrochloric acid. The temperature was slowly increased to 35-40℃ and held for 30-40 min. Then, the temperature was increased to 60-65℃ at a rate of 1℃ / min and held for 3-4 h. The mixture was then vacuum filtered, washed, and dried to obtain microcapsule powder.

7. The method for preparing a wear-resistant and antioxidant polyurea lubricant according to claim 6, characterized in that, The ratio of the amounts of urea, resorcinol, glyoxal aqueous solution, ammonium chloride, sodium lignosulfonate, deionized water, polyalphaolefin, n-octanol, and formaldehyde aqueous solution is 25-35g: 1.2-2.2g: 5-8g: 2.5-4.5g: 2-4g: 150-200mL: 75-95g: 0.8-1.0mL: 50-70g.

8. The method for preparing a wear-resistant and antioxidant polyurea lubricant according to claim 1, characterized in that, The preparation process of the polyurea lubricant matrix in step three is as follows: Microcapsule powder is added to a reaction vessel and heated to 80-85℃. Then, organic amine and diisocyanate are added and reacted at 300-500 r / min for 40-60 min. The temperature is then raised to 100-120℃, distilled water is added, and the temperature is maintained for 20-30 min. The temperature is then raised to 180-190℃ and stirred for 15-45 min. After stirring and refining, the mixture is cooled to room temperature and ground three times with a three-roll mill to obtain the polyurea lubricant matrix.

9. The method for preparing a wear-resistant and antioxidant polyurea lubricant according to claim 8, characterized in that, The ratio of the microcapsule powder, organic amine, and diisocyanate is 100-150g: 6-8g: 25-35g; The organic amine is one of octadecylamine and cyclohexylamine; The diisocyanate is one of hexamethylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate.

10. The method for preparing a wear-resistant and antioxidant polyurea lubricant according to claim 1, characterized in that, The preparation process of the wear-resistant and antioxidant polyurea lubricant described in step three is as follows: The polyurea lubricant matrix and acetone solution were added to a reaction vessel, followed by the addition of ionic liquid-modified nanocomposite powder and hindered phenolic antioxidant 1010. The mixture was sonicated for 2-3 hours, and the acetone was removed under conditions of 80-85℃ and 500-700r / min to obtain a wear-resistant and antioxidant polyurea lubricant. The ratio of the polyurea lubricant matrix, acetone solution, ionic liquid-modified nanocomposite powder, and hindered phenolic antioxidant 1010 is 50-70g: 15-25mL: 0.5-1.0g: 0.1-0.2g.