A high-temperature resistant lubricant composition and a preparation method thereof

Abstract

This application relates to the technical field of bearing greases, and specifically discloses a high-temperature resistant lubricant composition and a preparation method thereof. A high-temperature resistant lubricant composition comprises the following raw materials in parts by weight: 90 - 110 parts of base oil, 30 - 35 parts of thickener, 2 - 3.5 parts of modified nanoparticles, 0.5 - 1.5 parts of antioxidant, 1 - 3 parts of rust inhibitor, and 0.5 - 1 part of friction improver; the thickener comprises polyethylene glycol, modified polyurea grease and surfactant with a mass ratio of 1:0.3 - 0.5:0.1 - 0.15; the modified nanoparticles are 1-hexadecyl-3-methylimidazolium bromide ionic liquid modified nanoparticles, and the nanoparticles comprise carbon nanoparticles and nano tungsten disulfide with a mass ratio of 2 - 3:1. The grease composition of this application has the advantages of good nanoparticle dispersibility, strong high-temperature resistance, excellent oxidation stability and anti-wear and friction-reducing properties.

Description

Technical Field

[0001] The present application relates to the technical field of bearing greases, and more specifically, to a high-temperature resistant lubricant composition and a preparation method thereof. Background Art

[0002] As is well known, in the oilfield development industry, the lubricating performance of drilling fluids has a great impact on drilling operations. Therefore, the lubricants used in drilling fluids are required to enable the drilling fluids to reduce the torque, wear, and fatigue of drill strings, extend the service life of drill bit bearings, prevent sticking and jamming, and reduce bit balling, etc. A lubricant is a treatment agent added to drilling, completion, or fracturing fluids to improve lubricating performance. Its main function is to reduce the torque, wear, abrasion, and damage rate of the tools in the drilling process. Lubricants are classified into liquid and solid lubricants according to their phases. Liquid lubricants mainly include mineral oils, vegetable oils, alcohol ethers, esters, and nano-material lubricants, etc. Solid lubricants mainly include plastic balls, glass balls, graphite, and carbon black lubricants, etc.

[0003] Deep wells and ultra-deep wells are in high-temperature environments. Existing liquid lubricants are prone to volatilization, degradation, and cross-linking at high temperatures, resulting in problems such as loss of activity and failure. Existing lubricants for high-temperature resistant drilling fluids, completion fluids, and fracturing fluids cannot effectively solve the problems of lubricant inactivation and failure.

[0004] To improve the high-temperature resistance and extreme pressure wear resistance of lubricants, adding nano-particles to liquid lubricants, such as inorganic nano-particles with a layered structure (graphite flakes, MoS2), soft metal nano-particles (Cu, Pb), etc., can effectively reduce the friction coefficient of the lubricant, while improving its extreme pressure performance and load-carrying capacity. Regarding the above related technologies, the inventor found that these nano-particles are added in a solid form, with poor compatibility with liquid lubricants, low extreme pressure performance, and easy precipitation, which in turn affects the use effect of the lubricant under high temperature and high pressure conditions. Summary of the Invention

[0005] In order to improve the dispersibility and compatibility of nano-particles in lubricants, reduce precipitation and stratification, and enhance the high temperature and high pressure resistance ability, the present application provides a high-temperature resistant lubricant composition and a preparation method thereof.

[0006] In the first aspect, the present application provides a high-temperature resistant lubricant composition, adopting the following technical solution:

[0007] A high-temperature resistant lubricant composition, comprising the following raw materials in parts by weight: 90 - 110 parts of base oil, 30 - 35 parts of thickening agent, 2 - 3.5 parts of modified nano-particles, 0.5 - 1.5 parts of antioxidant, 1 - 3 parts of rust inhibitor, and 0.5 - 1 part of friction improver;

[0008] The thickener includes polyethylene glycol, modified polyurea grease and surfactant with a mass ratio of 1:0.3 - 0.5:0.1 - 0.15;

[0009] The modified nanoparticles are 1 - hexadecyl - 3 - methylimidazolium bromide ionic liquid - modified nanoparticles, and the nanoparticles include carbon nanoparticles and nano tungsten disulfide with a mass ratio of 2 - 3:1.

[0010] By adopting the above - mentioned technical solution, the nanoparticles are modified by 1 - hexadecyl - 3 - methylimidazolium bromide ionic liquid and incorporated into a thickener containing polyethylene glycol, modified polyurea grease and surfactant. Polyethylene glycol can form a protective film at the friction interface, effectively reducing the friction coefficient and wear. Polyethylene glycol has high stability, can maintain the stability of lubricating performance under high temperature and high pressure, and has strong antioxidant and corrosion - resistant properties, which can protect mechanical equipment from oxidation and corrosion. The dropping point of polyurea grease is usually as high as over 250 °C, can maintain lubricity in a high - temperature environment, is not easy to drip oil or coke, and can maintain its chemical stability even under high - temperature conditions, effectively preventing problems such as high - temperature caking and friction. Moreover, when used for a long time in a high - temperature environment, its consistency does not change significantly, maintaining good working performance, and has excellent antioxidant properties to resist oxidation reactions in a high - temperature environment, extending the service life. Surfactants can adjust the surface tension of polyethylene glycol and polyurea resin, improving the infiltration, contact and diffusibility between the two phases, and having strong interfacial binding force. Using polyethylene glycol and polyurea grease as thickeners can form a stable colloid system with base oil. The urea group (—NH—CO—NH—) in the polyurea molecule has strong polarity, and the molecules are combined by strong hydrogen bonds, making the whole colloid system in a very stable state. This stability helps the grease maintain its performance under harsh conditions such as high temperature and heavy load.

[0011] Nano tungsten disulfide is a new type of solid lubricant material with a layered hexagonal crystal system structure. Due to the relatively low bond energy of the six - element molecular bonds between layers, it is easy to slip during friction, so it has excellent tribological properties. Moreover, nano tungsten disulfide has a small particle size, a large specific surface area and high diffusion performance, and is easy to adsorb on the metal surface, thus improving the tribological properties of the lubricant composition, effectively reducing the friction coefficient of the bearing when working in a high - temperature environment, reducing energy consumption, reducing grease consumption, and extending the working life of the grease. Nano tungsten disulfide mainly relies on friction chemical reactions occurring on the friction pair surface to generate a chemical reaction film to reduce friction and wear. In the steel - steel friction, the formation process of this chemical reaction film is as follows: under the action of friction heat, tungsten disulfide decomposes to generate W and sulfur anions (S 2-), then W diffuses and deposits on the metal surface. At the same time, S reacts with the base metal Fe to generate wear-resistant and friction-reducing components such as FeS. This chemical reaction film not only organizes the direct contact between the friction surfaces, but also has a high load-bearing capacity, making the elastic deformation and plastic deformation caused by shear stress confined to the lubricating film area. Therefore, the adhesive wear and contact fatigue of the friction surface are effectively inhibited, playing a role in protecting the friction surface. Moreover, the thickness of the reaction film increases with the increase of the friction-generated heat temperature. Therefore, under high-temperature action, the lubricating effect of tungsten disulfide is better;

[0012] Carbon nanoparticles have excellent chemical and thermal stability, low cost, and inherent self-lubricating properties of carbon nanomaterials. In addition, the quasi-spherical and ultra-small particle size tend to eliminate the embedding stability obstacles of traditional carbon nanomaterials in the micro-convex friction interface, which is beneficial for carbon nanoparticles to act as ball bearings, filling the grooves on the friction surface, increasing the contact area, reducing the contact pressure, and enhancing the pressure resistance and extreme pressure resistance under load and lubrication conditions.

[0013] Ionic liquids are room-temperature molten salts, which can be flexibly constructed by combining cations and anions. Modifying nanoparticles with 1-hexadecyl-3-methylimidazolium bromide ionic liquid can improve the dispersibility of nanoparticles in base oils such as polyethylene glycol. 1-hexadecyl-3-methylimidazolium bromide ionic liquid can coat the surface of nanoparticles to obtain uniformly dispersed ionic liquid-modified nanoparticles, improve the dispersibility of nanoparticles in the composite base oil, enhance their interfacial interaction with the base oil, and reduce the agglomeration and sedimentation of nanoparticles in the base oil. Since the nanoparticles coated with alkyl chains have high reactivity, under harsh lubrication conditions, it is further beneficial for the formation of friction films. Moreover, the low-energy electrons emitted by the micro-convex points on the friction surface cause the friction interface to be positively charged. The long alkyl chain anions not only promote the dispersion of nanoparticles into the base oil, but also can be adsorbed on the friction interface, thus reducing friction and wear.

[0014] Optionally, the preparation method of the modified nanoparticles is as follows:

[0015] Mix 1-hexadecyl-3-methylimidazolium bromide ionic liquid with chloroform, heat to 40 - 50 °C and stir evenly, then add carbon nanoparticles and nano tungsten disulfide, ultrasonically oscillate for 1 - 2 h, dry and grind to obtain modified nanoparticles.

[0016] By adopting the above technical solution, after mixing the ionic liquid with carbon nanoparticles and nano tungsten disulfide and ultrasonicating, the ionic liquid can adhere to the surface of the base oil, wrap the nanoparticles, and generate compounds such as FeF3, WO3, FeSO4, etc. through chemical reactions. Due to the modification of the ionic liquid, it can prevent the friction film of direct contact between the steel-steel surfaces, reduce the wear degree during the friction process, and the ionic liquid is a polar liquid. The cations and anions are adsorbed onto the friction surface through the Coulomb force between molecules, and the ions in the base oil interact with the long alkyl chains to improve the lubrication performance. Thus, it can also adsorb the nanoparticles and improve the role of the modified nanoparticles during the friction process.

[0017] Optionally, the preparation method of the carbon nanoparticles is as follows:

[0018] Mix oleylamine, Tween-85, concentrated sulfuric acid and concentrated phosphoric acid, heat up to 150 - 160 °C, keep warm for 5 - 6 h, filter, wash, and freeze-dry to obtain porous carbon particles;

[0019] Add the porous carbon particles into DMF, ultrasonicate for 1 - 2 h, add melamine and triethylamine, after mixing evenly, add cyanuric chloride, ultrasonicate for 1 - 2 h, heat up to 120 - 130 °C, react for 20 - 24 h, cool to room temperature, wash, freeze-dry, and grind.

[0020] By adopting the above technical solution, a mixed acid of sulfuric acid and phosphoric acid is used as the reaction medium, which accelerates the dehydration process of Tween-85 molecules. The water generated by the decomposition of the polyoxyethylene group of Tween-85 rapidly vaporizes at 150 °C, which may act as a pore-forming agent during the polymerization and carbonization processes. A porous carbon material coated with long alkyl chains and ester groups with high thermal stability is gradually formed, which can act as a ball bearing under boundary lubrication conditions, playing a role in rolling, repairing and polishing, enhancing the load-bearing capacity of the friction film, significantly improving the anti-wear and friction-reducing performance of the base oil, and also playing a good antioxidant role; Oleylamine is used to modify the porous carbon material. Oleylamine molecules are covalently grafted onto the surface of the carbon material through amide bonds to form oleylamine-modified carbon particles. The lipophilic oleylamine groups can keep the porous carbon material stably dispersed in the base oil; Using the solvent method, melamine and cyanuric chloride are used as raw materials to prepare triazine-based two-dimensional covalent organic polymer nanosheets. With porous carbon particles as the core and two-dimensional covalent organic polymers as the shell layer, carbon nanoparticles with a core-shell structure are constructed. Since the triazine-based two-dimensional covalent organic polymer nanosheets are nitrogen-rich systems, they have better compatibility in the base oil. The CH…π interaction formed between them and the base oil also plays a decisive role in the stable dispersion in the base oil. Due to its graphene-like layered structure, the triazine-based two-dimensional covalent organic polymer nanosheets can be adsorbed on the bearing surface during the friction process to form a physical adsorption protective film, effectively reducing the occurrence of friction and wear. The surface lipophilic nanosheets can also effectively prevent the agglomeration between carbon particles and improve the compatibility of carbon particles in the oil, enabling the effective occurrence of the ball effect of carbon microspheres and the adsorption performance of nanosheets, thereby reducing friction and wear. The carbon nanoparticles act as micro ball bearings during rolling friction. Some nanosheets may peel off from the surface of the porous carbon particles and adhere to the friction surface to form an adsorption lubricating film, effectively preventing direct contact between the friction surfaces. At the same time, the carbon microspheres can still act as micro bearings, thus maintaining good lubrication effects for a long time. When the two friction pairs come into contact with each other, the interaction between the rough peaks and grooves constitutes the frictional force during the sliding process. The tribological performance is affected by the load on the friction surface, the actual contact area and the stress distribution. The introduction of nanosheets can increase the actual contact area between the contact surfaces during the friction test and make the contact pressure distribution more uniform, ultimately effectively reducing the friction coefficient and wear volume loss.

[0021] Optionally, the preparation method of the modified polyurea grease is as follows:

[0022] Under a nitrogen atmosphere, the fluorinated terminal amino polydimethylsiloxane is mixed with tetrahydrofuran. After heating to 85 - 90 °C, 4,4 - diisocyanatodicyclohexylmethane is added, and the mixture is kept warm for 20 - 24 h. After cooling to room temperature, isophthalaldehyde is added, and the reaction is carried out at room temperature for 5 - 6 h. Then it is heated to 50 - 60 °C and reacted for 1 - 2 h. Micro - nano silica mixed particles are added and ultrasonicated to be uniform, obtaining a modified polyurea grease. The mass ratio of the fluorinated terminal amino polydimethylsiloxane to the micro - nano silica mixed particles is 1:0.1 - 0.2.

[0023] By adopting the above - mentioned technical solution, fluorinated polysiloxane is synthesized from octamethylcyclotetrasiloxane and 3,3,3 - trifluoropropylcyclotrisiloxane. Through two - step reactions, a polyurea structure and dynamic imine bonds are introduced to prepare a fluorinated polysiloxane / polyurea structure with self - healing ability. It has a low surface energy, and hydrogen bonds and imine bonds construct a double - repair network. Moreover, the hydrogen - bond structure gives the modified polyurea grease stronger adhesion. Since polysiloxane has a certain elasticity, it can make the two ends of the scratch approach quickly. Secondly, the hydrogen - bond interaction between the polyurea structures in the polymer makes the broken ends more closely connected, enabling the modified polyurea grease to self - repair quickly. In addition, the micro - nano silica mixed particles are beneficial to filling the pores or defects between the modified polyurea grease and the substrate, thus playing a certain role in enhancing the bonding force, improving the viscosity of the grease. Moreover, the micron - and nano - sized silica shows low surface energy and biomimetic micro - nano structures in the formed lubricating film, enabling the lubricating film to have excellent hydrophobicity and anti - pollutant ability.

[0024] Optionally, the micro - nano silica mixed particles include micron - sized silica and nano - sized silica with a mass ratio of 1:0.2 - 0.5.

[0025] By adopting the above - mentioned technical solution, micro - nano structures are constructed in the lubricating film with micron - and nano - sized silica, thereby improving the hydrophobicity and anti - foreign - matter ability of the lubricating film and enhancing the viscosity and strength of the lubricating film.

[0026] Optionally, the friction modifier is a mixture of cellulose nanocrystals modified by ionic liquid and multi - walled carbon nanotubes. The specific preparation method is as follows:

[0027] The multi - walled carbon nanotubes and cellulose nanocrystals are mixed according to a mass ratio of 0.5 - 1:1, concentrated nitric acid with a concentration of 60 - 65 wt% is added, ultrasonicated for 1 - 2 h, heated to 100 - 120 °C for reflux condensation for 1 - 2 h, filtered, washed until the pH is 7, and dried in vacuum to obtain a carboxylated mixture;

[0028] Disperse the carboxyl compound in deionized water, ultrasonically disperse for 1 - 2 h, add 1 - aminopropyl - 3 - methylimidazolium bromide, perform rotary evaporation at 50 - 60 °C, react at 175 - 180 °C for 12 - 13 h under nitrogen protection, cool to room temperature, add deionized water, dialyze for 2 - 3 days, rotary evaporate the dialysate and then dry it under vacuum. The mass ratio of the carboxylated mixture to 1 - aminopropyl - 3 - methylimidazolium bromide is 1:30 - 33.

[0029] By adopting the above technical solution, oxygen - containing groups such as carboxyl and hydroxyl are introduced onto multi - walled carbon nanotubes and cellulose nanocrystals using concentrated nitric acid, and the ionic liquid can be covalently grafted onto the surfaces of carbon nanotubes and cellulose nanocrystals through amide bonds. As a result, due to the electrostatic repulsion between carbon nanotubes and cellulose nanocrystals, they can remain stably suspended in the base oil for a long time, thereby improving the anti - friction and anti - wear effects. Moreover, carbon nanotubes and cellulose nanocrystals can repair and fill the worn surface and form a deposition film to effectively protect the surface and play a role in anti - friction and anti - wear. After the grease is subjected to a shearing action, the soap fibers decompose to form finer fibers dispersed in the base oil, enhancing the viscosity of the oil film and promoting lubrication.

[0030] Optionally, the base oil is selected from at least one of methylphenyl silicone oil, methyl silicone oil, ethyl silicone oil, fluorosilicone oil, PAO10, PAO40, oleic acid, and castor oil.

[0031] By adopting the above technical solution, the above - synthesized base oil, vegetable base oil, base silicone oil, etc. all have high lubricity and excellent oxidation stability, and can greatly extend the service life of the bearing.

[0032] Optionally, the surfactant is selected from at least one of lecithin, distearoyl phosphatidylcholine, and 1,2 - dioleoyl lecithin.

[0033] By adopting the above technical solution, the surfactant can improve the compatibility of polyethylene glycol and modified polyurea grease, making the thickening effect of the lubricant composition better.

[0034] Optionally, the antioxidant is selected from at least one of alkylated phenylnaphthylamine, zinc dialkyldithiophosphate, and 2,6 - di - tert - butyl - 4 - methylphenol;

[0035] The rust inhibitor is any one of octyldecylimidazole, calcium petroleum sulfonate, calcium isooctanoate, and zinc isooctanoate.

[0036] By adopting the above technical solution, the antioxidant can effectively inhibit the oxidation reaction of the grease and extend its service life; the rust inhibitor can increase the protection ability of the grease for the bearing.

[0037] In a second aspect, the present application provides a preparation method of a high - temperature - resistant lubricant composition, adopting the following technical solution:

[0038] A preparation method of a high-temperature resistant lubricant composition, comprising the following steps: mixing a base oil and a thickening agent, heating to 100 - 120 °C, mixing for 1 - 2 h, adding modified nanoparticles, stirring for 2 - 3 h, cooling to 80 - 90 °C, adding an anti-rust agent, an antioxidant and a friction improver, stirring for 0.5 - 1 h, and performing degassing and filtration to obtain the lubricant composition.

[0039] In summary, the present application has the following beneficial effects:

[0040] 1. Since the present application uses 1-hexadecyl-3-methylimidazolium bromide ionic liquid to modify the nanoparticles, during the friction process, the ionic liquid and the nanoparticles are jointly attached to the surface of the friction pair together with the lubricating oil, playing a lubricating role. At high temperatures, an oxidation reaction occurs on the friction surface, interacting with the oxides on the friction surface to generate a dense per-friction film, so that the steel-steel surface does not directly contact, further improving the friction performance. Moreover, the ionic liquid can improve the dispersion performance of the nanoparticles in the base oil, enhance the interfacial interaction between the nanoparticles and the base oil, making them exhibit relatively good dispersion stability and compatibility in the base oil, and improving the extreme pressure wear resistance and the use effect at high temperatures.

[0041] 2. In the present application, oleic acid and Tween-85 are preferably used to prepare porous carbon particles, and then a triazine-based two-dimensional covalent organic polymer nanosheet is formed on the porous carbon particles by the solvent method. With the porous carbon particles as the core and the two-dimensional covalent nanosheet as the shell layer, the compatibility of the carbon nanoparticles in the base oil is improved, and the adsorption force between the carbon nanoparticles and the bearing is enhanced, reducing wear and friction, and further improving the lubricating effect.

[0042] 3. In the present application, a mixture of ionic liquid-modified cellulose nanocrystals and multi-walled carbon nanotubes is preferably used as a friction improver, which can be evenly dispersed in the base oil and deposit a protective film on the friction surface, increasing the lubricating effect and reducing wear. Specific embodiments

[0043] The following examples further illustrate the present application in detail.

[0044] Preparation Examples 1 - 7 of Modified Nanoparticles

[0045] Preparation Example 1: Mix 30 g of 1-hexadecyl-3-methylimidazolium bromide ionic liquid with 300 g of chloroform. After heating to 40 °C and stirring for 30 min, add 22.5 g of carbon nanoparticles and 7.5 g of tungsten disulfide nanoparticles. Ultrasonically oscillate at a power of 250 W for 2 h, dry at 80 °C for 24 h, and grind for 30 min to obtain modified nanoparticles. The mass ratio of 1-hexadecyl-3-methylimidazolium bromide ionic liquid to nanoparticles is 1:1. The carbon nanoparticles are selected from Zhejiang Manli Nano Technology, with the product number ML-C-N20 and a density of 2.33 g / cm 3 , and the tungsten disulfide is selected from Nangong Zhongzhou Alloy Materials, with the product number NO-S-001-1, an average particle size of 300 nm, and a density of 7.6 g / cm 3 .

[0046] Preparation Example 2: Mix 30 g of 1-hexadecyl-3-methylimidazolium bromide ionic liquid with 300 g of chloroform. After heating to 50 °C and stirring for 30 min, add 20 g of carbon nanoparticles and 10 g of tungsten disulfide nanoparticles. Ultrasonically oscillate at a power of 250 W for 2 h, dry at 80 °C for 24 h, and grind for 30 min to obtain modified nanoparticles. The mass ratio of 1-hexadecyl-3-methylimidazolium bromide ionic liquid to nanoparticles is 1:1. The carbon nanoparticles are selected from Zhejiang Manli Nano Technology, with the product number ML-C-N20 and a density of 2.33 g / cm 3 , and the tungsten disulfide is selected from Nangong Zhongzhou Alloy Materials, with the product number NO-S-001-1, an average particle size of 300 nm, and a density of 7.6 g / cm 3 .

[0047] Preparation Example 3: The difference from Preparation Example 1 is that no carbon nanoparticles are added.

[0048] Preparation Example 4: The difference from Preparation Example 1 is that an equal amount of tungsten disulfide is used to replace the carbon nanoparticles.

[0049] Preparation Example 5: The difference from Preparation Example 1 is that the carbon nanoparticles are made by the following method:

[0050] (1) Mix 75 ml of oleylamine, 100 ml of Tween-85, 300 ml of concentrated sulfuric acid, and 100 ml of concentrated phosphoric acid. Heat to 150 °C, keep warm for 6 h, filter, wash with pure water, and freeze-dry at -40 °C for 48 h to obtain porous carbon particles;

[0051] (2) Add 2 g of porous carbon particles to 600 ml of DMF, ultrasonically treat for 2 h, add 3.78 g of melamine and 10 ml of triethylamine. After mixing evenly, add 4.612 g of cyanuric chloride, ultrasonically treat for 2 h, heat to 120 °C, react for 24 h, cool to room temperature, wash, centrifuge, and freeze-dry for 12 h with absolute ethanol and deionized water, and grind to the nanoscale.

[0052] Preparation Example 6: The difference from Preparation Example 5 is that no oleylamine was added.

[0053] Preparation Example 7: The difference from Preparation Example 5 is that step (2) was not carried out, and the porous carbon particles were used as carbon nanoparticles.

[0054] Preparation Examples 8 - 12 of Modified Polyurea Grease

[0055] Preparation Example 8: Under a nitrogen atmosphere, 15 g of octamethylcyclotetrasiloxane, 10.56 g of trifluoropropylcyclotrisiloxane, 5.31 g of 1,3 - bis(3 - aminopropyl)-1,1,3,3 - tetramethyldisiloxane, and 0.03 g of tetramethylammonium hydroxide - anhydrous compound were mixed, heated to 110 °C in an oil bath, reacted for 12 h, heated to 170 °C under a vacuum environment, and kept warm for 30 min to synthesize fluorinated terminal amino polydimethylsiloxane;

[0056] Under a nitrogen atmosphere, 10 g of fluorinated terminal amino polydimethylsilane was mixed with 50 ml of tetrahydrofuran, heated to 90 °C, then 7.5 g of 4,4 - diisocyanatodicyclohexylmethane was added, kept warm for 24 h, cooled to room temperature, 2.5 g of isophthalaldehyde was added, reacted at room temperature for 5 h, heated to 60 °C, reacted for 1 h, 2 g of micro - nano silica mixed particles were added, and ultrasonically homogenized to obtain the modified polyurea grease. The micro - nano silica mixed particles include micron - sized silica and nano - sized silica with a mass ratio of 1:0.5. The average particle size of the micron - sized silica is 3 μm, selected from Chihan Metal in Qinghe County, with the product number CH - SiO2 - D03. The particle size of the nano - sized silica is 15 nm, selected from Zhejiang Jingcai Chemical Industry, with the model JC - SP20.

[0057] Preparation Example 9: Under a nitrogen atmosphere, 15 g of octamethylcyclotetrasiloxane, 10.56 g of trifluoropropylcyclotrisiloxane, 5.31 g of 1,3 - bis(3 - aminopropyl)-1,1,3,3 - tetramethyldisiloxane, and 0.03 g of tetramethylammonium hydroxide - anhydrous compound were mixed, heated to 110 °C in an oil bath, reacted for 12 h, heated to 170 °C under a vacuum environment, and kept warm for 30 min to synthesize fluorinated terminal amino polydimethylsiloxane;

[0058] Under a nitrogen atmosphere, 10 g of fluorinated terminal amino polydimethylsilane was mixed with 50 ml of tetrahydrofuran. After heating to 80 °C, 7.5 g of 4,4 - diisocyanate dicyclohexylmethane was added, and the mixture was kept at a constant temperature for 20 h. After cooling to room temperature, 2.5 g of isophthalaldehyde was added, and the reaction was carried out at room temperature for 6 h. Then the temperature was raised to 50 °C and the reaction was continued for 2 h. 1 g of micro - nano silica mixed particles was added and sonicated to be uniform, obtaining a modified polyurea grease. The micro - nano silica mixed particles include micron - sized silica and nano - sized silica with a mass ratio of 1:0.2. The average particle size of the micron - sized silica is 3 μm, which is selected from Chihan Metal in Qinghe County, and the product number is CH - SiO2 - D03. The particle size of the nano - sized silica is 15 nm, which is selected from Zhejiang Jingcai Chemical Industry, and the model is JC - SP20.

[0059] Preparation Example 10: The difference from Preparation Example 8 is that no micro - nano silica mixed particles were added.

[0060] Preparation Example 11: The difference from Preparation Example 8 is that an equal amount of micron - sized silica was used to replace nano - sized silica.

[0061] Preparation Example 12: The difference from Preparation Example 8 is that no fluorinated terminal amino polydimethylsiloxane was added. Example

[0062] Example 1: A high - temperature resistant lubricant composition, the raw materials are shown in Table 1. The base oil is PAO40, the kinematic viscosity at 40 °C is 386 mm 2 / s, at 100 °C is 40 mm 2 / s, the viscosity index is 147, the pour point is - 40 °C, the flash point is 295 °C, the antioxidant is di - tert - butyl - p - cresol, the rust inhibitor is calcium petroleum sulfonate, the friction modifier is zinc dialkyldithiophosphate, the thickener includes polyethylene glycol 200, modified polyurea grease and surfactant with a mass ratio of 1:0.5:0.15. The modified polyurea grease is made from Preparation Example 8, the surfactant is lecithin, and the modified nano - particles are 1 - hexadecyl - 3 - methylimidazolium bromide ionic liquid - modified nano - particles and are made from Preparation Example 1.

[0063] The preparation method of the above - mentioned high - temperature resistant lubricant composition includes the following steps:

[0064] Mix the base oil and the thickener, heat to 100 °C, mix for 2 h, add the modified nano - particles, stir for 3 h, cool to 90 °C, add the rust inhibitor, antioxidant and friction modifier, stir for 0.5 h, and obtain the lubricant composition through degassing and filtration.

[0065] Table 1 Raw material dosages of the high - temperature resistant lubricant composition in Examples 1 - 3

[0066]

[0067] Example 2: A high-temperature resistant lubricant composition, the raw materials are shown in Table 1, the base oil is PAO40, the kinematic viscosity at 40 °C is 386 mm 2 / s, and at 100 °C is 40 mm 2 / s, the viscosity index is 147, the pour point is -40 °C, the flash point is 295 °C, the antioxidant is di-tert-butyl-p-cresol, the rust inhibitor is calcium petroleum sulfonate, the friction modifier is zinc dialkyldithiophosphate, the thickener includes polyethylene glycol 200, modified polyurea grease and surfactant with a mass ratio of 1:0.3:0.1. The modified polyurea grease is made from Preparation Example 9, the surfactant is lecithin, the modified nanoparticles are brominated-1-hexadecyl-3-methylimidazolium ionic liquid modified nanoparticles, and are made from Preparation Example 2.

[0068] The preparation method of the above high-temperature resistant lubricant composition includes the following steps:

[0069] Mix the base oil and the thickener, heat up to 120 °C, mix for 1 h, add the modified nanoparticles, stir for 2 h, cool down to 80 °C, add the rust inhibitor, antioxidant and friction modifier, stir for 1 h, and after degassing and filtering, the lubricant composition is obtained.

[0070] Example 3: A high-temperature resistant lubricant composition, the raw materials are shown in Table 1, the base oil is PAO40, the kinematic viscosity at 40 °C is 386 mm 2 / s, and at 100 °C is 40 mm 2 / s, the viscosity index is 147, the pour point is -40 °C, the flash point is 295 °C, the antioxidant is di-tert-butyl-p-cresol, the rust inhibitor is calcium petroleum sulfonate, the friction modifier is zinc dialkyldithiophosphate, the thickener includes polyethylene glycol 200, modified polyurea grease and surfactant with a mass ratio of 1:0.5:0.15. The modified polyurea grease is made from Preparation Example 8, the surfactant is lecithin, the modified nanoparticles are brominated-1-hexadecyl-3-methylimidazolium ionic liquid modified nanoparticles, and are made from Preparation Example 2.

[0071] The preparation method of the above high-temperature resistant lubricant composition includes the following steps:

[0072] Mix the base oil and the thickener, heat up to 100 °C, mix for 2 h, add the modified nanoparticles, stir for 3 h, cool down to 90 °C, add the rust inhibitor, antioxidant and friction modifier, stir for 0.5 h, and after degassing and filtering, the lubricant composition is obtained.

[0073] Example 4: A high-temperature resistant lubricant composition, different from Example 1 in that the modified polyurea grease is made from Preparation Example 10.

[0074] Example 5: A high temperature resistant lubricant composition, which is different from Example 1 in that the modified polyurea grease is prepared from Preparation Example 11.

[0075] Example 6: A high temperature resistant lubricant composition, which is different from Example 1 in that the modified polyurea grease is prepared from Preparation Example 12.

[0076] Example 7: A high temperature resistant lubricant composition, which is different from Example 1 in that the modified nanoparticles are prepared by Preparation Example 5.

[0077] Example 8: A high temperature resistant lubricant composition, which is different from Example 7 in that the modified nanoparticles are prepared by Preparation Example 6.

[0078] Example 9: A high temperature resistant lubricant composition, which is different from Example 7 in that the modified nanoparticles are prepared by Preparation Example 7.

[0079] Example 10: A high temperature resistant lubricant composition, which differs from Example 7 in that the friction modifier is a mixture of cellulose nanocrystals and multi-walled carbon nanotubes modified with ionic liquids, and the specific preparation method is as follows:

[0080] 10g of multi-walled carbon nanotubes and cellulose nanocrystals were mixed in a mass ratio of 1:1, 600ml of nitric acid with a concentration of 65wt% was added, ultrasonicated at a power of 40kHz for 2h, heated to 100°C, condensed and refluxed for 2h, cooled to room temperature, filtered with a 0.22μm polytetrafluoroethylene filter membrane, washed to a pH of 7, and vacuum dried at 60°C for 12h to obtain a carboxylated mixture, wherein the multi-walled carbon nanotubes were selected from Sichuan Kenye Technology, model KY297C-12, and the cellulose nanocrystals were selected from Xi'an Qiyue Biotechnology, model CNC;

[0081] Disperse 3 g of carboxyl compound in 300 ml of deionized water, ultrasonicate at a power of 40 kHz for 1 h, add 100 g of 1-aminopropyl-3-methylimidazolium bromide, rotary evaporate at 50 ° C, react at 180 ° C for 12 h under nitrogen protection, cool to room temperature, add 200 ml of deionized water, dialyze for 3 days, change the water 6 times during the period, rotary evaporate the dialysate and vacuum dry it at 60 ° C for 20 h.

[0082] Example 11: A high temperature resistant lubricant composition, which differs from Example 7 in that the friction modifier is a mixture of cellulose nanocrystals and multi-walled carbon nanotubes modified with ionic liquids, and the specific preparation method is as follows:

[0083] 10g of multi-walled carbon nanotubes and cellulose nanocrystals were mixed in a mass ratio of 1:0.5, 500ml of 60wt% nitric acid was added, ultrasonicated at a power of 50kHz for 1h, heated to 120°C, condensed and refluxed for 1h, cooled to room temperature, filtered with a 0.22μm polytetrafluoroethylene filter membrane, washed to a pH of 7, and vacuum dried at 60°C for 12h to obtain a carboxylated mixture, the multi-walled carbon nanotubes were selected from Sichuan Kenye Technology, model KY297C-12, and the cellulose nanocrystals were selected from Xi'an Qiyue Biotechnology, model CNC;

[0084] Disperse 3 g of carboxyl compound in 300 ml of deionized water, ultrasonicate at a power of 50 kHz for 2 h, add 90 g of 1-aminopropyl-3-methylimidazolium bromide, rotary evaporate at 60 ° C, react at 175 ° C for 13 h under nitrogen protection, cool to room temperature, add 200 ml of deionized water, dialyze for 2 days, change the water 6 times during the period, rotary evaporate the dialysate and vacuum dry it at 60 ° C for 20 h.

[0085] Example 12: A high temperature resistant lubricant composition, which differs from Example 10 in that no cellulose nanocrystals are added.

[0086] Example 13: A high temperature resistant lubricant composition, which differs from Example 10 in that cellulose nanocrystals are used in equal amounts to replace multi-walled carbon nanotubes.

[0087] Example 14: A high temperature resistant lubricant composition, which differs from Example 10 in that 1-aminopropyl-2-methylimidazolium bromide is not used for treatment, and a carboxyl compound is used as a friction modifier.

[0088] Comparative Example

[0089] Comparative Example 1: A high temperature resistant lubricant composition, which differs from Example 1 in that the nanoparticles are not modified by bromide-1-hexadecyl-3-methylimidazolium ionic liquid, and a mixture of carbon nanoparticles and nano-tungsten disulfide in a mass ratio of 3:1 is used as the nanoparticles.

[0090] Comparative Example 2: A high temperature resistant lubricant composition, which is different from Example 1 in that the modified nanoparticles are prepared by Preparation Example 3.

[0091] Comparative Example 3: A high temperature resistant lubricant composition, which is different from Example 1 in that the modified nanoparticles are prepared by Preparation Example 4.

[0092] Comparative Example 4: A high temperature resistant lubricant composition, which is different from Example 1 in that polyethylene glycol is not added to the thickener.

[0093] Comparative Example 5: A high-temperature resistant lubricant composition, which is different from Example 1 in that the modified polyurea grease is not added to the thickener.

[0094] Comparative Example 6: A high-temperature resistant lubricant composition, which is different from Example 1 in that the thickener is 12-hydroxystearic acid.

[0095] Performance detection test

[0096] Prepare the lubricant composition according to the methods in the examples and comparative examples, and conduct performance detection with reference to the following methods. Record the detection results in Table 2.

[0097] 1. Work penetration: Measured with reference to ASTM D217-2017 standard. Put the grease sample into the standard working device, and after 60 shears at 25 °C, measure the penetration, in 0.1 mm.

[0098] 2. Oxidation stability: Measured with reference to SH / T 0193-2008 standard. Fill a certain amount of grease into an oxygen bomb filled with oxygen pressure, undergo oxidation at 100 °C, and determine the oxidation stability of the grease by the corresponding oxygen pressure drop after 30 h.

[0099] 3. Viscosity: Detected according to GB / T0681-1999 "Determination Method for Apparent Viscosity of Grease".

[0100] 4. Oil film strength: Conducted on an MRS-10A four-ball extreme pressure testing machine, with a rotation speed of 1450 r / min and a time of 10 s. The test balls are national grade II standard GCr bearing steel balls with a diameter of 12.7 mm and a hardness of HRC64-66. Test the oil film strength P of the grease at 200 °C. B value.

[0101] 5. Wear scar diameter: Detected according to NB / SH / T0189-2017 "Determination of Anti-wear Performance of Lubricating Oil - Four-ball Method". The test rotation speed is 1200 r / min, the temperature is 75 °C, the wear time is 30 min, and the test load is 196 N.

[0102] Table 2 Performance detection results of high-temperature resistant lubricant composition

[0103]

[0104] Combined with Examples 1-3 and the data in Table 2, it can be seen that the modified nanoparticles prepared in Preparation Examples 1 and 2, and the modified polyurea greases prepared in Examples 8 and 9 are used in Examples 1-3. It can be seen that the high-temperature resistant lubricant compositions prepared in Examples 1-3 have relatively high working penetration and viscosity, good oxidation stability, high high-temperature oil film strength, small wear scar diameter, good high-temperature resistance, and strong lubrication effect.

[0105] In Examples 4 and 5, the modified polyurea greases prepared in Preparation Examples 10 and 11 are used respectively. Compared with Preparation Example 8, micro-nano silica mixed particles are not added in Preparation Example 10, and only micron silica is used in Preparation Example 11. The oil film strength of the lubricant compositions prepared in Examples 4 and 5 decreases, the wear scar diameter increases, and the high-temperature resistance and lubrication ability decline.

[0106] In Example 6, the modified polyurea grease prepared in Preparation Example 12 is used. Compared with Preparation Example 8, fluorinated terminal amino polydimethylsiloxane is not added, the viscosity of the lubricant composition decreases, the penetration increases, but the oil film strength becomes poor.

[0107] In Example 7, the modified nanoparticles prepared in Preparation Example 1 are used. Compared with Preparation Example 1, the carbon material is modified with oleylamine and coated with triazine-based two-dimensional covalent organic polymer nanosheets. The obtained carbon nanoparticles have higher anti-wear and lubrication effects and stronger oil film strength at high temperatures.

[0108] Compared with Example 7, in Examples 8 and 9, the modified nanoparticles prepared in Preparation Examples 6 and 7 are used respectively. Oleylamine is not added in Preparation Example 6, and melamine, cyanuric chloride, etc. are not used in Preparation Example 7. As can be seen in Table 2, the high-temperature lubricity of the lubricant compositions prepared in Examples 8 and 9 decreases.

[0109] Compared with Example 7, in Examples 10 and 11, a mixture of ionic liquid-modified cellulose nanocrystals and multi-walled carbon nanotubes is used as a friction improver. As shown in Table 2, the wear scar diameter of the lubricant compositions prepared in Examples 10 and 11 decreases, the high-temperature resistance performance improves, and the working penetration increases.

[0110] Cellulose nanocrystals are not added in Example 12, and cellulose nanocrystals are used to replace multi-walled carbon nanotubes in Example 13. Compared with Example 10, the viscosity of the lubricant composition in Example 12 decreases, and the viscosity of the lubricant composition in Example 13 increases, while the working penetration decreases.

[0111] In Example 14, 1-aminopropyl-2-methylimidazole bromide is not used to modify the carboxyl compound, and the carboxyl compound is used as a friction improver. Compared with Example 10, the lubrication ability of the lubricant composition prepared in Example 14 declines.

[0112] In Comparative Example 1, 1-hexadecyl-3-methylimidazolium bromide ionic liquid was not used for modification, and only carbon nanoparticles and nano tungsten disulfide were used. The data in Table 2 show that the working penetration of the lubricant composition prepared in Comparative Example 1 decreased, the oil film strength decreased, and the lubrication effect became worse.

[0113] In Comparative Example 2, the modified nanoparticles prepared in Preparation Example 3 were used, and in Comparative Example 3, the modified nanoparticles prepared in Preparation Example 4 were used. Compared with Preparation Example 1, carbon nanoparticles were not added in Preparation Example 3, and tungsten disulfide was used to replace carbon nanoparticles in Preparation Example 4. The data in Table 2 show that the viscosity of the lubricant composition prepared in Comparative Example 2 decreased, the working penetration increased, and the fluidity increased, but the oxidation stability decreased, the oil film strength decreased, the wear scar diameter increased, and the lubrication effect decreased. For the lubricant composition prepared in Comparative Example 3, the viscosity changed little, but its oil film strength at 200 °C decreased, the high-temperature resistance ability weakened, the wear scar diameter increased, and the lubrication effect weakened.

[0114] Compared with Example 1, polyethylene glycol was not added in Comparative Example 4, and modified polyurea grease was not added in Comparative Example 5. Compared with Example 1, the lubricant compositions prepared in Comparative Example 4 and Comparative Example 5 had a slight decrease in viscosity and were difficult to form a dense lubricating film on the substrate, so the oil film strength and wear scar diameter both decreased.

[0115] In Comparative Example 6, 12-hydroxystearic acid was used as the thickener. Compared with Example 1, the working penetration of the lubricant composition prepared in Comparative Example 6 decreased, the viscosity became smaller, and the service performance became worse.

[0116] This specific embodiment is only an explanation of the present application, and it does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A high temperature resistant lubricant composition, characterized in that: The invention comprises the following raw materials in parts by weight: 90-110 parts of base oil, 30-35 parts of thickener, 2-3.5 parts of modified nanoparticles, 0.5-1.5 parts of antioxidant, 1-3 parts of rust inhibitor and 0.5-1 parts of friction modifier; The thickener comprises polyethylene glycol, modified polyurea grease and surfactant in a mass ratio of 1:0.3-0.5:0.1-0.15; The modified nanoparticles are bromide-1-hexadecyl-3-methylimidazolium-based ionic liquid modified nanoparticles, and the nanoparticles include carbon nanoparticles and nano-tungsten disulfide in a mass ratio of 2-3:1; The preparation method of the modified polyurea grease is as follows: In a nitrogen atmosphere, fluorinated amino-terminated polydimethylsilane is mixed with tetrahydrofuran, and the temperature is raised to 85-90°C, and then 4,4-diisocyanate dicyclohexylmethane is added. The mixture is kept warm for 20-24 hours, cooled to room temperature, and isophthalaldehyde is added. The mixture is reacted at room temperature for 5-6 hours, and the temperature is raised to 50-60°C, and the mixture is reacted for 1-2 hours. Micro-nano silica mixed particles are added, and the mixture is homogenized by ultrasound to obtain a modified polyurea grease. The mass ratio of fluorinated amino-terminated polydimethylsilane to micro-nano silica mixed particles is 1:0.1-0.

2.

2. The high temperature resistant lubricant composition according to claim 1, characterized in that: The preparation method of the modified nanoparticles is as follows: The bromide-1-hexadecyl-3-methylimidazolium ionic liquid is mixed with chloroform, the temperature is raised to 40-50° C., and the mixture is stirred evenly. Then, carbon nanoparticles and nano-tungsten disulfide are added, ultrasonically vibrated for 1-2 hours, dried and ground to obtain modified nanoparticles.

3. The high temperature resistant lubricant composition according to claim 2, characterized in that: The preparation method of the carbon nanoparticles is as follows: Mix oleylamine, Tween-85, concentrated sulfuric acid and concentrated phosphoric acid, raise the temperature to 150-160°C, keep the temperature for 5-6 hours, filter, wash, freeze-dry, and obtain porous carbon particles; The porous carbon particles were added to DMF, ultrasonicated for 1-2 hours, melamine and triethylamine were added, cyanuric chloride was added after mixing evenly, the mixture was ultrasonicated for 1-2 hours, the temperature was raised to 120-130°C, the reaction was performed for 20-24 hours, the mixture was cooled to room temperature, washed, freeze-dried and ground.

4. The high temperature resistant lubricant composition according to claim 1, characterized in that: The micro-nano silicon dioxide mixed particles include micron silicon dioxide and nano silicon dioxide in a mass ratio of 1:0.2-0.

5.

5. The high temperature resistant lubricant composition according to claim 1, characterized in that: The friction modifier is a mixture of cellulose nanocrystals and multi-walled carbon nanotubes modified by ionic liquids, and the specific preparation method is as follows: The multi-walled carbon nanotubes and cellulose nanocrystals are mixed in a mass ratio of 0.5-1:1, nitric acid with a concentration of 60-65wt% is added, ultrasonicated for 1-2h, heated to 100-120°C, condensed and refluxed for 1-2h, filtered, washed until the pH value is 7, and vacuum dried to obtain a carboxylation mixture; The carboxylation mixture is dispersed in deionized water, ultrasonically dispersed for 1-2 hours, 1-aminopropyl-3-methylimidazolium bromide is added, rotary evaporated at 50-60°C, reacted at 175-180°C for 12-13 hours under nitrogen protection, cooled to room temperature, deionized water is added, dialyzed for 2-3 days, the dialyzate is rotary evaporated and vacuum dried, and the mass ratio of the carboxylation mixture to 1-aminopropyl-3-methylimidazolium bromide is 1:30-33.

6. The high temperature resistant lubricant composition according to claim 1, characterized in that: The base oil is selected from at least one of methylphenyl silicone oil, methyl silicone oil, ethyl silicone oil, fluorosilicone oil, PAO10, PAO40, oleic acid and castor oil.

7. The high temperature resistant lubricant composition according to claim 1, characterized in that: The surfactant is selected from at least one of lecithin, distearoylphosphatidylcholine and 1,2-dioleoyl lecithin.

8. The high temperature resistant lubricant composition according to claim 1, characterized in that: The antioxidant is selected from at least one of alkylated phenylnaphthylamine, zinc dialkyl dithiophosphate and di-tert-butyl-p-cresol; The rust inhibitor is any one of octyl decidyl imidazole, calcium petroleum sulfonate, calcium isooctanoate and zinc isooctanoate.

9. The method for preparing the high temperature resistant lubricant composition according to any one of claims 1 to 8, characterized in that: The following steps are involved: The base oil and the thickener are mixed, heated to 100-120°C, mixed for 1-2 hours, the modified nanoparticles are added, stirred for 2-3 hours, cooled to 80-90°C, the rust inhibitor, antioxidant and friction modifier are added, stirred for 0.5-1 hour, degassed and filtered to obtain a lubricant composition.

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