Diesel engine lubricating oil composition and preparation method thereof

Abstract

The invention provides a diesel engine lubricating oil composition and a preparation method thereof. The diesel engine lubricating oil composition of the present invention comprises: (A) a viscosity index improver; (B) a boronized ashless dispersant and / or a polyisobutylene succinate ashless dispersant; (C) sulfonate and / or sulfurized alkylphenate metal detergents; (D) zinc dialkyl dithiophosphate; (E) a dialkyl dithiocarbamate; (F) an amine type antioxidant; (G) a thiophenol ester type antioxidant; (H) lubricating base oil; wherein the viscosity index improver is a copolymer of methyl acrylic acid C8-C12 alkyl ester, methyl acrylic acid C13-C18 alkyl ester and N-vinyl imidazole. The diesel engine lubricating oil composition has excellent soot dispersion, wear resistance and high-temperature cleaning performance, and can meet the requirements of API CI-4, ACEA E4 and E7-grade high-performance diesel engine lubricating oil.

Description

Technical Field

[0001] This invention relates to a lubricating oil composition, and more particularly to a diesel engine lubricating oil composition and its preparation method. Background Technology

[0002] Environmental protection, energy conservation, and extended oil change intervals are the driving forces behind the upgrading of internal combustion engine oils. With the improvement of diesel engine oil quality specifications, the performance requirements for oils in terms of soot dispersion, high-temperature detergency, anti-wear and friction reduction, and anti-oxidation are also becoming increasingly stringent. China implemented the China VI emission standard for heavy-duty diesel vehicles on July 1, 2021. However, for the foreseeable future, China IV and China V emission standard diesel vehicles still constitute a significant portion of the heavy-duty diesel vehicle market. China IV and China V diesel vehicles primarily use selective catalytic reduction (SCR) technology to control emissions and do not have exhaust particulate filters (DPF). Therefore, engine oils suitable for China IV and China V diesel vehicles are characterized by high performance, no restrictions on sulfur and phosphorus content, and the ability to have higher ash content. API CI-4 and ACEA E4 and E7 specification diesel engine oils can meet the lubrication requirements of China IV and China V diesel vehicles. Among them, ACEA E4 is a long-life oil that can meet the needs of OEMs for oils with longer oil change intervals. The above-mentioned oil products all have high requirements for soot dispersion, anti-wear, and high-temperature detergency performance.

[0003] High-performance oils require excellent low-temperature performance and high-temperature lubricity to reduce engine wear, lower fuel consumption, and extend lubricant life. Multi-grade engine oils generally require the addition of viscosity index improvers and pour point depressants to improve viscosity-temperature properties and low-temperature fluidity. To this end, existing technologies have developed many types of viscosity index improvers. Among them, viscosity index improvers with polymethyl methacrylate (PMA) structures have shown good effects in improving the viscosity index of lubricating oils. However, these are far from sufficient as single additives. With the development of lubricating oils, higher demands are being placed on the performance of viscosity index improvers. Developing multifunctional PMA viscosity index improvers is a trend in additive development. For example, developing PMA viscosity index improvers that combine viscosity increasing, pour point depressing, dispersing, and anti-wear properties can replace some dispersants and anti-wear agents during use, reducing the dosage, saving costs, and further improving fuel economy.

[0004] Therefore, existing technologies still require new multifunctional viscosity index improvers with superior performance, and engine oils can be formulated with these new multifunctional viscosity index improvers to give the oils excellent performance and hopefully meet the requirements of high-performance oils. Summary of the Invention

[0005] This invention proposes a diesel engine lubricating oil composition and its preparation method.

[0006] The diesel engine lubricating oil composition of the present invention comprises: (A) a viscosity index improver; (B) a boronized ashless dispersant and / or a polyisobutylene succinate ashless dispersant; (C) a sulfonate and / or a sulfurized alkylphenol salt metal detergent; (D) zinc dialkyl dithiophosphate; (E) a dialkyl dithiocarbamate; (F) an amine antioxidant; (G) a thiophenol ester antioxidant; and (H) a lubricating base oil; wherein the viscosity index improver is C8-C methacrylate. 12 Alkyl esters, C methacrylic acid 13 ~C 18 A copolymer of alkyl esters and N-vinylimidazole, in the viscosity index improver, comprising, by weight, 40% to 70% of C8-C4 methacrylic acid based on the monomer content. 12 Alkyl esters, 10%–50% (by weight) of C methacrylate 13 ~C 18 Alkyl esters, 5% to 40% (by weight) of N-vinylimidazole.

[0007] According to the present invention, the viscosity index improver contains 50% to 70% (by weight) of C8-C6 methacrylic acid, based on the number of monomers. 12 Alkyl esters, 20%–40% (by weight) of C methacrylate 13 ~C 18 Alkyl esters, 5% to 30% (by weight) of N-vinylimidazole.

[0008] According to the present invention, the viscosity index improver has a number-average molecular weight of 2,000 to 100,000 g / mol, preferably 10,000 to 50,000 g / mol. The number-average molecular weight is determined by gel permeation chromatography (GPC) using commercially available polymethyl methacrylate standards.

[0009] According to the present invention, the method for preparing the viscosity index improver includes: reacting methacrylic acid with C8-C64... 12 Alkyl esters, C methacrylic acid 13 ~C 18 Alkyl esters, N-vinylimidazole, chain transfer agents, initiators, and solvents are mixed uniformly and copolymerized under nitrogen protection. The viscosity index improver product is then collected.

[0010] According to the present invention, the temperature of the copolymerization reaction can be 50-150°C, preferably 60-100°C; the time of the copolymerization reaction can be 2-10 hours, preferably 3-8 hours.

[0011] According to the present invention, in preparing the viscosity index improver, the methacrylic acid C8-C6 is calculated based on the polymerizable monomers. 12 Alkyl esters, C methacrylic acid 13 ~C18 The molar ratio between alkyl ester and N-vinylimidazole can be 6:1 to 8:1 to 10, preferably 3:1 to 3:1 to 4.

[0012] According to the present invention, the chain transfer agent is trithiocarbonate alkyl propionic acid, for example, 2-(dodecyltrithiocarbonate)-2-methylpropionic acid. The amount of the chain transfer agent added is C8-C6 methacrylic acid. 12 Alkyl esters, C methacrylic acid 13 ~C 18 The alkyl ester and N-vinylimidazole together account for 0.1% to 3% by weight, preferably 0.3% to 2%.

[0013] According to the present invention, the initiator may be one or more selected from azobisisobutyronitrile, benzoyl peroxide, and tert-butyl peroxide, preferably azobisisobutyronitrile; the amount of the initiator added is C8-C6 methacrylic acid. 12 Alkyl esters, C methacrylic acid 13 ~C 18 The initiator is added at a weight of 0.1% to 3%, preferably 0.2% to 2%, of the sum of the weights of the alkyl ester and N-vinylimidazole. The initiator may be added all at once or in multiple additions, such as two or three times, without particular limitation.

[0014] According to the present invention, the solvent may be one or more selected from toluene, cyclohexane, n-hexane, and petroleum ether; the amount of solvent added is C8-C6 methacrylic acid. 12 Alkyl esters, C methacrylic acid 13 ~C 18 The alkyl ester and N-vinylimidazole together account for 10% to 200% by weight, preferably 20% to 150%.

[0015] According to the present invention, after the copolymerization reaction is completed, the reaction solution can be dropwise added to a C1-C4 alcohol, the precipitate can be collected, and after drying, the viscosity index improver of the present invention can be obtained. The C1-C4 alcohol can be one or more of methanol, ethanol, propanol, and butanol, preferably ethanol. The amount of the C1-C4 alcohol can be the same as that of the C8-C4 methacrylic acid. 12 Alkyl esters, C methacrylic acid 13 ~C 18 The total mass of alkyl esters and N-vinylimidazole is 50% to 1200%.

[0016] The viscosity index improver of the present invention has excellent viscosity-temperature properties and thickening ability, as well as good pour point depressing effect, and also has good anti-wear ability and dispersing performance. It is a multifunctional viscosity index improver.

[0017] According to the present invention, the viscosity index improver accounts for 0.1% to 20% (preferably 0.3% to 10%) of the total mass of the lubricating oil composition; the boronized ashless dispersant and / or polyisobutylene succinate ashless dispersant accounts for 0.5% to 20% (preferably 1% to 12%) of the total mass of the lubricating oil composition; the sulfonate and / or sulfurized alkylphenol salt metal detergent accounts for 0.2% to 10% (preferably 1% to 8%) of the total mass of the lubricating oil composition; and the dialkyl dithiophosphate zinc accounts for [missing information - likely a percentage] of the total mass of the lubricating oil composition. The lubricating oil composition comprises 0.1% to 5% (preferably 0.3% to 2.5%) by mass; the dialkyl dithiocarbamate comprises 0.02% to 5% (preferably 0.05% to 2%) by mass; the amine antioxidant comprises 0.1% to 6% (preferably 0.2% to 4%) by mass; the thiophenol ester antioxidant comprises 0.05% to 2% (preferably 0.1% to 0.8%) by mass; and the lubricating base oil constitutes the main component of the lubricating oil composition.

[0018] According to the present invention, the boronized ashless dispersant and / or the polyisobutylene succinate ashless dispersant is preferably a mixture of the boronized ashless dispersant and the polyisobutylene succinate ashless dispersant, and the mass ratio between the two can be 1:0.1 to 10. The number average molecular weight of the polyisobutylene groups in the boronized ashless dispersant can be 500 to 4000, preferably 700 to 3000, more preferably 1000 to 2400. The boronized ashless dispersant can be C-200 produced by Mobil, MX 3316 produced by Agip Petroli, Hitec 648 produced by Afton, etc.; the polyisobutylene succinate ashless dispersant can be one or more of pentaerythritol polyisobutylene succinate, glyceryl polyisobutylene succinate, and polyethylene polyisobutylene succinate, for example, LZ936 from Lubrizol.

[0019] According to the present invention, the sulfonate and / or alkylphenolate is preferably a mixture of calcium sulfonate and calcium alkylphenolate, more preferably a mixture of high-alkalinity calcium sulfonate with an alkalinity of (200-450) mgKOH / g and high-alkalinity calcium alkylphenolate with an alkalinity of (200-450) mgKOH / g, with a preferred mass ratio of 0.2-5:1. The sulfonate and / or alkylphenolate can be selected from T106B and S206 produced by Wuxi Southern Petroleum Additives Co., Ltd., LZL115B produced by Lanzhou Lubrizol Additives Co., Ltd., LZ6477C and LZ6478 produced by Lubrizol, E611 produced by Afton, OLOA219 produced by Chevron Oronite, C9330 and C9394 produced by Infineum, etc.

[0020] According to the present invention, the alkyl group in the zinc dialkyl dithiophosphate can be C2-C3. 12 The alkyl group, preferably C2-C8, includes, but is not limited to, one or more of ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl, n-octyl, and 2-ethylhexyl. The dialkyl dithiophosphate zinc can be selected from T202, T203, and T205 produced by Wuxi Southern Petroleum Additives Co., Ltd.; T202, T203, primary and secondary alkyl T204, and secondary alkyl T205 produced by Jinzhou Petrochemical Branch Additives Plant; LZ1371 and LZ1375 from Lubrizol; C9417, C9425, and C9426 from Infineum; and Hitec7169 and Hitec1656 from Afton.

[0021] According to the present invention, the alkyl group in the dialkyl dithiocarbamate is an alkyl group containing 2 to 12 carbon atoms, preferably an alkyl group containing 2 to 8 carbon atoms, and can be one or more selected from ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl, n-octyl, and 2-ethylhexyl. The dialkyl dithiocarbamate can be selected from T323 produced by Jinzhou Xinxing Petroleum Additives Co., Ltd., 7723 from Vanderbilt, etc.

[0022] According to the present invention, the amine-type antioxidant may be one or more of alkylaniline, alkyldiphenylamine, and phenyl-α-naphthylamine, wherein the alkyl carbon number may be C2 to C4. 12 The amine-type antioxidant can be selected from one or more of dibutyldiphenylamine, dioctyldiphenylamine, dinonyldiphenylamine, butyl-octyldiphenylamine, and phenyl-α-naphthylamine, preferably alkylated diphenylamine, such as IRGANOX L-01 and IRGANOX L-57 produced by BASF (Germany), T534 produced by Beijing Xingpu Fine Chemical Technology Development Co., Ltd., LZ5150A produced by Lanzhou Lubrizol Lanzhou Refinery Additives Co., Ltd., VANLUBE NA, VANLUBE 961, and dioctyldiphenylamine VANLUBE 81 produced by Vanderbilt (USA), and p,p'-diisooctyldiphenylamine RC7001 produced by Rhein Chemie (Germany), etc.

[0023] According to the present invention, the thiophenol ester type antioxidant can be selected from 2,2'-thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], for example, antioxidant 1035 produced by Sichuan Yongye Chemical Co., Ltd., IRGANOX L115 produced by BASF, etc.

[0024] According to the present invention, the lubricating base oil is selected from one or more of API Group I, II, III, IV and V base oils, preferably one or more of API Group II, III and IV base oils.

[0025] According to the present invention, the method for preparing the diesel engine lubricating oil composition includes the step of mixing the components of the aforementioned lubricating oil composition. The mixing temperature is preferably between 40°C and 90°C, and the mixing time is preferably between 1 and 6 hours.

[0026] The diesel engine lubricating oil composition of the present invention has excellent soot dispersion, anti-wear and high-temperature detergency properties, and can meet the requirements of high-performance diesel engine lubricating oils of API CI-4, ACEA E4 and E7 levels. Detailed Implementation

[0027] The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.

[0028] The main raw materials used are sourced from the following sources:

[0029] Methyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.

[0030] Isooctyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0031] Decyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0032] Dodecyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0033] Tetradecyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0034] Cetyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0035] Octadecyl methacrylate, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0036] 2-(dodecyltrithiocarbonate)-2-methylpropionic acid, analytical grade, Beijing Innocare Technology Co., Ltd.; azobisisobutyronitrile, analytical grade, Beijing Innocare Technology Co., Ltd.

[0037] Ethanol, analytical grade, Beijing Innocare Technology Co., Ltd.;

[0038] Toluene, analytical grade, Beijing Innocare Technology Co., Ltd.

[0039] III4 base oil, Guangdong Maoming Petrochemical Company.

[0040] The testing method for the viscosity index improver in this invention is shown in Table 1.

[0041] Table 1

[0042]

[0043] Example 1: Preparation of viscosity index improver

[0044] To a three-necked flask equipped with an electric stirrer, add 30 mL of toluene, 17.9 g of dodecyl methacrylate, 6.22 g of tetradecyl methacrylate, 2.17 g of N-vinylimidazole, 346 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 47 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 47 mg of AIBN, and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain a terpolymer of dodecyl methacrylate, tetradecyl methacrylate, and N-vinylimidazole, which is the viscosity index improver 1 of this invention.

[0045] Example 2: Preparation of viscosity index improver

[0046] To a three-necked flask equipped with an electric stirrer, add 90 mL of toluene, 97.62 g of dodecyl methacrylate, 33.9 g of tetradecyl methacrylate, 21.2 g of N-vinylimidazole, 1107 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 165 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 165 mg of AIBN, and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 720 mL of ethanol, collect the precipitate, and dry it to obtain a terpolymer of dodecyl methacrylate, tetradecyl methacrylate, and N-vinylimidazole, which is the viscosity index improver 2 of this invention.

[0047] Example 3: Preparation of viscosity index improver

[0048] To a three-necked flask equipped with an electric stirrer, add 30 mL of toluene, 16.3 g of dodecyl methacrylate, 5.7 g of tetradecyl methacrylate, 5.2 g of N-vinylimidazole, 412 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 50 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 50 mg of AIBN, and continue stirring at 70°C for another 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain a terpolymer of dodecyl methacrylate, tetradecyl methacrylate, and N-vinylimidazole, which is the viscosity index improver 3 of this invention.

[0049] Example 4: Preparation of viscosity index improver

[0050] To a three-necked flask equipped with an electric stirrer, add 60 mL of toluene, 42.76 g of isooctyl methacrylate, 24.9 g of hexadecyl methacrylate, 8.5 g of N-vinylimidazole, 550 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 145 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 145 mg of AIBN, and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain a terpolymer of isooctyl methacrylate, hexadecyl methacrylate, and N-vinylimidazole, which is the viscosity index improver 4 of this invention.

[0051] Example 5: Preparation of viscosity index improver

[0052] To a three-necked flask equipped with an electric stirrer, add 90 mL of toluene, 61 g of decyl methacrylate, 34 g of octadecyl methacrylate, 9.4 g of N-vinylimidazole, 685 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 150 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 150 mg of AIBN, and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 400 mL of ethanol, collect the precipitate, and dry it to obtain a terpolymer of decyl methacrylate, octadecyl methacrylate, and N-vinylimidazole, which is the viscosity index improver 5 of this invention.

[0053] Comparative Example 1: Preparation of a Comparative Viscosity Index Improver

[0054] To a three-necked flask equipped with an electric stirrer, add 30 mL of toluene, 37.82 g of dodecyl methacrylate, 13.12 g of tetradecyl methacrylate, 4.88 g of methyl methacrylate, 370 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 110 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 110 mg of AIBN, and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain a terpolymer of dodecyl methacrylate, tetradecyl methacrylate, and methyl methacrylate, which is the comparative viscosity index improver 1 of this invention.

[0055] Comparative Example 2: Preparation of a viscosity index improver

[0056] To a three-necked flask equipped with an electric stirrer, add 82 mL of toluene, 61 g of decyl methacrylate, 34 g of octadecyl methacrylate, 623 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 136 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 136 mg of AIBN and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 364 mL of ethanol, collect the precipitate, and dry it to obtain a copolymer of decyl methacrylate and octadecyl methacrylate, which is the comparative viscosity index improver 2 of this invention.

[0057] Comparative Example 3: Preparation of a viscosity index improver

[0058] To a three-necked flask equipped with an electric stirrer, add 30 mL of toluene, 41 g of dodecyl methacrylate, 15 g of tetradecyl methacrylate, 370 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 108 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 108 mg of AIBN and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain a copolymer of dodecyl methacrylate and tetradecyl methacrylate, which is the comparative viscosity index improver 3 of this invention.

[0059] Comparative Example 4: Preparation of a viscosity index improver

[0060] To a three-necked flask equipped with an electric stirrer, add 30 mL of toluene, 62 g of dodecyl methacrylate, 370 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 105 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 105 mg of AIBN and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain poly(dodecyl methacrylate), which is the comparative viscosity index improver 4 of this invention.

[0061] Comparative Example 5: Preparation of a Comparative Viscosity Index Improver

[0062] To a three-necked flask equipped with an electric stirrer, add 30 mL of toluene, 69 g of tetradecyl methacrylate, 180 mg of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, and 108 mg of azobisisobutyronitrile (AIBN), and mix thoroughly. Stir at 70°C for 2 h under nitrogen protection, then add another 108 mg of AIBN and continue stirring at 70°C for 5 h to complete the reaction. Drop the reaction mixture into 240 mL of ethanol, collect the precipitate, and dry it to obtain polytetradecyl methacrylate, which is the comparative viscosity index improver 5 of this invention.

[0063] According to the test methods in Table 1, the viscosity index, thickening ability, pour point depressing performance, dispersion performance and anti-wear performance of the viscosity index improvers prepared in the examples and comparative examples were determined respectively. The test results are shown in Table 2.

[0064] As shown in Table 2, the viscosity index improver of the present invention has excellent viscosity-temperature properties and thickening ability when the molecular weight is smaller than that of the alkyl methacrylate viscosity index improver in the comparative example. This indicates that the viscosity index improver of the present invention has excellent ability to improve viscosity index and thicken, while also having good pour point depressing effect, and good anti-wear ability and dispersing performance.

[0065] Generally, the larger the molecular weight of a polymer, the stronger its thickening ability. Although the molecular weight of the viscosity index improver of this invention is smaller than that of the comparative viscosity index improver, the thickening ability of the viscosity index improver of this invention is greater than that of the comparative example, indicating that the viscosity index improver of this invention has excellent thickening ability. Simultaneously, the viscosity index of the viscosity index improver of this invention is greater than that of the comparative example, indicating that the viscosity index improver of this invention has excellent thickening ability and viscosity-temperature properties; the viscosity index improvers of comparative examples 4 and 5 have almost no pour point depressing ability, which shows that the viscosity index improver of this invention has a good pour point depressing effect, and the viscosity index improver of this invention also has good anti-wear ability and dispersing properties. Therefore, the viscosity index improver of this invention is a multifunctional viscosity index improver.

[0066] Table 2

[0067]

[0068] Examples 6-10 and Comparative Examples 6-10 of diesel engine lubricating oil compositions

[0069] The formulations of Examples 6-10 and Comparative Examples 6-10 of the diesel engine lubricating oil compositions are shown in Table 3. Each component was added to a mixing container in the specified proportions, heated to 55°C, and stirred for 1 hour to prepare an API CI-4 / ACEA E4 / E7 diesel engine lubricating oil composition with a viscosity grade of 10W-40. The sources of the main additives and base oils used are shown in Table 4.

[0070] Table 3

[0071]

[0072] Table 4

[0073] Brand Number source Boronized succinimide Hitec 648 Afton Company Polyisobutylene succinate LZ 936 Lubrizol High-alkalinity calcium sulfonate T106B (TBN 306) Wuxi Southern Petroleum Additives Co., Ltd. High-base-value alkylphenol calcium sulfide S206 (TBN 260) Wuxi Southern Petroleum Additives Co., Ltd. Zinc dialkyl dithiophosphate T202 Wuxi Southern Petroleum Additives Co., Ltd. Dialkyl dithiocarbamate T323 Jinzhou Xinxing Petroleum Additives Co., Ltd. Alkyl diphenylamine T534 Beijing Xingpu Fine Chemical Technology Development Company Thiophenol ester L115 BASF Class III 6 China Petroleum & Chemical Corporation Class II 6 China Petroleum & Chemical Corporation

[0074] The soot dispersion performance of the above-mentioned oils was evaluated using a carbon black dispersion spot test. Acetylene black was used as a soot simulant. 0.1 g of acetylene black was added to 20 g of test oil, and the mixture was ultrasonically dispersed for 2 min. The sample was then aged in an oven at 150℃ for 6 h. The aged mixture was then dropped onto filter paper, and after 24 h, the diameter of the oil spot diffusion ring and the diameter of the oil ring were measured. The ratio of the two ratios was the carbon black dispersion index, which served as a parameter for evaluating the soot dispersion ability. The higher the dispersion index, the better the soot dispersion. The test results are shown in Table 5.

[0075] The anti-wear performance of the above-mentioned oils was evaluated using the HFRR high-frequency reciprocating friction test. The test conditions were: load 400g, frequency 20Hz, temperature 120℃, and test time 1 hour. The wear scar diameter was recorded. A smaller wear scar diameter indicates better anti-wear performance of the test sample. The test results are shown in Table 5.

[0076] The high-temperature detergency of the above-mentioned oils was examined using a heat pipe test. The test equipment used was an R1091 heat pipe oxidation tester. Oxygen was introduced into the heated and circulating oil within a glass tube. After a set time, the heat pipe deposition was classified into 11 grades (0-10) based on the color and length of the deposited film on the inner wall of the glass tube. Grade 0 was the best, and grade 10 was the worst, which can evaluate the detergency and high-temperature stability of the engine oil. The test conditions were: test temperature 300℃, test time 6 hours. The test results are shown in Table 5.

[0077] As shown in Table 5, the diesel engine lubricating oil composition of the present invention exhibits excellent soot dispersion, anti-wear, and high-temperature detergency properties. The results of Example 8 indicate that the viscosity index improver of the present invention can replace part of the dispersant, reducing the dosage of dispersant.

[0078] Table 5

[0079] oil sample Carbon black dispersion index HFRR wear scar diameter / μm Heat pipe test rating Example 6 0.74 156 3.0 Example 7 0.76 142 3.0 Example 8 0.70 160 4.0 Example 9 0.70 157 3.5 Example 10 0.72 161 2.5 Comparative Example 6 0.55 189 5.0 Comparative Example 7 0.58 191 4.5 Comparative Example 8 0.50 198 5.5 Comparative Example 9 0.53 182 5.0 Comparative Example 10 0.56 202 4.5

Claims

1. A diesel engine lubricating oil composition, comprising: (A) Viscosity index improver; (B) Borated ashless dispersant and / or polyisobutylene succinate ashless dispersant; (C) Sulfonate and / or sulfurized alkylphenol salt metal detergents; (D) Zinc dialkyl dithiophosphate; (E) Dialkyl dithiocarbamate; (F) Amine antioxidants; (G) Thiophenol ester antioxidants; (H) Lubricating base oil; wherein the viscosity index improver is C8-C6 methacrylic acid. 12 Alkyl esters, C methacrylic acid 13 ~C 18 A copolymer of alkyl esters and N-vinylimidazole, in the viscosity index improver, comprising, by weight, 40% to 70% of C8-C4 methacrylic acid based on the monomer content. 12 Alkyl esters, 10%–50% (by weight) of C methacrylate 13 ~C 18 Alkyl esters, 5% to 40% (by weight) of N-vinylimidazole.

2. The diesel engine lubricating oil composition according to claim 1, characterized in that, The viscosity index improver contains 50% to 70% (by weight) of C8-C4 methacrylic acid, based on the monomer content. 12 Alkyl esters, 20%–40% (by weight) of C methacrylate 13 ~C 18 Alkyl esters, 5% to 30% (by weight) of N-vinylimidazole.

3. The diesel engine lubricating oil composition according to claim 1, characterized in that, The viscosity index improver has a number average molecular weight of 2,000 to 100,000 g / mol.

4. The diesel engine lubricating oil composition according to claim 1, characterized in that, The method for preparing the viscosity index improver includes: reacting methacrylic acid (C8-C6) with C6-C6. 12 Alkyl esters, C methacrylic acid 13 ~C 18 Alkyl esters, N-vinylimidazole, chain transfer agents, initiators, and solvents are mixed uniformly and copolymerized under nitrogen protection. The viscosity index improver product is then collected.

5. The diesel engine lubricating oil composition according to claim 4, characterized in that, The copolymerization reaction is carried out at a temperature of 50–150°C (preferably 60–100°C) and for a duration of 2–10 h (preferably 3–8 h).

6. The diesel engine lubricating oil composition according to claim 4, characterized in that, In preparing the viscosity index improver, based on the polymer monomer, the methacrylic acid C8-C9... 12 Alkyl esters, C methacrylic acid 13 ~C 18 The molar ratio between alkyl ester and N-vinylimidazole is 6:1 to 8:1 to 10 (preferably 3:1 to 3:1 to 4).

7. The diesel engine lubricating oil composition according to claim 4, characterized in that, The chain transfer agent is trithiocarbonate alkylpropionic acid; and / or, the initiator is selected from one or more of azobisisobutyronitrile, benzoyl peroxide and tert-butyl peroxide; and / or, the solvent is one or more of toluene, cyclohexane, n-hexane and petroleum ether.

8. The diesel engine lubricating oil composition according to claim 4, characterized in that, After the copolymerization reaction is complete, the reaction solution is added dropwise to a C1-C4 alcohol, the precipitate is collected, and after drying, the viscosity index improver is obtained.

9. The diesel engine lubricating oil composition according to any one of claims 1 to 8, characterized in that, The viscosity index improver comprises 0.1% to 20% (preferably 0.3% to 10%) of the total mass of the lubricating oil composition; the boronized ashless dispersant and / or polyisobutylene succinate ashless dispersant comprises 0.5% to 20% (preferably 1% to 12%) of the total mass of the lubricating oil composition; the sulfonate and / or sulfurized alkylphenol salt metal detergent comprises 0.2% to 10% (preferably 1% to 8%) of the total mass of the lubricating oil composition; the dialkyl dithiophosphate zinc comprises... 0.1% to 5% (preferably 0.3% to 2.5%); the dialkyl dithiocarbamate accounts for 0.02% to 5% (preferably 0.05% to 2%) of the total mass of the lubricating oil composition; the amine antioxidant accounts for 0.1% to 6% (preferably 0.2% to 4%) of the total mass of the lubricating oil composition; the thiophenol ester antioxidant accounts for 0.05% to 2% (preferably 0.1% to 0.8%) of the total mass of the lubricating oil composition; the lubricating base oil constitutes the main component of the lubricating oil composition.

10. The diesel engine lubricating oil composition according to any one of claims 1 to 8, characterized in that, The boronized ashless dispersant and / or the polyisobutylene succinate ashless dispersant is a mixture of the boronized ashless dispersant and the polyisobutylene succinate ashless dispersant, with a mass ratio of 1:0.1 to 10; the sulfonate and / or the sulfurized alkylphenol salt is a mixture of calcium sulfonate and calcium sulfurized alkylphenol; the alkyl group in the dialkyl dithiophosphate zinc is C2 to C3. 12 The alkyl group; the alkyl group in the dialkyl dithiocarbamate is an alkyl group containing 2 to 12 carbon atoms; the amine antioxidant is one or more of alkylated aniline, alkylated diphenylamine and phenyl-α-naphthylamine; the thiophenol ester antioxidant is selected from 2,2'-thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; the lubricating base oil is selected from one or more of API Group I, II, III, IV and V base oils.

11. A method for preparing the diesel engine lubricating oil composition according to any one of claims 1 to 10, comprising the step of mixing its components.

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