Phosphorylated dispersants in fluids for electric vehicles

Abstract

The present disclosure relates to a lubricating fluid for an electric motor system and a method of lubricating a gear and cooling an electric machine in an electric motor system. In particular, the disclosed technology relates to a lubricating fluid for an electric vehicle comprising an oil of lubricating viscosity and at least one phosphorylated dispersant that exhibits an increased electrical resistivity after aging.

Description

[0001] This application is a divisional application of the Chinese patent application No. 2021108991680 (application date: August 5, 2021, invention name: Phosphorylated dispersant in fluid for electric vehicles). Technical Field

[0002] The present disclosure relates to a lubricating fluid for an electric motor system and a method for lubricating gears and cooling motors in an electric motor system. In particular, the disclosed technology relates to a lubricating fluid for an electric vehicle, the lubricating fluid comprising an oil of lubricating viscosity, at least one phosphorylated dispersant having between 2.0 wt% and 3.5 wt% phosphorus. The lubricating fluid has a resistivity of at least 50 MΩ.m after aging as measured at 30°C by a modified version of ASTM D2624-15. Background Art

[0003] The main challenges in developing lubricants for electric vehicle powertrains are achieving wear resistance, inhibiting copper corrosion, and ensuring compatibility of the lubricant with live components in the powertrain over the life of the lubricant. For example, gears within an electric vehicle powertrain require good wear protection. In addition, the copper present in the live components of the electric motor needs to be protected from high temperatures. Additionally, the resistivity of the lubricant needs to remain relatively high over the life of the lubricant to inhibit static electricity accumulation and discharge in the live components.

[0004] Despite advances in electric vehicle powertrain lubricant technology, there remains a need for an electric vehicle powertrain lubricant composition having desirable anti-wear properties, copper corrosion compatibility, and lubricant resistivity. Summary of the invention

[0005] In one aspect or embodiment, described herein is a lubricating composition for use in an electric vehicle or a hybrid electric vehicle. In one embodiment, the lubricating composition comprises: at least 95 weight percent of a lubricating base oil composition, the lubricating base oil composition comprising a base oil selected from the group consisting of: an API Group III base oil; or a blend of a Group III base oil with a Group II or Group V base oil; or a mixture thereof; a phosphorylated succinimide dispersant containing 2 wt% to 3.5 wt% of phosphorus, the phosphorylated succinimide dispersant providing 650 ppm or less of phosphorus to the lubricating composition; the lubricating composition having 700 ppm or less of total phosphorus, and the phosphorylated succinimide dispersant providing at least 70% of the total phosphorus; and wherein after aging the fluid at 150°C according to JIS K2514-1, the lubricating composition has a kinematic viscosity of 3 cSt to 6.5 cSt at 100°C and has a resistivity of at least 50 M Ω⋅m as measured at 1.5 volts and 30°C using the lubricating composition according to ASTM D2624-15; wherein if the lubricating base oil composition comprises API If the lubricating base oil composition comprises an API Group V base oil, the API Group V base oil is present in an amount of up to 15 wt% based on the total lubricating composition; wherein if the lubricating base oil composition comprises an API Group II base oil, the API Group II is present in an amount of up to 80 wt% based on the total lubricating composition.

[0006] In other embodiments, the lubricating composition may further include: wherein the phosphorylated succinimide dispersant is a first dispersant, and wherein the composition further comprises a second dispersant containing 0.2 wt % to 0.4 wt % phosphorus, the second dispersant providing 50 ppm or less of phosphorus to the lubricating composition; and / or wherein the phosphorylated succinimide dispersant contains 2.5 wt % to 3.0 wt % phosphorus.

[0007] In other embodiments, any lubricating composition herein may include the phosphorylated succinimide dispersant to provide 115 ppm to 600 ppm of phosphorus to the lubricating composition and / or the phosphorylated succinimide dispersant provides 115 ppm to 250 ppm of phosphorus to the lubricating composition; and / or the first dispersant delivers 115 ppm to 250 ppm of phosphorus to the lubricating composition and the second dispersant delivers 40 ppm or less of phosphorus to the lubricating composition; and / or wherein the phosphorylated succinimide dispersant provides 250 ppm or less of phosphorus to the lubricating composition, and wherein the lubricating composition has 300 ppm or less of total phosphorus.

[0008] In other embodiments, any of the lubricating compositions herein may have a resistivity of at least 115 MΩ⋅m after aging the fluid at 150°C in accordance with JIS K2514-1.

[0009] In other embodiments, any of the lubricating compositions herein may have a base oil composition selected from: an API Group III base oil; or a combination of an API Group II base oil and a mixture of API Group II and Group III base oils.

[0010] In another embodiment, any lubricating composition herein may include the phosphated succinimide dispersant to provide between 115 ppm and 250 ppm phosphorus to the lubricating composition; and the lubricating composition has between 160 ppm and 300 ppm total phosphorus, a kinematic viscosity of 5.5 cSt to 6.0 cSt at 100°C, and a resistivity of at least 115 MΩ⋅m after aging the fluid at 150°C according to JIS K2514-1.

[0011] In another aspect or embodiment of the present disclosure, a method of increasing the resistivity of a lubricating composition in an electric or hybrid electric vehicle is provided. In one embodiment, the method includes providing a lubricant for an electric or hybrid electric vehicle powertrain, the lubricant having a composition comprising: at least 95 weight percent of a lubricating base oil composition, the lubricating base oil composition comprising a base oil selected from the group consisting of: an API Group III base oil; or a blend of an API Group III base oil with an API Group II, API Group V base oil; or a mixture thereof; a phosphorylated succinimide dispersant containing 2 wt % to 3.5 wt % of phosphorus, the phosphorylated succinimide dispersant providing 650 ppm or less of phosphorus to the lubricating composition; the lubricating composition having 700 ppm or less of phosphorus, and the phosphorylated succinimide dispersant providing at least 70% of the total phosphorus; and wherein after aging the fluid at 150°C according to JIS K2514-1, the lubricating oil has a kinematic viscosity of 3 cSt to 6.5 cSt at 100°C and has a viscosity of at least 50 %; and wherein if the lubricating base oil composition comprises an API Group V base oil, the API Group V base oil is present in an amount of up to 15 wt% based on the total lubricating composition; and wherein if the lubricating base oil composition comprises an API Group II base oil, the API Group II is present in an amount of up to 80 wt% based on the total lubricating composition.

[0012] In other embodiments of the method, the phosphorylated succinimide dispersant is a first dispersant, and wherein the composition further comprises a second dispersant containing 0.2 wt % to 0.4 wt % phosphorus, the second dispersant providing 50 ppm or less of phosphorus to the lubricating composition; and / or wherein the phosphorylated succinimide dispersant contains 2.5 wt % to 3.0 wt % phosphorus.

[0013] In other embodiments of any of the methods herein, the phosphorylated succinimide dispersant provides 115 ppm to 600 ppm of phosphorus to the lubricating composition; and / or the phosphorylated succinimide dispersant provides 115 ppm to 250 ppm of phosphorus to the lubricating composition; and / or the first dispersant delivers 115 ppm to 250 ppm of phosphorus to the lubricating composition and the second dispersant delivers 40 ppm or less of phosphorus to the lubricating composition; and / or the phosphorylated succinimide dispersant provides 250 ppm or less of phosphorus to the lubricating composition, and wherein the lubricating composition has 300 ppm or less of total phosphorus.

[0014] In a further embodiment of any of the methods, the lubricating composition has a resistivity of at least 115 MΩ⋅m after aging the fluid at 150°C in accordance with JIS K2514-1; and / or the base oil composition is selected from: an API Group III base oil; or a blend of API Group II and Group III base oils; or a mixture thereof; and / or the phosphated succinimide dispersant provides 115 ppm to 250 ppm of phosphorus to the lubricating composition, and the lubricating composition has 160 ppm to 300 ppm of total phosphorus, a kinematic viscosity of 5.5 cSt to 6.0 cSt at 100°C, and a resistivity of at least 115 MΩ⋅m after aging the fluid at 150°C in accordance with JIS K2514-1.

[0015] In other embodiments, the present disclosure provides the use of a lubricating composition comprising a phosphorylated succinimide dispersant in a hybrid or electric vehicle for improving the electrical resistance durability of the lubricating composition, wherein the lubricating composition is described above and in any embodiment herein. In other embodiments, the use of a lubricating composition in a hybrid or electric vehicle is provided, the lubricating composition comprising a phosphorylated succinimide dispersant as described in any embodiment herein to achieve a resistivity of at least 50 M Ω⋅m after aging the fluid at 150°C according to JIS K2514-1. In further embodiments, the use of a lubricating composition in a hybrid or electric vehicle is described, the lubricating composition comprising a phosphorylated succinimide dispersant as described in any embodiment herein to achieve one or more of the following: a resistivity of at least 50 M Ω⋅m after aging the fluid at 150°C according to JIS K2514-1, and / or for reducing the copper corrosion of the lubricating composition.

[0016] Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein.

[0017] The following definitions of terms are provided to clarify the meaning of certain terms as used herein.

[0018] The terms "lubricating oil," "lubricant composition," "lubricating composition," "lubricant," and "lubricating and cooling fluid" refer to a finished lubricating product comprising a major amount of base oil and a minor amount of an additive composition.

[0019] As used herein, the terms "additive package," "additive concentrate," "additive composition," and "transmission fluid additive package" refer to that portion of a lubricating oil composition that excludes a major amount of base oil.

[0020] As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl" is used in its ordinary sense, which is well known to those skilled in the art. Specifically, it refers to a group having carbon atoms directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Each hydrocarbyl group is independently selected from hydrocarbyl substituents and substituted hydrocarbyl substituents containing one or more of the following: halo, hydroxy, alkoxy, mercapto, nitro, nitroso, amino, pyridyl, furanyl, imidazolyl, oxygen and nitrogen, and wherein no more than two non-hydrocarbyl substituents are present for every ten carbon atoms in the hydrocarbyl group.

[0021] Unless expressly stated otherwise, as used herein, the term "weight percent" or "wt %" refers to the percentage of the component by weight of the entire composition.

[0022] The terms "soluble", "oil-soluble" or "dispersible" as used herein may mean, but do not necessarily mean, that a compound or additive is soluble, dissolvable, miscible or capable of being suspended in oil in all proportions. However, the above terms do mean that they are, for example, soluble, suspendable, dissolvable or stably dispersible in oil to a sufficient extent to exert their intended effect in the environment in which the oil is used. In addition, the addition of other additives may also allow for the addition of higher levels of a particular additive, if desired.

[0023] As used herein, the term "alkyl" refers to a straight chain, branched chain, cyclic and / or substituted saturated chain moiety of about 1 to about 200 carbon atoms.

[0024] As used herein, the term "alkenyl" refers to a straight chain, branched, cyclic and / or substituted unsaturated chain moiety of about 3 to about 30 carbon atoms.

[0025] As used herein, the term "aryl" refers to monocyclic and polycyclic aromatic compounds which may include alkyl, alkenyl, alkaryl, amino, hydroxy, alkoxy, halide substituents and / or heteroatoms including, but not limited to, nitrogen and oxygen.

[0026] As used herein, "number average molecular weight" or "Mn" is determined by gel permeation chromatography (GPC) using commercially available polystyrene standards with a Mn of 180 to about 18,000 as a calibration reference.

[0027] It should be understood that throughout this disclosure, the terms "comprising," "including," "containing," and the like are considered open ended and include any elements, steps, or ingredients not expressly listed. The term "consisting essentially of" is intended to include any expressly listed elements, steps, or ingredients, as well as any additional elements, steps, or ingredients that do not materially affect the basic and novel aspects of the invention. This disclosure also contemplates that any composition described using the terms "comprising," "including," "containing" should also be interpreted as including disclosure of the same composition as "consisting essentially of" or "consisting of" the specifically listed components thereof.

[0028] This application also involves the following specific technical solutions:

[0029] 1. A lubricating composition for an electric vehicle, the lubricating composition comprising:

[0030] At least 95 weight percent of a lubricating base oil composition, the lubricating base oil composition comprising a base oil selected from the group consisting of: API Group III base oil; or a blend of Group III base oil with Group II or Group V base oil; or a mixture thereof;

[0031] a phosphorylated succinimide dispersant containing 2 wt % to 3.5 wt % phosphorus, the phosphorylated succinimide dispersant providing 650 ppm or less phosphorus to the lubricating composition;

[0032] The lubricating composition has 700 ppm or less total phosphorus, and the phosphorylated succinimide dispersant provides at least 70% of the total phosphorus; and

[0033] wherein the lubricating composition has a kinematic viscosity of 3 cSt to 6.5 cSt at 100°C and a resistivity of at least 50 M Ω⋅m as measured at 1.5 volts and 30°C using the lubricating composition according to ASTM D2624-15 after aging the fluid at 150°C according to JIS K2514-1;

[0034] wherein if the lubricating base oil composition comprises an API Group V base oil, the API Group V base oil is present in an amount of up to 15 wt% based on the total lubricating composition;

[0035] Wherein if the lubricating base oil composition comprises an API Group II base oil, the API Group II is present in an amount of up to 80 wt% based on the total lubricating composition.

[0036] 2. The lubricating composition of claim 1, wherein the phosphorylated succinimide dispersant is a first dispersant, and wherein the composition further comprises a second dispersant containing 0.2 wt % to 0.4 wt % of phosphorus, the second dispersant providing 50 ppm or less of phosphorus to the lubricating composition.

[0037] 3. A lubricating composition as described in claim 1, wherein the phosphorylated succinimide dispersant contains 2.5 wt% to 3.0 wt% phosphorus; and / or wherein the phosphorylated succinimide dispersant provides 115 ppm to 600 ppm of phosphorus to the lubricating composition; and / or wherein the phosphorylated succinimide dispersant provides 115 ppm to 250 ppm of phosphorus to the lubricating composition; and / or wherein the phosphorylated succinimide dispersant provides 250 ppm or less of phosphorus to the lubricating composition, and wherein the lubricating composition has 300 ppm or less of total phosphorus.

[0038] 4. The lubricating composition of item 2, wherein the first dispersant delivers 115 ppm to 250 ppm of phosphorus to the lubricating composition, and the second dispersant delivers 40 ppm or less of phosphorus to the lubricating composition.

[0039] 5. The lubricating composition of item 1, wherein the lubricating composition has a resistivity of at least 115 MΩ⋅m after aging the fluid at 150°C according to JIS K2514-1.

[0040] 6. The lubricating composition of claim 1, wherein the base oil composition is selected from: an API Group III base oil; or a mixture of API Group II and Group III base oils.

[0041] 7. A lubricating composition as described in claim 6, wherein the phosphorylated succinimide dispersant provides between 115 ppm and 250 ppm of phosphorus to the lubricating composition; and / or the lubricating composition has between 160 ppm and 300 ppm of total phosphorus, a kinematic viscosity of 5.5 cSt to 6.0 cSt at 100°C, and a resistivity of at least 115 M Ω⋅m after aging the fluid at 150°C in accordance with JIS K2514-1.

[0042] 8. A method of increasing the resistivity of a lubricating composition in an electric vehicle, the method comprising providing a lubricating oil to an electric vehicle powertrain, the lubricating oil having a composition comprising:

[0043] At least 95 weight percent of a lubricating base oil composition, the lubricating base oil composition comprising a base oil selected from the group consisting of: an API Group III base oil; or a blend of an API Group III base oil with an API Group II or API Group V base oil; or a mixture thereof;

[0044] a phosphorylated succinimide dispersant containing 2 wt % to 3.5 wt % phosphorus, the phosphorylated succinimide dispersant providing 650 ppm or less phosphorus to the lubricating composition;

[0045] The lubricating composition has 700 ppm or less phosphorus, and the phosphorylated succinimide dispersant provides at least 70% of the total phosphorus; and

[0046] wherein the lubricating oil has a kinematic viscosity of 3 cSt to 6.5 cSt at 100°C and a resistivity of at least 50 MΩ⋅m as measured at 1.5 volts and 30°C using the lubricating composition according to ASTM D2624-15 after aging the fluid at 150°C according to JIS K2514-1; and

[0047] wherein if the lubricating base oil composition comprises an API Group V base oil, the API Group V base oil is present in an amount of up to 15 wt% based on the total lubricating composition;

[0048] Wherein if the lubricating base oil composition comprises an API Group II base oil, the API Group II is present in an amount of up to 80 wt% based on the total lubricating composition.

[0049] 9. The method of claim 8, wherein the phosphorylated succinimide dispersant is a first dispersant, and wherein the composition further comprises a second dispersant containing 0.2 wt % to 0.4 wt % phosphorus, the second dispersant providing 50 ppm or less of phosphorus to the lubricating composition.

[0050] 10. A method as described in claim 8, wherein the phosphorylated succinimide dispersant contains 2.5 wt% to 3.0 wt% phosphorus; and / or wherein the phosphorylated succinimide dispersant provides 115 ppm to 600 ppm of phosphorus to the lubricating composition; and / or wherein the phosphorylated succinimide dispersant provides 115 ppm to 250 ppm of phosphorus to the lubricating composition.

[0051] 11. The method of clause 9, wherein the first dispersant delivers 115 ppm to 250 ppm of phosphorus to the lubricating composition, and the second dispersant delivers 40 ppm or less of phosphorus to the lubricating composition.

[0052] 12. The method of clause 8, wherein the phosphorylated succinimide dispersant provides 250 ppm or less phosphorus to the lubricating composition, and wherein the lubricating composition has 300 ppm or less total phosphorus.

[0053] 13. The method of clause 8, wherein the lubricating composition has a resistivity of at least 115 MΩ⋅m after aging the fluid at 150°C in accordance with JIS K2514-1.

[0054] 14. The method of claim 8, wherein the base oil composition is selected from: API Group III base oil; or a blend of API Group II and Group III base oils; or a mixture thereof.

[0055] 15. The method of claim 14, wherein the phosphorylated succinimide dispersant provides 115 ppm to 250 ppm of phosphorus to the lubricating composition, and the lubricating composition has 160 ppm to 300 ppm of total phosphorus, a kinematic viscosity of 5.5 cSt to 6.0 cSt at 100°C, and a resistivity of at least 115 MΩ⋅m after aging the fluid at 150°C in accordance with JIS K2514-1. DETAILED DESCRIPTION

[0056] According to exemplary embodiments, described herein is a lubricating fluid for an electric or hybrid electric vehicle, the lubricating fluid containing a base oil and at least one phosphorylated succinimide dispersant having 2.0 wt % to 3.5 wt % phosphorus. In one embodiment, the phosphorylated succinimide dispersant having 2.0 wt % to 3.5 wt % phosphorus delivers less than 650 ppm phosphorus to the lubricating fluid. In other embodiments, the phosphorylated succinimide dispersant has 2.5 wt % to 3.2 wt % phosphorus, in other embodiments, the phosphorylated succinimide dispersant has 2.8 wt % to 3.2 wt % phosphorus, and in further embodiments, the phosphorylated succinimide dispersant has about 3 wt % phosphorus. In any embodiment herein, the phosphorylated succinimide dispersant can provide up to 650 ppm of phosphorus to the fluid, up to 600 ppm of phosphorus to the fluid, up to 500 ppm of phosphorus, up to 400 ppm of phosphorus, up to 300 ppm of phosphorus, or up to 250 ppm of phosphorus. In other embodiments, the phosphorylated succinimide dispersant can provide at least 100 ppm of phosphorus, at least 120 ppm of phosphorus, or at least 150 ppm of phosphorus to the fluid herein.

[0057] Fluid herein can also contain other phosphorus sources, but the total phosphorus content of fluid can be 700 ppm or less, 650ppm or less, 600ppm or less, 550ppm or less, 500ppm or less, 450ppm or less, 400ppm or less, 350ppm or less, 300ppm or less, 250ppm or less or 200ppm or less.Fluid can also include 100ppm or more total phosphorus.In the embodiment with other phosphorus sources, the phosphorus provided by the phosphorylated succinimide dispersant provides at least about 70%, at least about 75%, at least about 80%, at least about 90% or even at least about 92% of the total phosphorus in the fluid.In other ways, the phosphorus provided by the phosphorylated succinimide dispersant provides 100% of total phosphorus or less, 98% of total phosphorus or less, 95% or less or 90% or less.

[0058] As discussed in more detail below, the fluids herein having a base oil and at least one phosphated succinimide dispersant typically have a kinematic viscosity of 3 cSt to 6.5 cSt at 100°C as measured according to ASTM D2624-15 (at 1.5 volts and 30°C using the lubricating composition as described herein) after aging the fluid at 150°C according to JIS K2514-1 and have a resistivity of at least 50 MΩ⋅m.

[0059] Base Oil:Base oils suitable for formulating lubricating fluids for electric vehicles according to the present disclosure may be selected from any suitable synthetic or natural oils or mixtures thereof having a suitable lubricating viscosity.

[0060] Natural oils may include animal and vegetable oils (eg, castor oil, lard oil) and mineral oils such as liquid petroleum and solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types.

[0061] Oil derived from coal or shale may also be applicable. In addition, oil derived from the Fischer-Tropsch gas-to-liquid process is also applicable. The hydrocarbons synthesized by Fischer-Tropsch are prepared by using a Fischer-Tropsch catalyst from a synthesis gas containing H2 and CO. Such hydrocarbons generally require further processing to be used as base oils. These types of oils are generally referred to as gas-to-liquid (GTL). For example, hydrocarbons may be hydroisomerized using the process disclosed in U.S. Patent Nos. 6,103,099 or 6,180,575; hydrocracking and hydroisomerization using the process disclosed in U.S. Patent Nos. 4,943,672 or 6,096,940; dewaxing using the process disclosed in U.S. Patent No. 5,882,505; or hydroisomerization and dewaxing using the process disclosed in U.S. Patent Nos. 6,013,171, 6,080,301 or 6,165,949. The base oil may have a kinematic viscosity at 100°C of 2 to 15 cSt as measured by ASTM D2270-10 (2016).

[0062] The base oil used in the present invention as herein described can be a single base oil or can be a mixture of two or more base oils. One or more base oils can be selected from any base oil in the II to V class specified in the American Petroleum Institute (API) base oil interchangeability guide. In some embodiments, the base oil is a combination of one or more of Class III base oil or Class III base oil and Class II or Class V base oil. These base oils are shown in the following table 1:

[0063] Table 1

[0064]

[0065] In a variation, in any of the foregoing embodiments, the base oil may be selected from a group II to a group V base oil, or a mixture of these base oils. In one embodiment, the base oil comprises a group III base oil or a blend of a group III base oil with a group II and / or group V base oil. In one embodiment, the lubricating composition comprises at least 75 wt% of a group II and / or group III base oil. In another embodiment, the lubricating composition comprises at least 90 wt% of a group III base oil. In another embodiment, the lubricating composition comprises at least 10 wt% of a group V base oil.

[0066] In other embodiments, when the lubricating composition includes a Group V base oil, the Group V base oil is present in the lubricating composition in an amount ranging from at least about 5 wt%, at least about 8 wt%, or at least about 10 wt% and / or up to 20 wt%, up to 15 wt%, or up to 12 wt% (with the remainder being Group III base oil). In other embodiments, when the lubricating composition includes a Group II base oil, the Group II base oil is present in the lubricating composition in an amount ranging from at least about 50 wt%, at least about 75 wt%, or at least about 77 wt% and / or up to 80 wt%, up to 78 wt%, or up to 77 wt% (with the remainder being Group II and / or Group V base oils).

[0067] V-class base oils include synthetic and natural ester base oils. Synthetic esters can include esters of dicarboxylic acids and monohydric alcohols. Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, behenyl sebacate, and the 2-ethylhexyl diester of linoleic acid dimer. Other synthetic esters include C5 to C 12 Those made from monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol and tripentaerythritol, etc. The esters may also be monoesters of monocarboxylic acids and monohydric alcohols.

[0068] Natural esters refer to substances derived from renewable biological resources, organisms or entities, other than substances derived from petroleum or equivalent raw materials. Natural esters include fatty acid triglycerides, hydrolyzed or partially hydrolyzed triglycerides, or transesterified triglycerides, such as fatty acid methyl esters (or FAME). Suitable triglycerides include, but are not limited to, palm oil, soybean oil, sunflower oil, rapeseed oil, olive oil, linseed oil, and related substances.

[0069] The base oil can be combined with the additive composition disclosed in the embodiments as herein to provide a lubricating fluid for an electric vehicle. Thus, the base oil can be present in the lubricating fluid in an amount greater than about 90 wt % by the total weight of the lubricating fluid. In some embodiments, the base oil can be present in the lubricating fluid in an amount greater than about 95 wt % by the total weight of the lubricating fluid.

[0070] Additive composition

[0071] Phosphated succinimide dispersant: The lubricating fluids described herein contain at least one phosphorylated succinimide dispersant.

[0072] Hydrocarbyl dicarboxylic acids or anhydrides are reacted with polyalkylene polyamines to prepare succinimide dispersants. Succinimide dispersants and their preparation are disclosed in, for example, U.S. Patent No. 7,897,696 and U.S. Patent No. 4,234,435, which are incorporated herein by reference. The hydrocarbyl moiety of the hydrocarbyl dicarboxylic acid or anhydride can be derived from a butene polymer, such as a polymer of isobutylene. Suitable polyisobutylenes suitable for use herein include those formed from conventional polyisobutylene or a highly reactive polyisobutylene having at least about 60% (such as about 70% to 90% and above) terminal vinylidene content. Suitable polyisobutylenes may include those prepared using a BF3 catalyst.

[0073] The number average molecular weight of the polyisobutylene substituent can vary over a wide range, for example, from 500 to 5000 as measured by gel permeation chromatography (GPC) using polystyrene (which has a number average molecular weight of 180 to about 18,000) as a calibration reference. The GPC method additionally provides molecular weight distribution information; see, for example, WW Yau, JJ Kirkland and DD Bly, Modern Size Exclusion Liquid Chromatography, John Wiley and Sons, New York, 1979, which is also incorporated herein by reference.

[0074] The polyisobutylene portion of the dispersant preferably has a polydispersity index (PDI), which is determined by the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn). Polymers with Mw / Mn less than 2.2, preferably less than 2.0, are most desirable. Suitable polyisobutylene substituents have a polydispersity of about 1.5 to 2.1, or about 1.6 to about 1.8.

[0075] The dicarboxylic acid or anhydride can be selected from carboxylic acid reactants, such as maleic anhydride, maleic acid, fumaric acid, malic acid, tartaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, ethyl maleic anhydride, dimethyl maleic anhydride, ethyl maleic acid, dimethyl maleic acid, hexyl maleic acid, etc., including corresponding acyl halides and C1-C4 aliphatic esters. The molar ratio of the dicarboxylic acid or anhydride to the alkyl part in the reaction mixture for preparing the alkyl-dicarboxylic acid or anhydride can be widely varied. Therefore, the molar ratio can be varied to 5:1 to 1:5, for example 3:1 to 1:3. The particularly suitable molar ratio of acid or anhydride to the alkyl part is 1:1 to less than 1.6:1. Another useful molar ratio of the dicarboxylic acid or anhydride to the alkyl part is 1:1 to 1.7:1 or 1:1 to 1.6:1 or 1:1 to 1.5:1.

[0076] Any of many polyalkylene polyamines can be used as a dispersant additive. Non-limiting exemplary polyamines can include aminoguanidine bicarbonate (AGBC), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA) and heavy polyamines. Heavy polyamines can include a mixture of polyalkylene polyamines with a small amount of polyamine oligomers, such as TEPA and PEHA, but mainly oligomers with seven or more nitrogen atoms, two or more primary amines per molecule, and more extensive branching than conventional polyamine mixtures. Typically, these heavy polyamines have an average of 6.5 nitrogen atoms per molecule. Other non-limiting polyamines that can be used to prepare alkyl-substituted succinimide dispersants are disclosed in U.S. Patent No. 6,548,458, the disclosure of which is incorporated herein by reference in its entirety. The molar ratio of alkyl-dicarboxylic acid or anhydride to polyalkylene polyamines can be from about 1:1 to about 3:1.

[0077] The dispersants described herein are phosphated. These dispersants are typically the reaction product of at least one phosphorus compound and at least one ashless succinimide dispersant as described above.

[0078] Suitable phosphorus compounds for forming the dispersants herein include phosphorus compounds or mixtures of phosphorus compounds capable of introducing phosphorus-containing materials into the ashless dispersant. Thus, any organic or inorganic phosphorus compound capable of such a reaction may be used. Thus, such inorganic phosphorus compounds as inorganic phosphoric acid and inorganic phosphorus oxides, including their hydrates, may be used. Typical organophosphorus compounds include full and partial esters of phosphoric acid, such as monoesters, diesters and triesters of phosphoric acid, thiophosphoric acid, dithiophosphoric acid, trithiophosphoric acid and tetrathiophosphoric acid; monoesters, diesters and triesters of phosphorous acid, thiophosphorous acid, dithiophosphorous acid and trithiophosphorous acid; trihydrocarbyl phosphine oxides; trihydrocarbyl phosphine sulfides; mono- and dihydrocarbyl phosphonates (RPO(OR')(OR"), wherein R and R' are hydrocarbyl groups, and R" is a hydrogen atom or a hydrocarbyl group) and their mono-, di- and trithio analogs; mono- and dihydrocarbyl phosphites (RP(OR')(OR"), wherein R and R' are hydrocarbyl groups, and R" is a hydrogen atom or a hydrocarbyl group) and their mono- and dithio analogs; and the like. Thus, compounds such as phosphorous acid (H3PO3, sometimes described as H2(HPO3) and sometimes referred to as orthophosphorous acid or phosphonic acid), phosphoric acid (H3PO4, sometimes referred to as orthophosphoric acid), hypophosphorous acid (H4P2O6), metaphosphoric acid (HPO3), pyrophosphoric acid (H4P2O7), hypophosphorous acid (H3PO2, sometimes referred to as phosphinic acid), pyrophosphorous acid (H4P2O5, sometimes referred to as pyrophosphoric acid), phosphinic acid (H3PO), tripolyphosphoric acid (H5P3O 10 ), tetrapolyphosphate (H5P4O 13), trimetaphosphoric acid (H3P3O9), phosphorus trioxide, phosphorus tetroxide, phosphorus pentoxide, etc. Partial sulfur or full sulfur analogs such as tetrathiophosphoric acid (H3PS4), thiophosphoric acid (H3PO3S), dithiophosphoric acid (H3PO2S2), trithiophosphoric acid (H3POS3), phosphorus sesquisulfide, phosphorus heptasulfide and phosphorus pentasulfide (P2S5, sometimes called P4S 10 ), can also be used to form the dispersant of the present disclosure. Inorganic phosphorus halides can also be used, such as PCl3, PBr3, POCl3, PSCl3, etc.

[0079] Likewise, organophosphorus compounds may be used, such as monoesters, diesters, and triesters of phosphoric acid (e.g., trialkyl phosphates, dialkyl monoacid phosphates, monoalkyl diacid phosphates, and mixtures thereof), monoesters, diesters, and triesters of phosphorous acid (e.g., trialkyl phosphites, dialkyl hydrogen phosphites, hydrocarbon diacid phosphites, and mixtures thereof), phosphonates ("primary" RP(O)(OR)2 and "secondary" R2P(O)(OR)), phosphinates, phosphonyl halides (e.g., RP(O)Cl2 and R2P(O)Cl), halogenated Phosphites (e.g., (RO)PCl2 and (RO)2PCl), halophosphates (e.g., ROP(O)Cl2 and (RO)2P(O)Cl), tertiary pyrophosphates (e.g., (RO)2P(O)—O—P(O)(OR)2), and all- or partially-sulfur analogs of any of the foregoing organophosphorus compounds, wherein each hydrocarbyl group contains up to about 100 carbon atoms, preferably up to about 50 carbon atoms, more preferably up to about 24 carbon atoms, and most preferably up to about 12 carbon atoms. Halophosphine halides (e.g., hydrocarbyl phosphorus tetrahalides, dihydrocarbyl phosphorus trihalides, and trihydrocarbyl phosphorus dihalides) and halophosphines (monohalogenated and dihalogenated phosphines) may also be used.

[0080] In embodiments, the phosphorylated dispersant is the reaction product of a succinimide molecule and a phosphorus source. In one example, polyisobutyl succinimide (PIBSI) or other suitable succinimide is heated to about 100 ° C. Phosphoric acid or other phosphorus sources are then added under a slight vacuum (700 mm Hg) and kept for 30 minutes to 1 hour (to remove any water). Next, slowly warm to about 160 ° C and then keep for about 2 hours. Finally, the solution is placed under vacuum and kept for about 1 to 2 hours to form a phosphorylated succinimide dispersant.

[0081] In some embodiments, the succinimide dispersant can also be optionally further post-processed with a boron source. Suitable boron compounds that can be used to form the dispersant herein include any boron compound or a mixture of boron compounds that can introduce boron-containing substances into the ashless dispersant. Any organic or inorganic boron compound that can react can be used. Therefore, boron oxide, boron oxide hydrate, boron trifluoride, boron tribromide, boron trichloride, HBF4 boric acid such as borous acid (e.g., alkyl-B (OH) 2 or aryl-B (OH) 2), boric acid (i.e., H3BO3), tetraboric acid (i.e., H2B5O7), metaboric acid (i.e., HBO2), ammonium salts of such boric acids and esters of such boric acids can be used. Using a complex of boron trihalide with ether, organic acid, inorganic acid or hydrocarbon is a convenient method for introducing a boron reactant into a reaction mixture. Such complexes are known, for example boron trifluoride-diethyl ether, boron trifluoride-phenol, boron trifluoride-phosphoric acid, boron trichloride-chloroacetic acid, boron tribromide-dioxane and boron trifluoride-methyl ethyl ether.

[0082] In some embodiments, the dispersant used in the present disclosure comprises a polyisobutylene moiety having a number average molecular weight in the range of about 800 to 2500, or 900 to 1200, or 975 to 1175 and is present in the lubricating fluid in an amount sufficient to deliver greater than 50 ppm nitrogen, or greater than 100 ppm nitrogen, or greater than 250 ppm nitrogen, or between 50 and 300 ppm nitrogen, or between 50 and 120 ppm nitrogen, or between 120 and 300 ppm nitrogen.

[0083] The dispersant used in the present invention is present in the lubricating fluid in an amount sufficient to deliver greater than 100 ppm phosphorus, or greater than 200 ppm phosphorus, or greater than 550 ppm phosphorus, or between 100 and 700 ppm phosphorus, or between 100 and 300 ppm phosphorus, or between 300 and 700 ppm phosphorus.

[0084] In one embodiment, the dispersant in the invention described herein can be obtained from HR-PIB having an Mn between 975 and 1175, an Mw between 1700 and 2100, and a PDI of 1.8 or less in some embodiments. In addition, the dispersant can have a molar ratio of (A) polyisobutylene-substituted succinic anhydride to (B) polyamine ranging from 4:3 to 5:2, and a phosphorus content between 2.5 wt% and 3.25 wt%.

[0085] As shown in the Examples herein, when a succinimide dispersant having 2.0 wt% to 3.5 wt% (in other embodiments 2.5 to 3.2 wt%, 2.8 to 3.2 wt%, or about 3 wt%) phosphorus is present in a lubricating fluid in an amount to deliver between 100 and 650 ppm phosphorus (or other ranges as disclosed herein), the resulting composition has increased resistivity and suitable wear protection and copper compatibility even after aging.

[0086] Other additives: The lubricating fluids described herein may also include one or more of at least one component selected from the group consisting of antioxidants, friction modifiers, detergents, corrosion inhibitors, copper corrosion inhibitors, defoamers, seal swell agents, extreme pressure agents, anti-wear agents, viscosity modifiers, additional dispersants, and combinations thereof. In addition to those noted above, other performance additives may also include one or more of metal passivators, demulsifiers, pour point depressants, and mixtures thereof.

[0087] Antioxidants: In some embodiments, the lubricating fluid contains one or more antioxidants. Suitable antioxidants include phenolic antioxidants, aromatic amine antioxidants, sulfur-containing antioxidants, and organic phosphites.

[0088] Examples of phenolic antioxidants include: 2,6-di-tert-butylphenol, liquid mixtures of tert-butylated phenols, 2,6-di-tert-butyl-4-methylphenol, 4,4'-methylenebis(2,6-di-tert-butylphenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol) and mixed methylene bridged polyalkylphenols, and 4,4'-thiobis(2-methyl-6-tert-butylphenol). N,N'-di-sec-butyl-phenylenediamine, 4-isopropylaminodiphenylamine, phenyl-α-naphthylamine, phenyl-α-naphthylamine and cycloalkylated diphenylamine. Examples include hindered tert-butylphenol, bisphenol and cinnamic acid derivatives and combinations thereof.

[0089] Aromatic amine antioxidants include, but are not limited to, diarylamines having the formula:

[0090]

[0091] wherein R' and R" each independently represent a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. Examples of substituents of the aryl group include aliphatic hydrocarbon groups such as: alkyl groups having 1 to 30 carbon atoms; hydroxyl groups; halogen radicals; carboxylic acid or ester groups; or nitro groups.

[0092] The aryl group is preferably a substituted or unsubstituted phenyl or naphthyl group, in particular, wherein one or both aryl groups are substituted by at least one alkyl group having 4 to 30 carbon atoms, preferably 4 to 18 carbon atoms, most preferably 4 to 9 carbon atoms. Preferably, one or both aryl groups are substituted, for example monoalkylated diphenylamine, dialkylated diphenylamine, or a mixture of mono- and dialkylated diphenylamines.

[0093] Examples of diarylamines that can be used include, but are not limited to: diphenylamine; various alkylated diphenylamines; 3-hydroxydiphenylamine; N-phenyl-1,2-phenylenediamine; N-phenyl-1,4-phenylenediamine; monobutyldiphenylamine; dibutyldiphenylamine; monooctyldiphenylamine; dioctyldiphenylamine; monononyldiphenylamine; dinonyldiphenylamine; monotetradecyldiphenylamine; tetracosyldiphenylamine; phenyl-α-naphthylamine; monooctylphenyl-α-naphthylamine; phenyl-β-naphthylamine; monoheptyldiphenylamine; diheptyldiphenylamine; para-styrenated diphenylamine; mixed butyloctyldiphenylamines; and mixed octylstyryldiphenylamines.

[0094] Sulfur-containing antioxidants include, but are not limited to, sulfurized olefins, characterized by the type of olefin used in their production and the final sulfur content of the antioxidant. High molecular weight olefins (i.e., those olefins having an average molecular weight of 168 to 351 g / mole) are preferred. Examples of olefins that can be used include: alpha-olefins, isomerized alpha-olefins, branched olefins, cyclic olefins, and combinations thereof.

[0095] Alpha-olefins include, but are not limited to, any C4 to C25 alpha-olefins. The alpha-olefins may be isomerized prior to or during the sulfurization reaction. Structural and / or conformational isomers of alpha-olefins containing internal double bonds and / or branching may also be used. For example, isobutylene is the branched olefin counterpart of the alpha-olefin 1-butene.

[0096] Sulfur sources that can be used in the olefin sulfurization reaction include elemental sulfur, sulfur monochloride, sulfur dichloride, sodium sulfide, sodium polysulfide and mixtures thereof, which are added together or at different stages of the sulfurization process.

[0097] Unsaturated oils, due to their unsaturation, can also be sulfurized and used as antioxidants. Examples of oils or fats that can be used include corn oil, canola oil, cottonseed oil, grapeseed oil, olive oil, palm oil, peanut oil, coconut oil, rapeseed oil, safflower oil, sesame seed oil, soybean oil, sunflower seed oil, tallow, and combinations of these.

[0098] The total amount of antioxidant in the lubricating fluids described herein may be present in an amount to deliver up to 200 ppm nitrogen, or up to 100 ppm nitrogen, or up to 150 ppm nitrogen, or between 100 and 150 ppm nitrogen.

[0099] Friction Modifiers:Additional suitable friction modifiers may include metal-containing and metal-free friction modifiers and may include, but are not limited to, imidazolines, aliphatic fatty acid amides, fatty amines, succinimides, alkoxylated fatty amines, etheramines, alkoxylated etheramines, amine oxides, amidoamines, nitriles, betaines, quaternary ammonium, imines, amine salts, aminoguanidine, alkanolamides, phosphonates, metal-containing compounds, glycerides, sulfurized fatty compounds and olefins, sunflower oil and other naturally occurring plant or animal oils, dicarboxylic acid esters, esters or partial esters of polyols and one or more aliphatic or aromatic carboxylic acids, and the like.

[0100] Suitable friction modifiers may contain a hydrocarbon group selected from a linear, branched or aromatic hydrocarbon group or a mixture thereof, and such hydrocarbon groups may be saturated or unsaturated. The hydrocarbon group may be composed of carbon and hydrogen or heteroatoms (such as sulfur or oxygen). The hydrocarbon group may be between 12 and 25 carbon atoms. In some embodiments, the friction modifier may be a long-chain fatty acid ester. In another embodiment, the long-chain fatty acid ester may be a monoester or a diester or a (tri) glyceride. The friction modifier may be a long-chain fatty amide, a long-chain fatty ester, a long-chain fatty epoxide derivative or a long-chain imidazoline.

[0101] Other suitable friction modifiers may include organic, ashless (metal-free), nitrogen-free organic friction modifiers. Such friction modifiers may include esters formed by reacting carboxylic acids and anhydrides with alkanols, and generally include polar end groups (e.g., carboxyl or hydroxyl groups) covalently bonded to oleophilic hydrocarbon chains. An example of an organic ashless, nitrogen-free friction modifier is generally known as glyceryl monooleate (GMO), which may contain monoesters, diesters, and triesters of oleic acid. Other suitable friction modifiers are described in U.S. Pat. No. 6,723,685.

[0102] Amine friction modifiers may include amines or polyamines. Such compounds may have straight chain saturated or unsaturated hydrocarbon groups or mixtures thereof, and may contain 12 to 25 carbon atoms. Other examples of suitable friction modifiers include alkoxylated amines and alkoxylated ether amines. Such compounds may have straight chain, saturated or unsaturated hydrocarbon groups, or mixtures thereof. They may contain from about 12 to about 25 carbon atoms. Examples include ethoxylated amines and ethoxylated ether amines.

[0103] The amines and amides may be used as such or as adducts or reaction products with boron compounds such as boron oxide, boron halides, metaborates, boric acid or mono-, di- or tri-alkyl borate. Other suitable friction modifiers are described in US Pat. No. 6,300,291.

[0104] If the additional friction modifier contains nitrogen, such additional friction modifier may be present in the lubricating fluid in an amount to deliver up to 200 ppm nitrogen, or up to 150 ppm nitrogen, or between 100 and 150 ppm nitrogen.

[0105] Cleaners: The metal detergent that can be included in the lubricating fluid described herein generally comprises a polar head with a long hydrophobic tail, wherein the polar head comprises a metal salt of an acidic organic compound. The salt can contain a substantially stoichiometric amount of metal, in which case they are generally described as a normal salt or a neutral salt, and generally have a total base number or TBN (measured by ASTM D2896) of 0 to less than 150. By reacting an excess of a metallic compound (such as an oxide or hydroxide) with an acidic gas (such as carbon dioxide), a large amount of metallic alkali can be included. The resulting high alkalinity detergent comprises a micelle of a neutralizing detergent around an inorganic metal base (such as a hydrated carbonate) core. Such high alkalinity detergents can have a TBN of 150 or more, such as 150 to 450 or more.

[0106] Detergents that may be suitable for use in embodiments of the present invention include oil-soluble high-based, low-based and neutral sulfonates, phenates, sulfurized phenates and metal salicylates, particularly alkali metals or alkaline earth metals, such as sodium, potassium, lithium, calcium and magnesium. More than one metal may be present, such as calcium and magnesium. Mixtures of calcium and / or magnesium with sodium may also be suitable. Suitable metal detergents may be high-based calcium or magnesium sulfonates having a TBN of 150 to 450 TBN, high-based calcium or magnesium phenates or sulfurized phenates having a TBN of 150 to 300 TBN, and high-based calcium or magnesium salicylates having a TBN of 130 to 350. Mixtures of these salts may also be used.

[0107] The metal-containing detergent may be present in the lubricating fluid in an amount sufficient to improve the rust resistance of the fluid. The metal-containing detergent may be present in the fluid in an amount sufficient to provide up to 300 ppm of alkali metals and / or alkaline earth metals, based on the total weight of the lubricating fluid. In one example, the metal-containing detergent may be present in an amount sufficient to provide 100 to 300 ppm of alkali metals and / or alkaline earth metals. In another embodiment, the metal-containing detergent may be present in an amount sufficient to provide 220 to 250 ppm of alkali metals and / or alkaline earth metals.

[0108] Corrosion Inhibitors:Rust inhibitors or corrosion inhibitors may also be included in the lubricating compositions described herein. Suitable copper corrosion inhibitors include etheramines, polyethoxylated compounds such as ethoxylated amines and ethoxylated alcohols, imidazolines, mono- and di-alkyl thiadiazoles, and the like. Additional compounds include monocarboxylic acids and polycarboxylic acids. Examples of suitable monocarboxylic acids are octanoic acid, decanoic acid, and dodecanoic acid. Suitable polycarboxylic acids include dimer acids and trimer acids, such as those produced from acids such as tall oil fatty acid, oleic acid, linoleic acid, or the like.

[0109] Thiazoles, triazoles and thiadiazoles may also be used in lubricants. Examples include: benzotriazole; toluenetriazole; octyltriazole; decyltriazole; dodecyltriazole; 2-mercaptobenzotriazole; 2,5-dimercapto-1,3,4-thiadiazole; 2-mercapto-5-alkylthio-1,3,4-thiadiazole; and 2-mercapto-5-alkylthio-1,3,4-thiadiazole. Preferred compounds are 1,3,4-thiadiazoles, especially 2-alkyldithio-5-mercapto-1,3,4-dithiadiazoles, many of which are commercially available.

[0110] Another type of useful rust inhibitor may be the alkenyl succinic acid and alkenyl succinic anhydride corrosion inhibitors such as, for example, tetrapropenyl succinic acid, tetrapropenyl succinic anhydride, tetradecenyl succinic acid, tetradecenyl succinic anhydride, hexadecenyl succinic acid, hexadecenyl succinic anhydride, etc. Also useful are the half esters of alkenyl succinic acids having 8 to 24 carbon atoms in the alkenyl group with alcohols such as polyethylene glycol.

[0111] Mixtures of such rust or corrosion inhibitors may be used.When present in the lubricating compositions described herein, the total amount of corrosion inhibitor may range up to 2.0 wt% or 0.01 to 1.0 wt%, based on the total weight of the lubricating composition.

[0112] Extreme pressure agent:The lubricating fluids described herein may optionally include one or more extreme pressure (EP) agents. EP agents soluble in oil include sulfur-containing and chlorine-containing sulfur-containing EP agents, chlorinated hydrocarbon EP agents, and phosphorus EP agents. Examples of such EP agents include: chlorinated waxes; organic sulfides and polysulfides, such as dibenzyl disulfide, bis(chlorobenzyl) disulfide, dibutyl tetrasulfide, methyl sulfide of oleic acid, sulfide of alkylphenols, sulfide of dipentene, sulfide of terpenes, and sulfide of Diels-Alder adducts; phosphosulfurized hydrocarbons, such as the reaction product of phosphorus sulfide with turpentine or methyl oleate; phosphorus esters, such as di- and tri-alkyl phosphites, for example, dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, amylphenyl phosphite; diamylphenyl phosphite, tridecyl phosphite, distearyl phosphite, and phenyl phosphite substituted with polypropylene; metal thiocarbamates, such as zinc dioctyldithiocarbamate and barium heptylphenol dioate; amine salts of alkyl and dialkyl phosphoric acids, including, for example, amine salts of the reaction product of dialkyldithiophosphoric acids with propylene oxide; and mixtures thereof.

[0113] Antiwear agents: The lubricating oil compositions herein may also optionally contain one or more antiwear agents. Examples of suitable antiwear agents include, but are not limited to: metal thiophosphates; metal dialkyl dithiophosphates; phosphates or salts thereof; phosphate esters; phosphites; phosphorus-containing carboxylates, ethers or amides; sulfurized olefins; compounds containing thiocarbamates, including thiocarbamates, alkylene-coupled thiocarbamates, and bis(S-alkyldithiocarbamoyl)disulfides; and mixtures thereof. A suitable antiwear agent may be molybdenum dithiocarbamates. Phosphorus-containing antiwear agents are more fully described in European Patent 612 839. The metal in the dialkyl dithiophosphate may be an alkali metal, an alkaline earth metal, aluminum, lead, tin, molybdenum, manganese, nickel, copper, titanium or zinc.

[0114] Further examples of suitable antiwear agents include titanium compounds, tartrates, tartrimides, oil-soluble amine salts of phosphorus compounds, sulphurized olefins, phosphites (such as dibutyl phosphite), phosphonates, thiocarbamate-containing compounds (such as thiocarbamates, thiocarbamate amides, thiocarbamate ethers, alkylene coupled thiocarbamates and bis (S-alkyl dithiocarbamoyl) disulfides). The tartrate or tartrimide may contain an alkyl ester group, wherein the total number of carbon atoms in the alkyl group may be at least 8. In one embodiment, the antiwear agent may include a citrate ester.

[0115] Antiwear agents may be present in ranges including about 0 wt % to about 15 wt %, in other approaches about 0.01 wt % to about 10 wt %, in other approaches about 0.05 wt % to about 5 wt %, or in further approaches about 0.1 wt % to about 3 wt % of the lubricating oil composition.

[0116] Viscosity Modifiers: The lubricating fluid may optionally contain one or more viscosity modifiers. Suitable viscosity modifiers may include: polyolefins, olefin copolymers, ethylene / propylene copolymers, polyisobutylene, hydrogenated styrene-isoprene polymers, styrene / maleate copolymers, hydrogenated styrene / butadiene copolymers, hydrogenated isoprene polymers, alpha-olefin maleic anhydride copolymers, polymethacrylates, polyacrylates, polyalkylstyrenes, hydrogenated alkenyl aryl conjugated diene copolymers, or mixtures thereof. Viscosity modifiers may include star polymers, and suitable examples are described in U.S. Publication No. 2012 / 0101017 A1.

[0117] In addition to or in place of a viscosity modifier, the lubricating fluids described herein may optionally contain one or more dispersant viscosity modifiers. Suitable dispersant viscosity modifiers may include functionalized polyolefins, such as ethylene-propylene copolymers that have been functionalized with the reaction product of an acylating agent (such as maleic anhydride) and an amine; polymethacrylates functionalized with amines, or esterified maleic anhydride-styrene copolymers reacted with amines.

[0118] The total amount of viscosity modifier and / or dispersant viscosity modifier (when present) may be up to 1.0 wt%, or up to 0.5 wt%, or up to 0.3 wt%, based on the total weight of the lubricating fluid.

[0119] Additional dispersants: The lubricating fluid may include one additional dispersant more than the above-mentioned phosphorylated succinimide dispersant. The additional dispersant is an ashless dispersant having a polar group attached to a relatively high molecular weight hydrocarbon chain. Examples of such dispersants are N-substituted long chain alkenyl succinimides, succinate dispersants, succinate-amide dispersants, Mannich base dispersants, polymeric polyamine dispersants, phosphorylated forms thereof, and boronized forms thereof. The dispersant may be terminated with an acidic molecule capable of reacting with a secondary amino group.

[0120] The N-substituted long chain alkenyl succinimide may include a polyisobutylene (PIB) substituent, wherein the number average molecular weight of the polyisobutylene substituent as determined by the above-mentioned GPC method is in the range of about 500 to 5000. The PIB substituent for the dispersant also has a viscosity of about 2100 to about 2700 cSt at 100° C. as determined by ASTM D445.

[0121] The polyisobutylene portion of the dispersant preferably has a narrow molecular weight distribution (MWD), also referred to as polydispersity, as determined by the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn). Polymers with Mw / Mn less than 2.2, preferably less than 2.0, are most desirable. Suitable polyisobutylene substituents have a polydispersity of about 1.5 to 2.1, or about 1.6 to about 1.8.

[0122] The dicarboxylic acid or anhydride can be selected from carboxylic acid reactants, such as maleic anhydride, maleic acid, fumaric acid, malic acid, tartaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, ethyl maleic anhydride, dimethyl maleic anhydride, ethyl maleic acid, dimethyl maleic acid, hexyl maleic acid, etc., including corresponding acyl halides and C1-C4 aliphatic esters. The molar ratio of the dicarboxylic acid or anhydride to the alkyl part in the reaction mixture for preparing the alkyl-dicarboxylic acid or anhydride can be widely varied. Therefore, the molar ratio can be varied to 5:1 to 1:5, for example 3:1 to 1:3. The particularly suitable molar ratio of acid or anhydride to the alkyl part is 1:1 to less than 1.6:1. Another useful molar ratio of dicarboxylic acid or anhydride to the alkyl part is 1.3:1 to 1.7:1 or 1.3:1 to 1.6:1 or 1.3:1 to 1.5:1.

[0123] Any of many polyalkylene polyamines can be used as a dispersant additive. Non-limiting exemplary polyamines can include aminoguanidine bicarbonate (AGBC), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA) and heavy polyamines. Heavy polyamines can include a mixture of polyalkylene polyamines with a small amount of polyamine oligomers, such as TEPA and PEHA, but mainly oligomers with seven or more nitrogen atoms, two or more primary amines per molecule, and more extensive branching than conventional polyamine mixtures. Typically, these heavy polyamines have an average of 6.5 nitrogen atoms per molecule. Other non-limiting polyamines that can be used to prepare alkyl-substituted succinimide dispersants are disclosed in U.S. Patent No. 6,548,458, the disclosure of which is incorporated herein by reference in its entirety. The molar ratio of alkyl-dicarboxylic acid or anhydride to polyalkylene polyamines can be from about 1:1 to about 3.0:1.

[0124] Mannich base dispersants can be the reaction product of an alkylphenol, typically having long chain alkyl substituents on the ring, with one or more aliphatic aldehydes containing from about 1 to about 7 carbon atoms, especially formaldehyde and its derivatives, and a polyamine, especially a polyalkylene polyamine. For example, a Mannich base ashless dispersant can be formed by condensing a long chain hydrocarbon substituted phenol having about a molar ratio of about 1 mole to about 2.5 moles of formaldehyde and about 0.5 mole to about 2 moles of a polyalkylene polyamine.

[0125] The additional dispersants described herein may be boronated and / or phosphated. Such dispersants are typically the reaction product of i) at least one phosphorus compound and / or boron compound and ii) at least one ashless dispersant.

[0126] Suitable boron compounds that can be used to form the dispersant of this article include any boron compound or mixture of boron compounds that can introduce boron-containing substances into the ashless dispersant. Any organic or inorganic boron compound that can carry out this reaction can be used. Therefore, boron oxide, boron oxide hydrate, boron trifluoride, boron tribromide, boron trichloride, HBF4boric acid such as borous acid (e.g., alkyl-B (OH) 2 or aryl-B (OH) 2), boric acid (i.e., H3BO3), tetraboric acid (i.e., H2B5O7), metaboric acid (i.e., HBO2), ammonium salts of such boric acids and esters of such boric acids can be used. Using a complex of a trihalide boron with an ether, an organic acid, an inorganic acid or a hydrocarbon is a convenient method for introducing a boron reactant into a reaction mixture. Such complexes are known, such as boron trifluoride-diethyl ether, boron trifluoride-phenol, boron trifluoride-phosphoric acid, boron trichloride-chloroacetic acid, boron tribromide-dioxane and boron trifluoride-methyl ethyl ether.

[0127] Suitable phosphorus compounds for forming the dispersants herein include phosphorus compounds or mixtures of phosphorus compounds capable of introducing phosphorus-containing materials into the ashless dispersant. Thus, any organic or inorganic phosphorus compound capable of such a reaction may be used. Thus, such inorganic phosphorus compounds as inorganic phosphoric acid and inorganic phosphorus oxides, including their hydrates, may be used. Typical organophosphorus compounds include full and partial esters of phosphoric acid, such as monoesters, diesters and triesters of phosphoric acid, thiophosphoric acid, dithiophosphoric acid, trithiophosphoric acid and tetrathiophosphoric acid; monoesters, diesters and triesters of phosphorous acid, thiophosphorous acid, dithiophosphorous acid and trithiophosphorous acid; trihydrocarbyl phosphine oxides; trihydrocarbyl phosphine sulfides; mono- and dihydrocarbyl phosphonates (RPO(OR')(OR"), wherein R and R' are hydrocarbyl groups, and R" is a hydrogen atom or a hydrocarbyl group) and their mono-, di- and trithio analogs; mono- and dihydrocarbyl phosphites (RP(OR')(OR"), wherein R and R' are hydrocarbyl groups, and R" is a hydrogen atom or a hydrocarbyl group) and their mono- and dithio analogs; and the like. Thus, compounds such as phosphorous acid (H3PO3, sometimes described as H2(HPO3) and sometimes referred to as orthophosphorous acid or phosphonic acid), phosphoric acid (H3PO4, sometimes referred to as orthophosphoric acid), hypophosphorous acid (H4P2O6), metaphosphoric acid (HPO3), pyrophosphoric acid (H4P2O7), hypophosphorous acid (H3PO2, sometimes referred to as phosphinic acid), pyrophosphorous acid (H4P2O5, sometimes referred to as pyrophosphoric acid), phosphinic acid (H3PO), tripolyphosphoric acid (H5P3O 10 ), tetrapolyphosphate (H5P4O 13), trimetaphosphoric acid (H3P3O9), phosphorus trioxide, phosphorus tetroxide, phosphorus pentoxide, etc. Partial sulfur or full sulfur analogs such as tetrathiophosphoric acid (H3PS4), thiophosphoric acid (H3PO3S), dithiophosphoric acid (H3PO2S2), trithiophosphoric acid (H3POS3), phosphorus sesquisulfide, phosphorus heptasulfide and phosphorus pentasulfide (P2S5, sometimes called P4S 10 ), can also be used to form the dispersant of the present disclosure. Inorganic phosphorus halides can also be used, such as PCl3, PBr3, POCl3, PSCl3, etc.

[0128] Likewise, organophosphorus compounds may be used, such as monoesters, diesters, and triesters of phosphoric acid (e.g., trialkyl phosphates, dialkyl monoacid phosphates, monoalkyl diacid phosphates, and mixtures thereof), monoesters, diesters, and triesters of phosphorous acid (e.g., trialkyl phosphites, dialkyl hydrogen phosphites, hydrocarbon diacid phosphites, and mixtures thereof), phosphonates ("primary" RP(O)(OR)2 and "secondary" R2P(O)(OR)), phosphinates, phosphonyl halides (e.g., RP(O)Cl2 and R2P(O)Cl), halogenated Phosphites (e.g., (RO)PCl2 and (RO)2PCl), halophosphates (e.g., ROP(O)Cl2 and (RO)2P(O)Cl), tertiary pyrophosphates (e.g., (RO)2P(O)—O—P(O)(OR)2), and all- or partially-sulfur analogs of any of the foregoing organophosphorus compounds, wherein each hydrocarbyl group contains up to about 100 carbon atoms, preferably up to about 50 carbon atoms, more preferably up to about 24 carbon atoms, and most preferably up to about 12 carbon atoms. Halophosphine halides (e.g., hydrocarbyl phosphorus tetrahalides, dihydrocarbyl phosphorus trihalides, and trihydrocarbyl phosphorus dihalides) and halophosphines (monohalogenated and dihalogenated phosphines) may also be used.

[0129] The lubricants described herein may include mixtures of one or more of the above-described boronated and phosphated dispersants in combination with non-borated and non-phosphated dispersants.

[0130] If used, such dispersants are provided in the lubricant at a treat rate of about 1 to about 15 weight percent, in other embodiments about 2 to about 13 weight percent, and in other embodiments about 4 to about 10 weight percent.

[0131] Defoaming agent: Defoamers for reducing or preventing the formation of stable foam include silicones, polyacrylates or organic polymers. Foam suppressors useful in the compositions of the disclosed invention include polysiloxanes, copolymers of ethyl acrylate and 2-ethylhexyl acrylate, and optionally vinyl acetate. When present, the amount of defoamer in the lubricating fluid may be up to 0.1 wt%, or up to 0.08 wt%, or less than 0.07 wt%, based on the total weight of the lubricating fluid.

[0132] Seal Swelling Agent The fluids of the present disclosure may also include seal swell agents. Seal swell agents (such as esters, adipates, sebacates, azelates, phthalates, sulfones, alcohols, alkylbenzenes, substituted sulfolanes, aromatic hydrocarbons, or mineral oils) cause swelling of elastomeric materials used as seals in engines and automatic transmissions.

[0133] Alcohol seal swell agents are typically low volatility straight chain alkyl alcohols such as decanol, tridecanol and tetradecanol. Alkylbenzenes that can be used as seal swell agents include dodecylbenzene, tetradecylbenzene, dinonyl-benzene, di(2-ethylhexyl)benzene, etc. Substituted sulfolanes (such as those described in U.S. Pat. No. 4,029,588, which is incorporated herein by reference) can also be used as seal swell agents in the compositions according to the present invention. Mineral oils that can be used as seal swell agents in the present disclosure include low viscosity mineral oils with high cycloparaffin or aromatic content.

[0134] In general, the lubricating fluids described herein may include additive components within the ranges listed in Table 2.

[0135] Table 2

[0136]

[0137] The percentages of the above components represent the weight percentages of the components by the total weight of the lubricating fluid containing the components. The additives used to formulate the compositions described herein can be blended into the base oil individually or in various sub-combinations. However, it is also suitable to use an additive concentrate (i.e., additives plus diluents, such as hydrocarbon solvents) to blend all components simultaneously. The use of additive concentrates takes advantage of the mutual compatibility provided by the combination of ingredients in the form of additive concentrates. In addition, the use of concentrates reduces blending time and reduces the possibility of blending errors.

[0138] Examples

[0139] The following non-limiting examples illustrate features and advantages of one or more embodiments of the present disclosure.Unless otherwise indicated or apparent from the context of the discussion, all percentages, ratios and parts indicated in the examples and throughout this disclosure are by weight.

[0140] It is beneficial for a motor transmission fluid to exhibit high volume resistivity, thus acting to some extent as an insulator. A higher resistivity score indicates the ability of the fluid to act as an insulator. To demonstrate how a phosphorylated succinimide dispersant with a phosphorus content between 2.0 wt% and 3.5 wt% increases the resistivity of a fluid, an exemplary finished fluid was formulated, aged, and evaluated.

[0141] To age the fluids, the fluids were subjected to accelerated oxidation using the Indiana Stirring Oxidation Test at 150° C. (a modified version of JIS K2514-1). The resistivity of the oxidized fluids was measured after the fluids were cooled to 30° C. The resistivity of the fluids was measured according to a modified version of ASTM D2624-15 (testing lubricants, not fuels) at 30° C. using an Epsilon + conductivity meter (Flucon Fluid Control GmbH) or equivalent meter at 1.5 volts to obtain at least one reading for each fluid evaluated.

[0142] The fluids were also evaluated for wear resistance and copper corrosion compatibility. The wear resistance of the fluids was measured according to ASTM D4172. Copper corrosion compatibility was measured using the Extended Copper Corrosion Test (a modified version of ASTM D130-18), in which a copper strip is immersed in the lubricant for a set period of time and a given temperature. The copper content in the oil is evaluated. A higher copper content in the oil indicates that the lubricant is corrosive to copper. In the following examples, the temperature was maintained at 150°C for 120 hours.

[0143] The formulations tested in Table 3 below all contained the same basic additive package, which contained friction modifiers, corrosion inhibitors, detergents, antioxidants, boronated and phosphorylated dispersants, and copper corrosion inhibitors. The formulations also contained a phosphorus source. The formulations of the present invention contained a phosphorylated succinimide dispersant as described herein, while the comparative formulations contained other types of phosphorus-containing compounds. The details of these components are described below. The formulations were tested in a wide range of base oils, with kinematic viscosities ranging from 4.10 to 4.33 cSt at 100°C.

[0144] Phosphorus Source A: Phosphorylated succinimide dispersant made from HR-polyisobutylene with Mn between 975 and 1175, maleic anhydride, a mixture of polyalkylene polyamines having an average of 6.5 nitrogen atoms per molecule, and phosphorous acid. The dispersant is the reaction product of succinimide and phosphorus. The dispersant has about 3.0 wt% phosphorus and about 1.4 wt% nitrogen.

[0145] Phosphorus Source B: Phosphorylated and borated succinimide dispersant made from conventional polyisobutylene having a Mn of 900 to 980, maleic anhydride, a mixture of polyalkylene polyamines having an average of 6.5 nitrogen atoms per molecule, phosphorous acid, and boric acid. This dispersant has about 0.76 wt% phosphorus, about 0.35 wt% boron, and about 1.75 wt% nitrogen.

[0146] Phosphorus Source C: The reaction product of sulfur and dibutyl hydrogenphosphonate salified with an amine; this phosphorus source has about 6 wt% phosphorus, about 6.3 wt% sulfur, and about 3.1 wt% nitrogen.

[0147] Phosphorus Source D: Alkyl thiophosphate having about 9 wt % phosphorus and about 19 wt % sulfur.

[0148] The formulations of the present invention containing phosphorus source A and highly phosphorylated succinimide dispersants unexpectedly achieve improved lubricant resistivity. In addition, the formulations of the present invention containing phosphorus source A also achieve suitable copper corrosion compatibility and wear resistance.

[0149] Table 3

[0150]

[0151] In Table 3, Inventive Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were formulated to have approximately the same kinematic viscosity. Each formulation contained a different phosphorus source but had a similar phosphorus treatment rate. Inventive Example 1 containing phosphorus source A had a higher resistivity after aging than the corresponding Comparative Examples 1, 2, and 3. In addition, Inventive Example 1 maintained suitable wear resistance and copper corrosion compatibility. Although Comparative Example 1 containing phosphorus source B had slightly less wear scars than Inventive Example 1, its oil contained more copper, so it had poorer ability to inhibit copper corrosion and lower resistivity after aging. Although Comparative Example 3 containing phosphorus source D had slightly better copper corrosion performance than Inventive Example 1, it had larger wear scars and lower resistivity after aging. Comparative Example 2 did not perform as well as Inventive Example 1 in terms of wear, copper corrosion compatibility, and resistivity.

[0152] Inventive Example 2 and Comparative Example 4 were formulated to have approximately the same kinematic viscosity. Each formulation contained a different phosphorus source but had similar phosphorus treatment rates. Inventive Example 2, which contained phosphorus source A, had higher resistivity and better copper corrosion compatibility and wear resistance than Comparative Example 4.

[0153] Inventive Examples 3-5 and Comparative Examples 5 and 6 are additional examples of inventive and comparative fluids formulated at various kinematic viscosities and phosphorus treatment rates, as shown below in Table 4. Although Comparative Samples 5 and 6 used Phosphorus Source A and may have lower wear scarring and copper corrosion, they both exhibited poor resistivity, which is believed to be due in part to the base oil.

[0154] Table 4

[0155]

[0156] It should be understood that although the lubricating compositions and compositions of the present disclosure have been described in conjunction with the detailed description thereof and the summary herein, the foregoing description is intended to illustrate rather than limit the scope of the present disclosure, which is defined by the scope of the appended claims. Other aspects, advantages and modifications are also within the scope of the claims. It is intended that the specification and examples be considered illustrative only, with the true scope of the present disclosure being indicated by the appended claims.

[0157] After considering the practice of this specification and the embodiments disclosed herein, other embodiments of the present disclosure will be apparent to those skilled in the art. As used throughout the specification and claims, "one / one (kind) (a)" and / or "one / one (kind) (an)" may refer to one or more than one. Unless otherwise indicated, all numerals expressing the amount of components, characteristics, such as molecular weight, percentage, ratio, reaction conditions, etc., used in this specification are understood to be modified by the term "about" in all cases, regardless of whether the term "about" exists. Therefore, unless otherwise indicated, the numerical parameters set forth in this specification are approximate values ​​that may vary depending on the desired characteristics attempted to be obtained by the present disclosure. Minimally, and without attempting to limit the application of the principle of equivalents to the scope of the claims, each numerical parameter should be interpreted at least according to the number of reported significant figures and by applying general rounding techniques. Although the numerical range and parameters of the wide range of the present disclosure are approximate values, the numerical values ​​set forth in the specific examples are reported as accurately as possible. However, any numerical value inherently contains some errors that are inevitably caused by the standard deviation found in its corresponding test measurement value.

[0158] It should be understood that each component, compound, substituent or parameter disclosed herein should be interpreted as disclosed for use alone or in combination with one or more of each of the other components, compounds, substituents or parameters disclosed herein.

[0159] It should also be understood that each range disclosed herein should be interpreted as a disclosure of each specific value having the same number of significant digits within the disclosed range. Thus, a range of 1-4 would be interpreted as an explicit disclosure of the values ​​1, 2, 3, and 4, as well as any range of these values, such as 1-4, 1-3, 1-2, 2-4, 2-3, etc.

[0160] It should also be understood that each lower limit of each range disclosed herein should be interpreted as disclosed in combination with each upper limit of each range and each specific value in each range for the same component, compound, substituent or parameter disclosed herein. Therefore, this disclosure will be interpreted as the disclosure of all ranges obtained by combining each lower limit of each range with each upper limit of each range or each specific value in each range, or by combining each upper limit of each range with each specific value in each range.

[0161] In addition, the specific amounts / values ​​of components, compounds, substituents or parameters disclosed in this specification or the examples should be interpreted as a disclosure of the lower or upper limit of a range, and therefore can be combined with the lower or upper limit of any other range or the specific amounts / values ​​of the same components, compounds, substituents or parameters disclosed elsewhere in this application to form the range of the components, compounds, substituents or parameters.

Claims

1. A lubricating composition for an electric vehicle, the lubricating composition comprising: At least 95 weight percent of a lubricating base oil composition, the lubricating base oil composition comprising a base oil selected from the group consisting of: API Group III base oil; or a blend of Group III base oil with Group II or Group V base oil; or a mixture thereof; a phosphorylated succinimide dispersant containing 2 wt % to 3.5 wt % phosphorus, the phosphorylated succinimide dispersant providing 650 ppm or less phosphorus to the lubricating composition; The lubricating composition has 700 ppm or less total phosphorus, and the phosphorylated succinimide dispersant provides at least 70% of the total phosphorus; and wherein the lubricating composition has a kinematic viscosity of 3 cSt to 6.5 cSt at 100°C and a resistivity of at least 50 M Ω⋅m as measured at 1.5 volts and 30°C using the lubricating composition according to ASTM D2624-15 after aging the fluid at 150°C according to JIS K2514-1; Wherein if the lubricating base oil composition comprises an API V group base oil, the API V group base oil is present in an amount of up to 15 wt% based on the total lubricating composition; Wherein if the lubricating base oil composition comprises an API Group II base oil, the API Group II is present in an amount of up to 80 wt% based on the total lubricating composition.

2. The lubricating composition of claim 1, wherein the phosphorylated succinimide dispersant is a first dispersant, and wherein the composition further comprises a second dispersant containing 0.2 wt % to 0.4 wt % phosphorus, the second dispersant providing 50 ppm or less of phosphorus to the lubricating composition.

3. The lubricating composition of claim 1, wherein the phosphorylated succinimide dispersant contains 2.5 wt% to 3.0 wt% phosphorus; and / or wherein the phosphorylated succinimide dispersant provides 115 ppm to 600 ppm phosphorus to the lubricating composition; and / or wherein the phosphorylated succinimide dispersant provides 115 ppm to 250 ppm phosphorus to the lubricating composition; and / or wherein the phosphorylated succinimide dispersant provides 250 ppm or less phosphorus to the lubricating composition, and wherein the lubricating composition has 300 ppm or less total phosphorus.

4. The lubricating composition of claim 2, wherein the first dispersant delivers 115 ppm to 250 ppm of phosphorus to the lubricating composition, and the second dispersant delivers 40 ppm or less of phosphorus to the lubricating composition.

5. The lubricating composition of claim 1, wherein the lubricating composition has a resistivity of at least 115 MΩ⋅m after aging the fluid at 150°C according to JIS K2514-1.

6. The lubricating composition of claim 1, wherein the base oil composition is selected from: an API Group III base oil; or a mixture of API Group II and Group III base oils.

7. The lubricating composition of claim 6, wherein the phosphorylated succinimide dispersant provides between 115 ppm and 250 ppm phosphorus to the lubricating composition; and / or the lubricating composition has between 160 ppm and 300 ppm total phosphorus, a kinematic viscosity of 5.5 cSt to 6.0 cSt at 100°C, and a resistivity of at least 115 MΩ⋅m after aging the fluid at 150°C in accordance with JIS K2514-1.

8. A method of increasing the resistivity of a lubricating composition in an electric vehicle, the method comprising providing a lubricating oil to an electric vehicle powertrain, the lubricating oil having a composition comprising: At least 95 weight percent of a lubricating base oil composition, the lubricating base oil composition comprising a base oil selected from the group consisting of: an API Group III base oil; or a blend of an API Group III base oil with an API Group II or API Group V base oil; or a mixture thereof; a phosphorylated succinimide dispersant containing 2 wt % to 3.5 wt % phosphorus, the phosphorylated succinimide dispersant providing 650 ppm or less phosphorus to the lubricating composition; The lubricating composition has 700 ppm or less phosphorus, and the phosphorylated succinimide dispersant provides at least 70% of the total phosphorus; and wherein the lubricating oil has a kinematic viscosity of 3 cSt to 6.5 cSt at 100°C and a resistivity of at least 50 M Ω⋅m as measured at 1.5 volts and 30°C using the lubricating composition according to ASTM D2624-15 after aging the fluid at 150°C according to JIS K2514-1; and Wherein if the lubricating base oil composition comprises an API V group base oil, the API V group base oil is present in an amount of up to 15 wt% based on the total lubricating composition; Wherein if the lubricating base oil composition comprises an API Group II base oil, the API Group II is present in an amount of up to 80 wt% based on the total lubricating composition.

9. The method of claim 8, wherein the phosphorylated succinimide dispersant is a first dispersant, and wherein the composition further comprises a second dispersant containing 0.2 wt% to 0.4 wt% phosphorus, the second dispersant providing 50 ppm or less phosphorus to the lubricating composition.

10. The method of claim 8, wherein the phosphorylated succinimide dispersant contains 2.5 wt% to 3.0 wt% phosphorus; and / or wherein the phosphorylated succinimide dispersant provides 115 ppm to 600 ppm phosphorus to the lubricating composition; and / or wherein the phosphorylated succinimide dispersant provides 115 ppm to 250 ppm phosphorus to the lubricating composition.

11. The method of claim 9, wherein the first dispersant delivers 115 ppm to 250 ppm phosphorus to the lubricating composition and the second dispersant delivers 40 ppm or less phosphorus to the lubricating composition.

12. The method of claim 8, wherein the phosphorylated succinimide dispersant provides 250 ppm or less phosphorus to the lubricating composition, and wherein the lubricating composition has 300 ppm or less total phosphorus.

13. The method of claim 8, wherein the lubricating composition has a resistivity of at least 115 MΩ⋅m after aging the fluid at 150°C in accordance with JIS K2514-1.

14. The method of claim 8, wherein the base oil composition is selected from: API Group III base oil; or a blend of API Group III and Group III base oils; or a mixture thereof.

15. The method of claim 14, wherein the phosphorylated succinimide dispersant provides 115 ppm to 250 ppm phosphorus to the lubricating composition, and the lubricating composition has 160 ppm to 300 ppm total phosphorus, a kinematic viscosity of 5.5 cSt to 6.0 cSt at 100°C, and a resistivity of at least 115 MΩ⋅m after aging the fluid at 150°C in accordance with JIS K2514-1.

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