Lubricating oil composition

Abstract

The present invention provides a lubricating oil composition comprising a base oil composition and a friction modifier, wherein the base oil composition comprises i. a first base oil selected from Fischer-Tropsch group III base oils, and ii. a further base oil consisting of a monoester base oil in an amount of 25% by weight or less relative to the total weight of the lubricating oil composition, the friction modifier is present in an amount ranging from 0.25 to 2.5% by weight relative to the total weight of the lubricating oil composition and is selected from glycerol monoester and monoester amine salts of formula (I), where R is selected from saturated or unsaturated C4-C22 hydrocarbon groups, R1 is selected from saturated or unsaturated C1-C24 hydrocarbon groups, and n is an integer in the range of 1 to 4, and the lubricating oil composition is 1.5 to 4.0 mm 2 It has kinematic viscosity at 100°C in the range of / second, measured by the open-cup method, a flash point of at least 160°C, and an aniline point of at least 80°C. JPEG2026522025000013.jpg16128

Description

[Technical Field]

[0001] The present invention relates to a lubricating oil composition and the use of the aforementioned lubricating oil composition as a reduction gear oil in electric vehicles. [Background technology]

[0002] Electric mobility refers to vehicles powered at least partially by batteries, and includes fully battery-powered electric vehicles and the full range of hybrid vehicles (e.g., plug-in hybrids, series hybrids, etc.). The number of these vehicles on the road has increased rapidly in recent years, and the utilization rate of vehicles that rely on some form of battery power is expected to continue to increase considerably over the next few decades.

[0003] At least partially, the growth of electric vehicles has led to an increased demand for fluids suitable for use in the powertrains of such vehicles. There is less uniformity between different types of electric vehicle (EV) powertrains than in internal combustion engine (ICE) vehicles. This is partly due to the degree of electrification of any given vehicle, but also to differences in powertrain design by different manufacturers for vehicles with similar levels of electrification. Designing fluids suitable for a range of electric mobility options presents many challenges.

[0004] Transmissions in pure battery-operated vehicles (BEVs) typically have a simple reduction gear set. Such vehicles have higher torque at low speeds and much higher rotational speeds than ICE powertrains. The absence of an internal combustion engine usually means that BEVs operate at lower temperatures than ICE vehicles. Creating fluids that function effectively under these conditions is a challenge. Providing lubricant compositions for reduction gear systems in electric or hybrid electric vehicles requires a careful balance to provide low-viscosity compositions that still offer excellent friction properties. Typically, reducing the viscosity of a lubricant composition negatively impacts performance properties such as flash point and wear resistance. The use of friction modifiers often leads to copper corrosion, which can damage key components in electric or hybrid vehicles.

[0005] JP2019-0137829 describes a lubricating oil composition for electric vehicles that, in addition to a base oil, comprises a phosphite or its amine salt, borate, a sulfur-based extreme pressure agent, and an organic friction modifier.

[0006] Further improvements are still needed to provide the necessary properties for lubricant compositions suitable for use as reduction gear oil in electric vehicles, such as improved efficiency by reducing friction without compromising other properties such as flash point, wear protection, and copper corrosion. [Overview of the Initiative]

[0007] The present invention provides a lubricating oil composition comprising a base oil composition and a friction modifier, wherein the base oil composition is i. A first base oil selected from Fischer-Tropsch group III base oils, and ii. The lubricating oil composition contains a further base oil consisting of a monoester base oil in an amount of 25% by weight or less relative to the total weight of the lubricating oil composition. The friction modifier is present in an amount ranging from 0.25 to 2.5% by weight of the total weight of the lubricating oil composition and is selected from glycerol monoesters and monoesteramine salts of formula (I).

[0008] [ka]

[0009] In the formula, R is selected from saturated or unsaturated C4-C22 hydrocarbon groups, R1 is selected from saturated or unsaturated C1-C24 hydrocarbon groups, and n is an integer in the range of 1 to 4. The lubricating oil composition is 1.5~4.0 mm 2 It has a kinematic viscosity at 100°C in the range of / seconds, a flash point at least 160°C as measured by the open-cup method, and an aniline point at least 80°C.

[0010] The present invention also provides the use of such lubricating oil compositions as reduction gear oil in electric vehicles. [Modes for carrying out the invention]

[0011] One or more specific embodiments of the present disclosure are described below. These embodiments described are examples of the technology disclosed herein. In addition, not all features of actual implementations may be described herein in order to provide a concise description of these embodiments.

[0012] When describing elements of the various embodiments of this disclosure, the articles “a,” “an,” and “the” are intended to mean that one or more of the elements exist. The terms “equip,” “include,” and “have” are intended to be inclusive and mean that additional elements other than those listed may exist. In addition, references to “one embodiment” or “embodiment” in this disclosure should not be interpreted as excluding the existence of additional embodiments that also incorporate the listed features.

[0013] In relation to the present invention, if a composition contains two or more components, these components should be selected in an amount not exceeding 100% by weight.

[0014] The inventors have found that, surprisingly, by using a low-viscosity lubricating oil composition comprising a Fischer-Tropsch base oil, optionally an ester base oil, and a friction modifier selected from glycerol monoesters and monoester amine salts, excellent results can be achieved with respect to wear, friction, copper corrosion, and durability, and that the formulation ensures that the kinematic viscosity, flash point, and aniline point at 100°C are within a specific range.

[0015] The present invention provides a lubricating oil composition comprising a base oil composition and a friction modifier. The base oil composition comprises at least a Fischer-Tropsch base oil.

[0016] Fischer-Tropsch-derived base oils are well known in the art. The term "Fischer-Tropsch-derived" means that the base oil is either a synthetic product of the Fischer-Tropsch process or derived from the Fischer-Tropsch process.

[0017] Fischer-Tropsch base oils are often classified by the starting materials used in the Fischer-Tropsch process (i.e., "X-to-liquids" or "XTL" where X represents the starting material). Some examples of Fischer-Tropsch processes for producing base fluids include biomass-to-liquid (BTL) processes, coal-to-liquid (CTL) processes, and gas-to-liquid (GTL) processes. Preferably, Fischer-Tropsch base oils are GTL (gas-to-liquid) base oils. Suitable Fischer-Tropsch base oils that can be conveniently used in the present invention are, for example, those disclosed in European Patent No. 0776959, No. 0668342, International Publication No. 97021788, No. 0015736, No. 0014188, No. 0014187, No. 0014183, No. 0014179, No. 0008115, No. 9941332, European Patent No. 1029029, International Publication No. 0118156, and No. 0157166.

[0018] The Fischer-Tropsch-derived base oil for use in the present invention preferably has a kinematic viscosity at 100 °C in the range of 1.5 to 4.5 mm 2 / sec, more preferably in the range of 1.5 to 4.0 mm 2 / sec. Further, the Fischer-Tropsch-derived base oil preferably has a density at 15 °C of less than 0.83 g / cm 3 as measured in accordance with JIS K 2249-1.

[0019] The total amount of the Fischer-Tropsch-derived base oil present in the lubricating oil composition is preferably at least 50.0% by weight, more preferably at least 55.0% by weight, still more preferably at least 60.0% by weight, and most preferably at least 65.0% by weight based on the total weight of the lubricating oil composition. The total amount of the Fischer-Tropsch-derived base oil present in the lubricating oil composition is preferably at most 99.0% by weight, more preferably at most 95.0% by weight, and most preferably at most 93.0% by weight based on the total weight of the lubricating oil composition.

[0020] Examples of the Fischer-Tropsch-derived base oil that can be used alone or in combination in the present invention are Fischer-Tropsch-derived base oils commercially available from Shell Plc. as Risella X 415, Risella X411, and Risella X420. These Fischer-Tropsch-derived base oils can be used alone or in combination of two or more.

[0021] If necessary, the base oil composition may contain, based on the total weight of the lubricating oil composition, up to 25% by weight of a further base oil consisting of a monoester base oil. The ester base oil falls into Group V of the API base oil classification.

[0022] Suitable monoesters include branched or unbranched saturated or unsaturated monoesters of fatty acids and alcohols. The fatty acid is preferably C6-C 22is a branched or unbranched saturated or unsaturated fatty acid. Such fatty acids include, but are not limited to, stearic acid and oleic acid. The alcohol is preferably a C4-C 20 branched or unbranched saturated or unsaturated alcohol.

[0023] When used in a lubricating oil composition, the monoester base oil preferably has a kinematic viscosity at 100 °C in the range of 1.5 to 4.0 mm 2 / s, more preferably in the range of 2.0 to 3.5 mm 2 / s.

[0024] When the base oil composition contains a monoester base oil, preferably, the aforementioned monoester base oil is present in an amount of at least 5% by weight, more preferably at least 10% by weight, even more preferably at least 15% by weight, based on the total weight of the lubricating oil composition.

[0025] The lubricating oil composition also contains a friction modifier present in an amount in the range of 0.25 to 2.5% by weight based on the total weight of the lubricating oil composition. Preferably, the aforementioned friction modifier is present in an amount in the range of at least 0.5% by weight based on the total weight of the lubricating oil composition. Also preferably, the aforementioned friction modifier is present in an amount in the range of at most 2.0% by weight based on the total weight of the lubricating oil composition.

[0026] The friction modifier is selected from glycerol monoesters and monoester amine salts of formula (I),

[0027]

Chemical formula

[0028] wherein R is selected from saturated or unsaturated C4-C22 hydrocarbons, R1 is selected from saturated or unsaturated C1-C24 hydrocarbons, and n is an integer in the range of 1 to 4.

[0029] Preferably, when the friction modifier is a glycerol monoester, the glycerol monoester includes glycerol monooleate.

[0030] When the friction modifier includes a monoester amine salt of formula (I), R is selected from linear or branched saturated or unsaturated C4-C22 hydrocarbon groups. For example, R can be selected from an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, and an aralkyl group. Preferably, R is an alkyl group or an alkenyl group having 4 to 22 carbons, more preferably 8 to 22 carbons.

[0031] Preferably, R 1 represents a branched, unbranched or cyclic hydrocarbon group. Preferably, the total number of carbon atoms of the hydrocarbon group represented by NR 1 3 is in the range of 3 to 24, more preferably 9 to 18, and even more preferably 12 to 18.

[0032] The lubricating oil composition has a kinematic viscosity at 100 °C in the range of 1.5 to 4.0 mm 2 / s. Preferably, the lubricating oil composition has a kinematic viscosity at 100 °C in the range of 2.0 to 3.7 mm 2 / s.

[0033] The lubricating oil composition has a flash point of at least 160 °C measured by the open cup method in accordance with JIS K 2265-4.

[0034] The lubricating oil composition has an aniline point of at least 80 °C measured in accordance with JIS K 2256.

[0035] Similar to the base oil composition and the friction modifier, the lubricating oil composition may contain one or more further additives. The additives can be incorporated into the lubricating oil composition as individual additives or as part of a composite additive package. As is well known, each additive or additive package can be provided in a diluent fluid (e.g., a base oil) as required.

[0036] Typical additives in the lubricating oil composition of the present invention include extreme pressure additives, anti-wear additives, viscosity index improvers, antioxidants, and metal deactivators.

number

[0037] The phosphorus concentration in the lubricating oil composition is preferably at least 0.025% by weight of the total weight of the composition. Preferably, the phosphorus concentration in the lubricating oil composition is 0.06% by weight or less, more preferably 0.04% by weight or less, of the total weight of the composition.

[0038] The lubricating oil composition can be used in any suitable application. However, it is preferable that the lubricating oil composition be used as a reduction gear oil for electric vehicles. The electric vehicle may be a fully battery-powered electric vehicle or any form of hybrid electric vehicle in which at least part of the power is supplied by an electric motor.

[0039] The present invention will be further described here by reference to the following non-limiting embodiments. [Examples]

[0040] The formulations listed in Tables 4-8 were prepared using standard methods. The base oils used were those shown in Table 1.

[0041] [Table 1]

[0042] Two standard reduction gear oil additive packages were used (Adpack 1 and 2 in Tables 4-9). The following friction modifiers were tested:

[0043] [Table 2]

[0044] The following tests were completed on the composition.

[0045] Table 3 The kinematic viscosity was measured at 40 and 100°C in accordance with JIS K 2283. The viscosity index was calculated according to JIS K 2293. Elemental analysis was performed in accordance with JPI 5S 38, JIS K 2541-4, and JIS K 2609. The aniline point was measured according to JIS K 2256. The flash point COC (open cup method) was measured according to JIS K 2265-4. MTM (PCS Instruments) EHD friction was measured under the following conditions: oil temperature 40°C, Pmax 1.0 GPa, and sliding speed 1.5 m / s. AISI 52100 ball and disc test specimens with a surface roughness of Ra < 0.01 μm were used. MTM (PCS Instruments) boundary friction was measured under the following conditions: oil temperature 40°C, Pmax 1.0 GPa, and sliding speed 0.005 m / sec. AISI 52100 ball and disk test specimens with a surface roughness of Ra < 0.01 μm were used. Copper corrosion was measured according to JIS K 2513 at 150°C for a test period of 48 hours. The wear of four balls was measured according to ASTM D 417 at an oil temperature of 100°C, a load of 40 kgf, a rotational speed of 1500 rpm, and a test duration of 1 hour.

[0046] The results of the examples are shown in Tables 4-8.

[0047] [Table 3]

[0048] [Table 4]

[0049] [Table 5]

[0050] [Table 6]

[0051] [Table 7]

[0052] The embodiments of the present invention can be readily compared with comparative examples to demonstrate the technical effects of the combination of base oil and friction modifier, as well as the required kinematic viscosity, flash point, and aniline point. Examples 1 to 10 of the present invention demonstrate excellent friction properties without impairing other properties such as wear protection and copper corrosion.

[0053] Comparative Examples 1, 8, 9, and 11 contain no friction modifiers and include a range of base oils. Each of these examples exhibits worse performance with respect to at least one of friction, wear resistance, and copper corrosion. Comparative Examples 2, 3, and 4 also exhibit worse performance with respect to at least one of friction, wear resistance, and copper corrosion when different friction modifiers are used in the lubricating oil composition. The importance of the amount of friction modifier is demonstrated by Comparative Examples 5 and 6. Comparative Example 7 highlights the importance of the kinematic viscosity limit at 100°C. Base oil compositions outside the range required in Claim 1 also provide worse performance with respect to at least one of friction, wear resistance, and copper corrosion, as demonstrated in Comparative Example 10.

Claims

1. A lubricating oil composition comprising a base oil composition and a friction modifier, wherein the base oil composition is i. A first base oil selected from Fischer-Tropsch Group III base oils, and ii. The lubricating oil composition comprises a further base oil consisting of a monoester base oil in an amount of 25% by weight or less relative to the total weight of the lubricating oil composition. The friction modifier is present in an amount ranging from 0.25 to 2.5% by weight of the total weight of the lubricating oil composition, and is selected from glycerol monoesters and monoesteramine salts of formula (I). 【Chemistry 1】 In the formula, R is selected from saturated or unsaturated C4-C22 hydrocarbon groups, R1 is selected from saturated or unsaturated C1-C24 hydrocarbon groups, and n is an integer in the range of 1 to 4. The lubricating oil composition is 1.5 to 4.0 mm ２ A lubricating oil composition having a kinematic viscosity at 100°C in the range of 0 / second, a flash point at least 160°C as measured by the open-cup method, and an aniline point at least 80°C.

2. The lubricating oil composition according to claim 1, wherein the lubricating oil composition contains at least 0.025% by weight of phosphorus based on the total weight of the composition.

3. The aforementioned Fischer-Tropsch-derived group III base oil is 1.5 to 4.5 mm ２ In the range of / second, preferably 1.5 to 4.0 mm ２ A lubricating oil composition according to claim 1 or 2, having a kinematic viscosity at 100°C in the range of 1 / second.

4. The lubricating oil composition according to any one of claims 1 to 3, wherein the monoester base oil is present in an amount of at least 5% by weight, preferably at least 10% by weight, and more preferably at least 15% by weight.

5. The lubricating oil composition according to any one of claims 1 to 4, wherein the friction modifier is present in an amount ranging from 0.5 to 2.0% by weight of the total weight of the lubricating oil composition.

6. Use of the lubricating oil composition according to any one of claims 1 to 5 as a reduction gear oil in an electric vehicle.

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