An engine oil composition with improved water tolerance and a method of making the same

Abstract

This invention relates to the field of lubricating oil technology, and more particularly to an engine oil composition with improved water resistance and its preparation method. The engine oil composition includes a complexing agent, a base oil, a viscosity index improver, and a pour point depressant. The complexing agent is a mixture of detergent, dispersant, zinc dialkyl dithiophosphate, antioxidant, friction improver, emulsifier retainer, and corrosion inhibitor. The emulsifier retainer is a polymethacrylate with an N-vinylpyrrolidone branched structure and / or a styrene-maleic anhydride polymer. The engine oil composition of this invention, by employing a specific complexing agent and mixing it with other functional additives, exhibits excellent formulation balance and compatibility, and can well meet the requirements of automobile manufacturers for the water resistance, fuel economy, and emission performance of hybrid engine oils.

Description

Technical Field

[0001] This invention relates to the field of lubricating oil technology, and more particularly to an engine oil composition with improved water resistance and its preparation method. Background Technology

[0002] Domestic and international traditional automakers have launched their own hybrid models. Because hybrid operating modes differ from gasoline operating modes, their performance requirements for the matching lubricating oils also differ.

[0003] For hybrid electric vehicles (HEVs) with a high degree of power integration, the engine is often idle for extended periods, resulting in lower engine oil temperatures compared to traditional gasoline engines. This makes it easier for water to remain in the engine oil, hindering its evaporation and leading to a higher water content. High water content can cause hydrolysis of functional additives in the engine oil, resulting in uneven distribution of effective additive components and a decline in overall engine oil performance. Water can also cause the formation of white sludge in the engine oil, leading to localized corrosion and rust. During cold starts in winter, the water in the engine oil can easily crystallize or even freeze, severely affecting its fluidity. Therefore, the impact of water on hybrid vehicle engine oils must be considered. Hybrid vehicle engine oils must possess good water resistance and emulsification properties, forming a stable "water-in-oil" emulsion to prevent oil-water separation, thereby reducing corrosion and rust, and addressing lubrication failure caused by water freezing at low temperatures.

[0004] According to relevant cold-weather road tests, using ordinary engine oils or hybrid-specific engine oils from certain brands, hybrid vehicles occasionally experience oil pressure loss during cold starts in environments below -20°C due to water freezing in the engine oil, causing blockages in the oil lines. This can lead to wear on moving parts of the engine and, in severe cases, cylinder scoring and bearing failure. Therefore, hybrid vehicles, especially in cold regions, require engine oils with excellent water resistance to meet the lubrication needs of hybrid engines under cold operating conditions. Summary of the Invention

[0005] This invention provides an engine oil composition with improved water resistance and its preparation method. Through the synergistic effect between the components, the resulting engine oil composition has excellent water resistance. In addition to improving water resistance, the engine oil composition of this invention also has excellent fuel economy and emission performance, and is particularly suitable for engine lubrication in harsh cold environments.

[0006] According to a first aspect of the present invention, the present invention provides an engine oil composition for improving water resistance, comprising a complex agent, a base oil, a viscosity index improver, and a pour point depressant; wherein the complex agent is a mixture of a detergent, a dispersant, zinc dialkyl dithiophosphate, an antioxidant, a friction improver, an emulsifier retainer, and a corrosion inhibitor, and wherein the emulsifier retainer is a polymethacrylate and / or a styrene-maleic anhydride polymer with an N-vinylpyrrolidone branched structure.

[0007] In the above-described scheme, the engine oil composition for improving water resistance of the present invention uses polymethacrylate and / or styrene-maleic anhydride polymers with N-vinylpyrrolidone branched structures as emulsifiers. These emulsifiers have both hydrophilic and hydrophobic groups. By reducing the interfacial tension of the components in the oil / water mixture and forming a more robust film on the surface of microdroplets, or by forming an electric double layer on the surface of microdroplets through the charge provided by the emulsifier, they prevent microdroplets from agglomerating, thereby maintaining a uniform emulsion phase and improving water resistance.

[0008] Polymethacrylates with N-vinylpyrrolidone branched structures have the following general structural formula:

[0009] Preferably, the polymethacrylate is selected from a mixture of or one of Evonik's Vx6-054, Vx6-565, Vx6-850, and Vx6-700.

[0010] Styrene-maleic anhydride polymers have the following general structural formula:

[0011] Preferably, the styrene-maleic anhydride polymer is selected from a mixture of V362, V385, V385, V387 from Infineon Technologies AG or Hitec-672 from Afton Laboratories, or one of them.

[0012] Further, in the composite agent, the weight ratio of detergent, dispersant, zinc dialkyl dithiophosphate, antioxidant, friction modifier, emulsifier retainer, and corrosion inhibitor is (0.5~10):(0.5~10):(0.5~3)(0.1~2):(0.1~2):(0.1~1):(0.01~0.1). Preferably, it is (2~8):(4~9):(0.5~2)(0.5~1.5):(0.5~1.5):(0.3~1):(0.01~0.08), more preferably (3~7):(5~8):(1~1.5)(0.8~1.4):(0.8~1.4):(0.3~1):(0.03~0.06).

[0013] In the above scheme, by limiting the amount of each component in the compound to a reasonable range, the components can exert a better synergistic effect, and more effectively improve the water resistance, fuel economy and emission performance of the engine oil composition, so as to better meet the requirements of automobile manufacturers for the water resistance, fuel economy and emission performance of hybrid engine oils.

[0014] Furthermore, the detergent can be a conventional detergent in the art, including calcium alkylbenzene sulfonate, magnesium alkylbenzene sulfonate, etc. in some specific embodiments. In some specific embodiments, the detergent includes calcium alkylbenzene sulfonate and magnesium alkylbenzene sulfonate, and the weight ratio of calcium alkylbenzene sulfonate to magnesium alkylbenzene sulfonate is (0.5-3):1, preferably (1-2):1.

[0015] Furthermore, the antioxidant can be a conventional antioxidant in the art. In some specific embodiments, the antioxidant includes a high molecular weight phenolic compound and an alkylated diphenylamine, with the weight ratio of the high molecular weight phenolic compound and the alkylated diphenylamine being (0.5-3):1, preferably (0.5-1.5):1.

[0016] Compared with the prior art, the engine oil composition provided by the present invention, by using a composite agent with a specific composition, especially by using emulsifier retainers and corrosion inhibitors, and mixing with other functional additives, has excellent formulation balance and compatibility, and can well meet the requirements of automobile manufacturers for the water resistance, fuel economy and emission performance of hybrid engine oils.

[0017] Furthermore, the composite agent satisfies the following conditions: based on the total amount of the composite agent, the nitrogen content is ≥1.10 wt%, the calcium content is ≤1.27 wt%, and the magnesium content is ≤0.55 wt%, as determined by ASTM D5185.

[0018] Further, the raw materials include the following parts by weight: 10.0-20.0 parts of compound agent, 60.0-80.0 parts of base oil, 3.0-8.0 parts of viscosity index improver, and 0.1-1.0 parts of pour point depressant. Preferably, the components include the following parts by weight: 14-15 parts of compound agent, 78-80 parts of base oil, 5-6 parts of viscosity index improver, and 0.2-0.4 parts of pour point depressant. More preferably, the components include the following parts by weight: 14.5 parts of compound agent, 79.7 parts of base oil, 5.5 parts of viscosity index improver, and 0.3 parts of pour point depressant.

[0019] In the above solution, by limiting the amount of each component in the engine oil composition to a reasonable range, the components can exert a better synergistic effect, and more effectively improve the water resistance, fuel economy and emission performance of the engine oil composition, so as to better meet the requirements of automobile manufacturers for the water resistance, fuel economy and emission performance of hybrid engine oils.

[0020] To further improve the water resistance, fuel economy, and emission performance of the engine oil composition, the corrosion inhibitor is further described as a benzotriazole derivative.

[0021] It has the following general structural formula:

[0022] Preferably, the benzotriazole derivative is selected from BASF IR39 or Hangzhou Green Spectrum TMO820.

[0023] To further improve the water resistance, fuel economy, and emission performance of the engine oil composition, the base oil is further defined as an HVI Group III base oil and / or a PAO base oil, and the kinematic viscosity of the base oil at 100°C is between 3.9 and 4.5 mm. 2 / s; Preferably, the HVI III base oil has a viscosity index of not less than 120 and a pour point not higher than -15°C; the PAO base oil has a viscosity index of not less than 135 and a pour point not higher than -45°C; the weight ratio of the HVI III base oil to the PAO base oil is (60~80):(0~20). In some specific embodiments, the weight ratio of the HVI III base oil to the PAO base oil is (3~5):1; further, in some specific embodiments, the weight ratio of the HVI III base oil to the PAO base oil is (3.5~4.5):1.

[0024] Furthermore, the HVI Group III base oil is preferably Sinopec HVI III4 base oil, and the PAO base oil is preferably Sinopec PAO4 base oil (pure decene).

[0025] To further improve the water resistance, fuel economy, and emission performance of the engine oil composition, the viscosity index improver is a hydrogenated styrene diene copolymer with a shear stability index (SSI) of no more than 30.

[0026] To further improve the water resistance, fuel economy and emission performance of the engine oil composition, the friction modifier is further selected from at least one of glyceryl oleate and molybdenum dialkyldithiocarbamate and its derivatives. Preferably, the molybdenum dialkyldithiocarbamate and its derivatives are ternary molybdenum compounds, and the weight ratio of glyceryl oleate to molybdenum dialkyldithiocarbamate and its derivatives is (0.01~1):(0.09~1).

[0027] The engine oil composition of the present invention can be prepared using processes disclosed in the prior art. To ensure and improve the performance of the engine oil composition, according to a second aspect of the present invention, a preferred preparation method is provided, comprising the following steps: (1) Mix the base oil, viscosity index improver, and pour point depressant at 50~60℃ to obtain homogeneous liquid I; (2) The homogeneous liquid I is mixed with the composite agent at 55~60℃ to obtain the final product.

[0028] The engine oil composition prepared by the method described in this invention can meet SP / GF-6A and general Dexos1 specifications, and includes, but is not limited to, 0W-20 lubricating oil, with a sulfur content of no more than 0.3% (mass fraction), a phosphorus content of no more than 0.08% (mass fraction), and a sulfate ash content of no more than 0.8% (mass fraction). It is a high-grade hybrid engine oil with low sulfur, low phosphorus, and low ash content.

[0029] According to a third aspect of the invention, the invention also provides the application of the above-described engine oil composition in hybrid vehicle engines. Preferably, it is used in light-duty hybrid vehicle engines, and more preferably in plug-in hybrid electric vehicles and range-extended hybrid electric vehicles, which can reduce the risk of lubrication failure caused by oil-water separation due to condensed water mixing with the engine oil under extreme operating conditions in hybrid vehicles.

[0030] This invention provides an engine oil composition with improved water resistance. Utilizing specific types and amounts of raw materials, it fully leverages compatibility to enhance the water resistance, fuel efficiency, and emission performance of the resulting engine oil composition. This solves the technical challenge of ordinary engine oils failing to meet the lubrication requirements of hybrid vehicles during cold starts in cold regions. The selected high-performance compound formulation effectively improves the oil's water resistance, fuel efficiency, and emission performance. Real-vehicle testing by an OEM showed a significant improvement in the engine oil composition's water resistance compared to existing reference oils. Fuel economy bench tests and emission bench tests further validated its excellent overall performance in terms of fuel economy and emission performance.

[0031] This invention provides an engine oil composition with improved water resistance. It has a wide range of applications, and is especially suitable for the lubrication of light-duty hybrid vehicles that have special requirements for the water resistance, fuel economy and emission performance of the matching oil. It is also suitable for the lubrication of light-duty gasoline engines that require the use of 0W-20 viscosity grade engine oil in cold winter regions. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a graph showing the emulsification retention performance (0℃ / 25℃) of the engine oil composition of Example 1 of the present invention.

[0034] Figure 2 This is a graph showing the emulsification retention performance (0℃ / 25℃) of the engine oil composition of Comparative Example 1 of the present invention.

[0035] Figure 3 This is a low-temperature water resistance test diagram of the engine oil composition of Example 1 of the present invention.

[0036] Figure 4 This is a low-temperature water resistance test diagram of the engine oil composition of Comparative Example 1 of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0038] The present invention will be described in detail below through examples. In the following examples 1-5, the engine oil compound meets the following requirements: nitrogen content ≥1.10% by weight, calcium content ≤1.27% by weight, and magnesium content ≤0.55% by weight, as determined by ASTM D5185.

[0039] Unless otherwise specified, the technical means used in the embodiments of the present invention are all conventional means well known to those skilled in the art, and the raw materials used are all commercially available.

[0040] The main sources of raw materials used in the following examples are: Base oil: Sinopec HVI III4 base oil and PAO4 base oil, in a ratio of 4:1; Viscosity index improver: hydrogenated styrene diene copolymer; Pour point depressant: polymethyl methacrylate polymer; Detergent: calcium alkylbenzene sulfonate and magnesium alkylbenzene sulfonate in a ratio of 1.4:1; Dispersant: Polyisobutylene succinimide; Antioxidant: high molecular weight phenolic compounds and alkylated diphenylamine, in a ratio of 1:1; Corrosion inhibitor: benzotriazole derivative.

[0041] Example 1

[0042] This embodiment provides an engine oil composition for improving water resistance, comprising, by weight, 14.5 parts of a complex agent (3.3 parts of detergent, 7 parts of dispersant, 1.4 parts of ZDDP, 1.2 parts of antioxidant, 1.1 parts of friction modifier, 0.45 parts of emulsion retainer, and 0.05 parts of corrosion inhibitor), 79.7 parts of base oil, 5.5 parts of viscosity index improver, and 0.3 parts of pour point depressant. The emulsion retainer is polymethacrylate with an N-vinylpyrrolidone branched structure.

[0043] The preparation method of the engine oil composition in this embodiment is as follows: the raw base oil, viscosity index improver and pour point depressant are added to the blending kettle in sequence, then stirring is started and the temperature is raised to 45~50℃, and stirred for 15~20 min to obtain homogeneous liquid I. Subsequently, a composite agent is added to homogeneous liquid I, and the mixture is stirred at 50~60℃ for 60~80 min to prepare the final product.

[0044] Example 2

[0045] This embodiment provides an engine oil composition for improving water resistance, comprising, by weight, 14.5 parts of a complex agent (3.3 parts of detergent, 7 parts of dispersant, 1.4 parts of ZDDP, 1.2 parts of antioxidant, 1.1 parts of friction modifier, 0.45 parts of emulsion retainer, and 0.05 parts of corrosion inhibitor), 80 parts of base oil, 5.2 parts of viscosity index improver, and 0.3 parts of pour point depressant. The emulsion retainer is a styrene-maleic anhydride polymer.

[0046] The preparation method is the same as in Example 1.

[0047] Example 3

[0048] This embodiment provides an engine oil composition for improving water resistance, comprising, by weight, 14.5 parts of a complex agent (3.3 parts of detergent, 7 parts of dispersant, 1.4 parts of ZDDP, 1.2 parts of antioxidant, 1.1 parts of friction modifier, 0.45 parts of emulsion retainer, and 0.05 parts of corrosion inhibitor), 79.5 parts of base oil, 5.7 parts of viscosity index improver, and 0.3 parts of pour point depressant. The emulsion retainer is a mixture of polymethacrylate with an N-vinylpyrrolidone branched structure and a styrene-maleic anhydride polymer (in a 1:1 ratio).

[0049] The preparation method is the same as in Example 1.

[0050] Example 4

[0051] This embodiment provides an engine oil composition for improving water resistance, comprising, by weight, 14.5 parts of a complex agent (3.3 parts of detergent, 7 parts of dispersant, 1.4 parts of ZDDP, 1.2 parts of antioxidant, 1.1 parts of friction modifier, 0.45 parts of emulsion retainer, and 0.05 parts of corrosion inhibitor), 79.6 parts of base oil, 5.4 parts of viscosity index improver, and 0.5 parts of pour point depressant. The emulsion retainer is a styrene-maleic anhydride polymer.

[0052] The preparation method is the same as in Example 1.

[0053] Example 5

[0054] This embodiment provides an engine oil composition for improving water resistance, comprising, by weight, 14.7 parts of a complex agent (3.35 parts of detergent, 7.1 parts of dispersant, 1.42 parts of ZDDP, 1.21 parts of antioxidant, 1.11 parts of friction modifier, 0.46 parts of emulsion retainer, and 0.05 parts of corrosion inhibitor), 79.5 parts of base oil, 5.5 parts of viscosity index improver, and 0.3 parts of pour point depressant. The emulsion retainer is a styrene-maleic anhydride polymer.

[0055] The preparation method is the same as in Example 1.

[0056] Comparative Example 1

[0057] This comparative example provides an engine oil composition that differs from Example 1 in that it does not use emulsifiers or corrosion inhibitors. Its preparation method is the same as in Example 1.

[0058] To further verify the performance of the engine oil composition obtained by the present invention, the inventors conducted further verification experiments. Due to space limitations, only the most representative experimental examples are listed here.

[0059] Experimental Example 1

[0060] 1. Experimental verification

[0061] Experimental subjects: Experimental Group 1: The engine oil composition obtained in Example 1 of this invention; Control group 1: The engine oil composition obtained in Comparative Example 1 of the present invention.

[0062] 2. Emulsification retention test

[0063] The emulsification capacity of experimental group 1 and control group 1 for water and simulated Ed85 fuel was evaluated using the test method of NB / SH / T 0957 "Evaluation method of engine oil emulsification capacity for water and simulated Ed85 fuel". The results are shown in Table 1.

[0064] Table 1 Results of Emulsification Retention Test

[0065] Through Table 1 and appendices Figure 1 Appendix Figure 2 The results of the low-temperature water resistance test for the experimental and control groups show that the oil in control group 1 showed ice formation at the bottom at the end of the test and failed. However, experimental group 1, which used the preferred raw materials of this invention, did not show any ice formation at the end of the test and passed the internal index requirements of the low-temperature water resistance test, indicating that the engine oil composition of this invention has good low-temperature water resistance and anti-icing properties.

[0066] The above experimental examples were repeated for the engine oil compositions obtained in other embodiments 2-5 of the present invention, and the same experimental conclusions were obtained. Furthermore, to further verify the engine oil compositions obtained by the present invention, the inventors conducted further relevant verification experiments, all of which achieved good experimental results. Due to space limitations, these will not be described in detail here.

[0067] 3. Physicochemical and performance properties of the engine oil composition

[0068] The engine oil composition of Example 1 was subjected to the physicochemical properties test and the performance test (fuel economy and emission performance) test as shown in Table 2 below. The test results are shown in Table 2 below.

[0069] Table 2

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An engine oil composition with improved water resistance, characterized in that, It includes a compounding agent, base oil, viscosity index improver, and pour point depressant; the compounding agent is a mixture of detergent, dispersant, zinc dialkyl dithiophosphate, antioxidant, friction improver, emulsifier retainer, and corrosion inhibitor; the emulsifier retainer is a polymethacrylate and / or styrene-maleic anhydride polymer with an N-vinylpyrrolidone branched structure.

2. The engine oil composition according to claim 1, characterized in that, In the composite agent, the weight ratio of detergent, dispersant, zinc dialkyl dithiophosphate, antioxidant, friction modifier, emulsifier retainer and corrosion inhibitor is (0.5~10):(0.5~10):(0.5~3)(0.1~2):(0.1~2):(0.1~1):(0.01~0.1).

3. The engine oil composition according to claim 1 or 2, characterized in that, The composite agent satisfies the following conditions: based on the total amount of the composite agent, the nitrogen content is ≥1.10% by weight, the calcium content is ≤1.27% by weight, and the magnesium content is ≤0.55% by weight, as determined by ASTM D5185.

4. The engine oil composition according to any one of claims 1-3, characterized in that, It includes the following raw materials in parts by weight: 10.0~20.0 parts of compound agent, 60.0~80.0 parts of base oil, 3.0~8.0 parts of viscosity index improver, and 0.1~1.0 parts of pour point depressant.

5. The engine oil composition according to claim 1, characterized in that, The corrosion inhibitor is a benzotriazole derivative.

6. The engine oil composition according to claim 1, characterized in that, The base oil is an HVI Group III base oil and / or a PAO base oil, and the kinematic viscosity of the base oil at 100°C is 3.9-4.5 mm. 2 / s; Preferably, the viscosity index of the HVI III base oil is not less than 120 and the pour point is not higher than -15℃; the viscosity index of the PAO base oil is not less than 135 and the pour point is not higher than -45℃; the weight ratio of the HVI III base oil to the PAO base oil is (60~80):(0~20).

7. The engine oil composition according to claim 1, characterized in that, The viscosity index improver is a hydrogenated styrene diene copolymer with a shear stability index (SSI) of no more than 30.

8. The engine oil composition according to claim 1, characterized in that, The friction modifier is at least one of glyceryl oleate and molybdenum dialkyldithiocarbamate and its derivatives. Preferably, the molybdenum dialkyldithiocarbamate and its derivatives are ternary molybdenum compounds, and the weight ratio of glyceryl oleate to molybdenum dialkyldithiocarbamate and its derivatives is (0.01~1):(0.09~1).

9. A method for preparing the engine oil composition according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Mix the base oil, viscosity index improver, and pour point depressant at 50~60℃ to obtain homogeneous liquid I; (2) The homogeneous liquid I is mixed with the composite agent at 55~60℃ to obtain the final product.

10. The use of the engine oil composition according to any one of claims 1-8 in a hybrid vehicle engine.

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