Lubricating oil special for methanol engine and preparation method thereof

Abstract

The invention provides special lubricating oil for a methanol engine, which is prepared from the following components in parts by weight: 75 to 95 parts of base oil, 0.3 to 2.5 parts of an antioxidant, 0.1 to 1 part of an anti-rust agent, 0.5 to 3 parts of a clearing agent, 0.2 to 3 parts of a dispersing agent, 0.001 to 0.1 part of an anti-foaming agent, 0.5 to 5 parts of an anti-friction and anti-wear agent, 1 to 10 parts of a viscosity index improver, 0.1 to 0.5 part of a pour point depressant and 0.5 to 7 parts of a polarity improver, the polarity improver is dimer acid / polyethylene glycol ester, and the molecular weight of the polarity improver is 800 to 1500 g / mol. The lubricating oil provided by the invention has excellent wear resistance, viscosity-temperature performance, rust resistance, corrosion resistance and oxidation resistance. The invention further provides a preparation method of the lubricating oil.

Description

Technical Field

[0001] The invention relates to the technical field of engine lubrication, and in particular to a special lubricating oil for a methanol engine and a preparation method thereof. Background Art

[0002] Methanol, as the simplest fatty alcohol, is regarded as a preferred petroleum fuel substitute due to its wide sources, renewable nature, comparable combustion performance to petroleum fuel, good anti-knock performance, low toxic emission, and clean combustion. Accordingly, with the advancement of technology and the guidance of policy measures, vehicles using methanol engines and methanol fuel are increasing year by year.

[0003] As people continue to study methanol engines and methanol fuel, they find that methanol still faces many problems in actual use. For example, the current mainstream lubrication technology for methanol engines still uses the same lubricating oil as gasoline engines. However, unlike gasoline, methanol produces formaldehyde, formic acid, water and other substances during combustion. These substances have varying degrees of negative impact on the tribological properties, detergency, dispersibility, anti-oxidation and nitration, viscosity and other aspects of engine lubricating oil.

[0004] On the one hand, during the operation of the engine, more or less fuel will enter the crankcase, diluting the lubricating oil and reducing its lubrication performance. In particular, methanol has a high latent heat of vaporization (about 4 times that of gasoline). The methanol sprayed from the fuel injector cannot be fully vaporized and is prone to forming small droplets, which cannot be fully burned. Compared with gasoline, it is more likely to cause lubricating oil dilution. In addition, methanol sprayed onto the cylinder wall of the combustion chamber is likely to wash away the thin film of lubricating oil on the cylinder wall, causing increased wear between the cylinder liner and the piston ring.

[0005] On the other hand, methanol produces formaldehyde and formic acid during the combustion process, which not only reduces the performance of the lubricating oil but also corrodes the cast iron, cast aluminum and other parts of the engine. Summary of the invention

[0006] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a lubricating oil having excellent anti-wear performance, viscosity-temperature performance, rust and corrosion resistance and antioxidant performance.

[0007] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0008] A special lubricant for a methanol engine comprises, by weight, 75-95 parts of base oil, 0.3-2.5 parts of an antioxidant, 0.1-1 parts of a rust inhibitor, 0.5-3 parts of a detergent, 0.2-3 parts of a dispersant, 0.001-0.1 parts of an antifoaming agent, 0.5-5 parts of a friction reducing and antiwear agent, 1-10 parts of a viscosity index improver, 0.1-0.5 parts of a pour point depressant, and 0.5-7 parts of a polarity improver, wherein the polarity improver is dimer acid / polyethylene glycol ester, and the molecular weight of the polarity improver is 800-1500 g / mol.

[0009] In some possible embodiments, the kinematic viscosity of the base oil is 3.0 mm 2 / s-10.0mm 2 / s, and the measuring temperature of the kinematic viscosity is 100°C.

[0010] In some possible embodiments, the antioxidant is selected from at least one of 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl mixed phenol, N-phenyl-α-naphthylamine, alkyl diphenylamine, benzotriazole derivatives, thiadiazole derivatives, octyl / butyl diphenylamine, hindered phenol antioxidants, and aromatic amine antioxidants.

[0011] In some possible implementations, the pour point depressant is selected from at least one of fumarate and vinyl acetate copolymers, maleate, acrylate and vinyl acetate copolymers, polymethacrylate, alkyl naphthalene pour point depressants, and poly-alpha olefin pour point depressants.

[0012] In some possible implementations, the viscosity index improver is selected from at least one of polymethacrylate, ethylene-propylene copolymer, hydrogenated styrene-diene copolymer, and polyisobutylene.

[0013] In some possible implementations, the anti-foaming agent is selected from at least one of methyl silicone oil, methyl silicone ester, polyacrylate compounds and composite anti-foaming agents.

[0014] In some possible implementations, the rust inhibitor is selected from at least one of benzotriazole, dodecenylsuccinate half ester, dodecenylsuccinic acid, sorbitol monooleate, zinc cyclohexaneate, calcium sulfonate, barium sulfonate, and sodium sulfonate.

[0015] In some possible implementations, the dispersant is selected from at least one of boronated high molecular weight polyisobutylene succinimide, polyisobutylene polysuccinimide, polyisobutylene succinimide, monosuccinimide, and bissuccinimide.

[0016] In some possible embodiments, the detergent is selected from at least one of petroleum calcium sulfonate, calcium alkyl salicylate, super high base synthetic magnesium sulfonate, and alkyl phenol calcium sulfide, and the friction reducer and anti-wear agent is selected from at least one of butyl octyl zinc thiophosphate, primary alkyl zinc thiophosphate, dioctyl zinc thiophosphate, di-secondary alkyl zinc thiophosphate, dialkyl dithiophosphate oxymolybdenum, dialkyl dithiocarbamate molybdenum, sulfided isobutylene, dibenzyl disulfide, and aminothioester.

[0017] The present application also provides a method for preparing lubricating oil, using the components of the lubricating oil as raw materials, and the preparation method comprises the following steps:

[0018] Add the base oil into the blending device and stir;

[0019] Adding an antioxidant to the base oil and heating the mixture to form a first mixed liquid, wherein the heating temperature is 50-55° C.;

[0020] Adding a polarity improver to the first mixed solution, stirring at a constant temperature of 50-55° C. for 0.5-1 hour, to obtain a second mixed solution;

[0021] Add detergent, dispersant, rust inhibitor and friction reducer to the second mixed liquid, raise the temperature to 55-60° C. and stir at constant temperature for 0.5-1 hour to obtain a third mixed liquid;

[0022] Adding a viscosity index improver and a pour point depressant to the third mixed liquid, stirring at a constant temperature of 55-60° C. until the system is uniform, transparent and free of impurities, and then continuing to stir at a constant temperature of 55-60° C. for at least half an hour to obtain a fourth mixed liquid;

[0023] Add antifoaming agent to the fourth mixed liquid, stir at a constant temperature of 55-60° C. for 10-20 minutes to obtain lubricating oil.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] In the present application, by selecting a polarity improver with a specific molecular weight and molecular structure and combining it with a specific proportion of base oil, antioxidant, rust inhibitor, detergent, dispersant, antifoaming agent, friction and antiwear agent, viscosity index improver and pour point depressant, the lubricating oil provided in the present application has excellent anti-wear performance, viscosity-temperature performance, anti-rust and anti-corrosion performance and antioxidant performance.

[0026] The preparation method of the present application facilitates uniform dispersion of each functional agent in the base oil, thereby maximizing the synergistic effect of each functional agent.

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A roadmap for preparing dimer acid / polyethylene glycol ester provided in one embodiment of the present application. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0031] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0032] An embodiment of the present application provides a lubricating oil, which includes, by weight, 75-95 parts of base oil, 0.3-2.5 parts of antioxidant, 0.1-1 parts of rust inhibitor, 0.5-3 parts of detergent, 0.2-3 parts of dispersant, 0.001-0.1 parts of anti-foaming agent, 0.5-5 parts of friction reducing and anti-wear agent, 1-10 parts of viscosity index improver, 0.1-0.5 parts of pour point depressant, and 0.5-7 parts of polarity improver, wherein the polarity improver is dimer acid / polyethylene glycol ester, and the molecular weight of the polarity improver is 800-1500 g / mol.

[0033] Exemplarily, in the lubricating oil, the weight proportion of the base oil may be 75 parts, 76 parts, 78 parts, 80 parts, 82 parts, 85 parts, 90 parts, 95 parts. The weight proportion of the antioxidant may be 0.3 parts, 0.5 parts, 0.7 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts. The weight proportion of the rust inhibitor may be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 parts. The weight proportion of the detergent may be 0.5 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts, 3 parts. The weight proportion of the dispersant may be 0.2 parts, 0.5 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts, 3 parts. The weight proportion of the antifoaming agent may be 0.001 parts, 0.01 parts, 0.1 parts. The weight proportion of the friction reducing and antiwear agent can be 0.5, 1, 1.5, 2, 2.5, 3, 4, or 5. The weight proportion of the viscosity index improver can be 1, 2, 3, 4, 5, 6, 7, 8, or 10. The weight proportion of the pour point depressant can be 0.1, 0.2, 0.3, 0.4, or 0.5. The weight proportion of the polarity improver can be 0.5, 1, 2, 3, 4, 5, 6, or 7.

[0034] The polarity modifier of dimer acid / polyethylene glycol ester can be prepared by polymerization of diacid and diol, as shown in Figure 1 The catalyst for the polymerization reaction can be selected from at least one of concentrated sulfuric acid, stannous chloride, glacial acetic acid, and p-aminobenzenesulfonic acid. The polymerization temperature is 150°C-220°C, and the polymerization time is 2-6 hours. The product with a molecular weight cutoff of 800-1500 g / mol can be separated by gel permeation chromatography as the polarity improver of the present formula. The polarity improver with the above molecular weight is conducive to maintaining the viscosity of the lubricating oil, thereby ensuring the corresponding sealing and preventing the oil film from rupturing.

[0035] In some embodiments, the kinematic viscosity of the base oil is 3.0 mm 2 / s-10.0mm 2 / s to balance high temperature performance and low temperature performance, for example, it can be 3.0mm 2 / s、3.5mm 2 / s, 4mm 2 / s, 5mm 2 / s, 6mm 2 / s、7mm 2 / s, 8mm 2 / s, 9mm 2 / s, 10.0mm 2 / s, and the kinematic viscosity is measured at a temperature of 100°C. In some embodiments, the base oil may be at least one of AD 4CST, AD 6CST, AD 8CST, ARAMCO ULTRA 4, ARAMCO ULTRA 6, ARAMCO ULTRA 8, SINOPURE 15, SINOPURE 32, GS 4, GS 6, YUBASE 4, YUBASE 6, ETRO 4, ETRO 6, RisellaX420, RisellaX430, SpectraSyn 4, SpectraSyn 6, Durasyn 164, or Durasyn 126. The base oils of the above-mentioned brands can all be purchased from the market. Exemplarily, the base oil may be selected from three or four types of base oils commonly found on the market.

[0036] In some embodiments, the antioxidant is selected from at least one of 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl mixed phenol, N-phenyl-α-naphthylamine, alkyl diphenylamine, benzotriazole derivatives, thiadiazole derivatives, octyl / butyl diphenylamine, hindered phenol antioxidants, and aromatic amine antioxidants.

[0037] In some embodiments, the pour point depressant is selected from at least one of fumarate and vinyl acetate copolymers, maleates, acrylate and vinyl acetate copolymers, polymethacrylates, alkyl naphthalene pour point depressants, and polyalphaolefin pour point depressants. The above specific pour point depressants are beneficial to reducing the intermolecular forces within the base oil of the present application, reducing the precipitation of "wax", and thus further improving the low temperature fluidity of the oil product.

[0038] In some embodiments, the viscosity index improver is selected from at least one of polymethacrylate, ethylene-propylene copolymer, hydrogenated styrene-diene copolymer, and polyisobutylene. The above specific viscosity index improver is conducive to further regulating the viscosity index of the system to further improve the apparent viscosity of the system.

[0039] In some embodiments, the antifoaming agent is selected from at least one of methyl silicone oil, methyl silicone ester, polyacrylate compound and composite antifoaming agent. The above specific types of antifoaming agents have a good antifoaming effect on the system of the present application.

[0040] In some embodiments, the rust inhibitor is selected from at least one of benzotriazole, dodecenylsuccinate half ester, dodecenylsuccinic acid, sorbitan monooleate, zinc cyclohexaneate, calcium sulfonate, barium sulfonate, and sodium sulfonate.

[0041] In some embodiments, the dispersant is selected from at least one of boronated high molecular weight polyisobutylene succinimide, polyisobutylene polysuccinimide, polyisobutylene succinimide, monosuccinimide, and bissuccinimide.

[0042] In some embodiments, the detergent is selected from at least one of petroleum calcium sulfonate, calcium alkyl salicylate, super-based synthetic magnesium sulfonate, and sulfide alkyl phenol calcium, and the friction reducing and anti-wear agent is selected from at least one of thiophosphate butyl octyl zinc salt, thiophosphate primary alkyl zinc salt, thiophosphate dioctyl zinc salt, thiophosphate di-secondary alkyl zinc salt, dialkyl dithiophosphate oxymolybdenum, dialkyl dithiocarbamate molybdenum, sulfide isobutylene, dibenzyl disulfide, and aminothioester. Exemplarily, a base number greater than 400 can be defined as super-based.

[0043] In the present application, by selecting a polarity improver with a specific molecular weight and molecular structure and combining it with a specific proportion of base oil, antioxidant, rust inhibitor, detergent, dispersant, antifoaming agent, friction and antiwear agent, viscosity index improver and pour point depressant, the lubricating oil provided in the present application has excellent anti-wear performance, viscosity-temperature performance, anti-rust and anti-corrosion performance and antioxidant performance.

[0044] The lubricating oil provided in this application can be specifically used in methanol engines.

[0045] Another embodiment of the present application also provides a method for preparing lubricating oil, wherein the method uses the above-mentioned components of lubricating oil as raw materials, that is, the corresponding raw materials are the same in weight, so they are not described in detail. The method comprises the following steps:

[0046] Add the base oil into the blending device and stir. In this embodiment, a blending kettle with heating, temperature control and stirring functions can be used as the blending device.

[0047] An antioxidant is added to the base oil and heated to form a first mixed liquid. The heating temperature is 50-55°C, for example, 50°C, 51°C, 52°C, 53°C, 54°C, or 55°C.

[0048] Add polarity improver to the first mixed liquid, stir at a constant temperature of 50-55° C. for 0.5-1 hour to obtain a second mixed liquid. The constant temperature stirring time and temperature can make the polarity improver uniformly dispersed in the base oil.

[0049] Add detergent, dispersant, rust inhibitor and anti-friction and anti-wear agent to the second mixed liquid, heat it to 55-60°C and stir it at constant temperature for 0.5-1 hour to obtain a third mixed liquid. For example, the temperature of constant temperature stirring can be 56°C, 57°C, 58°C, 59°C. For example, detergent, dispersant, rust inhibitor and anti-friction and anti-wear agent can be added simultaneously. Stirring at constant temperature after heating is conducive to uniformly dispersing the above functional agents in the base oil.

[0050] Add viscosity index improver and pour point depressant to the third mixed solution, stir at a constant temperature of 55-60° C. until the system is uniform, transparent and free of impurities, and then continue stirring at a constant temperature of 55-60° C. for at least half an hour to obtain a fourth mixed solution.

[0051] Add antifoaming agent to the fourth mixed liquid, stir at a constant temperature of 55-60° C. for 10-20 minutes to obtain lubricating oil.

[0052] The preparation method of the present application facilitates uniform dispersion of each functional agent in the base oil, thereby maximizing the synergistic effect of each functional agent.

[0053] Specific:

[0054] Embodiment 1:

[0055] A lubricating oil, wherein the lubricating oil comprises, by weight, 25 parts of a base oil of the brand SpectraSyn 4, 56.89 parts of a base oil of the brand SpectraSyn 6, 0.1 parts of a rust inhibitor, the rust inhibitor being dodecenyl succinic acid half ester, and 7.2 parts of a viscosity index improver, the viscosity index improver being polymethacrylate (Evonik VISCOPLEX 3-510), 1.5 parts of high base synthetic calcium sulfonate (detergent, Jinzhou Xinxing T106), 0.5 parts of super-based synthetic magnesium sulfonate (detergent, Jinzhou Xinxing T107), 0.5 parts of sulfurized alkyl phenol calcium (detergent, Jinzhou Kangtai P250), 1 part of high molecular weight polyisobutylene succinimide (dispersant, Jinzhou Xinxing T161), 0.5 parts of bis-succinimide (dispersant), 1 part of primary alkyl zinc salt of sulfur phosphorus (friction reducer and anti-wear agent), 0.3 parts of dialkyl dithiocarbamate molybdenum (friction reducer and anti-wear agent), 4 parts of dimer acid / polyethylene glycol ester (polarity improver), the molecular weight of dimer acid / polyethylene glycol ester is 800-1500g / mol, 0.4 parts of polymethyl methacrylate (pour point depressant, Evonik VISCOPLEX 1-248), 0.6 parts of 2,6-di-tert-butyl-p-cresol (antioxidant), 0.5 parts of alkyl diphenylamine (antioxidant), 0.01 parts of composite antifoaming agent (Jinzhou Kangtai KT992).

[0056] Specifically, the preparation method of lubricating oil is:

[0057] While starting stirring, add antioxidant to the base oil, then raise the temperature to 55°C; add polarity improver and stir at a constant temperature for 0.5 hour; then add detergent, dispersant, rust inhibitor, friction reducer and anti-wear agent in sequence, raise the temperature to 60°C, and stir at a constant temperature for 0.5 hour; add viscosity index improver and pour point depressant, and stir at the temperature for 0.5 hour; add anti-foaming agent and stir at the temperature for 15 minutes.

[0058] Embodiment 2:

[0059] A lubricating oil, which comprises, by weight, 37 parts of a base oil with a brand name of ETRO 4, 44.79 parts of a base oil with a brand name of ETRO 6, 0.1 parts of a rust inhibitor, which is dodecenyl succinate, 8.5 parts of a viscosity index improver, which is polymethacrylate (Evonik VISCOPLEX 6-054), 2 parts of an overbased synthetic calcium sulfonate (detergent, Jinzhou Kangtai BD 400), 0.5 parts of a sulfurized alkylphenol calcium (detergent, Jinzhou Kangtai KT P150), 1.2 parts of monosuccinimide (dispersant), 0.3 parts of bissuccinimide (dispersant), 0.7 parts of octyl zinc thiophosphate (friction reducing and anti-wear agent), 0.5 parts of molybdenum dialkyl dithiocarbamate (friction reducing and anti-wear agent), 3 parts of dimer acid / polyethylene glycol ester (polarity improver), the molecular weight of dimer acid / polyethylene glycol ester is 800-1500g / mol, 0.4 parts of polymethyl methacrylate (pour point depressant, Evonik VISCOPLEX 1-300), 0.5 parts of 2,6-di-tert-butyl mixed phenol (antioxidant), 0.5 parts of alkyl diphenylamine (antioxidant, Jinzhou Xinxing L557), 0.01 parts of composite antifoaming agent (Jinzhou Xinxing T922).

[0060] Embodiment 3:

[0061] A lubricating oil, which comprises, by weight, 30 parts of a base oil with a brand name of Risella X420, 48.29 parts of a base oil with a brand name of ARAMCO ULTRA 6, 0.1 parts of a rust inhibitor, which is zinc cyclohexaneate, 8.1 parts of a viscosity index improver, which is an ethylene-propylene copolymer (Chevron-Oronai VISTON 8900EL), 1.4 parts of a high-base synthetic calcium sulfonate (detergent, Jinzhou Kangtai BD C300), 0.9 parts of alkyl calcium salicylate (detergent, Jinzhou Kangtai KT SA250), 1.5 parts of polyisobutylene succinimide (dispersant, Jinzhou Xinxing T154A), 0.3 parts of bis-succinimide (dispersant), 0.8 parts of disulphur phosphate dioctyl zinc salt (friction reducing and anti-wear agent), 0.3 parts of dialkyl dithiophosphate oxymolybdenum (friction reducing and anti-wear agent), 7 parts of dimer acid / polyethylene glycol ester (polarity improver), the molecular weight of dimer acid / polyethylene glycol ester is 800-1500g / mol, 0.3 parts of polymethyl methacrylate (pour point depressant, Evonik VISCOPLEX 1-300), 0.7 parts of 2,6-di-tert-butyl-p-cresol (antioxidant), 0.3 parts of N-phenyl-α-naphthylamine (antioxidant), 0.01 parts of composite antifoaming agent (Jinzhou Xinxing T922).

[0062] Embodiment 4:

[0063] A lubricating oil, which comprises, by weight, 10 parts of a base oil with a brand name of Durasyn 164, 20 parts of a base oil with a brand name of Risella X420, 50.29 parts of a base oil with a brand name of YUBASE 6, 0.1 parts of a rust inhibitor, which is dodecenyl succinic acid half ester, 6.8 parts of a viscosity index improver, which is a hydrogenated styrene-diene copolymer (Runyinglian SV261), 1.5 parts of an overbased synthetic calcium sulfonate (detergent, Jinzhou Kangtai BD M400), 0.5 parts of an alkyl calcium salicylate (detergent, Jinzhou Kangtai KT SA250), 0.5 parts of sulfurized alkyl phenol calcium (detergent, Jinzhou Kangtai KTP150), 1 part of polyisobutylene succinimide (dispersant, Jinzhou Xinxing T154A), 0.5 parts of boronated polyisobutylene bissuccinimide (dispersant, Jinzhou Xinxing T154B), 0.8 parts of octyl alkyl zinc salt of thiophosphorus (friction reducer and anti-wear agent, Jinzhou Kangtai KT2048), 0.4 parts of dialkyl dithiocarbamate molybdenum (friction reducer and anti-wear agent), 6 parts of dimer acid / polyethylene glycol ester (polarity improver), the molecular weight of dimer acid / polyethylene glycol ester is 800-1500g / mol, 0.4 parts of polymethyl methacrylate (pour point depressant, Shenyang Great Wall SCR 1-248), 0.9 parts of 2,6-di-tert-butyl-p-cresol (antioxidant), 0.3 parts of octyl / butyl diphenylamine (antioxidant), and 0.01 parts of composite antifoaming agent (Jinzhou Xinxing T922).

[0064] Embodiment 5:

[0065] A lubricating oil, measured by weight, comprises 35 parts of a base oil with a brand name of Risella X420, 45.49 parts of a base oil with a brand name of ARAMCO ULTRA 8, 0.1 parts of a rust inhibitor, which is dodecenylsuccinic acid, 6 parts of a viscosity index improver, which is a hydrogenated styrene-diene copolymer (Runyinglian SV261), 1.5 parts of a high-base synthetic calcium sulfonate (detergent, Jinzhou Xinxing T106), 0.6 parts of an over-base synthetic magnesium sulfonate (detergent, Chevron-Olonai OLOA 65725), 0.5 parts of a sulfurized alkyl phenol calcium (detergent, Jinzhou Kangtai KT P150), 1.3 parts of high molecular weight polyisobutylene succinimide (dispersant, Jinzhou Kangtai KT1961), 0.3 parts of bis-succinimide (dispersant), 1 part of disulphur phosphate dioctyl zinc salt (friction reducer and anti-wear agent), 0.5 parts of dialkyl dithiocarbamate molybdenum (friction reducer and anti-wear agent, Pacific Union LPUPC 1002), 6 parts of dimer acid / polyethylene glycol ester (polarity improver), the molecular weight of dimer acid / polyethylene glycol ester is 800-1500g / mol, 0.4 parts of polymethyl methacrylate (pour point depressant, Evonik VISCOPLEX 1-300), 0.8 parts of 2,6-di-tert-butyl-p-cresol (antioxidant), 0.5 parts of alkyl diphenylamine (antioxidant, Jinzhou Kangtai KT5534), 0.01 parts of composite antifoaming agent (Jinzhou Xinxing T922).

[0066] Embodiment 6:

[0067] A lubricating oil, which comprises, by weight, 35 parts of a base oil with a brand name of ARAMCO ULTRA 4, 44.69 parts of a base oil with a brand name of Risella X430, 0.1 parts of a rust inhibitor, which is dodecenyl succinic acid half ester, 7.8 parts of a viscosity index improver, which is an ethylene-propylene copolymer (Chevron-Oronai VISTON8900EL), 1.8 parts of an over-based synthetic calcium sulfonate (detergent Jinzhou Kangtai BD C350G), 0.7 parts of super-based synthetic magnesium sulfonate (detergent, Jinzhou Xinxing T107), 1.3 parts of high molecular weight polyisobutylene succinimide (dispersant, Jinzhou Xinxing T161), 0.5 parts of monosuccinimide (dispersant), 1.2 parts of primary alkyl zinc salt of sulfur phosphorus (friction reducer and anti-wear agent, Jinzhou Kangtai KT3054), 0.3 parts of dialkyl dithiocarbamate molybdenum (friction reducer and anti-wear agent), 5 parts of dimer acid / polyethylene glycol ester (polarity improver), the molecular weight of dimer acid / polyethylene glycol ester is 800-1500g / mol, 0.4 parts of polymethyl methacrylate (pour point depressant, Evonik VISCOPLEX 1-248), 0.7 parts of 2,6-di-tert-butyl-p-cresol (antioxidant), 0.5 parts of N-phenyl-α-naphthylamine (antioxidant), 0.01 parts of composite antifoaming agent (Jinzhou Kangtai KT992).

[0068] The polarity improvers in the above-mentioned embodiments can be synthesized by themselves. The remaining reagents are all conventional reagents that can be purchased from the market, and the molecular structures and properties of the reagents whose specific manufacturers and brands are not listed are clear.

[0069] The test results of the lubricating oils obtained in Examples 1 to 6 of the present application and several lubricating oils purchased on the market are shown in Tables 1 and 2. A, B, C, and D are respectively mainstream SAE 5W-30 engine lubricating oil products on the market.

[0070] Table 1 shows the test results of Example 1 and several lubricating oils purchased on the market.

[0071]

[0072]

[0073] Table 2 shows the test results of Examples 2 to 6.

[0074]

[0075] It can be seen from the data in Table 1 and Table 2 that the lubricating oil obtained in this application has great advantages over the mainstream SAE 5W-30 engine oil products on the market in terms of viscosity index, pour point, low-temperature apparent viscosity (CCS), total base number, evaporation loss, oxidation induction period, friction coefficient, and wear spot diameter, and other performance indicators are excellent. In practical applications, under the condition of equivalent high-temperature viscosity, a higher viscosity index, a lower CCS, and a smaller friction coefficient can have a better fuel economy performance and save more fuel. A higher total base number can provide a stronger acid comprehensive ability, which can effectively neutralize corrosive substances such as formaldehyde and formic acid produced by methanol combustion to protect the engine. A longer oxidation induction period indicates that the engine oil has better antioxidant ability, slows down the aging rate of the engine oil itself, and prolongs the service life of the engine oil. A better wear spot diameter indicates that the oil has better anti-wear performance, provides better anti-wear protection for the engine, and reduces engine wear. Among them, HTHS refers to high temperature high shear viscosity.

[0076] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A special lubricating oil for methanol engine, characterized in that: The lubricating oil comprises, by weight, 75-95 parts of base oil, 0.3-2.5 parts of antioxidant, 0.1-1 parts of rust inhibitor, 0.5-3 parts of detergent, 0.2-3 parts of dispersant, 0.001-0.1 parts of antifoaming agent, 0.5-5 parts of friction reducing and antiwear agent, 1-10 parts of viscosity index improver, 0.1-0.5 parts of pour point depressant, and 0.5-7 parts of polarity improver, wherein the polarity improver is dimer acid / polyethylene glycol ester, and the molecular weight of the polarity improver is 800-1500 g / mol.

2. The special lubricating oil for methanol engine according to claim 1, characterized in that: The kinematic viscosity of the base oil is 3.0 mm 2 / s-10.0mm 2 / s, and the measuring temperature of the kinematic viscosity is 100°C.

3. The special lubricating oil for methanol engine according to claim 1, characterized in that: The antioxidant is selected from at least one of 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl mixed phenol, N-phenyl-α-naphthylamine, alkyl diphenylamine, benzotriazole derivatives, thiadiazole derivatives, octyl / butyl diphenylamine, hindered phenol antioxidants, and aromatic amine antioxidants.

4. The special lubricating oil for methanol engine according to claim 1, characterized in that: The pour point depressant is selected from at least one of fumarate and vinyl acetate copolymers, maleate, acrylate and vinyl acetate copolymers, polymethacrylate, alkyl naphthalene pour point depressants, and poly-alpha olefin pour point depressants.

5. The special lubricating oil for methanol engine according to claim 1, characterized in that: The viscosity index improver is selected from at least one of polymethacrylate, ethylene-propylene copolymer, hydrogenated styrene-diene copolymer and polyisobutylene.

6. The special lubricating oil for methanol engine according to claim 1, characterized in that: The anti-foaming agent is selected from at least one of methyl silicone oil, methyl silicone ester, polyacrylate compounds and composite anti-foaming agents.

7. The special lubricating oil for methanol engine according to claim 1, characterized in that: The rust inhibitor is selected from at least one of benzotriazole, dodecenylsuccinic acid half ester, dodecenylsuccinic acid, sorbitol monooleate, zinc cyclohexaneate, calcium sulfonate, barium sulfonate and sodium sulfonate.

8. The special lubricating oil for methanol engine according to claim 1, characterized in that: The dispersant is selected from at least one of boronated high molecular weight polyisobutylene succinimide, polyisobutylene polysuccinimide, polyisobutylene succinimide, monosuccinimide and bissuccinimide.

9. The special lubricating oil for methanol engine according to claim 1, characterized in that: The detergent is selected from at least one of petroleum calcium sulfonate, calcium alkyl salicylate, super high base synthetic magnesium sulfonate, and alkyl phenol calcium sulfide. The friction reducing and anti-wear agent is selected from at least one of butyl octyl zinc thiophosphate, primary alkyl zinc thiophosphate, disoctyl zinc thiophosphate, di-secondary alkyl zinc thiophosphate, molybdenum dialkyl dithiophosphate, molybdenum dialkyl dithiocarbamate, isobutylene sulfide, dibenzyl disulfide, and aminothioester.

10. A method for preparing lubricating oil, characterized in that: Using the components of the methanol engine special lubricating oil as claimed in any one of claims 1 to 9 as raw materials, the preparation method comprises the following steps: Add the base oil into the blending device and stir; Adding an antioxidant to the base oil and heating the mixture to form a first mixed liquid, wherein the heating temperature is 50-55° C.; Adding a polarity improver to the first mixed solution, stirring at a constant temperature of 50-55° C. for 0.5-1 hour, to obtain a second mixed solution; Add detergent, dispersant, rust inhibitor and friction reducer to the second mixed liquid, raise the temperature to 55-60° C. and stir at constant temperature for 0.5-1 hour to obtain a third mixed liquid; Adding a viscosity index improver and a pour point depressant to the third mixed liquid, stirring at a constant temperature of 55-60° C. until the system is uniform, transparent and free of impurities, and then continuing to stir at a constant temperature of 55-60° C. for at least half an hour to obtain a fourth mixed liquid; Add antifoaming agent to the fourth mixed liquid, stir at a constant temperature of 55-60° C. for 10-20 minutes to obtain lubricating oil.

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