Low-temperature-resistant lubricating oil and production process thereof

Abstract

The invention relates to the field of lubricating oil, and particularly discloses low-temperature-resistant lubricating oil and a production process thereof. The low-temperature-resistant lubricating oil is prepared from the following raw materials in parts by weight: 12 to 18 parts of ester plant-based synthetic oil, 6 to 9 parts of poly-alpha-olefin synthetic oil, 0.2 to 0.6 part of a viscosity index improver, 0.2 to 0.5 part of a preservative, 0.2 to 0.5 part of a de-foaming agent, 18 to 22 parts of water, 0.2 to 0.6 part of an anti-friction and anti-wear agent and 1 to 2 parts of a pour point depressant, the pour point depressant is prepared from an ethylene-vinyl acetate-vinyl alcohol terpolymer, modified silicon dioxide and graphene oxide according to the mass ratio of 1: (0.2 to 0.4): (0.1 to 0.3). The lubricating oil provided by the invention has the advantages of low condensation point, good low-temperature fluidity and strong anti-attrition and anti-wear capability.

Description

Technical Field

[0001] The present application relates to the technical field of lubricating oils, and more specifically, to a low-temperature resistant lubricating oil and a production process thereof. Background Art

[0002] Lubricating oil is a liquid or semi-solid lubricant used in various types of automobiles and mechanical equipment to reduce friction and protect machinery and processed parts. It mainly plays the role of lubrication, auxiliary cooling, rust prevention, cleaning, sealing and buffering. Lubricating oil is generally composed of two parts: base oil and additives. The base oil is the main component of the lubricating oil and determines the basic properties of the lubricating oil. The additives can make up for and improve the deficiencies in the performance of the base oil and give the lubricating oil new properties.

[0003] Lubricating oil products are usually used in very low ambient temperatures, especially in winter and when the machine is cold. Therefore, the lubricating oil used is required to have good low-temperature flow properties, which is not only conducive to the normal start-up and operation of the machine, but also can reduce the wear of the machine during the startup process.

[0004] However, at low temperatures, crystals in the lubricating base oil crystallize and precipitate, forming a three-dimensional network structure and losing fluidity. In order to maintain the low-temperature fluidity of the oil, there are two ways. One is to deeply dewax the base oil, which can obtain a lubricating oil with a low pour point, but it will damage the quality of the oil; the other is to add a small amount of pour point depressant to the lubricating oil, which can significantly improve the morphology and structure of the wax crystals in the oil, thereby reducing the freezing point. The alkyl side chain of the general pour point depressant is copolymerized with monomers with different carbon numbers, and its average side chain carbon number is adjusted to adapt to different lubricating base oils. However, most of these pour point depressants use monoesters or polyesters with large relative molecular weight. The pour point depressant of monoester or polyester only has a significant pour point depressing effect on ordinary lubricating oils based on mineral oils, while the pour point depressing effect on green and high-grade lubricating oils based on vegetable oils is not obvious, and even slightly increases the pour point. Therefore, how to improve the low temperature resistance of lubricating oils, especially the low temperature resistance of lubricating oils based on vegetable oils, is a problem to be solved in this field. Summary of the invention

[0005] In order to improve the low temperature resistance of lubricating oil based on vegetable oil, the present application provides a low temperature resistant lubricating oil and a production process thereof.

[0006] In the first aspect, the present application provides a low temperature resistant lubricating oil, which adopts the following technical solution:

[0007] A low-temperature resistant lubricating oil comprises the following raw materials in parts by weight: 12-18 parts of ester plant-based synthetic oil, 6-9 parts of poly-α-olefin synthetic oil, 0.2-0.6 parts of viscosity index improver, 0.2-0.5 parts of preservative, 0.2-0.5 parts of defoamer, 18-22 parts of water, 0.2-0.6 parts of friction reducer and anti-wear agent and 1-2 parts of pour point depressant, wherein the pour point depressant comprises ethylene-vinyl acetate-vinyl alcohol terpolymer, modified silicon dioxide and graphene oxide in a mass ratio of 1:0.2-0.4:0.1-0.3.

[0008] By adopting the above technical scheme, ester plant-based synthetic oil and poly-α-olefin synthetic oil are used as base oils in a certain ratio, and a certain amount of preservatives, rust inhibitors, and viscosity index improvers are added. The ester plant-based synthetic oil has a lower pour point, and the pour point of the poly-α-olefin synthetic oil is -64°C, both of which can meet the low-temperature performance of the grease, and both are transparent liquids with appearance that meets the requirements, so the overall pour point of the lubricant can be effectively reduced. In addition, ethylene-vinyl acetate-vinyl alcohol terpolymer (EVAL), modified silica and graphene oxide are used as the pour point reducer. Coagulant, in which EVAL inhibits the formation of the base oil gel structure, weakens the elasticity of the base oil gel structure under low temperature conditions, destroys the three-dimensional network structure of the wax crystal, allows more liquid oil to flow, reduces the viscoelastic properties of the oil sample, and improves the wax crystal morphology of the oil sample with EVAL added. The wax crystal is larger and denser, and the degree of dispersion is higher, making it difficult for the system to form a three-dimensional network structure to wrap more liquid oil, thereby improving the flow characteristics of the lubricating oil at low temperatures. The presence of hydroxyl groups in EVAL increases the polarity of the wax crystal and increases the electrostatic repulsion between the wax crystals. The polar groups of EVAL are distributed on the surface of large wax crystal aggregates formed by a single polymer inhibitor, so that a certain electric repulsion is formed between the wax crystal aggregates, which hinders the flocculation of the wax crystal aggregates. Therefore, the wax crystals are difficult to connect, and the increase in the gap releases the liquid oil, thereby improving the low-temperature fluidity of the lubricating oil.

[0009] The ethylene-vinyl acetate-vinyl alcohol terpolymer contains hydroxyl groups, and graphene oxide has rich oxygen-containing functional groups. Hydroxyl groups and epoxy groups are mainly distributed on the plane of the graphene oxide sheet, while other oxygen-containing functional groups are distributed on the edge of the sheet. The hydroxyl groups in graphene oxide can undergo esterification reaction with the hydroxyl groups in the ethylene-vinyl acetate-vinyl alcohol terpolymer, thereby being grafted on the graphene oxide. The ethylene-vinyl acetate-vinyl alcohol terpolymer and the graphene oxide composite have good oil dispersibility and good miscibility with organic solvents. Wax crystals form a growth system with the nanocomposite pour point depressant as the center, and the paraffin in the base oil forms a large number of small and inconspicuous crystals on this basis. The addition of the ethylene-vinyl acetate-vinyl alcohol terpolymer and the graphene oxide composite increases the solubility of the wax, reduces the amount of wax precipitation, increases the dispersibility of the wax, makes the wax crystals repel each other, and is not easy to form a network structure, so that the pour point of the lubricating oil is significantly reduced and the fluidity is greatly enhanced.

[0010] Nano-silicon dioxide, due to its extremely small particle size and high specific surface area, can effectively improve the internal structure of lubricating oil, lower the freezing point of lubricating oil, and thus improve its low-temperature fluidity. It can play a role similar to "ball bearings" in lubricating oil, reducing the friction between lubricating oil molecules and improving its fluidity. In addition, nano-silicon dioxide can also react with long-chain alkanes in lubricating oil, breaking the original wax crystal structure and forming more fine and uniform wax crystals, thereby reducing the viscosity of lubricating oil and improving its low-temperature fluidity.

[0011] Optionally, the modified silica is prepared by the following method: mercaptosilica, octadecyl acrylate and tetrahydrofuran are mixed, ultrasonically treated for 30-40 minutes, then benzoin dimethyl ether is added, sealed, heated to 30-35°C, stirred, and irradiated with a 36-40W ultraviolet lamp at a distance of 10 cm for 2 hours, then methanol is added and stirred until flocs are precipitated, filtered, washed with methanol, and vacuum dried, the molar ratio of mercaptosilica and octadecyl acrylate is 3-4:4, and the concentration of benzoin dimethyl ether is 1-4%.

[0012] By adopting the above technical scheme, long-chain alkane acrylate octadecyl is grafted on the surface of mercaptosilica, wax molecules are solubilized through eutectic action, and the wax precipitation point of lubricating oil is reduced. In addition, the polar groups on the 0A alkyl chain can increase the interfacial tension between wax crystals and the oil phase, thereby increasing the nucleation barrier for the crystallization of wax molecules, making it difficult for wax molecules to crystallize and precipitate, and also promoting the reduction of the wax precipitation point of lubricating oil. Under the joint action of nucleation and eutectic, the structure of wax crystals changes, and it is easy to overlap to form a network structure, which binds the liquid oil phase therein, and the growth of wax molecules along the needle direction is inhibited, while the growth of the vertical surface is promoted. The wax crystal changes from a slender needle to a short and thick rod-like structure, which is more dense and compact, reducing the crystal-liquid interface and the binding of liquid oil, so it is not easy to gel in a low temperature environment, and the rheological properties are improved.

[0013] Optionally, the ester plant-based synthetic oil is epoxy soybean methyl ester or ethoxylated fatty acid methyl ester.

[0014] By adopting the above technical scheme, hydroxyl groups are introduced into the epoxy soybean oil formate after ring opening, and hydroxyl groups are strong polar groups with outstanding metal adsorption and can form a strong oil film on the friction surface, so it has good friction reduction performance. The viscosity of epoxy soybean acid methyl ester is lower than that of epoxy soybean oil, but its viscosity index is larger and its low-temperature fluidity is improved. After the epoxy soybean acid methyl ester undergoes a ring-opening reaction with ethanol, the viscosity is significantly improved, the viscosity index increases, and the low-temperature fluidity is better.

[0015] Optionally, the preparation method of the wear reducing and anti-wear agent is as follows:

[0016] The cellulose is mixed with deionized water to prepare a suspension with a concentration of 4-5 wt%, filtered, hot pressed at 80-90° C. and 8-10 MPa for 1-1.5 h, and cooled to obtain a cellulose membrane;

[0017] Dissolve chitosan in acetic acid solution to prepare solution A with a concentration of 1.5-2wt%, disperse nano-silicon dioxide in a mixture of ethanol and water, disperse by ultrasonication, and adjust the pH to 3.5 with 0.1M hydrochloric acid to prepare solution B with a concentration of 1.5-2wt%;

[0018] The cellulose membrane is immersed in solution A for 20-30 minutes, washed and dried, then immersed in solution B for 20-30 minutes, washed and dried, and the immersion in solution A and solution B is repeated n times, where n is a multiple of 2, and then immersed in 0.5M trichloromethylsilane solution for 40-50 minutes, washed, dried and crushed.

[0019] By adopting the above technical scheme, cellulose is first made into a cellulose film by hot pressing, which can reduce the pores between cellulose and increase its density. Nano-silicon dioxide has a large specific surface area, and the number of repeated immersions is a multiple of 2, so the outermost layer is nano-silicon dioxide, which has a good thickening effect. The cellulose is in the shape of short rods at the micron level, and the hydroxyl groups on its surface can form a hydrogen bond network structure with the hydroxyl groups of chitosan, and the hydroxyl groups in chitosan can also form a hydrogen bond cross-linked network structure with the silicon hydroxyl groups in nano-silicon dioxide, thereby improving the colloidal stability of the lubricating oil and improving the viscosity-temperature property of the grease. In addition, trichloromethylsilane is used for hydrophobic treatment to improve the dispersing effect of the anti-friction agent, reduce the hydrophilicity of cellulose, reduce the freezing of cellulose in a low-temperature environment, and avoid cellulose affecting the low-temperature performance of the lubricating oil; the nano-silicon dioxide and cellulose in the anti-friction agent are subjected to shear force during the friction process, can move relative to each other, exert a synergistic effect, and improve the anti-friction performance of the lubricating oil.

[0020] Optionally, the defoaming agent is at least one of polyoxyethylene polyoxypropylene pentaerythritol ether, methyl silicone oil, fluorosilicone oil, and polyacrylate.

[0021] By adopting the above technical scheme, polyoxyethylene polyoxypropylene pentaerythritol ether is used as a lubricant additive, and its defoaming principle is mainly based on its special chemical structure and properties. This compound can form a good dispersion and emulsification effect in the lubricant, thereby reducing the surface tension of the bubbles and making the bubbles easier to rupture and dissipate. Specifically, when bubbles are formed, polyoxyethylene polyoxypropylene pentaerythritol ether molecules will quickly adsorb to the bubble surface, changing the surface properties of the bubbles and making them more unstable, thereby accelerating the rupture of the bubbles. In addition, the compound can also increase the viscosity of the lubricant, further reducing the generation and stability of bubbles.

[0022] Methyl silicone oil has a very low surface tension, which allows it to quickly diffuse to the surface of bubbles in the lubricant. Once the methyl silicone oil molecules reach the bubble surface, they will destroy the stability of the bubble wall, causing the bubble to quickly rupture and disappear. In addition, methyl silicone oil also has good chemical stability, which means that it will not react adversely with other lubricant ingredients during use, thus ensuring the durability of the defoaming effect and the overall performance of the lubricant.

[0023] Fluorosilicone oil has a very low surface tension, which allows it to spread quickly on the surface of the foam. In this way, fluorosilicone oil can effectively reduce the surface tension of the foam, causing the foam to burst. In addition, it can form a thin oil film in the metalworking fluid, further preventing the formation of foam.

[0024] Polyacrylate is a type of high molecular polymer that has both hydrophilic and hydrophobic properties. This amphiphilic property enables it to form a film on the surface of lubricating oil, reducing surface tension and thus preventing the generation of foam. At the same time, the chemical structure of polyacrylate also enables it to effectively destroy the bubbles that have already formed, because it can quickly diffuse into the liquid film of the bubble, making the liquid film thinner and eventually rupture. Polyacrylate also has good thermal and chemical stability, and can maintain defoaming performance at high temperatures and in complex environments. Therefore, it is used in lubricating oil as a defoaming agent to improve the performance and stability of the lubricating oil.

[0025] Optionally, the preservative is at least one of sodium diacetate, alkylated diphenylamine, phenyl-α-naphthylamine, and benzotriazole.

[0026] By adopting the above technical scheme, sodium diacetate is an effective preservative and antibacterial agent with a broad-spectrum bactericidal and antibacterial effect. It can achieve the preservative and antibacterial effects by destroying the structure of microorganisms and inhibiting their growth and reproduction. It can also neutralize acidic substances that may be produced in lubricating oil, maintain the acid-base balance of the lubricating oil, and thus extend its service life.

[0027] Alkylated diphenylamine is a class of aromatic amine compounds with long-chain alkyl groups. In lubricating oils, they can interfere with the cell membrane of microorganisms and destroy their integrity, thereby achieving antibacterial and antiseptic effects. The long-chain alkyl groups in the alkylated diphenylamine molecules can be inserted into the lipid bilayer of the microbial cell membrane, disrupting its original structure, causing the cell membrane to lose its integrity, leading to leakage of cell contents, and thus killing microorganisms. In addition, alkylated diphenylamine also has certain antioxidant properties, which can delay the oxidation process of lubricating oils and further protect lubricating oils from contamination and damage by microorganisms.

[0028] Phenyl-α-naphthylamine contains active groups such as benzene rings and amino groups, which can react with certain components in microbial cells, thereby destroying the living environment or life activities of microorganisms, achieving anti-corrosion and antibacterial effects. After adding phenyl-α-naphthylamine to lubricating oil, it can effectively extend the service life of lubricating oil, reduce the contamination and degradation of lubricating oil by microorganisms, and improve the performance and stability of lubricating oil.

[0029] Benzotriazole can react chemically with the metal surface to form a stable chemical film, thereby preventing the corrosive medium from directly contacting the metal and playing an anti-corrosion role. At the same time, benzotriazole also has a certain antibacterial effect, which may be because it can react with certain components in microbial cells, interfere with the normal metabolism of microorganisms, and thus inhibit the growth and reproduction of microorganisms. Adding benzotriazole to lubricating oil can effectively extend the service life of the lubricating oil and keep the mechanical equipment in good operating condition.

[0030] Optionally, the viscosity index improver is ethylene bisstearamide or fatty acid lithium soap.

[0031] By adopting the above technical scheme, ethylene bisstearamide has a unique molecular structure, can form a certain network structure in the lubricating oil, maintain the viscosity of the lubricating oil at high temperature, improve the viscosity index, change the interaction force between molecules, reduce the formation of wax crystals in the lubricating oil, ensure effective lubrication at low temperature, and enable it to maintain good lubricity under high temperature, low temperature and high load conditions. Fatty acid lithium soap can improve the structural stability and lubrication performance of the lubricating oil. Since lithium soap has good colloidal stability and mechanical stability, the grease can also maintain good performance under high and low temperature conditions. Under low temperature conditions, the interaction force between lithium soap molecules is enhanced, and it is easy to form a network structure, thereby limiting the flow of the lubricating oil. The existence of this network structure can, on the one hand, improve the viscosity index of the lubricating oil and improve its lubrication performance under high temperature conditions; on the other hand, it may also cause the lubricating oil to have reduced fluidity under low temperature conditions, or even solidify.

[0032] In a second aspect, the present application provides a production process for low-temperature resistant lubricating oil, which adopts the following technical solution:

[0033] A production process of low temperature resistant lubricating oil comprises the following steps:

[0034] Mix ester plant-based synthetic oil, water and pour point depressant, heat to 190-230°C, stir at 0.4-0.48MPa for 30-40min, release the pressure, add poly-α-olefin synthetic oil, viscosity index improver, preservative, defoamer, friction reducer and anti-wear agent, stir evenly, homogenize, degas and fill.

[0035] In summary, this application has the following beneficial effects:

[0037] 1. Since the present application adopts phenolic plant-based synthetic oil and poly-α-olefin synthetic oil as base oil, the pour point of the emulsion can be reduced and the antifreeze property can be improved. In addition, ethylene-vinyl acetate-vinyl alcohol terpolymer, modified silica and graphene oxide are used as pour point depressants, which can hinder the flocculation of wax crystal aggregates, increase the solubility of wax crystals, reduce the precipitation of wax crystals, improve the dispersibility of wax crystals, and thus improve the low-temperature fluidity.

[0038] 2. In the present application, mercaptosilica and octadecyl acrylate are preferably used to prepare modified silica, which can increase the solubility of wax molecules through eutectic effect and increase the nucleation barrier of wax molecule crystallization, thereby changing the wax crystal structure, reducing the gelation of lubricating oil at low temperatures, and improving the ability to resist low-temperature freezing.

[0039] 3. In this application, cellulose membrane is used to repeatedly stack chitosan and nano-silica in sequence, and trichloromethylsilane is used for hydrophobic modification to prepare a friction reducer and anti-wear agent, thereby improving the dispersibility of the friction reducer and anti-wear agent in the lubricating oil, increasing the colloid stability and viscosity-temperature properties, and improving the low-temperature resistance effect. DETAILED DESCRIPTION

[0040] The following examples further illustrate the present application in detail.

[0041] Preparation Example 1-2 of Modified Silica

[0042] Preparation Example 1: 5 g of mercaptosilica, octadecyl acrylate and 29.4 g of tetrahydrofuran were mixed and ultrasonically treated for 40 min, then benzoin dimethyl ether was added, sealed, heated to 30°C, stirred, and irradiated with a 36 W ultraviolet lamp at a distance of 10 cm for 2 h, then methanol was added and stirred until flocs precipitated, filtered, washed with methanol, and vacuum dried. The molar ratio of mercaptosilica to octadecyl acrylate was 3:4, the concentration of benzoin dimethyl ether was 4%, and the mercapto-modified silica had a particle size of 500 nm, which was selected from Shaanxi Xingbei Aike Biotechnology Co., Ltd.

[0043] Preparation Example 2: 5 g of mercaptosilica, octadecyl acrylate and 29.4 g of tetrahydrofuran were mixed and ultrasonically treated for 30 min, then benzoin dimethyl ether was added, sealed, heated to 35°C, stirred, and irradiated with a 40 W ultraviolet lamp at a distance of 10 cm for 2 h, then methanol was added and stirred until flocs precipitated, filtered, washed with methanol, and vacuum dried. The molar ratio of mercaptosilica and octadecyl acrylate was 4:4, the concentration of benzoin dimethyl ether was 4%, and the mercapto-modified silica had a particle size of 500 nm, which was selected from Shaanxi Xingbei Aike Biotechnology Co., Ltd.

[0044] Preparation Example 3-7 of anti-friction agent

[0045] Preparation Example 3: Mix cellulose with deionized water to prepare a suspension with a concentration of 5 wt%, filter, hot press at 80° C. and 10 MPa for 1 h, and cool to obtain a cellulose membrane;

[0046] Chitosan was dissolved in a 2% acetic acid solution to prepare a solution A with a concentration of 2wt%, nano-silicon dioxide was dispersed in a mixture of ethanol and water (volume ratio of 9:1), ultrasonically dispersed, and the pH was adjusted to 3.5 with 0.1M hydrochloric acid to prepare a solution B with a concentration of 2wt%;

[0047] The cellulose membrane was immersed in solution A for 20 min, washed with distilled water for 3 times, dried at 60°C, then immersed in solution B for 20 min, washed with distilled water for 3 times, dried at 60°C, and the immersion in solution A and solution B was repeated. One immersion in solution A and one immersion in solution B was counted as one immersion. The alternating immersion in solution A and solution B was repeated 6 times in total, and then immersed in 0.5 M trichloromethylsilane solution for 40 min. Then, it was washed with anhydrous toluene, ethanol, anhydrous ethanol, and distilled water in sequence, and then dried and crushed at 60°C.

[0048] Preparation Example 4: Mix cellulose with deionized water to prepare a suspension with a concentration of 4 wt%, filter, hot press at 90° C. and 8 MPa for 1.5 h, and cool to obtain a cellulose membrane;

[0049] Chitosan was dissolved in 2% acetic acid solution to prepare solution A with a concentration of 1.5wt%, nano-silicon dioxide was dispersed in a mixture of ethanol and water (volume ratio of 9:1), ultrasonically dispersed, and the pH was adjusted to 3.5 with 0.1M hydrochloric acid to prepare solution B with a concentration of 1.5wt%;

[0050] The cellulose membrane was immersed in solution A for 30 min, washed with distilled water for 3 times, dried at 60°C, then immersed in solution B for 30 min, washed with distilled water for 3 times, dried at 60°C, and the immersion in solution A and solution B was repeated. One immersion in solution A and one immersion in solution B was counted as one immersion. The alternating immersion in solution A and solution B was repeated 6 times in total, and then immersed in 0.5 M trichloromethylsilane solution for 50 min. Then, it was washed with anhydrous toluene, ethanol, anhydrous ethanol, and distilled water in sequence, and then dried and crushed at 60°C.

[0051] Preparation Example 5: The difference from Preparation Example 4 is that chitosan is not impregnated.

[0052] Preparation Example 6: The difference from Preparation Example 4 is that nano-silica is not impregnated.

[0053] Preparation Example 7: The difference from Preparation Example 4 is that no immersion in trichloromethylsilane solution was performed.

[0054] Example

[0055] Embodiment 1: A low-temperature resistant lubricating oil, the raw material dosage is as shown in Table 1, wherein the ester plant-based synthetic oil is epoxy soybean methyl ester, and the preparation method is as follows: epoxy soybean oil with an epoxy value of 6.25% is mixed with potassium hydroxide and methanol, the temperature is raised to 55°C, the reaction is stirred for 60 minutes, and the upper methyl ester is neutralized with dilute sulfuric acid to neutrality, and the methanol is recovered by atmospheric distillation after washing with water, and dried. The molar ratio of epoxy soybean oil to methanol is 1:6, and the amount of catalyst is 1.1% of the total amount of the two; the polyalphaolefin synthetic oil is selected from Exxon, the model is PAO4, the pour point is -66°C, the viscosity index improver is ethylene bis stearic acid amide, the preservative is sodium diacetate, the defoamer is polyoxyethylene polyoxypropylene pentaerythritol ether, the friction and anti-wear agent is fumed silica, and the pour point depressant includes Ethylene-vinyl acetate-vinyl alcohol terpolymer, modified silicon dioxide and graphene oxide in a mass ratio of 1:0.4:0.3, the modified silicon dioxide is prepared by Preparation Example 1, the graphene oxide is selected from Suzhou Carbon Graphite, the item number is TF-12041, and the preparation method of ethylene-vinyl acetate-vinyl alcohol terpolymer is as follows: dissolve sodium hydroxide in deionized water (the mass ratio of sodium hydroxide to water is 1:5), add methanol to make the volume reach 100mL, and prepare a mixed solution with a sodium hydroxide solution concentration of 20g / L, dissolve ethylene-vinyl acetate with a VA content of 26% in toluene, add methanol solution, stir at 60°C for 30min, add the mixed solution, cool to 45°C, react for 3h, filter, wash with methanol, and dry in vacuo at 60°C.

[0056] The production process of the above-mentioned low-temperature resistant lubricating oil comprises the following steps:

[0057] Mix ester plant-based synthetic oil, water and pour point depressant, heat to 190°C, stir at 0.48 MPa for 30 minutes, release the pressure, add poly-α-olefin synthetic oil, viscosity index improver, preservative, defoamer, friction reducer and anti-wear agent, stir evenly, homogenize, degas and fill.

[0058] Table 1 Raw material dosage of low temperature resistant lubricating oil in Examples 1-3

[0059]

[0060] Example 2-3: A low-temperature resistant lubricating oil, which is different from Example 1 in that the amounts of raw materials used are as shown in Table 1.

[0061] Example 4: A low-temperature resistant lubricating oil, which differs from Example 1 in that the ester plant base oil is ethoxylated fatty acid methyl ester, and the preparation method is as follows: 50 g of epoxy soybean oil methyl ester is mixed with tetrafluoroboric acid and ethanol, the temperature is raised to 55°C, and the reaction is stirred for 90 minutes. Dichloromethane is used as an extractant, the reaction mixture is mixed with dichloromethane, extracted, and washed with water to remove excess ethanol and catalyst, and the lower organic phase is taken and distilled under reduced pressure to obtain ethoxylated fatty acid methyl ester. The molar ratio of epoxy soybean oil formate to ethanol is 4:1, and the amount of tetrafluoroboric acid used is 0.5% of the total amount of the two.

[0062] Example 5: A low-temperature resistant lubricating oil, which differs from Example 1 in that the pour point depressant includes ethylene-vinyl acetate-vinyl alcohol terpolymer, modified silica and graphene oxide in a mass ratio of 1:0.2:0.1, and the modified silica is prepared by Preparation Example 2.

[0063] Example 6: A low-temperature resistant lubricating oil, which differs from Example 1 in that the friction reducing and anti-wear agent is prepared from Preparation Example 3.

[0064] Example 7: A low-temperature resistant lubricating oil, which is different from Example 1 in that the friction reducing and anti-wear agent is prepared from Preparation Example 4.

[0065] Example 8: A low-temperature resistant lubricating oil, which is different from Example 1 in that the friction reducing and anti-wear agent is prepared from Preparation Example 5.

[0066] Example 9: A low-temperature resistant lubricating oil, which differs from Example 1 in that the friction reducing and anti-wear agent is prepared from Preparation Example 6.

[0067] Example 10: A low-temperature resistant lubricating oil, which differs from Example 1 in that the friction reducing and anti-wear agent is prepared from Preparation Example 7.

[0068] Comparative Example

[0069] Comparative Example 1: A low-temperature resistant lubricating oil, which differs from Example 1 in that no pour point depressant is added.

[0070] Comparative Example 2: A low-temperature resistant lubricating oil, which differs from Example 1 in that an equal amount of modified silicon dioxide is used in the pour point depressant instead of graphene oxide.

[0071] Comparative Example 3: A low-temperature resistant lubricating oil, which is different from Example 1 in that no modified silica is added to the pour point depressant.

[0072] Comparative Example 4: A low-temperature resistant lubricating oil, which differs from Example 1 in that an equal amount of polymethacrylate is used to replace the pour point depressant.

[0073] Comparative Example 5: A low-temperature resistant lubricating oil, which differs from Example 1 in that an equal amount of ester plant-based synthetic oil is used to replace the poly-α-olefin synthetic oil.

[0074] Performance testing

[0075] Lubricating oils were prepared according to the examples and comparative examples, and performance tests were carried out according to the following methods. The test results are recorded in Table 2.

[0076] 1. Pour point (℃): Tested in accordance with GB / T3535-2006 "Determination of pour point of petroleum products".

[0077] 2. Low temperature dynamic viscosity (-25°C, mPa·s): Test in accordance with GB / T6538-2022 "Determination of low temperature dynamic viscosity of engine oil - Cold start simulator method".

[0078] 3. Wear spot diameter of four-ball machine test (54°C, 1800r / min, 392N, 60min): Test in accordance with SH / T0189-1992 "Determination of anti-wear performance of lubricating oil (four-ball method)".

[0079] Table 2 Performance test results of low temperature resistant grease

[0080]

[0081]

[0082] It can be seen from the data in Table 2 that in Examples 1-3, epoxidized soybean methyl ester is used as the ester plant-based synthetic oil, and is combined with poly-α-olefin synthetic oil as the base oil, and ethylene-vinyl acetate-vinyl alcohol terpolymer, modified silica and graphene oxide are used as pour point depressants. The pour point of the grease obtained thereby reaches below -60°C, and the low-temperature kinematic viscosity is small, the fluidity is good during low-temperature operation, and the friction-reducing and lubricating effect is strong.

[0083] In Example 4, ethoxylated fatty acid methyl ester is used as the ester plant base oil, and the pour point and low-temperature dynamic viscosity of the lubricating oil are similar to those in Example 1, indicating that a lubricating oil with good low-temperature fluidity can also be obtained by using ethoxylated fatty acid methyl ester.

[0084] Compared with Example 1, the amounts of the three raw materials in the pour point depressant are adjusted. From the data comparison in Table 2, it can be seen that the lubricating oil prepared in Example 5 has a lower pour point, good low-temperature fluidity, and strong lubricity and anti-wear effects.

[0085] In Examples 6-7, the friction-reducing and anti-wear agents prepared in Preparation Example 3 and Preparation Example 4 were used respectively. Compared with Example 1, the low-temperature dynamic viscosity was reduced, the low-temperature fluidity was increased, and the wear spot diameter of the lubricating oil was significantly reduced, indicating that the lubrication effect was increased and the friction-reducing and anti-wear performance was improved.

[0086] In Example 8, the friction-reducing and anti-wear agent prepared in Preparation Example 5 was used. Compared with Example 6, chitosan was not deposited on the cellulose membrane. In Example 9, the friction-reducing and anti-wear agent prepared in Preparation Example 6 was used. Compared with Example 6, nano-silicon dioxide was not deposited on the cellulose membrane. It can be seen that the wear spot diameter of the lubricating oil increased, the anti-wear effect weakened, the low-temperature dynamic viscosity increased, and the low-temperature fluidity deteriorated.

[0087] Compared with Example 6, the friction reducing and anti-wear agent in Example 10 was not impregnated with trichloromethylsilane, and the low-temperature dynamic viscosity of the lubricating oil prepared in Example 10 was increased, and the fluidity was weakened.

[0088] In Comparative Example 1, no pour point depressant was added. Compared with Example 1, it can be seen that the pour point of the lubricating oil is increased, the low temperature resistance is weakened, the low temperature fluidity is deteriorated, and the lubricating effect is also reduced.

[0089] In Comparative Example 2, modified silicon dioxide is used in place of graphene oxide in the pour point depressant. Compared with Example 1, the wear spot diameter of the lubricating oil increases, the low-temperature fluidity deteriorates, and the low-temperature resistance weakens.

[0090] Compared with Example 1, no modified silica is added to the pour point depressant in Comparative Example 3. It can be seen that the low temperature resistance of the lubricating oil prepared in Comparative Example 3 is weakened, and the wear reduction and anti-wear capabilities are reduced.

[0091] Comparative Example 4 Compared with Example 1, polymethacrylate is used as a pour point depressant. It can be seen that the low-temperature fluidity of the lubricating oil is deteriorated, the low-temperature resistance is reduced, and the anti-wear property is slightly weakened.

[0092] In Comparative Example 5, ester plant synthetic oil is used instead of poly-α-olefin synthetic oil. The pour point of the lubricating oil prepared in Comparative Example 5 is low and the low-temperature fluidity is the worst.

[0093] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A low temperature resistant lubricating oil, characterized in that: The invention comprises the following raw materials in parts by weight: 12-18 parts of ester plant-based synthetic oil, 6-9 parts of poly-alpha-olefin synthetic oil, 0.2-0.6 parts of viscosity index improver, 0.2-0.5 parts of preservative, 0.2-0.5 parts of defoamer, 18-22 parts of water, 0.2-0.6 parts of friction reducer and anti-wear agent and 1-2 parts of pour point depressant, wherein the pour point depressant comprises ethylene-vinyl acetate-vinyl alcohol terpolymer, modified silicon dioxide and graphene oxide in a mass ratio of 1:0.2-0.4:0.1-0.

3.

2. The low temperature resistant lubricating oil according to claim 1, characterized in that: The modified silica is prepared by the following method: mercaptosilica, octadecyl acrylate and tetrahydrofuran are mixed, ultrasonically treated for 30-40 minutes, then benzoin dimethyl ether is added, sealed, heated to 30-35°C, stirred, and irradiated for 2 hours using a 36-40W ultraviolet lamp at a distance of 10 cm, then methanol is added and stirred until floccules are precipitated, filtered, washed with methanol, and vacuum dried. The molar ratio of mercaptosilica to octadecyl acrylate is 3-4:4, and the concentration of benzoin dimethyl ether is 1-4%.

3. The low temperature resistant lubricating oil according to claim 1, characterized in that: The ester plant-based synthetic oil is epoxy soybean methyl ester or ethoxylated fatty acid methyl ester.

4. The low temperature resistant lubricating oil according to claim 1, characterized in that: The preparation method of the anti-wear agent is as follows: The cellulose is mixed with deionized water to prepare a suspension with a concentration of 4-5 wt%, filtered, hot-pressed at 80-90° C. and 8-10 MPa for 1-1.5 h, and cooled to obtain a cellulose membrane; Dissolve chitosan in acetic acid solution to prepare solution A with a concentration of 1.5-2wt%, disperse nano-silicon dioxide in a mixture of ethanol and water, disperse by ultrasonication, and adjust the pH to 3.5 with 0.1M hydrochloric acid to prepare solution B with a concentration of 1.5-2wt%; The cellulose membrane is immersed in solution A for 20-30 minutes, washed and dried, then immersed in solution B for 20-30 minutes, washed and dried, and the immersion in solution A and solution B is repeated n times, where n is a multiple of 2, and then immersed in 0.5M trichloromethylsilane solution for 40-50 minutes, washed, dried and crushed.

5. The low temperature resistant lubricating oil according to claim 1, characterized in that: The defoaming agent is at least one of polyoxyethylene polyoxypropylene pentaerythritol ether, methyl silicone oil, fluorosilicone oil, and polyacrylate.

6. The low temperature resistant lubricating oil according to claim 1, characterized in that: The preservative is at least one of sodium diacetate, alkylated diphenylamine, phenyl-α-naphthylamine and benzotriazole.

7. The low temperature resistant lubricating oil according to claim 1, characterized in that: The viscosity index improver is ethylene bis stearic acid amide or fatty acid lithium soap.

8. The production process of the low temperature resistant lubricating oil according to any one of claims 1 to 7, characterized in that: The following steps are involved: Mix ester plant-based synthetic oil, water and pour point depressant, heat to 190-230°C, stir at 0.4-0.48MPa for 30-40min, release the pressure, add poly-α-olefin synthetic oil, viscosity index improver, preservative, defoamer, friction reducer and anti-wear agent, stir evenly, homogenize, degas and fill.

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