Low-viscosity high-lubrication low-temperature gear oil and preparation process thereof

Abstract

The invention discloses low-viscosity high-lubrication low-temperature gear oil and a preparation process thereof, and relates to the technical field of lubricating oil. The invention discloses low-viscosity high-lubrication low-temperature gear oil. The lubricating oil is prepared from the following raw materials in parts by weight: 65 to 75 parts of base oil, 5 to 8 parts of modified polymethacrylate, 3 to 5 parts of nano silicon dioxide loaded sulfurized isobutylene, 2 to 3 parts of a composite antioxidant, 1 to 3 parts of an anti-rust agent, 1 to 3 parts of a demulsifying agent, 0.05 to 0.1 part of an anti-foaming agent, 0.5 to 1.0 part of an alkylated diphenylamine metal deactivator, 0.2 to 0.5 part of modified nano graphene and 0.3 to 0.6 part of a pour point depressant. The low-viscosity high-lubrication low-temperature gear oil disclosed by the invention has remarkable advantages. The modified polymethacrylate reduces viscosity, increases lubricity and inhibits foam; nano-silica-loaded sulfurized isobutylene provides extreme pressure protection, improves low-temperature performance and resists emulsification; and the modified nano graphene optimizes the overall performance. The composite antioxidant and the anti-rust agent prolong the service life of the oil product, the demulsifying agent and the anti-foaming agent guarantee the state of the oil product, and the pour point depressant improves the low-temperature fluidity, so that various harsh working conditions are met.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricating oils, and specifically to a low-viscosity and high-lubricity low-temperature gear oil and its preparation process. Background Art

[0002] In the fields of modern industry and transportation, gear transmission, as a key mechanical transmission method, is widely used in many devices such as automobiles, aerospace, ships, and industrial machinery. With the increasingly complex operating environment of the devices and the continuous improvement of working conditions requirements, more stringent standards are put forward for the performance of gear oils.

[0003] In low-temperature environments, traditional gear oils face many challenges. On the one hand, low temperature will cause the viscosity of the gear oil to increase sharply, making its fluidity worse, difficult to quickly reach each lubrication part, resulting in difficult equipment startup, increased energy consumption, and increased gear wear, seriously affecting the normal operation and service life of the equipment. On the other hand, under the working conditions of low temperature and high load, the lubrication performance of ordinary gear oils is insufficient, unable to effectively reduce the friction and wear between gears, easily causing failure problems such as gear surface fatigue, scuffing, and even galling, reducing the reliability and safety of the equipment.

[0004] At the same time, in complex use environments, gear oils also need to have good comprehensive performance. For example, in a humid environment, gear oils should have excellent anti-emulsification performance to prevent water from mixing in and causing the oil to emulsify and deteriorate, affecting the lubrication effect; during long-term operation, gear oils should have excellent antioxidant performance to reduce acidic substances and deposits generated by oxidation, avoiding corrosion of equipment and blockage of oil circuits. However, existing gear oils often fail to achieve an ideal balance in these aspects and cannot fully meet the requirements of modern equipment for high-performance gear oils.

[0005] The present invention is precisely proposed based on in-depth research and analysis of the above problems, aiming to develop a low-viscosity and high-lubricity low-temperature gear oil to effectively solve the problems of insufficient fluidity, lubricity, and comprehensive performance of existing gear oils in low-temperature environments, provide reliable guarantee for the stable operation of various devices under complex working conditions, and promote the efficient development of related industries. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a low-viscosity and high-lubricity low-temperature gear oil to solve the above problems.

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0008] Low-viscosity and high-lubricity low-temperature gear oil, comprising the following raw materials in parts by weight: 65 - 75 parts of base oil, 5 - 8 parts of modified polymethacrylate, 3 - 5 parts of nano-silica supported sulfurized isobutene, 2 - 3 parts of compound antioxidant, 1 - 3 parts of rust inhibitor, 1 - 3 parts of demulsifier, 0.05 - 0.1 part of antifoaming agent, 0.5 - 1.0 part of alkylated diphenylamine metal deactivator, 0.2 - 0.5 part of modified nano-graphene, 0.3 - 0.6 part of pour point depressant.

[0009] Among them, the preparation steps of the modified polymethacrylate are as follows:

[0010] A1. Add polymethacrylate and toluene into a four-necked flask, heat up to 60 °C, stir at 300 r / min to dissolve the polymethacrylate in toluene, then add azobisisobutyronitrile, and pass nitrogen at a flow rate of 0.5 L / min to displace oxygen for 30 minutes; add nano-zinc oxide surface-modified with stearic acid, maintain the reaction temperature at 60 °C, and stir at a speed of 500 r / min for 1 hour to uniformly disperse the nano-zinc oxide in the reaction system; the dosage ratio of polymethacrylate, toluene, azobisisobutyronitrile, and surface-modified nano-zinc oxide is 40 g: 160 mL: 0.4 g: 1 g;

[0011] A2. Slowly dropwise add perfluorooctyl acrylate monomer through a constant pressure dropping funnel, stir at 400 r / min for 20 minutes, then dropwise add lauryl methacrylate and vinyltrimethoxysilane, continue to stir for 30 minutes, then add dimethyl silicone oil, and react at 80 °C under nitrogen protection and stirring at 400 r / min for 6 hours. Pass an appropriate amount of carbon dioxide gas into the reaction system every 1 hour, the ventilation time is 10 minutes, and the flow rate is controlled at 0.2 L / min; the dosage ratio of polymethacrylate, perfluorooctyl acrylate monomer, lauryl methacrylate, vinyltrimethoxysilane, and dimethyl silicone oil is 40 g: 12.5 g: 5 g: 3 g: 2 g;

[0012] A3. After the reaction is completed and the reaction solution is cooled to room temperature, slowly pour it into excessive methanol for precipitation, centrifuge and separate at 8000 r / min for 15 minutes, wash the product with methanol 3 times, transfer it to a vacuum drying oven, and dry it at 60 °C and -0.08 MPa for 12 hours to obtain a light yellow solid modified polymethacrylate.

[0013] In step A1, azobisisobutyronitrile decomposes when heated at 60°C. The N=N bond in the molecule breaks, generating two isobutyronitrile radicals. In step A2, azobisisobutyronitrile decomposes upon heating to produce radicals, initiating a radical addition reaction with the double bonds of perfluorooctyl acrylate monomer, lauryl methacrylate, and vinyltrimethoxysilane. The polymethacrylate radicals attack the double bonds of these three monomers respectively, gradually forming a modified polymethacrylate long chain grafted with multiple side chains. The long-chain alkyl side chain of lauryl methacrylate can further reduce the intermolecular force, enhance the viscosity reduction effect, and improve the lubrication performance. After hydrolysis, vinyltrimethoxysilane can crosslink with polymethacrylate, enhancing the structural stability of the polymer, and thus improving the performance of the gear oil under high temperature and high load.

[0014] Furthermore, the base oil is compounded from polyalphaolefin and pentaerythritol ester at a mass ratio of 3:1.

[0015] Furthermore, the preparation steps of the nano-silica supported sulfurized isobutene are as follows:

[0016] B1. Disperse nano-silica in an ethanol solution with a mass-volume fraction of 5%, add silane coupling agent KH-550, ultrasonically treat the system for 30 minutes, then reflux and react at 60°C for 4 hours, centrifuge at 8000 r / min for 10 minutes, wash the product with ethanol three times, and then vacuum dry at 60°C to obtain amino-functionalized silica. Then add nano-copper powder modified with oleic acid and stir at 400 r / min at 30°C for 2 hours. The dosage ratio of nano-silica, ethanol solution, silane coupling agent KH-550, and nano-copper powder modified with oleic acid is 20 g:400 mL:2 g:0.2 g;

[0017] B2. Add sulfurized isobutene and maleic anhydride into a three-necked flask, then add toluene solvent and tricresyl phosphate, heat to 60°C under nitrogen protection, stir and react at 500 r / min for 2 hours, and distill off toluene under reduced pressure at 60°C and 4 kPa to obtain carboxylated sulfurized isobutene. The dosage ratio of sulfurized isobutene, maleic anhydride, toluene, and tricresyl phosphate is 15 g:8.8 g:75 mL:1 g;

[0018] B3. Add amino-functionalized silica and carboxylated isobutene sulfide into ethanol, stir at 300 r / min for 20 minutes, then add molybdenum disulfide nanoparticles, oleic acid-modified carbon nanotubes and catalyst 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide for ultrasonic dispersion. After centrifuging at 10,000 r / min for 15 minutes, conduct vacuum drying treatment at 60 °C for 12 hours to obtain isobutene sulfide supported on nano-silica. The dosage ratio of amino-functionalized silica, carboxylated isobutene sulfide, molybdenum disulfide nanoparticles, oleic acid-modified carbon nanotubes, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and ethanol is 20 g:16 g:0.5 g:0.3 g:0.6 g:240 mL.

[0019] In step B1, the silane coupling agent KH-550 contains siloxane groups and amino groups in its molecule. During ultrasonic treatment and reflux reaction at 60 °C, the siloxane groups of the silane coupling agent hydrolyze, the Si-O-R bond breaks, and a condensation reaction occurs with the hydroxyl groups on the surface of nano-silica to form Si-O-Si bonds, introducing amino groups onto the surface of nano-silica to achieve the amino-functionalization of nano-silica. In step B2, the carbon-carbon double bond in isobutene sulfide undergoes a diene addition reaction with maleic anhydride. As the diene body, the π bond of the carbon-carbon double bond in isobutene sulfide breaks, and as the dienophile, the π bond of the carbon-carbon double bond in maleic anhydride also breaks to form new carbon-carbon single bonds, generating carboxylated isobutene sulfide, and at the same time constructing a new six-membered ring structure. In step B3, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide acts as a catalyst to promote the dehydration condensation reaction between the carboxyl group of carboxylated isobutene sulfide and the amino group of amino-functionalized silica. The C-OH bond in the carboxyl group breaks, the N-H bond in the amino group breaks, generating C-N bonds and water molecules, thereby loading isobutene sulfide onto the surface of nano-silica. Isobutene sulfide provides extreme pressure protection, and silica enhances the load-bearing capacity. The uniform dispersion of nano-silica improves the low-temperature performance, and the hydrophobicity of nano-SiO 2 supported isobutene sulfide inhibits water emulsification. In the crystal structure of molybdenum disulfide, sulfur atoms have a strong chemical adsorption effect on the metal surface. When the gear surfaces rub against each other, under the local high-temperature and high-pressure environment, the sulfur atoms of molybdenum disulfide nanoparticles will chemically react with the iron atoms on the gear metal surface to form a protective film of iron sulfide. The friction coefficient of iron sulfide is much smaller than that of the metal, which can effectively reduce the friction between gears and play an anti-wear role. The long-chain hydrocarbon group of oleic acid has lipophilicity, which greatly improves the dispersibility of the modified carbon nanotubes in an organic medium such as gear oil, enabling them to be evenly dispersed in the system and avoiding agglomeration, thereby effectively exerting their strengthening effect.

[0020] Furthermore, the compound antioxidant is prepared by compounding 2,6-di-tert-butyl-p-cresol and N-phenyl-α-naphthylamine at a molar ratio of 1:1; the rust inhibitor is one of calcium borated sulfonate, dodecenyl succinic acid, and barium petroleum sulfonate.

[0021] Further, the demulsifier is one of ethylene oxide-propylene oxide copolymer, polypropylene glycol, and alkylphenol polyoxyethylene ether.

[0022] Further, the antifoaming agent is one of polydimethylsiloxane and acrylate polymer.

[0023] Further, the alkylated diphenylamine metal deactivator is one of alkylated diphenylamine, benzotriazole, and 2-methyl-1,2,3-thiadiazole.

[0024] Further, for the modified nano-graphene, the specific operation steps are as follows:

[0025] C1. Disperse nano-graphene in toluene, perform ultrasonic treatment for 30 minutes to ensure uniform dispersion of graphene, transfer the dispersion liquid to a three-necked flask, add azobisisobutyronitrile, and pass nitrogen at a flow rate of 0.5 L / min to displace oxygen for 30 minutes; the dosage ratio of nano-graphene, toluene, and azobisisobutyronitrile is 1.0 g: 200 mL: 0.1 g;

[0026] C2. Add octadecylamine to the flask, heat up to 80 °C, and stir and react at 500 r / min for 6 hours under nitrogen protection; the dosage ratio of octadecylamine to nano-graphene is 5.0 g: 1.0 g;

[0027] C3. After the reaction is completed, cool to room temperature, transfer the reaction solution to a centrifuge tube, centrifuge at 10000 r / min for 15 minutes; wash the precipitate with toluene 3 times; transfer the modified graphene to a vacuum drying oven and dry at 60 °C for 12 hours to obtain dry modified nano-graphene powder.

[0028] Azobisisobutyronitrile decomposes when heated, the N=N bond breaks, and isobutyronitrile radicals are generated. Under the action of the radicals generated by the decomposition of azobisisobutyronitrile, octadecylamine undergoes a radical substitution reaction. The N-H bond of octadecylamine breaks, and the generated alkyl radicals attack the defect sites on the surface of graphene, such as carboxyl groups, hydroxyl groups, or edge carbon atoms, to achieve the modification of graphene.

[0029] Further, the pour point depressant is one of polymethacrylate alkyl ester, poly-α-olefin pour point depressant, and ethylene-vinyl acetate copolymer.

[0030] The preparation method of the low-viscosity and high-lubricity low-temperature gear oil specifically includes the following steps:

[0031] Weigh each raw material by weight parts and add the base oil into a double-layer jacketed reactor. Heat it up to 60 °C and stir at 500 r / min for 30 minutes until the system is transparent and without stratification. Add the modified polymethacrylate and dissolve it in the base oil by ultrasonic treatment at 50 °C until the transmittance measured at a wavelength of 660 nm is greater than 95%. Circulate and shear the nano-silica supported sulfurized isobutene and the modified nano-graphene through a high-shear homogenizer at 60 °C and 12,000 r / min for 30 minutes to make the particle size less than 200 nm and then add them. Then, add the antioxidant, rust inhibitor, anti-emulsifier, and alkylated diphenylamine metal deactivator in sequence, and maintain stirring at 60 °C for 2 hours. Wait for the system to cool down to 40 °C, add the anti-foaming agent and pour point depressant, filter through a 0.1 μm filter membrane, and perform degassing treatment to obtain a low-viscosity and high-lubricity low-temperature gear oil.

[0032] The present invention provides a low-viscosity and high-lubricity low-temperature gear oil and its preparation process. It has the following beneficial effects:

[0033] 1. Excellent low-temperature performance: Through the reasonable selection of the pour point depressant and its synergistic effect with other components, the low-temperature fluidity of the gear oil is greatly improved, and the pour point is significantly reduced. In a cold environment, the gear oil can quickly reach each lubricating part, ensuring the rapid startup of the equipment, reducing wear caused by low temperature, enhancing the operation reliability of the equipment under low-temperature conditions, and effectively expanding the operating temperature range of the equipment.

[0034] 2. Outstanding lubrication and anti-wear ability: The modified polymethacrylate endows the gear oil with good lubrication performance by virtue of the low surface energy characteristics of the fluorine-containing chain segment; the nano-silica supported sulfurized isobutene can provide strong extreme pressure protection under high load, effectively reducing the friction coefficient; the modified nano-graphene further optimizes the overall lubrication effect. The three work together to greatly reduce the wear between gears, extend the service life of gears and equipment, and reduce maintenance costs.

[0035] 3. Good stability and durability: The composite antioxidant is composed of carefully proportioned components, significantly improving the antioxidant ability of the gear oil, effectively delaying the aging and deterioration rate of the oil product, and extending the oil product replacement cycle; the rust inhibitor tightly adsorbs on the metal surface to form a strong protective film, resisting the erosion of moisture and corrosive substances, and preventing metal rust and corrosion; the hydrophobicity of the anti-emulsifier and the nano-silica supported sulfurized isobutene effectively inhibits water emulsification, ensuring the stable performance of the oil product in a humid environment and maintaining the long-term stable operation of the equipment.

[0036] 4. High operating performance: The special structure of the modified polymethacrylate reduces the intermolecular force through the steric hindrance effect of the fluorinated side chain, significantly reducing the viscosity of the gear oil, reducing the energy loss during the transmission process, and improving the power output efficiency of the equipment; The anti-foaming agent inhibits the generation of foam, avoids poor lubrication and energy loss caused by foam, makes the equipment operate more smoothly and efficiently during operation, reduces energy consumption, and improves production efficiency. Detailed implementation mode

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0038] Example 1. Preparation of modified polymethacrylate, the specific steps are as follows:

[0039] A1. Add 40 g of polymethacrylate and 160 mL of toluene into a four-necked flask, heat up to 60 °C, stir at 300 r / min to dissolve the polymethacrylate in toluene, then add 0.4 g of azobisisobutyronitrile, and pass nitrogen at a flow rate of 0.5 L / min to displace oxygen for 30 minutes; Add 1 g of nano-zinc oxide surface-modified with stearic acid, maintain the reaction temperature at 60 °C, and stir at a speed of 500 r / min for 1 hour to uniformly disperse the nano-zinc oxide in the reaction system;

[0040] A2. Slowly drop 12.5 g of perfluorooctyl acrylate monomer through a constant pressure dropping funnel. After stirring at 400 r / min for 20 minutes, then drop 5 g of lauryl methacrylate and 3 g of vinyltrimethoxysilane, continue stirring for 30 minutes, and then add 2 g of dimethyl silicone oil. Under nitrogen protection at 80 °C, react under stirring conditions of 400 r / min for 6 hours. Pass an appropriate amount of carbon dioxide gas into the reaction system every 1 hour, the ventilation time is 10 minutes, and the flow rate is controlled at 0.2 L / min;

[0041] A3. After the reaction is completed and the reaction solution is cooled to room temperature, slowly pour it into an excess of methanol for precipitation, centrifuge at 8000 r / min for 15 minutes, wash the product with methanol 3 times, transfer it to a vacuum drying oven and dry it at 60 °C and -0.08 MPa for 12 hours to obtain a light yellow solid modified polymethacrylate.

[0042] Example 2. Preparation of nano-silica supported sulfurized isobutene, the specific steps are as follows:

[0043] B1. Disperse 20 g of nano-silica in 400 mL of an ethanol solution with a mass-volume fraction of 5%, add 2 g of silane coupling agent KH-550, ultrasonically treat the system for 30 minutes, then reflux at 60 °C for 4 hours, centrifuge at 8000 r / min for 10 minutes, wash the product with ethanol three times, and then vacuum dry at 60 °C to obtain amino-functionalized silica; then add 0.2 g of nano-copper powder modified with oleic acid and stir at 30 °C at 400 r / min for 2 hours;

[0044] B2. Add 15 g of isobutene sulfide and 8.8 g of maleic anhydride to a three-necked flask, then add 75 mL of toluene solvent and 1 g of tricresyl phosphate, heat to 60 °C under nitrogen protection, stir and react at 500 r / min for 2 hours, and distill off toluene under reduced pressure at 60 °C and 4 kPa to obtain carboxylated isobutene sulfide;

[0045] B3. Add 20 g of amino-functionalized silica and 16 g of carboxylated isobutene sulfide to 240 mL of ethanol, stir at 300 r / min for 20 minutes, then add 0.5 g of molybdenum disulfide nanoparticles, 0.3 g of oleic acid-modified carbon nanotubes and 0.6 g of catalyst 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide for ultrasonic dispersion, centrifuge at 10000 r / min for 15 minutes, and then vacuum dry at 60 °C for 12 hours to prepare nano-silica supported isobutene sulfide.

[0046] Example 3. Prepare modified nano-graphene, and the specific steps are as follows:

[0047] C1. Disperse 1.0 g of nano-graphene in 200 mL of toluene, ultrasonically treat for 30 minutes to ensure uniform dispersion of graphene, transfer the dispersion to a three-necked flask, add 0.1 g of azobisisobutyronitrile, and purge with nitrogen at a flow rate of 0.5 L / min for 30 minutes to displace oxygen;

[0048] C2. Add 5.0 g of octadecylamine to the flask, heat to 80 °C, and stir and react at 500 r / min for 6 hours under nitrogen protection;

[0049] C3. After the reaction is completed, cool to room temperature, transfer the reaction solution to a centrifuge tube, centrifuge at 10000 r / min for 15 minutes, and wash the precipitate with toluene three times; transfer the modified graphene to a vacuum drying oven and dry at 60 °C for 12 hours to obtain dry modified nano-graphene powder.

[0050] Example 4. Prepare a low-viscosity and high-lubricity low-temperature gear oil, and the specific steps are as follows:

[0051] Weigh each raw material by weight parts, add 65 parts of base oil into a double-layer jacketed reactor, heat up to 60 °C, stir at 500 r / min for 30 minutes until the system is transparent and has no layering; add 5 parts of the modified polymethacrylate prepared in Example 1, and ultrasonically treat it at 50 °C to dissolve it in the base oil until the light transmittance measured at a wavelength of 660 nm is greater than 95%; subject 3 parts of the nano-silica supported sulfurized isobutene prepared in Example 2 and 0.2 parts of the modified nano-graphene prepared in Example 3 to cyclic shearing for 30 minutes at 60 °C and 12,000 r / min by a high-shear homogenizer to make the particle size less than 200 nm and add it; then sequentially add 2 parts of a compound antioxidant, 1 part of calcium borated sulfonate, 1 part of ethylene oxide-propylene oxide copolymer, and 0.5 part of alkylated diphenylamine, and maintain stirring at 60 °C for 2 hours; wait for the system to cool down to 40 °C, add 0.05 part of polydimethylsiloxane and 0.3 part of polymethacrylate alkyl ester, filter through a 0.1 μm filter membrane, and perform degassing treatment to obtain a low-viscosity and high-lubricity low-temperature gear oil.

[0052] Example 5. To prepare a low-viscosity and high-lubricity low-temperature gear oil, the specific steps are as follows:

[0053] Weigh each raw material by weight parts, add 75 parts of base oil into a double-layer jacketed reactor, heat up to 60 °C, stir at 500 r / min for 30 minutes until the system is transparent and has no layering; add 8 parts of the modified polymethacrylate prepared in Example 1, and ultrasonically treat it at 50 °C to dissolve it in the base oil until the light transmittance measured at a wavelength of 660 nm is greater than 95%; subject 5 parts of the nano-silica supported sulfurized isobutene prepared in Example 2 and 0.5 part of the modified nano-graphene prepared in Example 3 to cyclic shearing for 30 minutes at 60 °C and 12,000 r / min by a high-shear homogenizer to make the particle size less than 200 nm and add it; then sequentially add 3 parts of a compound antioxidant, 3 parts of dodecenyl succinic acid, 3 parts of polypropylene glycol, and 1.0 part of benzotriazole, and maintain stirring at 60 °C for 2 hours; wait for the system to cool down to 40 °C, add 0.1 part of acrylate polymer and 0.6 part of poly-α-olefin pour point depressant, filter through a 0.1 μm filter membrane, and perform degassing treatment to obtain a low-viscosity and high-lubricity low-temperature gear oil.

[0054] Example 6. To prepare a low-viscosity and high-lubricity low-temperature gear oil, the specific steps are as follows:

[0055] Weigh each raw material by weight parts and add 70 parts of base oil into a double-layer jacketed reactor. Heat it up to 60 °C and stir at 500 r / min for 30 minutes until the system is transparent and has no layering. Add 6 parts of the modified polymethacrylate prepared in Example 1 and ultrasonically treat it at 50 °C to dissolve it in the base oil until the transmittance measured at a wavelength of 660 nm is greater than 95%. Add 4 parts of the nano-silica supported sulfurized isobutene prepared in Example 2 and 0.3 parts of the modified nano-graphene prepared in Example 3, and circulate and shear them through a high-shear homogenizer at 60 °C and 12,000 r / min for 30 minutes to make the particle size less than 200 nm and then add them. Then, add 2.5 parts of compound antioxidant, 2 parts of barium petroleum sulfonate, 2 parts of alkylphenol polyoxyethylene ether, and 0.7 part of 2-methyl-1,2,3-thiadiazole in sequence, and maintain stirring at 60 °C for 2 hours. Wait for the system to cool down to 40 °C, add 0.07 part of acrylate polymer and 0.4 part of ethylene-vinyl acetate, filter through a 0.1 μm filter membrane, and perform degassing treatment to obtain a low-viscosity and high-lubricity low-temperature gear oil.

[0056] Comparative Example 1: To prepare a low-viscosity and high-lubricity low-temperature gear oil, the specific steps are as follows:

[0057] The remaining steps remain unchanged. Only replace the modified polymethacrylate in Example 5 with untreated polymethacrylate to prepare the gear oil.

[0058] Comparative Example 2: To prepare a low-viscosity and high-lubricity low-temperature gear oil, the specific steps are as follows:

[0059] The remaining steps remain unchanged. Only replace the nano-silica supported sulfurized isobutene in Example 5 with untreated nano-silica to prepare the gear oil.

[0060] Comparative Example 3: To prepare a low-viscosity and high-lubricity low-temperature gear oil, the specific steps are as follows:

[0061] The remaining steps remain unchanged. Only replace the modified nano-graphene in Example 5 with untreated nano-graphene to prepare the gear oil.

[0062] Performance Test

[0063] Test method:

[0064] 1. Kinematic viscosity: It is measured in accordance with GB / T 265-1988 "Determination Method of Kinematic Viscosity and Calculation Method of Dynamic Viscosity for Petroleum Products".

[0065] 2. Low-temperature fluidity: It is measured according to GB / T 3535-2006 "Determination Method for Pour Point of Petroleum Products".

[0066] 3. Lubrication performance: Using a four-ball friction and wear tester, in accordance with SH / T0189-1992 "Determination Method for Anti-wear Performance of Lubricating Oil (Four-ball Machine Method)", test for 30 minutes under the conditions of 1200 r / min, 392 N, and room temperature, and measure the wear scar diameter.

[0067] 4. Oxidation resistance performance: According to SH / T0193-2016 "Determination of Oxidation Stability of Lubricating Oil - Rotating Bomb Method", test under the conditions of 150 °C and an oxygen pressure of 620 kPa.

[0068] 5. Rust prevention performance: In accordance with GB / T2361-1992 "Humidity-heat Test Method for Rust Preventive Oils and Greases", place the test piece in an environment with a humidity of 95% ± 2% and a temperature of 49 °C ± 1 °C, and observe the rusting situation of the test piece.

[0069] 6. Anti-emulsification performance: According to GB / T7305-2003 "Determination Method for Water Separation of Petroleum and Synthetic Fluids", mix 40 mL of gear oil with 40 mL of distilled water, stir at 54 °C for 5 minutes, and measure the volume of the emulsion layer after standing for 30 minutes.

[0070]

[0071] The kinematic viscosities of Examples 4-6 are between 45-48 mm 2 / s, while the kinematic viscosities of Comparative Examples 1-3 are between 50-55 mm 2Between / s, this indicates that components such as modified polymethacrylate, nano-silica supported isobutene sulfide, and modified nano-graphene have a significant effect on reducing the viscosity of gear oil, which helps to improve the starting performance and operating efficiency of gears in low-temperature environments. The pour points of Examples 4-6 are between -40°C and -42°C, significantly lower than those of Comparative Examples 1-3, which are between -35°C and -37°C. This shows that the synergistic effect of the pour point depressant and other components in this gear oil effectively improves the low-temperature fluidity and can better meet the usage requirements in low-temperature environments. The wear scar diameters of Examples 4-6 are between 0.42-0.45 mm, smaller than those of Comparative Examples 1-3, which are between 0.50-0.55 mm. This means that the modified components enhance the lubrication performance of the gear oil, can effectively reduce gear wear, and extend the service life of gears. The rotary oxygen bomb times of Examples 4-6 are between 280-300 min, significantly longer than those of Comparative Examples 1-3, which are between 200-240 min. This proves that the combined action of the compound antioxidant and other components improves the antioxidant ability of the gear oil and extends the service life of the oil product. Examples 4-6 have no rust in the damp heat test for 720 h, while slight rust spots appear in Comparative Examples 1-3 at 480-600 h respectively. This shows that the rust inhibitor in this gear oil and the overall formulation design can effectively prevent metal parts from rusting and provide good rust protection. The emulsion layer volumes of Examples 4-6 are between 1.5-2 mL, smaller than those of Comparative Examples 1-3, which are between 3.5-5 mL. This indicates that the hydrophobicity of the demulsifier and nano-silica supported isobutene sulfide effectively inhibits water emulsification and ensures that the gear oil can still maintain good performance in a humid environment.

[0072] The above content is only an example and illustration of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods for substitution. As long as they do not deviate from the invention or exceed the scope defined by this claim book, they shall fall within the protection scope of the present invention.

Claims

1. Low viscosity, high lubricity, low temperature gear oil, characterized by: The invention comprises the following raw materials in parts by weight: 65-75 parts of base oil, 5-8 parts of modified polymethacrylate, 3-5 parts of nano-silicon dioxide-loaded sulfided isobutylene, 2-3 parts of composite antioxidant, 1-3 parts of rust inhibitor, 1-3 parts of anti-emulsifier, 0.05-0.1 parts of anti-foaming agent, 0.5-1.0 parts of alkylated diphenylamine metal passivator, 0.2-0.5 parts of modified nano-graphene, and 0.3-0.6 parts of pour point depressant; Wherein, the modified polymethacrylate is specifically prepared in the following steps: A1. Add polymethacrylate and toluene into a four-necked flask, heat to 60°C, stir at 300r / min to dissolve polymethacrylate in toluene, then add diisobutylene azobis(2-nitropropyronitrile), and introduce nitrogen at a flow rate of 0.5L / min to replace oxygen for 30 minutes; add nano zinc oxide surface-modified with stearic acid, maintain the reaction temperature at 60°C, stir at a speed of 500r / min for 1 hour, and evenly disperse the nano zinc oxide in the reaction system; the dosage ratio of polymethacrylate, toluene, diisobutylene azobis(2-nitropropyronitrile), and surface-modified nano zinc oxide is 40g:160mL:0.4g:1g; A2. Slowly add perfluorooctyl acrylate monomer through a constant pressure dropping funnel, stir at 400r / min for 20 minutes, then add lauryl methacrylate and vinyl trimethoxysilane, continue stirring for 30 minutes, then add dimethyl silicone oil, react at 80°C and 400r / min under nitrogen protection for 6 hours, introduce an appropriate amount of carbon dioxide gas into the reaction system every hour, the ventilation time is 10 minutes, and the flow rate is controlled at 0.2L / min; the amount ratio of polymethacrylate, perfluorooctyl acrylate monomer, lauryl methacrylate, vinyl trimethoxysilane, and dimethyl silicone oil is 40g:12.5g:5g:3g; A3. After the reaction is completed, the reaction solution is cooled to room temperature and slowly poured into excess methanol for precipitation. The product is centrifuged at 8000 r / min for 15 minutes. The product is washed with methanol three times and transferred to a vacuum drying oven and dried at 60°C and -0.08 MPa for 12 hours to obtain a light yellow solid modified polymethacrylate.

2. The low-viscosity, high-lubricity, low-temperature gear oil according to claim 1, characterized in that: The base oil is compounded by poly-alpha-olefin and pentaerythritol ester in a mass ratio of 3:

1.

3. The low-viscosity, high-lubricity, low-temperature gear oil according to claim 1, characterized in that: The nano-silicon dioxide-loaded isobutylene sulfide is specifically prepared in the following steps: B1. Disperse nano-silica in an ethanol solution with a mass volume fraction of 5%, add silane coupling agent KH-550, ultrasonically treat the system for 30 minutes, then reflux at 60°C for 4 hours, centrifuge at 8000r / min for 10 minutes, wash the product with ethanol 3 times, and then vacuum dry at 60°C to obtain amino-silica; then add oleic acid-modified nano-copper powder, and stir at 400r / min at 30°C for 2 hours; the dosage ratio of nano-silica, ethanol solution, silane coupling agent KH-550, and oleic acid-modified nano-copper powder is 20g:400mL:2g:0.2g; B2. Add isobutylene sulfide and maleic anhydride into a three-necked flask, then add toluene solvent and tricresyl phosphate, heat to 60°C under nitrogen protection, stir at 500r / min for 2 hours, remove toluene by reduced pressure distillation at 60°C and 4kPa to obtain carboxylated isobutylene sulfide; the amount ratio of isobutylene sulfide, maleic anhydride, toluene and tricresyl phosphate is 15g:8.8g:75mL:1g; B3. Add amino silica and carboxylated isobutylene sulfide to ethanol and stir at 300 r / min for 20 minutes, then add molybdenum disulfide nanoparticles, oleic acid-modified carbon nanotubes and catalyst 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and ultrasonically disperse. Centrifuge at 10000 r / min for 15 minutes and then vacuum dry at 60°C for 12 hours to obtain nano-silica-loaded isobutylene sulfide; the amount ratio of amino silica, carboxylated isobutylene sulfide, molybdenum disulfide nanoparticles, oleic acid-modified carbon nanotubes, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and ethanol is 20g:16g:0.5g:0.3g:0.6g:240mL.

4. The low-viscosity, high-lubricity, low-temperature gear oil according to claim 1, characterized in that: The composite antioxidant is 2,6-di-tert-butyl-p-cresol and N-phenyl-α-naphthylamine mixed in a molar ratio of 1:1; the rust inhibitor is one of calcium boronate sulfonate, dodecenylsuccinic acid and barium petroleum sulfonate.

5. The low-viscosity, high-lubricity, low-temperature gear oil according to claim 1, characterized in that: The anti-emulsifier is one of ethylene oxide-propylene oxide copolymer, polypropylene glycol, and alkylphenol polyoxyethylene ether.

6. The low-viscosity, high-lubricity, low-temperature gear oil according to claim 1, characterized in that: The anti-foaming agent is one of polydimethylsiloxane and acrylate polymer.

7. The low-viscosity, high-lubricity, low-temperature gear oil according to claim 1, characterized in that: The alkylated diphenylamine metal passivator is one of alkylated diphenylamine, benzotriazole and 2-methyl-1,2,3-thiadiazole.

8. The low-viscosity, high-lubricity, low-temperature gear oil according to claim 1, characterized in that: The modified nano-graphene is specifically prepared by the following steps: C1. Disperse nanographene in toluene, perform ultrasonic treatment to ensure that the graphene is evenly dispersed, transfer the dispersion to a flask, add azobisisobutyronitrile, and introduce nitrogen to replace oxygen; the dosage ratio of nanographene, toluene, and azobisisobutyronitrile is 1.0g:200mL:0.1g; C2. Add octadecylamine to the flask, heat to 80°C, and stir to react under nitrogen protection; the ratio of octadecylamine to nanographene is 5.0g:1.0g; C3. After the reaction is completed, cool to room temperature, transfer the reaction solution to a centrifuge tube and centrifuge; wash the precipitate with toluene to remove residual reactants and impurities; transfer the modified graphene to a vacuum drying oven for drying to obtain dry modified nanographene powder.

9. The low-viscosity, high-lubricity, low-temperature gear oil according to claim 1, characterized in that: The pour point depressant is one of poly alkyl methacrylate, poly α-olefin pour point depressant, and ethylene-vinyl acetate copolymer.

10. The method for preparing low-viscosity, high-lubricity, low-temperature gear oil according to claim 1, characterized in that: The specific steps include: Weigh each raw material by weight and stir the base oil at 60°C and 500r / min for 30 minutes; dissolve the modified polymethacrylate in the base oil and perform ultrasonic treatment until the dispersion is transparent; disperse the nano-silica-loaded sulfided isobutylene and the modified nano-graphene through a high shear homogenizer and add them; add an antioxidant, a rust inhibitor and an anti-emulsifier in sequence, maintain stirring at 60°C for 2 hours; wait for the system to be cooled to 40°C, add an anti-foaming agent and a pour point depressant, filter through a 0.1μm filter membrane, and degas to obtain a low-viscosity and high-lubricity low-temperature gear oil.

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