Diesel engine lubricating oil composition and preparation method thereof

Abstract

The present invention discloses a diesel engine lubricating oil composition and a preparation method thereof. The composition comprises the following components, measured by mass percentage: 5.0% to 7.5% of a high-temperature detergent, 2.5% to 5.4% of a bis-succinimide dispersant, 0.5% to 2.0% of a zinc dialkyl dithiophosphate antioxidant and preservative, 0.5% to 1.5% of an auxiliary antioxidant, 0.5% to 2.0% of 2,3-dihydro-2,2-dimethyl-7-benzofuranyl-methyl-N-ylcarbamate, 0.2% to 0.5% of a pour point depressant, 0.0015% to 0.0050% of a methyl silicone oil antifoaming agent, and the balance being a catalytic hydrogenation base oil. The lubricating oil composition is prepared by uniformly stirring the above components at 60 to 70° C. The present invention solves the mutual inhibition between the water separation property of ship diesel engine oil, the water washability of additives, and the detergency, dispersibility, antioxidant properties, and wear resistance, by rationally compounding the various components, thereby greatly extending the oil change cycle of the oil product.

Description

Technical Field

[0001] The present invention belongs to the technical field of diesel engine lubricating oil compositions, and in particular relates to a diesel engine lubricating oil composition. The present invention also relates to a method for preparing the lubricating oil composition. Background Art

[0002] Ship diesel engines are quite different from ordinary marine diesel engines. Ship diesel engines are generally small medium- and high-speed diesel engines with high engine strengthening coefficients and high lubrication system temperatures. They require diesel engine lubricants to have a higher quality grade and excellent high-temperature anti-oxidation, high-temperature detergency, lubrication and anti-wear properties. However, the diesel fuel they use is of good quality and has a relatively low sulfur content, generally not exceeding 0.5%. Therefore, the requirements for the base number of the lubricating oil are relatively low. Civilian ship diesel engines are generally large, low-speed diesel engines with high engine power but low strengthening coefficient. They do not require high high-temperature performance and anti-wear performance of the lubricant. However, the diesel fuel they use is generally heavy oil, such as residual fuel. The sulfur content of the fuel is relatively high, even reaching more than 3%. The alkalinity of the lubricant is very high, generally requiring the alkalinity of the lubricant to be above 30 mgKOH / g. Therefore, civil ship diesel engine lubricants generally have no quality grades. Different brands of lubricant products are distinguished according to the alkalinity, such as No. 30, No. 40, No. 50, No. 60, No. 70, etc. Ship diesel engine lubricants and civil ship diesel engine lubricants are of completely different nature due to their different working conditions and cannot be replaced by each other.

[0003] Marine diesel engine lubricants and ordinary land-based diesel engine oils are not interchangeable. Considering that marine diesel engines may be mixed with a large amount of water, most marine diesel engines are equipped with centrifugal equipment to separate the water and other impurities mixed in the lubricant. This requires marine diesel engine lubricants to have the ability to quickly separate from water, including water separation and additive resistance to water washing. Ordinary land-based diesel engine oils do not have good water separation properties and will undergo severe emulsification after contact with water, which will cause a serious reduction in lubrication, rust prevention and other properties. Long-term use will cause irreversible damage to the engine hardware. In order to improve the water separation performance of the lubricant, a certain amount of demulsifier is usually added to the lubricant components to destroy the formed emulsion layer and achieve oil-water separation as quickly as possible. If the amount of demulsifier added is too low, the water separation effect is not obvious. If the amount added is too high, it is difficult to dissolve, affecting the appearance and transparency of the lubricant. How to meet the water separation performance requirements of marine diesel engine lubricants is also a major technical difficulty at present.

[0004] Currently, the oil change interval for marine diesel engine lubricants is generally short, mostly 300-500 hours. With the increasing demand for marine ocean voyages, marine diesel engines are required to operate continuously at sea for 5,000-6,000 hours or even longer. Currently, marine diesel engine oil needs to be changed more than 10 times. The storage of new lubricant oil and replaced old oil requires a large amount of ship storage space, seriously restricting the efficiency and continuous operation time of marine voyages. Chinese invention patent CN02103532.6 discloses a lubricant oil composition suitable for two-stroke crosshead marine diesel engines. However, this composition is only suitable for low-speed marine diesel engines and is not suitable for marine diesel engines. Chinese invention patent CN103184091 discloses a universal marine diesel engine lubricant oil composition. This composition is suitable for marine diesel engines and has good water separation and general performance, meeting the lubrication needs of marine diesel engines. However, the quality grade of this composition is equivalent to API CD level, and the oil change interval is short, only 500 hours.

[0005] In summary, there is an urgent need to develop a diesel engine lubricant with a long oil change period and suitable for ships. Summary of the Invention

[0006] The purpose of the present invention is to provide a diesel engine lubricating oil composition, which solves the problem of short lubricating oil replacement cycle in the prior art.

[0007] Another object of the present invention is to provide a method for preparing the above diesel engine lubricating oil composition.

[0008] The technical solution adopted by the present invention is that the diesel engine lubricating oil composition is composed of the following components, calculated by mass percentage: 5.0% to 7.5% of a high-temperature detergent, 2.5% to 5.4% of a bissuccinimide-type dispersant, 0.5% to 2.0% of a zinc dialkyl dithiophosphate antioxidant and preservative, 0.5% to 1.5% of an auxiliary antioxidant, 0.5% to 2.0% of 2,3-dihydro-2,2-dimethyl-7-benzofuranyl-methyl-N-ylcarbamate, 0.2% to 0.5% of a pour point depressant, 0.0015% to 0.0050% of a methyl silicone oil antifoaming agent, and the balance being catalytic hydrogenation base oil.

[0009] The characteristics of the present invention are as follows: the high-temperature detergent is composed of a sulfurized alkyl phenol salt, a low-base sulfonate salt, and an alkyl salicylate salt, wherein, by weight percentage, the sulfurized alkyl phenol salt accounts for 25% to 35% by weight, the low-base sulfonate salt accounts for 25% to 35% by weight, and the balance is the alkyl salicylate salt;

[0010] The sulfide alkyl phenate is composed of medium-alkalinity sulfide alkyl phenate calcium and high-alkalinity sulfide alkyl phenate calcium. Calculated by mass percentage, the medium-alkalinity sulfide alkyl phenate calcium accounts for 30% to 40% by mass, and the balance is high-alkalinity sulfide alkyl phenate calcium. The total alkalinity of the medium-alkalinity sulfide alkyl phenate calcium is 130 to 200 mgKOH / g, and the total alkalinity of the high-alkalinity sulfide alkyl phenate calcium is not less than 250 mgKOH / g.

[0011] The low base value sulfonate is any one of petroleum-based calcium sulfonate and synthetic calcium sulfonate, and its total base value is 20~35mgKOH / g;

[0012] The alkyl salicylate is composed of a compound of medium-base alkyl salicylate calcium and high-base alkyl salicylate magnesium. Calculated by mass percentage, the medium-base alkyl salicylate calcium accounts for 60% to 70% by mass, and the remainder is high-base alkyl salicylate magnesium. The total base number of the medium-base alkyl salicylate calcium is 160 to 250 mgKOH / g, and the total base number of the high-base alkyl salicylate magnesium is not less than 290 mgKOH / g.

[0013] The zinc dialkyl dithiophosphate antioxidant and preservative is any one of butyloctyl zinc dithiophosphate and bisoctyl zinc dithiophosphate.

[0014] The auxiliary antioxidant is any one of butyloctyldiphenylamine and dioctyldiphenylamine.

[0015] Catalytic hydrogenation base oil consists of medium component hydrogenation base oil and heavy component hydrogenation base oil, with the medium component hydrogenation base oil accounting for 70% to 90% by weight and the heavy component hydrogenation base oil accounting for 10% to 30% by weight; the kinematic viscosity of the medium component hydrogenation base oil at 100°C is 9.0 to 11.0 mm 2 / s, viscosity index is not less than 95, the kinematic viscosity of the heavy component hydrogenated base oil at 100 ° C is 28.0~34.0 mm 2 / s, viscosity index 80~90.

[0016] Another technical solution adopted by the present invention is a method for preparing a diesel engine lubricating oil composition, comprising the following steps:

[0017] Step 1: Weigh the following components by mass percentage: 5.0% to 7.5% of high-temperature detergent, 2.5% to 5.4% of bis-succinimide dispersant, 0.5% to 2.0% of zinc dialkyldithiophosphate antioxidant and preservative, 0.5% to 1.5% of auxiliary antioxidant, 0.5% to 2.0% of 2,3-dihydro-2,2-dimethyl-7-benzofuranyl-methyl-N-ylcarbamate, 0.2% to 0.5% of pour point depressant, 0.0015% to 0.0050% of methyl silicone oil antifoaming agent, and the balance being catalytic hydrogenation base oil;

[0018] Step 2: heating the components weighed in step 1 to 60-70° C. and stirring them uniformly to obtain a diesel engine lubricating oil composition.

[0019] The present invention is also characterized in that the high-temperature detergent is composed of a sulfurized alkyl phenol salt, a low-base sulfonate salt, and an alkyl salicylate salt, wherein, by weight percentage, the sulfurized alkyl phenol salt accounts for 25% to 35% by weight, the low-base sulfonate salt accounts for 25% to 35% by weight, and the balance is the alkyl salicylate salt;

[0020] The sulfide alkyl phenate is composed of medium-alkalinity sulfide alkyl phenate calcium and high-alkalinity sulfide alkyl phenate calcium. Calculated by mass percentage, the medium-alkalinity sulfide alkyl phenate calcium accounts for 30% to 40% by mass, and the balance is high-alkalinity sulfide alkyl phenate calcium. The total alkalinity of the medium-alkalinity sulfide alkyl phenate calcium is 130 to 200 mgKOH / g, and the total alkalinity of the high-alkalinity sulfide alkyl phenate calcium is not less than 250 mgKOH / g.

[0021] The low base value sulfonate is any one of petroleum-based calcium sulfonate and synthetic calcium sulfonate, and its total base value is 20~35mgKOH / g;

[0022] The alkyl salicylate is composed of a compound of medium-base alkyl salicylate calcium and high-base alkyl salicylate magnesium. Calculated by mass percentage, the medium-base alkyl salicylate calcium accounts for 60% to 70% by mass, and the balance is high-base alkyl salicylate magnesium. The total base value of the medium-base alkyl salicylate calcium is 160 to 250 mgKOH / g, and the total base value of the high-base alkyl salicylate magnesium is not less than 290 mgKOH / g.

[0023] The zinc dialkyl dithiophosphate antioxidant and preservative is any one of butyloctyl zinc dithiophosphate and bisoctyl zinc dithiophosphate.

[0024] The auxiliary antioxidant is any one of butyloctyldiphenylamine and dioctyldiphenylamine.

[0025] Catalytic hydrogenation base oil consists of medium component hydrogenation base oil and heavy component hydrogenation base oil, with the medium component hydrogenation base oil accounting for 70% to 90% by weight and the heavy component hydrogenation base oil accounting for 10% to 30% by weight; the kinematic viscosity of the medium component hydrogenation base oil at 100°C is 9.0 to 11.0 mm 2 / s, viscosity index is not less than 95, the kinematic viscosity of the heavy component hydrogenated base oil at 100 ° C is 28.0~34.0 mm 2 / s, viscosity index 80~90.

[0026] The beneficial effects of the present invention are as follows: the present invention balances and solves the mutual inhibition among the water separation property of ship diesel engine oil, the water washability of additives and the detergency, dispersibility, antioxidant and wear resistance by rationally compounding components such as high-temperature detergent, ashless dispersant, antioxidant and preservative, auxiliary antioxidant and additive; the composition of the present invention greatly prolongs the oil change cycle of the oil product from 500 hours to 1000 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a graph showing the kinematic viscosity change of the lubricating oil composition of Example 1 during a 1000-hour shipboard test;

[0028] Figure 2 This is a graph showing the pH value changes of the lubricating oil composition of Example 1 during a 1000-hour shipboard test;

[0029] Figure 3 This is a graph showing changes in wear element content in the lubricating oil composition of Example 1 during a 1000-hour ship test. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0031] A diesel engine lubricating oil composition comprises the following components, calculated by mass percentage: 5.0%-7.5% of a high-temperature detergent, 2.5%-5.4% of a bissuccinimide-type dispersant, 0.5%-2.0% of a zinc dialkyldithiophosphate antioxidant and preservative, 0.5%-1.5% of an auxiliary antioxidant, 0.5%-2.0% of 2,3-dihydro-2,2-dimethyl-7-benzofuranyl-methyl-N-ylcarbamate, 0.2%-0.5% of a pour point depressant, 0.0015%-0.0050% of a methyl silicone oil antifoaming agent, and the balance being a catalytic hydrogenation base oil.

[0032] The high-temperature detergent is composed of sulfonated alkylphenol, low-base sulfonate, and alkyl salicylate. Calculated by mass percentage, the sulfonated alkylphenol accounts for 25% to 35%, the low-base sulfonate accounts for 25% to 35%, and the balance is alkyl salicylate.

[0033] The sulfurized alkylphenol salt in the high-temperature detergent component is composed of medium-base sulfurized alkylphenol calcium and high-base sulfurized alkylphenol calcium. In terms of mass percentage, the medium-base sulfurized alkylphenol calcium accounts for 30% to 40% by mass, and the balance is high-base sulfurized alkylphenol calcium. Among them, too high or too low a proportion of medium-base sulfurized alkylphenol calcium will affect the anti-water washing performance and water separation performance of the additive in the composition of the present invention. The total base number of the medium-base sulfurized alkylphenol calcium is 130 to 200 mgKOH / g, and the total base number of the high-base sulfurized alkylphenol calcium is not less than 250 mgKOH / g.

[0034] The low base value sulfonate in the high temperature detergent component is any one of petroleum-based calcium sulfonate and synthetic calcium sulfonate, and its total base value is 20-35 mgKOH / g;

[0035] The alkyl salicylate in the high-temperature detergent component is composed of a composite of medium-base calcium alkyl salicylate and high-base magnesium alkyl salicylate. The medium-base calcium alkyl salicylate accounts for 60% to 70% by mass, and the balance is high-base magnesium alkyl salicylate. The total base number of the medium-base calcium alkyl salicylate is 160 to 250 mgKOH / g, and the total base number of the high-base magnesium alkyl salicylate is not less than 290 mgKOH / g. Excessively high or low proportions of magnesium alkyl salicylate will affect the anti-washing performance and water separation performance of the additive in the composition of the present invention.

[0036] The zinc dialkyl dithiophosphate antioxidant preservative is any one of butyloctyl zinc dithiophosphate and bisoctyl zinc dithiophosphate;

[0037] The auxiliary antioxidant is any one of butyloctyldiphenylamine and dioctyldiphenylamine;

[0038] Among them, in the present invention, 2,3-dihydro-2,2-dimethyl-7-benzofuranyl-methyl-N-ylcarbamate is used as an additive, and its structure is as follows:

[0039]

[0040] The carbamate and benzofuran groups contained in this additive form a conjugated structure, which can promptly capture free radical intermediates generated during engine oil oxidation, blocking the oxidation reaction chain and providing significant antioxidant effects. Furthermore, this additive has excellent metal adsorption capacity, forming a strong adsorption film on surfaces such as the engine piston ring and cylinder liner friction pairs and the crankshaft bearing friction pairs, thereby reducing friction and wear. This additive can significantly enhance the antioxidant and anti-wear properties of the composition of the present invention, effectively extending the oil change interval.

[0041] Catalytic hydrogenation base oil is composed of medium component hydrogenation base oil and heavy component hydrogenation base oil. The mass proportion of medium component hydrogenation base oil is 70%~90%. The kinematic viscosity of medium component hydrogenation base oil at 100℃ is 9.0~11.0 mm 2 / s, viscosity index not less than 95, heavy component hydrogenated base oil mass proportion 10%~30%, heavy component hydrogenated base oil kinematic viscosity at 100℃ is 28.0~34.0 mm 2 / s, viscosity index is 80~90.

[0042] The preparation method of the diesel engine lubricating oil composition comprises the following steps:

[0043] Step 1: Weigh the following components by mass percentage: 5.0% to 7.5% of high-temperature detergent, 2.5% to 5.4% of bis-succinimide dispersant, 0.5% to 2.0% of zinc dialkyldithiophosphate antioxidant and preservative, 0.5% to 1.5% of auxiliary antioxidant, 0.5% to 2.0% of 2,3-dihydro-2,2-dimethyl-7-benzofuranyl-methyl-N-ylcarbamate, 0.2% to 0.5% of pour point depressant, 0.0015% to 0.0050% of methyl silicone oil antifoaming agent, and the balance being catalytic hydrogenation base oil;

[0044] Step 2: heating the components weighed in step 1 to 60-70° C. and stirring evenly to obtain a diesel engine lubricating oil composition;

[0045] In step 1, the high-temperature detergent is composed of 25% to 35% of sulfurized alkylphenol salt, 25% to 35% of low-base sulfonate, and the balance is alkyl salicylate; further, the sulfurized alkylphenol salt in the high-temperature detergent component is composed of medium-base sulfurized alkylphenol calcium and high-base sulfurized alkylphenol calcium, wherein, by weight percentage, the medium-base sulfurized alkylphenol calcium accounts for 30% to 40% by weight, and the balance is high-base sulfurized alkylphenol calcium. Too high or too low a proportion of the medium-base sulfurized alkylphenol calcium will affect the anti-washing performance and water separation performance of the additive of the composition of the present invention. The total base number of the medium-base sulfurized alkylphenol calcium is 130 to 200 mgKOH / g, and the total base number of the high-base sulfurized alkylphenol calcium is not less than 250 mgKOH / g. OH / g; the low-base sulfonate in the high-temperature detergent component is any one of petroleum-based calcium sulfonate and synthetic calcium sulfonate, and its total base number is 20-35 mgKOH / g; the alkyl salicylate in the high-temperature detergent component is composed of a composite of medium-base alkyl salicylate calcium and high-base alkyl salicylate magnesium, in which, by weight percentage, the medium-base alkyl salicylate calcium accounts for 60%-70% by weight, and the balance is high-base alkyl salicylate magnesium, the total base number of the medium-base alkyl salicylate calcium is 160-250 mgKOH / g, and the total base number of the high-base alkyl salicylate magnesium is not less than 290 mgKOH / g. Excessively high or low proportions of alkyl salicylate magnesium will affect the anti-water washing performance and water separation performance of the additive of the composition of the present invention;

[0046] The zinc dialkyl dithiophosphate antioxidant and preservative is butyl octyl zinc dithiophosphate or dioctyl zinc dithiophosphate; the auxiliary antioxidant is butyl octyl diphenylamine or dioctyl diphenylamine; the catalytic hydrogenation base oil is composed of a medium component hydrogenation base oil and a heavy component hydrogenation base oil, with the medium component hydrogenation base oil accounting for 70% to 90% by weight and the kinematic viscosity of the medium component hydrogenation base oil at 100°C being 9.0 to 11.0 mm 2 / s, viscosity index not less than 95, heavy component hydrogenated base oil mass proportion 10%~30%, heavy component hydrogenated base oil kinematic viscosity at 100℃ is 28.0~34.0 mm2 / s, viscosity index is 80~90.

[0047] Example 1

[0048] Lubricating oil: 100%

[0049] Table 1 Composition and ratio of lubricating oil composition of Example 1

[0050]

[0051] The base oil composition is shown in Table 2: Base oil: 100%

[0052] Table 2 Composition and ratio of base oil in Example 1

[0053]

[0054] The above ingredients were heated to 60° C. and mixed uniformly to obtain a lubricating oil composition A. The test results of the physical and chemical properties of the lubricating oil composition A are shown in Table 3.

[0055] Table 3 Physical and chemical properties test results of lubricating oil composition A in Example 1

[0056]

[0057] It can be found from the data in Table 3 that the blended lubricating oil composition in this embodiment has excellent water separation and additive water washing resistance, and the volume of the emulsion layer after the water separation test is only 0.1 mL; on the other hand, it improves high-temperature detergency, oxidation resistance and extreme pressure anti-wear properties. The high-temperature detergency is measured by the coking plate test, and the coking weight is only 23 mg, while the coking weight of ordinary marine diesel engine oil is about 40 mg or more; the PDSC oxidation induction period can reach 86 min, far exceeding the ACEA E8-22 heavy-duty diesel engine oil specification requirement of not less than 65 min; the maximum no-seizure load of the SRV testing machine can reach 1800 N, while that of ordinary marine diesel engine oil is only about 1200 N.

[0058] The changes in the physical and chemical properties of the lubricating oil composition prepared in this embodiment during the 1000-hour ship sailing test are as follows: Figures 1-3 shown.

[0059] pass Figure 1 It can be seen that the lubricating oil composition prepared in this embodiment has been verified by a 1000-hour actual ship test. The kinematic viscosity of the oil remains stable during the test and no oxidation viscosity increase occurs. Figure 2 It can be seen that the base value has not decayed, the acid value has increased very little, and there is still a very large margin between the pH value, indicating that the oil has excellent base retention and the ability to inhibit the increase of oxidation acid value; Figure 3It can be seen that the content of wear elements such as iron, copper, aluminum, lead, etc. is extremely low, indicating that the oil has excellent anti-wear properties.

[0060] In summary, the lubricating oil composition can meet the 1000-h oil change cycle requirement of marine diesel engines and has the potential to be further extended.

[0061] Example 2

[0062] Lubricating oil: 100%

[0063] Table 4 Composition and ratio of lubricating oil composition of Example 2

[0064]

[0065] The base oil components are shown in Table 5:

[0066] Base oil: 100%

[0067] Table 5 Base oil composition and ratio of Example 2

[0068]

[0069] The above ingredients were heated to 70° C. and mixed evenly to obtain a lubricating oil composition B. The test results of the physical and chemical properties of the blended lubricating oil composition B in this example are shown in Table 6.

[0070] Table 6 Physical and chemical properties test results of lubricant combination B in Example 2

[0071]

[0072] It can be found from the data in Table 6 that the blended lubricating oil composition in this embodiment has excellent water separation and additive water washing resistance, and the volume of the emulsion layer after the water separation test is only 0.1 mL; on the other hand, it improves high-temperature detergency, oxidation resistance and extreme pressure anti-wear properties. The high-temperature detergency is measured by the coking plate test, and the coking weight is only 20 mg, while the coking weight of ordinary marine diesel engine oil is about 40 mg or more; the PDSC oxidation induction period is tested to be 88 min, far exceeding the ACEA E8-22 heavy-duty diesel engine oil specification requirement of not less than 65 min; the maximum no-seizure load of the SRV testing machine can reach 1900 N, while that of ordinary marine diesel engine oil is only about 1200 N.

[0073] The blended lubricating oil composition in this embodiment was verified by a 1000-hour actual ship test, and the lubricating oil composition can meet the use requirement of the 1000-hour oil change cycle of the ship diesel engine and has the potential to be further extended. In addition, the kinematic viscosity of the oil remained stable during the test, and no oxidation viscosity increase occurred.

[0074] Example 3

[0075] Lubricating oil: 100%

[0076] Table 7 Composition and ratio of lubricating oil composition of Example 3

[0077]

[0078] The base oil components are shown in Table 8:

[0079] Base oil: 100%

[0080] Table 8 Base oil composition and ratio of Example 3

[0081]

[0082] The above ingredients were heated to 65° C. and mixed uniformly to obtain a lubricating oil composition C. The test results of the physical and chemical properties of the blended lubricating oil composition C in this example are shown in Table 9.

[0083] Table 9 Physical and chemical properties test results of lubricating oil composition C of Example 3

[0084]

[0085] It can be found from the data in Table 9 that the blended lubricating oil composition in this embodiment has excellent water separation and additive water washing resistance, and the volume of the emulsion layer after the water separation test is only 0.1 mL; on the other hand, it improves high-temperature detergency, oxidation resistance and extreme pressure anti-wear properties. The high-temperature detergency is measured by the coking plate test, and the coking weight is only 25 mg, while the coking weight of ordinary marine diesel engine oil is about 40 mg or more; the PDSC oxidation induction period tested can reach 92 min, far exceeding the ACEA E8-22 heavy-duty diesel engine oil specification requirement of not less than 65 min; the maximum no-seizure load of the SRV testing machine tested can reach 1900 N, while that of ordinary marine diesel engine oil is only about 1200 N.

[0086] The blended lubricating oil composition in this embodiment was verified by a 1000-hour actual ship test, and the lubricating oil composition can meet the use requirement of the 1000-hour oil change cycle of the ship diesel engine and has the potential to be further extended. In addition, the kinematic viscosity of the oil remained stable during the test, and no oxidation viscosity increase occurred.

[0087] In summary, the test results of the physical and chemical properties of the lubricating oil compositions in each example and the 1000-hour onboard testing results demonstrate that the lubricating oil compositions formulated in Examples 1-3 all performed within specified parameters, exhibiting excellent water separation performance while significantly improving high-temperature detergency, oxidation resistance, and anti-wear properties. The lubricating oil compositions formulated in each example, when used in onboard testing, extended the oil change interval to over 1000 hours, a significant improvement compared to conventional marine diesel engine oils.

Claims

1. A diesel engine lubricating oil composition, characterized in that: The invention is composed of the following components in percentage by mass: 5.0% to 7.5% of high-temperature detergent, 2.5% to 5.4% of bis-succinimide dispersant, 0.5% to 2.0% of zinc dialkyl dithiophosphate antioxidant and preservative, 0.5% to 1.5% of auxiliary antioxidant, 0.5% to 2.0% of 2,3-dihydro-2,2-dimethyl-7-benzofuranyl-methyl-N-ylcarbamate, 0.2% to 0.5% of pour point depressant, 0.0015% to 0.0050% of methyl silicone oil antifoaming agent, and the balance being catalytic hydrogenation base oil; The high-temperature detergent is composed of sulfonated alkylphenol, low-base sulfonate, and alkyl salicylate. According to the mass percentage, the sulfonated alkylphenol accounts for 25% to 35% by mass, the low-base sulfonate accounts for 25% to 35% by mass, and the balance is alkyl salicylate. The sulfide alkyl phenate is composed of medium-base sulfide alkyl phenate calcium and high-base sulfide alkyl phenate calcium. According to the mass percentage, the medium-base sulfide alkyl phenate calcium accounts for 30% to 40% by mass, and the balance is high-base sulfide alkyl phenate calcium. The total base number of the medium-base sulfide alkyl phenate calcium is 130 to 200 mgKOH / g, and the total base number of the high-base sulfide alkyl phenate calcium is not less than 250 mgKOH / g. The low base value sulfonate is any one of petroleum-based calcium sulfonate and synthetic calcium sulfonate, and its total base value is 20-35 mgKOH / g; The alkyl salicylate is composed of a medium-base calcium alkyl salicylate and a high-base magnesium alkyl salicylate. In terms of mass percentage, the medium-base calcium alkyl salicylate accounts for 60% to 70% by mass, and the balance is the high-base magnesium alkyl salicylate. The total base number of the medium-base calcium alkyl salicylate is 160 to 250 mgKOH / g, and the total base number of the high-base magnesium alkyl salicylate is not less than 290 mgKOH / g. The catalytic hydrogenation base oil is composed of a medium component hydrogenation base oil and a heavy component hydrogenation base oil, wherein the medium component hydrogenation base oil accounts for 70% to 90% by weight and the heavy component hydrogenation base oil accounts for 10% to 30% by weight; the kinematic viscosity of the medium component hydrogenation base oil at 100° C. is 9.0 to 11.0 mm 2 / s, a viscosity index of not less than 95, and the kinematic viscosity of the heavy component hydrogenated base oil at 100°C is 28.0~34.0 mm 2 / s, viscosity index 80~90.

2. The diesel engine lubricating oil composition according to claim 1, characterized in that: The zinc dialkyl dithiophosphate antioxidant preservative is any one of butyl octyl zinc dithiophosphate and bisoctyl zinc dithiophosphate.

3. The diesel engine lubricating oil composition according to claim 1, characterized in that: The auxiliary antioxidant is any one of butyl octyl diphenylamine and dioctyl diphenylamine.

4. A method for preparing a diesel engine lubricating oil composition, characterized in that: The following steps are involved: Step 1: Weigh the following components by mass percentage: 5.0% to 7.5% of high-temperature detergent, 2.5% to 5.4% of bis-succinimide dispersant, 0.5% to 2.0% of zinc dialkyldithiophosphate antioxidant and preservative, 0.5% to 1.5% of auxiliary antioxidant, 0.5% to 2.0% of 2,3-dihydro-2,2-dimethyl-7-benzofuranyl-methyl-N-ylcarbamate, 0.2% to 0.5% of pour point depressant, 0.0015% to 0.0050% of methyl silicone oil antifoaming agent, and the balance being catalytic hydrogenation base oil; Step 2: heating the components weighed in step 1 to 60-70° C. and stirring evenly to obtain a diesel engine lubricating oil composition; The high-temperature detergent is composed of sulfonated alkylphenol, low-base sulfonate, and alkyl salicylate. According to the mass percentage, the sulfonated alkylphenol accounts for 25% to 35% by mass, the low-base sulfonate accounts for 25% to 35% by mass, and the balance is alkyl salicylate. The sulfide alkyl phenate is composed of medium-base sulfide alkyl phenate calcium and high-base sulfide alkyl phenate calcium. According to the mass percentage, the medium-base sulfide alkyl phenate calcium accounts for 30% to 40% by mass, and the balance is high-base sulfide alkyl phenate calcium. The total base number of the medium-base sulfide alkyl phenate calcium is 130 to 200 mgKOH / g, and the total base number of the high-base sulfide alkyl phenate calcium is not less than 250 mgKOH / g. The low base value sulfonate is any one of petroleum-based calcium sulfonate and synthetic calcium sulfonate, and its total base value is 20-35 mgKOH / g; The alkyl salicylate is composed of a medium-base calcium alkyl salicylate and a high-base magnesium alkyl salicylate. In terms of mass percentage, the medium-base calcium alkyl salicylate accounts for 60% to 70% by mass, and the balance is the high-base magnesium alkyl salicylate. The total base value of the medium-base calcium alkyl salicylate is 160 to 250 mgKOH / g, and the total base value of the high-base magnesium alkyl salicylate is not less than 290 mgKOH / g. The catalytic hydrogenation base oil is composed of a medium component hydrogenation base oil and a heavy component hydrogenation base oil, wherein the medium component hydrogenation base oil accounts for 70% to 90% by weight and the heavy component hydrogenation base oil accounts for 10% to 30% by weight; the kinematic viscosity of the medium component hydrogenation base oil at 100° C. is 9.0 to 11.0 mm 2 / s, a viscosity index of not less than 95, and the kinematic viscosity of the heavy component hydrogenated base oil at 100°C is 28.0~34.0 mm 2 / s, viscosity index 80~90.

5. The method for preparing the diesel engine lubricating oil composition according to claim 4, characterized in that: The zinc dialkyl dithiophosphate antioxidant preservative is any one of butyl octyl zinc dithiophosphate and bisoctyl zinc dithiophosphate.

6. The method for preparing the diesel engine lubricating oil composition according to claim 4, characterized in that: The auxiliary antioxidant is any one of butyl octyl diphenylamine and dioctyl diphenylamine.

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