Lubricating oil, method for its production and use

Abstract

The application provides a lubricating oil, a preparation method and application thereof. The lubricating oil comprises, in parts by weight, 49-80 parts of coal-based base oil, 15-30 parts of PAO 40 base oil, 8-10 parts of composite additive and 0.1-0.3 parts of pour point depressant; wherein the coal-based base oil is a type III base oil obtained by Fischer-Tropsch synthesis-hydrorefining of coal, and the lubricating oil does not contain a viscosity index improver. The coal-based base oil and the PAO 40 base oil are mixed and blended at low cost, the excellent high and low temperature performance and multiple viscosity levels of the coal-based base oil are utilized, different viscosity grades of lubricating oil are directly blended, and the viscosity index improver is not needed, so that the problem of viscosity deterioration of the lubricating oil caused by addition of the viscosity index improver is fundamentally eliminated, the lubricating oil can have excellent high and low temperature performance while keeping the oil viscosity stable for a long time, and the oil change cycle of the lubricating oil is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of petroleum chemical technology, in particular to a lubricating oil, a preparation method and application thereof. BACKGROUND

[0002] Engine is the heart of the car, and there are many metal surfaces rubbing against each other in the engine. These components move at high speed in a poor environment, and the working temperature can reach 400-600℃. Engine lubricating oil can play the roles of lubricating and reducing wear, assisting cooling, sealing, preventing rust and corrosion, and shock absorption. It is known as the "blood" of the car and is composed of base oil and additives. The base oil is the main component of lubricating oil, which determines the basic properties of lubricating oil. The additives can make up for and improve the performance of the base oil and endow the lubricating oil with new properties. The lubricating oil base oil is mainly divided into two categories: mineral base oil and synthetic base oil. Mineral base oil is widely used and accounts for more than 95% of the total amount. However, synthetic base oil must be used in some applications.

[0003] The working temperature range of the engine is wide. In order to meet the high and low temperature performance of the lubricating oil, an oil-soluble chain polymer, i.e. viscosity index improver, also known as tackifier, is added in the formula of the product. The viscosity index improver can not only thicken the base oil, but also improve the viscosity-temperature performance of the oil, so that the oil has good high-temperature lubricity and low-temperature fluidity. The viscosity index improver will be subjected to high-temperature oxidation and thermal oxidative decomposition in use, resulting in a decrease in viscosity and an increase in carbon deposition or sediment. Although the ethylene-propylene copolymer type viscosity index improver can meet the requirements of shear stability of diesel nozzle, tackifying effect, and other indicators in the physical and chemical performance test, it will cause a decrease in high-temperature viscosity of engine oil and a decrease in engine oil pressure during engine operation in actual use. At the same time, the ethylene-propylene copolymer type viscosity index improver produced by the traditional process has poor low-temperature performance in engine oil, especially in the low-temperature cold start performance test. The oil is prone to coagulation under low-temperature conditions, which causes the low-temperature cold start to be substandard.

[0004] When used in engine oil, the viscosity will decrease too fast due to the influence of long-time high temperature, which will greatly reduce the performance of the engine oil. In severe cases, it will cause a decrease in engine oil pressure, engine wear, a shortening of the oil change cycle, and even damage to the engine. At the same time, the viscosity index improver is prone to coagulation under low-temperature conditions, and the coagulation problem cannot be changed by using a coagulation inhibitor, which greatly affects the low-temperature performance. Therefore, the addition of the viscosity index improver will greatly affect the viscosity retention of the engine oil and increase the wear.

[0005] In the prior art, patent CN110951522A discloses a coal-based full-synthetic long-life gas turbine lubricating oil and a preparation method thereof, which comprises 98.0-99.5wt% of coal-based synthetic base oil and the rest of additives, the coal-based synthetic base oil is prepared from poly-alpha-olefin, the cost is too high, and a large amount of ultra-high viscosity PAO100 base oil, PAO150 base oil and the like are contained, the tendency of high-temperature oxidation is increased, the oil is prone to oxidation and gumming under long-term high-temperature conditions, the oil viscosity is increased, blockage is caused, the oil change mileage is shortened, and the low-temperature performance of the oil cannot be considered at the same time. Patent CN105132081A discloses a preparation method of a copolymer viscosity index improver, which solves the defects of traditional lubricating oil viscosity index improvers, such as rapid thermal degradation under high-temperature conditions and poor low-temperature performance, but the method needs to heat the viscosity improver at high temperature, the process risk is increased, and the problem of uneven dissolution still exists, and the viscosity index improver is still used, and the problem of viscosity reduction still exists. SUMMARY

[0006] The main purpose of the present application is to provide a lubricating oil, a preparation method and application thereof, so as to solve the problem that the lubricating oil in the prior art cannot consider low cost, good viscosity retention and high and low temperature performance at the same time.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a lubricating oil is provided, which comprises, by weight fraction: coal-based base oil 49-80 parts, PAO 40 base oil 15-30 parts, composite additive 8-10 parts, and pour point depressant 0.1-0.3 parts; wherein the coal-based base oil is a type III base oil obtained by Fischer-Tropsch synthesis-hydrorefining of coal, and the lubricating oil does not contain a viscosity index improver.

[0008] Further, the lubricating oil comprises, by weight fraction: coal-based base oil 59-71 parts, PAO 40 base oil 20-30 parts, composite additive 8-10 parts, and pour point depressant 0.1-0.3 parts.

[0009] Further, the mass ratio of the coal-based base oil and the PAO 40 base oil is (2.0-3.5):1; preferably, the 100℃ kinematic viscosity of the PAO 40 base oil is 20-60mm 2 / s, and the viscosity index is 150-160.

[0010] Further, the coal-based base oil comprises 4# coal-based base oil and 6# coal-based base oil.

[0011] Further, the mass ratio of the 4# coal-based base oil and the 6# coal-based base oil is (4-10):(45-70), and preferably (4.8-9.8):(53-66).

[0012] Further, the 100℃ kinematic viscosity of the 4# coal-based base oil is 4.0-4.2mm 2 / s, the viscosity index is 130-150, the -30℃ dynamic viscosity is 1086-1618mpa·s; and / or the 100℃ kinematic viscosity of the 6# coal-based base oil is 6.0-6.3mm 2 / s, the viscosity index is 140-160, the -30℃ dynamic viscosity is 2570-2702mpa·s.

[0013] Further, the complex additive includes a detergent, a dispersant, a rust inhibitor, an antioxidant and an antifoaming agent; preferably, the complex additive includes 0.8-5 parts of the detergent, 2.0-6.0 parts of the dispersant, 0.001-0.1 parts of the rust inhibitor, 0.1-1.0 parts of the antioxidant and 0-0.01 parts of the antifoaming agent by weight; more preferably, the detergent is synthetic calcium sulfonate and / or synthetic magnesium sulfonate; and / or the dispersant is boronized polyisobutylene succinimide; and / or the rust inhibitor is benzotriazole; and / or the antioxidant is one or more of p-octyldiphenylamine, di-tert-butyl dimethyl phenol and dialkyl thio carbamate; and / or the antifoaming agent is one or more of dimethyl silicone, methacrylate and polymethyl silicone oil; more preferably, the pour point depressant is one or more of polymethyl acrylate, hydrogenated styrene diene copolymer and polyisobutylene.

[0014] According to another aspect of the present application, a preparation method of the above-mentioned lubricating oil is provided, including the following steps: step S1, mixing the coal-based base oil and the PAO 40 base oil and performing first stirring to obtain a first mixture; step S2, sequentially adding the complex additive and the pour point depressant to the first mixture and performing second stirring to obtain a second mixture; and step S3, filtering the second mixture to obtain the lubricating oil.

[0015] Further, the speed of the first stirring is 500-1000 revolutions per minute, and the time is 30-120 minutes; and / or the speed of the second stirring is 200-400 revolutions per minute, the time is 1-2 hours, and the temperature is 40-80℃; and / or the filtering is three-stage filtering.

[0016] According to another aspect of the present application, the above-mentioned lubricating oil is applied in a diesel system, preferably the diesel system is a heavy-duty vehicle engine lubrication system.

[0017] The technical scheme of the present application is used to mix and blend the low-cost coal-based base oil of type III obtained by Fischer-Tropsch synthesis-hydrorefining with poly-alpha olefin (PAO 40) base oil. The coal-based base oil has excellent low-temperature performance and high-temperature performance, and has multiple viscosity levels. By controlling the blending ratio, the coal-based base oil can be directly blended with the PAO 40 base oil to obtain lubricating oil of different viscosity levels without adding viscosity index improver, thereby fundamentally eliminating the problem of viscosity deterioration of lubricating oil caused by the addition of viscosity index improver. The lubricating oil of the present application can maintain excellent high- and low-temperature performance while keeping the viscosity of the oil stable for a long time without decreasing, thereby prolonging the oil change cycle of the lubricating oil. DETAILED DESCRIPTION

[0018] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0019] It should be noted that the base oil and additives used in the present application can be self-made by conventional methods in the art or conveniently purchased from the market.

[0020] As described in the background art of the present application, there is a problem in the prior art that lubricating oil cannot simultaneously have low cost, good viscosity retention, and high and low temperature performance. In order to solve the above problem, in a typical embodiment of the present application, a lubricating oil is provided, which comprises, by weight fraction: coal-based base oil 49-80 parts, PAO 40 base oil 15-30 parts, composite additive 8-10 parts, and pour point depressant 0.1-0.3 parts; wherein the coal-based base oil is a type III base oil obtained by Fischer-Tropsch synthesis-hydrorefining of coal, and the lubricating oil does not contain a viscosity index improver. The composite additive and the pour point depressant can use conventional types in the art.

[0021] The coal-based base oil can be obtained by conventional Fischer-Tropsch synthesis-hydrorefining process in the art. For example, the coal-based base oil can be prepared by the following Fischer-Tropsch synthesis process: after hydroprocessing pretreatment of the Fischer-Tropsch synthesis product of coal liquefaction, using a fraction greater than 350℃ as the raw material, then performing hydroisomerization to convert n-alkanes to isomeric alkanes, and finally performing hydroprocessing to remove unsaturated components, then removing light components by vacuum distillation, and finally removing solvent and residual wax to obtain a type III+ hydrorefined lubricating oil base oil with very low pour point.

[0022] As described above, the engine lubricating oil has the dual requirements of low-temperature fluidity and high-temperature viscosity stability, the viscosity index agent can improve the temperature adaptability of the engine oil, that is, the viscosity of the oil changes less when the oil changes in a wide temperature range. However, the viscosity index agent will degrade in the high-temperature working environment of the engine, resulting in a larger decrease in the viscosity of the oil, and the low-viscosity oil can cause higher wear of the engine. At the same time, the addition of the viscosity index agent can greatly reduce the apparent viscosity index of the oil, so in the process of developing engine lubricating oil, it is hoped that the amount of viscosity index agent can be reduced as much as possible, or not used, but due to the performance limitation of the traditional base oil, it has always been unable to get rid of the viscosity index agent.

[0023] The inventors unexpectedly found during the research that the isomerized base oil obtained by Fischer-Tropsch synthesis technology and hydrofining has high purity, no impurities, excellent high-temperature and low-temperature performance, and has low-temperature performance comparable to that of the poly-a-olefin PAO series, but the cost is lower, and a low-cost engine oil with excellent low-temperature performance can be blended, the quality is equivalent to that of the base oil blended with the PAO synthetic oil, so that the viscosity index agent can not be added, the blending scheme of pure base oil is realized, the viscosity deterioration problem caused by the addition of the viscosity index agent is fundamentally avoided, the requirements of low cost, long period and high performance of the lubricating oil are met, and the comprehensive effect that cannot be achieved by the traditional base oil can be achieved. The coal-based base oil can well improve the low-temperature performance of other base oils, and especially a small amount of coal-based base oil can achieve the purpose of improving the low-temperature fluidity of the combined lubricating oil. Considering the need to balance the high-temperature and low-temperature performance and viscosity requirements of the lubricating oil, the present application selects PAO 40 base oil for compounding, and limits the content of each component of the lubricating oil in the specific range of the present application.

[0024] The present application mixes and blends the low-cost Fischer-Tropsch synthesis-hydrofining obtained Ⅲ coal-based base oil with poly-a-olefin PAO 40 base oil. The coal-based base oil has excellent low-temperature performance and high-temperature performance, and has multiple viscosity levels, which can be directly blended with PAO 40 base oil to obtain lubricating oil with different viscosity levels by controlling the blending ratio according to actual needs, and the 100℃ viscosity can reach 12.5-16.3mm 2 / s, the CCS (cold start simulator, -20℃) viscosity is <7000mpa.s. Without adding the viscosity index improver, the problem of poor lubrication caused by the aggregation of the viscosity index improver under low-temperature conditions or the decrease in viscosity under high-temperature conditions is avoided, the engine lubricating oil product can maintain a long-term stable high-temperature viscosity, the high-temperature viscosity change rate is ±0.5%, and the viscosity deterioration caused by the addition of the viscosity index improver is fundamentally eliminated, so that the good lubrication of the engine can be ensured.

[0025] In addition, the coal-based base oil has good high-temperature oxidation resistance, and the high-temperature detergency and dispersibility of the lubricating oil are excellent, so that the generation of sludge and carbon deposition can be reduced, the coking amount is low, and the oil change cycle is further prolonged. The lubricating oil of the present application can have excellent high and low temperature performance while maintaining long-term stable viscosity of the oil product, thereby prolonging the oil change cycle of the lubricating oil, and is more suitable for heavy-duty vehicle engine lubrication systems with high requirements for lubricating oil.

[0026] For the purpose of further improving the comprehensive performance of the lubricating oil such as high and low temperature performance and viscosity stability, in a preferred embodiment, the lubricating oil comprises, by weight fraction: coal-based base oil 59-71 parts, PAO 40 base oil 20-30 parts, composite additive 8-10 parts, and pour point depressant 0.1-0.3 parts.

[0027] In a preferred embodiment, the mass ratio of the coal-based base oil to the PAO 40 base oil is (2.0-3.5):1, so that the high and low temperature performance can be improved while better meeting the viscosity requirements. Preferably, the 100°C kinematic viscosity of the PAO 40 base oil is 20-60 mm 2 / s, and the viscosity index is 150-160.

[0028] The inventors unexpectedly found that, among coal-based base oils, 4# coal-based base oil and 6# coal-based base oil have more excellent low-temperature performance and are more suitable for compounding with PAO 40 base oil or other additives of the present application. A typical 4# coal-based oil has a low-temperature dynamic viscosity of 424 mPa.s (-15℃), 520 mPa.s (-20℃), 903 mPa.s (-25℃), 1086 mPa.s (-30℃), 1535 mPa.s (-35℃); a typical 6# coal-based oil has a low-temperature dynamic viscosity of 766 mPa.s (-15℃), 955 mPa.s (-20℃), 1099 mPa.s (-25℃), 2702 mPa.s (-30℃), 4637 mPa.s (-35℃); a typical PAO 4 has a low-temperature dynamic viscosity of 251 mPa.s (-15℃), 522 mPa.s (-20℃), 908 mPa.s (-25℃), 955 mPa.s (-30℃), 1500 mPa.s (-35℃); and a typical PAO 6 has a low-temperature dynamic viscosity of 436 mPa.s (-15℃), 647 mPa.s (-20℃), 1286 mPa.s (-25℃), 2093 mPa.s (-30℃), 3660 mPa.s (-35℃). The 4# coal-based base oil and the 6# coal-based base oil have low-temperature performance comparable to that of the PAO series, but have lower cost, and can be used to formulate engine oil with excellent low-temperature performance, which has a quality comparable to that of PAO synthetic oil. Therefore, in a preferred embodiment, the coal-based base oil comprises 4# coal-based base oil and 6# coal-based base oil.

[0029] In a preferred embodiment, the mass ratio of the 4# coal-based base oil to the 6# coal-based base oil is (4-10):(45-70), preferably (4.8-9.8):(53-66), which can further improve the high and low temperature performance and viscosity retention of the lubricating oil.

[0030] Specifically, in a preferred embodiment, the 4# coal-based base oil has a kinematic viscosity at 100℃ of 4.0-4.2 mm 2 / s, a viscosity index of 130-150, and a dynamic viscosity at -30℃ of 1086-1618 mPa.s; and / or the 6# coal-based base oil has a kinematic viscosity at 100℃ of 6.0-6.3 mm 2 / s, a viscosity index of 140-160, and a dynamic viscosity at -30℃ of 2570-2702 mPa.s, which are more suitable for compounding with the PAO 40 base oil of the present application to improve the high and low temperature performance of the lubricating oil.

[0031] For the purpose of further improving the comprehensive performance of the lubricating oil in use, in a preferred embodiment, the complex additive comprises a detergent, a dispersant, an anti-rust agent, an antioxidant and an antifoaming agent; preferably, the complex additive comprises 0.8-5 parts by weight of the detergent, 2.0-6.0 parts by weight of the dispersant, 0.001-0.1 parts by weight of the anti-rust agent, 0.1-1.0 parts by weight of the antioxidant and 0-0.01 parts by weight of the antifoaming agent;

[0032] More preferably, the detergent is synthetic calcium sulfonate and / or synthetic magnesium sulfonate; and / or the dispersant is boronized polyisobutylene succinimide; and / or the anti-rust agent is benzotriazole; and / or the antioxidant is one or more of p-octyldiphenylamine, di-tert-butyl-dimethylphenol and dialkyl dithiocarbamate; and / or the antifoaming agent is one or more of dimethyl silicone, methacrylate and polymethylsilicone oil; more preferably, the pour point depressant is one or more of polymethacrylate, hydrogenated styrene diene copolymer and polyisobutylene. The above-mentioned additives are more compatible with the coal-based base oil and the PAO 40 base oil of the present application, and have better blending performance.

[0033] In another typical embodiment of the present application, a preparation method of the above-mentioned lubricating oil of the present application is also provided, comprising the following steps: step S1, mixing the coal-based base oil and the PAO 40 base oil and performing first stirring to obtain a first mixture; step S2, sequentially adding the complex additive and the pour point depressant to the first mixture and performing second stirring to obtain a second mixture; and step S3, filtering the second mixture to obtain the lubricating oil.

[0034] Specifically, the coal-based base oil and the PAO 40 base oil are first mixed and stirred uniformly, so that the two base oils are uniformly mixed in advance, and then the complex additive and the pour point depressant are sequentially added, and after uniform stirring, the lubricating oil of the present application is obtained by filtering. The above-mentioned preparation method is simple and easy to operate, and the prepared lubricating oil can balance low cost and good high and low temperature performance and viscosity stability, and has a long oil change cycle.

[0035] To further improve the uniformity of the material mixing, in a preferred embodiment, the speed of the first stirring is 500-1000 rpm, and the time is 30-120 minutes; and / or the speed of the second stirring is 200-400 rpm, the time is 1-2 hours, and the temperature is 40-80°C; and / or the filtering is three-stage filtering. As mentioned above, the viscosity index improver used in the existing lubricating oil belongs to a high molecular polymer, and when it is used for preparing the lubricating oil, a long blending time is often required, and there is a risk of uneven dissolution of the viscosity index improver. However, the lubricating oil of the present application no longer adds the viscosity index improver, so that the dissolution is faster during the stirring and blending process, the product blending process is simpler, the required time is shorter, and the preparation method is more simple and fast.

[0036] In another typical embodiment of the present application, the application further provides a use of the above-mentioned lubricating oil in a diesel system, preferably a heavy-duty vehicle engine lubricating system. The diesel engine has the characteristics of high power and high temperature, and has high requirements for the viscosity maintaining ability of the lubricating oil. The coal-based base oil and PAO 40 used in the present application can meet the requirements of low cost, long cycle and high performance of the diesel engine lubricating oil, and can achieve the comprehensive effect that the traditional base oil cannot achieve.

[0037] Typically but not limitedly, the lubricating oil includes coal-based base oil 49 parts, 50 parts, 55 parts, 59 parts, 65 parts, 71 parts, 75 parts, 80 parts, or any range value composed of any two of the above values, PAO 40 base oil 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, or any range value composed of any two of the above values, composite additives 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, or any range value composed of any two of the above values, and pour point depressant 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, or any range value composed of any two of the above values.

[0038] Typically but not limitedly, the mass ratio of the coal-based base oil and the PAO 40 base oil is 2.0:1, 2.2:1, 2.5:1, 2.8:1, 3.0:1, 3.2:1, 3.5:1, or any range value composed of any two of the above values.

[0039] Typically but not limitedly, when the mass of the 4# coal-based base oil is 4, 4.8, 5, 6, 7, 8, 9, 9.8, 10, or any range value composed of any two of the above values, the mass of the 6# coal-based base oil is 45, 50, 53, 60, 66, 70, or any range value composed of any two of the above values.

[0040] Typically but not limitedly, the composite additives include 0.8 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, or any range value composed of any two of the above values of detergent, 2.0 parts, 3.0 parts, 4.0 parts, 5.0 parts, 6.0 parts, or any range value composed of any two of the above values of dispersant, 0.001 parts, 0.01 parts, 0.02 parts, 0.04 parts, 0.06 parts, 0.08 parts, 0.1 parts, or any range value composed of any two of the above values of rust inhibitor, 0.1 parts, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1.0 parts, or any range value composed of any two of the above values of antioxidant, and 0 parts, 0.002 parts, 0.005 parts, 0.008 parts, 0.01 parts, or any range value composed of any two of the above values of defoamer.

[0041] The present application will be further described in detail below in conjunction with specific examples, which cannot be understood as limiting the scope of the present application.

[0042] The properties of the base oil used in the following examples are shown in Table 1.

[0043] Table 1

[0044]

[0045] Example 1

[0046] The specific components of the lubricating oil of Example 1 are shown in Table 2.

[0047] The composite additive includes 1.5 parts of synthetic calcium sulfonate, 3.0 parts of boronized polyisobutylene succinimide, 0.05 parts of benzotriazole, 0.4 parts of p-octyldiphenylamine, and 0.005 parts of polymethylsilicone oil, and the pour point depressant is 0.15 parts of polymethyl acrylate.

[0048] The preparation method is as follows:

[0049] Step S1, the coal-based base oil and the PAO 40 base oil are mixed, and first stirring is performed at a stirring speed of 800 revolutions per minute for 80 minutes to obtain a first mixture;

[0050] Step S2, the composite additive and the pour point depressant are sequentially added to the first mixture, and second stirring is performed at a stirring speed of 300 revolutions per minute for 1.5 hours at a stirring temperature of 60°C to obtain a second mixture;

[0051] Step S3, the second mixture is subjected to three-stage filtration to obtain the lubricating oil.

[0052] Examples 2 to 6

[0053] The difference from Example 1 is that the specific components of the lubricating oil are different, as shown in Table 2.

[0054] Example 7

[0055] The difference from Example 1 is that the composite additive includes 0.8 parts of synthetic calcium sulfonate, 2.0 parts of boronized polyisobutylene succinimide, 0.001 parts of benzotriazole, and 0.1 parts of p-octyldiphenylamine.

[0056] Example 8

[0057] The difference from Example 1 is that the composite additive includes 5 parts of synthetic calcium sulfonate, 6.0 parts of boronized polyisobutylene succinimide, 0.1 parts of benzotriazole, 1.0 parts of p-octyldiphenylamine, and 0.01 parts of polymethylsilicone oil.

[0058] Example 9

[0059] The difference from Example 1 is that the preparation method is as follows:

[0060] Step S1, the coal-based base oil and PAO 40 base oil were mixed, and first stirring was carried out at a stirring speed of 500 rpm for 120 minutes to obtain a primary mixture;

[0061] Step S2, the composite additive and the pour point depressant were sequentially added to the primary mixture, and second stirring was carried out at a stirring speed of 200 rpm for 2 hours at a stirring temperature of 40℃ to obtain a secondary mixture;

[0062] Step S3, the secondary mixture was subjected to three-stage filtration to obtain the lubricating oil.

[0063] Example 10

[0064] The difference from Example 1 is that the preparation method is as follows:

[0065] Step S1, the coal-based base oil and PAO 40 base oil were mixed, and first stirring was carried out at a stirring speed of 1000 rpm for 30 minutes to obtain a primary mixture;

[0066] Step S2, the composite additive and the pour point depressant were sequentially added to the primary mixture, and second stirring was carried out at a stirring speed of 400 rpm for 1 hour at a stirring temperature of 80℃ to obtain a secondary mixture;

[0067] Step S3, the secondary mixture was subjected to three-stage filtration to obtain the lubricating oil.

[0068] Comparative Example 1

[0069] The lubricating oil of Comparative Example 1 was Mobil Black King 15w-40.

[0070] The viscosity performance of the lubricating oils of the above examples and comparative examples is shown in Table 3. The lubricating oils of the above examples and comparative examples were subjected to driving test on heavy truck vehicles (meeting the requirements of national VI emission standard), and the viscosity change rate at 100℃ was monitored by sampling, and the results are shown in Table 3.

[0071] Table 2

[0072] Parts by weight 4# coal-based base oil 6# coal-based base oil PAO 40 base oil Complex additive Pour point depressant Example 1 4.8 60 25 10 0.2 Example 2 9.8 55 25 10 0.2 Example 3 4.8 66 20 10 0.2 Example 4 6.8 53 30 10 0.2 Example 5 4 45 30 8 0.3 Example 6 10 70 15 10 0.1

[0073] Table 3

[0074]

[0075]

[0076] The engine lubricating oil change standard in China stipulates that when the 100 DEG C kinematic viscosity of the engine lubricating oil changes more than + / - 25%, the lubricating oil must be changed. As can be seen from the above, compared with the comparative examples, the lubricating oil of each embodiment of the present application has good high and low temperature viscosity performance, and does not need to add a viscosity index improver, and can meet a longer oil change period by combining according to the lubricating oil formula, meet the long life use requirements of heavy duty commercial vehicles, and solve the problem of long distance lubrication of the engine lubricating system under harsh conditions such as low ambient temperature. The oil change mileage of each embodiment of the present application reaches 30000 kilometers, and the final oil change index has not been reached, which also proves that each embodiment of the present application has excellent high temperature viscosity retention capability in actual driving test, and can greatly improve the oil change mileage of the engine.

[0077] That is, the lubricating oil of each embodiment of the present application mixes and blends the low-cost Fischer-Tropsch synthesis-hydrorefined type III coal-based base oil with polyalphaolefin PAO 40 base oil. The coal-based base oil has excellent low temperature performance and high temperature performance, and has multiple viscosity levels, and different viscosity grades of lubricating oil can be directly blended with PAO 40 base oil by controlling the blending ratio without adding a viscosity index improver, which fundamentally eliminates the problem of lubricating oil viscosity deterioration caused by the addition of a viscosity index improver. The lubricating oil of each embodiment of the present application can maintain long-term stable oil viscosity while having excellent high and low temperature performance, and can well extend the oil change period of the lubricating oil, and is a lubricating oil that can balance low cost, good viscosity retention and high and low temperature performance.

[0078] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A lubricating oil for use in a heavy duty engine lubricating system, characterised in that, consists of, by weight fraction: Coal-based base oil 49~80 parts, PAO 40 base oil 15~30 parts, Compound additive 8~10 parts, Pour point depressant 0.1~0.3 parts; The coal-based base oil is a type III base oil obtained by Fischer-Tropsch synthesis-hydrorefining of coal, and the lubricating oil does not contain a viscosity index improver. The coal-based base oil includes 4# coal-based base oil and 6# coal-based base oil; the mass ratio of the 4# coal-based base oil to the 6# coal-based base oil is (4~10):(45~70); the 100℃ kinematic viscosity of the 6# coal-based base oil is 6.0~6.3mm 2 / s, the viscosity index is 140~160, and the -30℃ dynamic viscosity is 2570~2702 mpa·s; The compound additive includes a detergent, a dispersant, a rust inhibitor, an antioxidant, and a defoaming agent; the detergent is synthetic calcium sulfonate and / or synthetic magnesium sulfonate; the dispersant is boronized polyisobutylene succinimide; the rust inhibitor is benzotriazole; the defoaming agent is one or more of dimethylsiloxane, methacrylate, and polymethylsilicone oil; and the pour point depressant is one or more of polymethacrylate, hydrogenated styrene diene copolymer, and polyisobutylene.

2. The lubricating oil of claim 1, wherein, The lubricating oil consists of, by weight fraction: Coal-based base oil 59~71 parts, PAO 40 base oil 20~30 parts, Compound additive 8~10 parts, Pour point depressant 0.1~0.3 parts.

3. The lubricating oil according to claim 1 or 2, characterized in that, The mass ratio of the coal-based base oil to the PAO 40 base oil is (2.0~3.5):

1.

4. The lubricating oil according to claim 1 or 2, characterized in that, The 100°C kinematic viscosity of the PAO 40 base oil is 20 to 60 mm 2 / s, viscosity index 150 to 160.

5. The lubricating oil of claim 1, wherein, The mass ratio of the 4# coal-based base oil to the 6# coal-based base oil is (4.8~9.8):(53~66).

6. The lubricating oil of claim 1, wherein, The 100℃ kinematic viscosity of the 4# coal-based base oil is 4.0~4.2mm 2 / s, viscosity index 130~150, -30℃ dynamic viscosity is 1086 ~1618mpa·s.

7. The lubricating oil according to claim 1 or 2, characterized in that, The compound additive includes, by weight fraction, 0.8~5 parts of the detergent, 2.0~6.0 parts of the dispersant, 0.001~0.1 parts of the rust inhibitor, 0.1~1.0 parts of the antioxidant, and 0~0.01 parts of the defoaming agent.

8. The lubricating oil of claim 1 or 2, wherein, The antioxidant is one or more of p-octyl diphenylamine, di-tert-butyl dimethyl phenol, and dialkyl thio carbamate.

9. The method of producing a lubricating oil according to any one of claims 1 to 8, characterized in that, The method comprises the following steps: Step S1, mixing coal-based base oil and PAO 40 base oil and performing first stirring to obtain a primary mixture; Step S2, sequentially adding compound additive and pour point depressant to the primary mixture and performing second stirring to obtain a secondary mixture; Step S3, filtering the secondary mixture to obtain the lubricating oil.

10. The preparation method of claim 9, wherein: The speed of the first stirring is 500~1000 revolutions per minute, and the time is 30~120 minutes; and / or The speed of the second stirring is 200~400 revolutions per minute, the time is 1~2 hours, and the temperature is 40~80℃; and / or The filtering is three-stage filtering.

11. Use of the lubricating oil of any one of claims 1 to 8 in a diesel system.

12. Use according to claim 11, characterized in that, The diesel system is a heavy-duty vehicle engine lubrication system.

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