Patent Description:
In electric vehicle powertrains that include an electric motor as the sole driving source, a single lubricant may be required to both lubricate the gears and clutches and cool the electric motor. A major challenge in developing these types of lubricants is achieving wear performance, friction performance, and oxidation stability, while ensuring lubricant compatibility with electrified components in the powertrain. For example, the lubricant must provide gears and clutches within the electric vehicle powertrain good wear protection and friction performance, respectively. However, because the lubricant is also used to cool the electric motor (e.g., by contacting the copper windings in the stator which operate at high temperatures), the lubricant must also provide copper corrosion protection and have relatively low electrical conductivity to inhibit electrostatic buildup and discharge in the electrified components.

Despite advances in lubricant technology for electric vehicle powertrains, there is a need for an electric vehicle powertrain lubricant composition having desired wear performance, oxidation stability, copper corrosion inhibition, and/or relatively low lubricant electrical conductivity.

<CIT> discloses the use of a succinimide compound as an anti-corrosion additive in a lubricant composition intended for a propulsion system of an electric or hybrid vehicle. The disclosure concerns the use of at least one succinimide-type compound as an anti-corrosion additive in a lubricant composition intended for a propulsion system of an electric or hybrid vehicle and comprising one or more amine and/or sulfur anti-wear additive(s). The disclosure also relates to the use of a lubricant composition for lubricating a propulsion system of an electric or hybrid vehicle.

<CIT> discloses methods of lubricating an electric or a hybrid-electric transmission using a lubricant including a solvent system with a blend of one or more base oils with a branched diester and one or more poly(meth)acrylate copolymers, transmissions therefor, and lubricating compositions suitable for such applications that exhibit good lubricant properties, good electrical properties, and good cooling efficiency at the same time. <CIT> discloses a lubricant composition comprising an oil of lubricating viscosity and a protic acid salt of an N-hydrocarbyl-substituted gamma-(y-) or delta-amino(thio)ester. The invention further relates to a method of lubricating a mechanical device with the lubricant composition.

In one embodiment, a method for lubricating gears and clutches in an electric motor system and simultaneously cooling a motor thereof is provided by the present disclosure as defined in the claims. The method includes operating an electric motor system, containing a lubricating and cooling fluid, such that a temperature of the lubricating and cooling fluid in a sump of the electric motor system is about <NUM> to <NUM> and the temperature of copper windings in a stator of the electric motor system is between <NUM> to <NUM>; lubricating gears and clutches in the electric motor system with the lubricating and cooling fluid and simultaneously cooling the motor in the electric motor system by contacting the copper windings with the lubricating and cooling fluid; and wherein the lubricating and cooling fluid includes an oil of lubricating viscosity including an API Group III base oil, API Group IV base oil, or mixtures thereof; at least one thiadiazole or hydrocarbyl-substituted derivatives thereof delivering <NUM> to <NUM> ppm sulfur to the lubricating fluid; a dispersant system including (i) a first dispersant obtained from polyisobutylene having a number average molecular weight of <NUM> to <NUM> and delivering up to <NUM> ppm nitrogen to the lubricating and cooling fluid and (ii) a second dispersant obtained from polyisobutylene having a number average molecular weight of <NUM> or less and delivering up to <NUM> ppm nitrogen to the lubricating fluid; an alkoxylated aliphatic amine delivering up to <NUM> ppm nitrogen to the lubricating and cooling fluid; an ether amine delivering up to <NUM> ppm nitrogen to the lubricating and cooling fluid. Another embodiment of the present invention is the lubricating and cooling fluid defined in the claims.

At least one of the first dispersant and the second dispersant is borated and phosphorylated such that a total amount of the boron and phosphorus in the dispersant system relative to the nitrogen in the dispersant system is from <NUM> to <NUM> and wherein the first and second dispersants deliver up to <NUM> ppm of total boron and phosphorus per <NUM> number average molecular weight of the combined polyisobutylenes used to obtain the first and second dispersants.

In other approaches or embodiments, the lubricating and cooling fluid used in any of the methods described above may include optional features in any combination. These embodiments may include: the at least one thiadiazole or hydrocarbyl-substituted derivatives thereof includes one or more compounds having a structure of Formula I:
<CHM>
wherein each R<NUM> is independently hydrogen or sulfur; each R<NUM> is independently an alkyl group; n is an integer of <NUM> or <NUM> and if R<NUM> is hydrogen then the integer n of the adjacent R<NUM> moiety is <NUM> and if R<NUM> is sulfur then the n of the adjacent R<NUM> moiety is <NUM>; and wherein at least one R<NUM> is sulfur; and/or wherein the at least one thiadiazole or hydrocarbyl-substituted derivatives thereof is a mixture of hydrocarbyl substituted derivatives of <NUM>,<NUM> dimercapto <NUM>,<NUM><NUM> thiadiazole including one of <NUM>,<NUM>-bis-(nonyldithio)-<NUM>,<NUM>,<NUM>-thiadiazole, <NUM>,<NUM>-mono-(nonyldithio)-<NUM>,<NUM>,<NUM>-thiadiazole, or combinations thereof; and/or wherein the lubricating and cooling fluid further comprises a fatty diamine delivering up to <NUM> ppm nitrogen to the lubricating and cooling fluid; and/or wherein the alkoxylated aliphatic amine, ether amine, and fatty diamine deliver up to <NUM> ppm nitrogen to the lubricating and cooling fluid; and/or wherein the alkoxylated aliphatic amine is a di(hydroxyalkyl) aliphatic tertiary amine comprising hydroxyalkyl groups each containing from <NUM> to <NUM> carbon atoms, and further comprising an acyclic hydrocarbyl group containing from <NUM> to <NUM> carbon atoms; and/or wherein the ether amine comprises isodecyloxypropylamine; and/or wherein the fatty diamine comprises n-oleyl-<NUM>,<NUM>-diaminopropane; and/or wherein the alkoxylated aliphatic amine and ether amine each deliver up to <NUM> ppm nitrogen to the lubricating and cooling fluid, and wherein the at least one thiadiazole or hydrocarbyl-substituted derivatives thereof is a thiadiazole mixture of hydrocarbyl substituted derivatives of <NUM>,<NUM> dimercapto <NUM>,<NUM>,<NUM> thiadiazole including one of <NUM>,<NUM>-bis-(nonyldithio)-<NUM>,<NUM>,<NUM>-thiadiazole, <NUM>,<NUM>-mono-(nonyldithio)-<NUM>,<NUM>,<NUM>-thiadiazole, or combinations thereof, and wherein the thiadiazole mixture and the optional sulfurized ester deliver <NUM> to <NUM> ppm sulfur to the lubricating and cooling fluid.

In yet further approaches or embodiments, the lubricating and cooling fluid used in any of the methods described above may also include the first dispersant present in an amount to deliver up to <NUM> ppm nitrogen to the lubricating and cooling fluid; and/or wherein the second dispersant is present in an amount to deliver <NUM> ppm nitrogen to the lubricating and cooling fluid; and/or wherein the first dispersant is obtained from polyisobutylene having a number average molecular weight of <NUM> to <NUM> and the second dispersant is obtained from polyisobutylene having a number average molecular weight of <NUM>; and/or wherein the first dispersant is present in an amount to deliver up to <NUM> ppm of boron and up to <NUM> ppm of phosphorus to the lubricating and cooling fluid; and/or wherein the lubricating fluid has a sulfurized ester delivering <NUM> to <NUM> ppm sulfur to the lubricating and cooling fluid; and/or wherein the at least one thiadiazole or hydrocarbyl-substituted derivatives thereof and the sulfurized ester deliver <NUM> to <NUM> ppm sulfur to the lubricating fluid; and/or wherein the sulfurized ester comprises sulfurized transesterified triglycerides.

In embodiments, the lubricating and cooling fluid used in any methods herein may include a Group III base oil; and/or a gas-to-liquid (GTL) base oil; and/or a polyalphaolefin (PAO) base oil.

The lubricating and cooling fluid used in any of the methods herein, has an initial electrical conductivity of <NUM> nS/M or less, as measured by a modified ASTM D2624-<NUM> using the lubricating and cooling fluid and measured at <NUM> and at <NUM>.

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

The following definitions of terms are provided in order to clarify the meanings of certain terms as used herein.

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

As used herein, the terms "additive package," "additive concentrate," "additive composition," and "transmission fluid additive package" refer the portion of the lubricating oil composition excluding the major amount of base oil.

Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having a predominantly hydrocarbon character. Each hydrocarbyl group is independently selected from hydrocarbon substituents, and substituted hydrocarbon substituents containing one or more of halo groups, hydroxyl groups, alkoxy groups, mercapto groups, nitro groups, nitroso groups, amino groups, pyridyl groups, furyl groups, imidazolyl groups, oxygen and nitrogen, and wherein no more than two non-hydrocarbon substituents are present for every ten carbon atoms in the hydrocarbyl group.

As used herein, the term "percent by weight" or "wt%", unless expressly stated otherwise, means the percentage the recited component represents to the weight of the entire composition.

The term "alkyl" as employed herein refers to straight, branched, cyclic, and/or substituted saturated chain moieties from <NUM> to <NUM> carbon atoms.

The term "alkenyl" as employed herein refers to straight, branched, cyclic, and/or substituted unsaturated chain moieties from <NUM> to <NUM> carbon atoms.

The term "aryl" as employed herein refers to single and multi-ring aromatic compounds that may include alkyl, alkenyl, alkylaryl, amino, hydroxyl, alkoxy, halo substituents, and/or heteroatoms including, but not limited to, nitrogen, and oxygen.

As used herein, the "average number molecular weight" or "Mn" is determined by gel permeation chromatography (GPC) using commercially available polystyrene standards (with a Mn of <NUM> to <NUM>,<NUM> as the calibration reference).

It is to be understood that throughout the present disclosure, the terms "comprises," "includes," "contains," are considered open-ended and include any element, step, or ingredient not explicitly listed. The phrase "consists essentially of" is meant to include any expressly listed element, step, or ingredient and any additional elements, steps, or ingredients that do not materially affect the basic and novel aspects of the invention. The present disclosure also contemplates that any composition described using the terms, "comprises," "includes," "contains," is also to be interpreted as including a disclosure of the same composition "consisting essentially of" or "consisting of" the specifically listed components thereof.

According to an exemplary embodiment, a lubricating and cooling fluid for an electric motor system includes a lubricating base oil of an API Group III base oil, an API Group IV base oil, or mixtures thereof, at least one sulfurized component, a dispersant system comprising at least two dispersants, and a friction modifier system comprising at least two friction modifiers. The at least one sulfurized component includes select additives and amounts of sulfur to achieve relatively low conductivity and good copper corrosion performance. The two dispersants are selected to maintain relatively low conductivity even when providing elements known to be highly conductive. One of the dispersants has a relatively high number average molecular weight of <NUM> to <NUM>, and the other dispersant has a relatively low number average molecular weight of less than <NUM>. The friction modifiers comprise an alkoxylated aliphatic amine, an ether amine, and optionally a fatty diamine. In another embodiment, the lubricating and cooling fluid includes two sulfurized components. In any embodiment, the lubricating and cooling fluid has a kinematic viscosity of less than <NUM> cSt at <NUM>, as measured by ASTM D2270-<NUM>, and/or has an initial electric conductivity of less than <NUM> nS/M, as measured by a modified version ASTM D2624, described in more detail herein.

With fluids for electric motor systems that need to provide not only wear and friction performance but also cooling, low copper corrosion, and low conductivity, there are challenges developing such a robust fluid because elements and components traditionally used in internal combustion engines and transmissions, which contain sulfur, boron, and phosphorus, can negatively impact copper corrosion and/or electrical conductivity. For instance, sulfur can be corrosive to copper, and phosphorus and boron can increase the conductivity of fluids. These undesired effects are magnified at elevated temperatures. Thus, carefully developed fluids are required for electric motors and gears that operate at elevated temperatures. For example, according to the invention, the fluid sump temperatures of the electrical motor system described herein reaches from <NUM> to <NUM>. Further, according to the invention, the temperature of the copper windings in the stator of the electrical motor system described herein is between <NUM> and <NUM>. At these elevated temperatures, additives in the fluid used to achieve good wear and friction performance can be detrimental to maintaining the desired electrical conductivity and copper compatibility.

It was discovered herein, however, that sulfur, phosphorus, and boron can be provided to a fluid for such electric mobility ("e-mobility") applications if such elements are provided by the unique combination of the at least one sulfur component, friction modifier system, and dispersant system described herein. The at least one sulfur component includes select amounts of thiadiazole additives, the friction modifier system includes select amounts of aliphatic amine, ether amine, and optionally, diamine, and the dispersant system includes select amounts of at least two different dispersant additives. According to the invention, at least one of the first dispersant and/or the second dispersant is borated and phosphorylated such that a total amount of boron and phosphorus in the dispersant system relative to the nitrogen in the dispersant system is from <NUM> to <NUM> and wherein the first and second dispersants deliver up to <NUM> ppm of total boron and phosphorus per <NUM> number average molecular weight of the combined polyisobutylene moieties used in the dispersant system.

In such a composition, the fluids herein (even with elements previously known to negatively affect conductivity) results in an initial electric conductivity of less than <NUM> nS/M, as measured by a modified version ASTM D2624, described in more detail herein.

In another exemplary embodiment, the disclosure relates to a method of lubricating gears and clutches in an electric motor system while simultaneously cooling an electric motor in the electric motor system. According to this method, the electric motor system, containing a lubricating and cooling fluid, is operated such that the temperature of the lubricating and cooling fluid in electric motor reaches at least <NUM> in a sump of the electric motor system and, in other embodiments, the lubricating and cooling fluid is <NUM> to <NUM> in the sump of the electric motor system. According to the invention, the electric motor system, containing a lubricating and cooling fluid, is operated such that the lubricating and cooling fluid contacts the copper windings in the stator of the electrical motor system and such that the copper windings reach a temperature of between <NUM> and <NUM>. In other embodiments, the electric motor system, containing the lubricating and cooling is operated such that the lubricating and cooling fluid contacts the copper windings and such that the copper windings reach a temperature of at least <NUM>. The lubricating and cooling fluid used in this method comprises at least one lubricating base oil comprising an API Group III base oil, API Group IV base oil, or mixtures thereof, at least one sulfurized component, a dispersant system comprising two dispersants, and a friction modifier system comprising at least two friction modifiers. One of the dispersants has a relatively high number average molecular weight of <NUM> to <NUM>. The other dispersant has a relatively low number average molecular weight of less than <NUM>. The friction modifiers comprise an alkoxylated aliphatic amine and an ether amine. In an alternate embodiment, the lubricating and cooling fluid contains a fatty diamine as an additional friction modifier. In another embodiment, the lubricating and cooling fluid includes two sulfurized components. In any of the above embodiments of the methods, the lubricating and cooling fluid may have a kinematic viscosity of less than <NUM> cSt at <NUM>, as measured by ASTM D2270-<NUM>, and has an initial electric conductivity of less than <NUM> nS/M, as measured by a modified version ASTM D2624, described in more detail herein. Any embodiment of the methods herein may also include the noted ratios and relationships of the boron, phosphorus, and nitrogen and/or amounts relative to the molecular weights of the dispersants described above for the lubricating fluids used in the method.

BASE OIL: Base oils suitable for use in formulating the lubricating and cooling fluids for use in electric motor vehicles according to the disclosure have lubricating viscosity and comprise an API Group III base oil, an API Group IV base oil, or mixtures thereof. These base oils may be selected from any of suitable synthetic or natural oils or mixtures thereof having a suitable lubricating viscosity. Natural oils may include animal oils and vegetable oils (e.g., castor oil, lard oil) as well as mineral oils such as liquid petroleum oils and solvent treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types. Oils derived from coal or shale may also be suitable. Further, oil derived from a gas-to-liquid process is also suitable. The base oil may have a kinematic viscosity at <NUM> of <NUM> to <NUM> cSt, as measured by ASTM D2270-<NUM>.

The base oil as used in the invention described herein may be a single base oil or may be a mixture of two or more base oils. The one or more base oil(s) are selected from any of the base oils in Groups III or IV as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. Such base oil groups are shown in Table <NUM> as follows:.

According to the invention, the base oil is selected from an API Group III base oil, or an API Group IV base oil, or a mixture of these base oils. Alternatively, the base oil may be a mixture of two or more of an API Group III base oils, or two or more of an API Group IV base oils.

API Group III base oils may include oil derived from Fischer-Tropsch synthesized hydrocarbons. These types of oils are commonly referred to as gas-to-liquids (GTLs). For example, the hydrocarbons may be hydroisomerized using processes disclosed in <CIT> or <CIT>; hydrocracked and hydroisomerized using processes disclosed in <CIT> or <CIT>; dewaxed using processes disclosed in <CIT>; or hydroisomerized and dewaxed using processes disclosed in <CIT><CIT> or<CIT>.

API Group IV base oils, PAOs, are typically derived from monomers having from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM> carbon atoms. Examples of PAOs that may be used in the present invention include those derived from octene, decene, mixtures thereof. PAOs may have a kinematic viscosity of from <NUM> to <NUM>, or from <NUM> to <NUM>, or from <NUM> to <NUM> cSt at <NUM>, as measured by ASTM D2270-<NUM>. Examples of PAOs include <NUM> cSt at <NUM> PAOs, <NUM> cSt at <NUM> PAOs, and mixtures thereof.

The base oil(s) are combined with an additive composition as disclosed in embodiments herein to provide a lubricating and cooling fluid for use in an electric motor system having an electric motor, gears, and clutches. Accordingly, the base oil may be present in the lubricating and cooling fluid in an amount greater than <NUM> wt % based on the total weight of the lubricating and cooling fluid. In some embodiments, the base oil may be present in the lubricating and cooling fluid in an amount greater than <NUM> wt % based on the total weight of the lubricating and cooling fluid.

ADDITIVE COMPOSITION: The fluids herein include an additive composition that includes at least a sulfurized component, a friction modifier system, and a dispersant system. Each will be described below.

THE SULFURIZED COMPONENT: The lubricating and cooling fluid includes at least a first sulfurized component in balanced amounts to improve wear performance and copper protection. Optionally, a second sulfurized component may also be used in some applications.

The first sulfurized component is one or more thiadiazole compounds or hydrocarbyl-substituted derivatives thereof or, in other approaches, may be a mixture of thiadiazole compounds or hydrocarbyl-substituted derivatives thereof. Examples of the thiadiazole compound that may be used include <NUM>,<NUM>-dimercapto-<NUM>,<NUM>,<NUM>-thiadiazole, <NUM>-mercapto-<NUM>-hydrocarbylthio-<NUM>,<NUM>,<NUM>-thiadiazole, <NUM>-mercapto-<NUM>-hydrocarbyldithio-<NUM>,<NUM>,<NUM>-thiadiazole, <NUM>,<NUM>-bis(hydrocarbylthio)- <NUM>,<NUM>,<NUM>-thiadiazole, or <NUM>,<NUM>-bis(hydrocarbyldithio)- <NUM>,<NUM>,<NUM>-thiadiazoles. The <NUM>,<NUM>,<NUM>-thiadiazoles are generally synthesized from hydrazine and carbon disulfide by known procedures. See, for example, <CIT><CIT><CIT><CIT><CIT><CIT><CIT>and <CIT>.

Surprisingly, the form and amounts of the first sulfurized additive herein contributes to the ability of the fluids to maintain a low conductivity, lower copper corrosion, and also meeting other desired friction and wear performance characteristics at the same time. In approaches, the at least one thiadiazole or hydrocarbyl-substituted derivatives thereof includes one or more compounds having a structure of Formula I:
<CHM>
wherein each R<NUM> is independently hydrogen or sulfur, each R<NUM> is independently an alkyl group, n is an integer of <NUM> or <NUM> and if R<NUM> is hydrogen then the integer n of the adjacent R<NUM> moiety is <NUM> and if R<NUM> is sulfur then the n of the adjacent R<NUM> moiety is <NUM>, and with the proviso that at least one R<NUM> is sulfur. In other approaches, the at least one thiadiazole or hydrocarbyl-substituted derivatives thereof is a blend of compounds of Formula Ia and Formula Ib shown below:
<CHM>
wherein within Formula Ia each integer n is <NUM>, each R<NUM> is sulfur, and each R<NUM> is a C5 to C15 alkyl group, preferably a C8 to C12 alkyl group; and
<CHM>
wherein within Formula Ib one integer n is <NUM> with an associated R<NUM> group being a C5 to C15 alkyl group (preferably a C8 to C12 alkyl group) and the other integer n is <NUM> and with both R<NUM> groups being sulfur. In some embodiments, the first sulfurized additive includes a blend of Formula Ia and Ib with Formula Ia being a majority of the blend and in other approaches, the blend of Ia and Ib is <NUM> to <NUM> weight percent of Ia and <NUM> to <NUM> weight percent of Ib (or other ranges therewithin). In another approach, the first sulfurized additive is a <NUM>,<NUM> dimercapto <NUM>,<NUM>,<NUM> thiadiazole including a blend of <NUM>,<NUM>-bis-(nonyldithio)-<NUM>,<NUM>,<NUM>-thiadiazole (such as <NUM> to <NUM>%) and <NUM>,<NUM>-mono-(nonyldithio)-<NUM>,<NUM>,<NUM>-thiadiazole (such as <NUM> to <NUM>%).

The at least one thiadiazole or hydrocarbyl-substituted derivative thereof are present in the lubricating and cooling fluid in an amount to deliver <NUM> to <NUM> ppm sulfur, <NUM> to <NUM> ppm sulfur, or <NUM> to <NUM> ppm sulfur (or other ranges therewithin). In one embodiment, the at least one thiadiazole or hydrocarbyl-substituted derivatives thereof is <NUM>,<NUM>-dimercapto-<NUM>,<NUM>,<NUM>-thiadiazole and this thiadiazole compound is present in the lubricating and cooling fluid an amount to deliver <NUM> to <NUM> ppm sulfur, <NUM> to <NUM> ppm sulfur, or <NUM> to <NUM> ppm sulfur (or other ranges therewithin).

As shown in the examples herein, when the first sulfurized component is present in the lubricating and cooling fluid in an amount to deliver <NUM> to <NUM> ppm sulfur, <NUM><NUM> ppm sulfur, or <NUM> to <NUM> ppm sulfur (or other ranges therewithin), the resulting composition provides for improved FZG Scuffing scores and/or decreased copper corrosion. When the first sulfurized component is present in the lubricating and cooling fluid in an amount less than <NUM> ppm sulfur or greater than <NUM> ppm sulfur, the resulting composition provides poor FZG Scuffing score and/or increased copper corrosion.

The lubricating and cooling fluid may optionally comprise a second sulfurized component in the form of a sulfurized ester. Examples of sulfurized esters include those produced by sulfurizing animal or vegetable fats and oils such as beef tallow lard, fish oil, rapeseed oil, and soybean oil; unsaturated fatty acid esters produced by reacting unsaturated fatty acids such as oleic acid, linoleic acid, and fatty acids extracted from the foregoing animal or vegetable fats and oils with various alcohols; or mixtures thereof, by any suitable method. In one embodiment, the sulfurized component is sperm oil or synthetic sperm oil and is comprised of sulfurized transesterified triglycerides.

The optional sulfurized ester may be present in the lubricating and cooling fluid in an amount to deliver up to <NUM> ppm sulfur, <NUM> to <NUM> ppm sulfur, or <NUM> to <NUM> ppm sulfur (or other ranges therewithin). In one embodiment, the optional sulfurized ester is sulfurized synthetic sperm oil comprised of sulfurized transesterified triglycerides and may be present in the lubricating and cooling fluid an amount to deliver <NUM> to <NUM> ppm sulfur or <NUM> to <NUM> ppm sulfur (or other ranges therewithin).

When both sulfurized components are present in the lubricating and cooling fluid, they are present in an amount to deliver a total sulfur in an amount of <NUM> to <NUM> ppm sulfur or <NUM> to <NUM> ppm sulfur (or other ranges therewithin). In one embodiment the first sulfurized component is <NUM>,<NUM>-dimercapto-<NUM>,<NUM>,<NUM>-thiadiazole and/or a hydrocarbyl-substituted derivative thereof and the optional second sulfurized component is sulfurized synthetic sperm oil comprised of sulfurized transesterified triglycerides. In this embodiment, the first sulfurized component is present in the lubricating and cooling fluid in an amount to deliver <NUM> to <NUM> ppm sulfur and the optional second sulfurized component is present in the lubricating and cooling fluid in an amount to deliver <NUM> to <NUM> ppm sulfur. In this embodiment, the first and optional second sulfurized components may be present in the lubricating and cooling fluid in an amount to deliver <NUM> to <NUM> ppm total sulfur.

THE DISPERSANT SYSTEM: The lubricating and cooling fluid described herein contains a dispersant system including at least two dispersants, such as oil-soluble ashless dispersants selected from the group consisting of succinimide dispersants, succinic ester dispersants, succinic ester-amide dispersants, Mannich base dispersants, polymeric polyamine dispersants, phosphorylated forms thereof, and borated forms thereof. The dispersants may be capped with acidic molecules capable of reacting with secondary amino groups.

Hydrocarbyl-dicarboxylic acid or anhydrides reacted with polyalkylene polyamines are used to make succinimide dispersants. Succinimide dispersants and their preparation are disclosed in <CIT> and <CIT>. The hydrocarbyl moiety of the hydrocarbyl-dicarboxylic acid or anhydride is derived from polymers of isobutylene. Suitable polyisobutenes for use herein include those formed from conventional polyisobutylene or highly reactive polyisobutylene having at least <NUM>%, such as <NUM>% to <NUM>% and above, terminal vinylidene content. Suitable polyisobutenes may include those prepared using BF<NUM> catalysts.

The average number molecular weight of the polyisobutylene substituent of the dispersants may vary over a wide range, i.e. for the first dispersant example from <NUM> to <NUM>, and for the second dispersant <NUM> or less as determined by gel permeation chromatography (GPC) using polystyrene (with a number average molecular weight of <NUM> to <NUM>,<NUM>) as the calibration reference. The GPC method additionally provides molecular weight distribution information; see, for example,<NPL>.

The polyisobutylene moiety in a 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 having a Mw/Mn of less than <NUM>, preferably less than <NUM>, are most desirable. Suitable polyisobutylene substituents have a polydispersity of from <NUM> to <NUM>, or from <NUM> to <NUM>.

The dicarboxylic acid or anhydride of may be selected from carboxylic reactants such as maleic anhydride, maleic acid, fumaric acid, malic acid, tartaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, ethylmaleic anhydride, dimethylmaleic anhydride, ethylmaleic acid, dimethylmaleic acid, hexylmaleic acid, including the corresponding acid halides and C<NUM>-C<NUM> aliphatic esters. A mole ratio of dicarboxylic acid or anhydride to hydrocarbyl moiety in a reaction mixture used to make the hydrocarbyl-dicarboxylic acid or anhydride may vary widely. Accordingly, the mole ratio may vary from <NUM>:<NUM> to <NUM>:<NUM>, for example from <NUM>:<NUM> to <NUM>:<NUM>. A particularly suitable molar ratio of acid or anhydride to hydrocarbyl moiety is from <NUM>:<NUM> to less than <NUM>:<NUM>. Another useful molar ratio of dicarboxylic acid or anhydride to hydrocarbyl moiety is <NUM>:<NUM> to <NUM>:<NUM>, or <NUM>:<NUM> to <NUM>:<NUM>, or <NUM>:<NUM> to <NUM>:<NUM>.

Any of numerous polyalkylene polyamines can be used as in preparing the dispersant additive. Non-limiting exemplary polyamines may include aminoguanidine bicarbonate (AGBC), diethylene triamine (DETA), triethylene tetramine (TETA), tetraethylene pentamine (TEPA), pentaethylene hexamine (PEHA) and heavy polyamines. A heavy polyamine may comprise a mixture of polyalkylenepolyamines having small amounts of polyamine oligomers such as TEPA and PEHA, but primarily oligomers having 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 <NUM> nitrogen atoms per molecule. Additional non-limiting polyamines which may be used to prepare the hydrocarbyl-substituted succinimide dispersant are disclosed in <CIT>. The molar ratio of hydrocarbyl-dicarboxylic acid or anhydrides to polyalkylene polyamines may be from <NUM>:<NUM> to <NUM>: <NUM>.

In one embodiment, the dispersants in the present disclosure described herein may be the reaction product of a polyisobutenyl succinic anhydride (PIBSA), and a polyamine, for example heavy polyamines. The dispersants herein may have a molar ratio of (A) polyisobutenyl-substituted succinic anhydride to (B) polyamine in the range of <NUM>:<NUM> to <NUM>:<NUM>.

The Mannich base dispersants may be a reaction product of an alkyl phenol, typically having a long chain alkyl substituent on the ring, with one or more aliphatic aldehydes containing from <NUM> to <NUM> carbon atoms (especially formaldehyde and derivatives thereof), and polyamines (especially polyalkylene polyamines). For example, a Mannich base ashless dispersants may be formed by condensing about one molar proportion of long chain hydrocarbon-substituted phenol with from <NUM> to <NUM> moles of formaldehyde and from <NUM> to <NUM> moles of polyalkylene polyamine.

The dispersant systems herein include at least two different dispersants. At least one of the dispersants described herein may be borated and/or phosphorylated and, preferably, only the dispersant having the longer chain polyisobutenyl moiety is borated and phosphorylated. These dispersants are generally the reaction products of i) at least one phosphorus compound and/or a boron compound and ii) at least one ashless dispersant.

Suitable boron compounds useful in forming the dispersants herein include any boron compound or mixtures of boron compounds capable of introducing boron-containing species into the ashless dispersant. Any boron compound, organic or inorganic, capable of undergoing such reaction can be used. Accordingly, use can be made of boron oxide, boron oxide hydrate, boron trifluoride, boron tribromide, boron trichloride, HBF<NUM> boron acids such as boronic acid (e.g. alkyl-B(OH)<NUM> or aryl-B(OH)<NUM>), boric acid, (i.e., H<NUM>BO<NUM>), tetraboric acid (i.e., H<NUM>B<NUM>O<NUM>), metaboric acid (i.e., HBO<NUM>), ammonium salts of such boron acids, and esters of such boron acids. The use of complexes of a boron trihalide with ethers, organic acids, inorganic acids, or hydrocarbons is a convenient means of introducing the boron reactant into the reaction mixture. Such complexes are known and are exemplified by boron trifluoride-diethyl ether, boron trifluoride-phenol, boron trifluoride-phosphoric acid, boron trichloride-chloroacetic acid, boron tribromide-dioxane, and boron trifluoride-methyl ethyl ether.

Suitable phosphorus compounds for forming the dispersants herein include phosphorus compounds or mixtures of phosphorus compounds capable of introducing a phosphorus-containing species into the ashless dispersant. Any phosphorus compound, organic or inorganic, capable of undergoing such reaction can thus be used. Accordingly, use can be made of such inorganic phosphorus compounds as the inorganic phosphorus acids, and the inorganic phosphorus oxides, including their hydrates. Typical organic phosphorus compounds include full and partial esters of phosphorus acids, such as mono-, di-, and tri esters of phosphoric acid, thiophosphoric acid, dithiophosphoric acid, trithiophosphoric acid and tetrathiophosphoric acid; mono-, di-, and tri esters of phosphorous acid, thiophosphorous acid, dithiophosphorous acid and trithiophosphorous acid; trihydrocarbyl phosphine oxide; trihydrocarbyl phosphine sulfide; mono- and dihydrocarbyl phosphonates, (RPO(OR')(OR") where R and R' are hydrocarbyl and R" is a hydrogen atom or a hydrocarbyl group), and their mono-, di- and trithio analogs; mono- and dihydrocarbyl phosphonites, (RP(OR')(OR") where R and R' are hydrocarbyl and R" is a hydrogen atom or a hydrocarbyl group) and their mono- and dithio analogs. Thus, use can be made of such compounds as, for example, phosphorous acid (H<NUM>PO<NUM>, sometimes depicted as H<NUM>(HPO<NUM>), and sometimes called ortho-phosphorous acid or phosphonic acid), phosphoric acid (H<NUM>PO<NUM>, sometimes called orthophosphoric acid), hypophosphoric acid (H<NUM>P<NUM>O<NUM>), metaphosphoric acid (HPO<NUM>), pyrophosphoric acid (H<NUM>P<NUM>O<NUM>), hypophosphorous acid (H<NUM>PO<NUM>, sometimes called phosphinic acid), pyrophosphorous acid (H<NUM>P<NUM>O<NUM>, sometimes called pyrophosphonic acid), phosphinous acid (H<NUM>PO), tripolyphosphoric acid (H<NUM>P<NUM>O<NUM>), tetrapolyphosphoric acid (H<NUM>P<NUM>O<NUM>), trimetaphosphoric acid (H<NUM>P<NUM>O<NUM>), phosphorus trioxide, phosphorus tetraoxide, phosphorus pentoxide. Partial or total sulfur analogs such as phosphorotetrathioic acid (H<NUM>PS<NUM>) acid, phosphoromonothioic acid (H<NUM>PO<NUM>S), phosphorodithioic acid (H<NUM>PO<NUM>S<NUM>), phosphorotrithioic acid (H<NUM>POS<NUM>), phosphorus sesquisulfide, phosphorus heptasulfide, and phosphorus pentasulfide (P<NUM>S<NUM>, sometimes referred to as P<NUM>S<NUM>) can also be used in forming dispersants for this disclosure. Also usable, are the inorganic phosphorus halide compounds such as PCl<NUM>, PBr<NUM>, POCl<NUM>, PSCl<NUM>.

Likewise, use can be made of such organic phosphorus compounds as mono-, di-, and triesters of phosphoric acid (e.g., trihydrocarbyl phosphates, dihydrocarbyl monoacid phosphates, monohydrocarbyl diacid phosphates, and mixtures thereof), mono-, di-, and triesters of phosphorous acid (e.g., trihydrocarbyl phosphites, dihydrocarbyl hydrogen phosphites, hydrocarbyl diacid phosphites, and mixtures thereof), esters of phosphonic acids (both "primary", RP(O)(OR)<NUM>, and "secondary". R<NUM>P(O)(OR)), esters of phosphinic acids, phosphonyl halides (e.g., RP(O)Cl<NUM> and R<NUM>P(O)Cl), halophosphites (e.g., (RO)PCl<NUM> and (RO) <NUM>PCl), halophosphates (e.g., ROP(O)Cl<NUM> and (RO) <NUM>P(O)Cl), tertiary pyrophosphate esters (e.g., (RO) <NUM>P(O)-O-P(O)(OR)<NUM>), and the total or partial sulfur analogs of any of the foregoing organic phosphorus compounds, wherein each hydrocarbyl group contains up to <NUM> carbon atoms, preferably up to <NUM> carbon atoms, more preferably up to <NUM> carbon atoms, and most preferably up to <NUM> carbon atoms. Also usable are the halophosphine halides (e.g., hydrocarbyl phosphorus tetrahalides, dihydrocarbyl phosphorus trihalides, and trihydrocarbyl phosphorus dihalides), and the halophosphines (monohalophosphines and dihalophosphines).

As discussed above, the dispersant system of the lubricating and cooling fluids described herein include at least two dispersants, (i) one obtained from a polyisobutylene having a relatively high number average molecular weight and (ii) the other obtained from a polyisobutylene having a relatively lower number average molecular weight. The amounts of the two dispersants and the provision of phosphorus and boron are balanced relative to dispersant amounts and dispersant polyisobutylene moieties to improve lubricant electric conductivity and maintain suitable wear and friction performance.

In one embodiment, the first dispersant used in the dispersant system includes a polyisobutenyl moiety having a number average molecular weight in the range from <NUM> to <NUM> and is present in the lubricating and cooling fluid in an amount sufficient to deliver greater than <NUM> ppm nitrogen, greater than <NUM> ppm nitrogen, <NUM> to <NUM> ppm nitrogen, <NUM> to <NUM> ppm nitrogen, or up to <NUM> ppm, or up to <NUM> ppm nitrogen (or other ranges therewithin).

The first dispersant may be borated and/or phosphorylated. Accordingly, in one embodiment, the first dispersant has a boron content from <NUM> to <NUM> wt%, a phosphorus content from <NUM> to <NUM> wt% phosphorus, and a nitrogen content from <NUM> to <NUM> wt% nitrogen. In another embodiment, the first dispersant has a boron content of from <NUM> to <NUM> wt%, a phosphorus content of from <NUM> to <NUM> wt% phosphorus, and a nitrogen content of rom <NUM> to <NUM> wt% nitrogen. In some cases, the first dispersant is borated and phosphorylated and has a boron plus phosphorus to nitrogen ((B+P)/N) weight ratio of from <NUM>:<NUM> to <NUM>:<NUM>, or from <NUM>:<NUM> to <NUM>:<NUM>, or from <NUM>:<NUM> to <NUM>:<NUM> to <NUM>:<NUM>.

In one embodiment, the first dispersant of the dispersant system is borated and phosphorylated and is present in the lubricating and cooling fluid an amount sufficient to deliver less than <NUM> ppm boron, less than <NUM> ppm phosphorus, less than <NUM> ppm nitrogen, or less than <NUM> ppm. In another embodiment, the first dispersant is borated and phosphorylated and is present in the lubricating and cooling fluid an amount sufficient to deliver less than <NUM> ppm boron, less than <NUM> ppm phosphorus, and less than <NUM> ppm nitrogen. In yet another embodiment, first dispersant is borated and phosphorylated and is present in the lubricating and cooling fluid in an amount sufficient to deliver <NUM> to <NUM> ppm boron, <NUM> to <NUM> ppm phosphorus, and <NUM> ppm to <NUM> ppm of nitrogen or any other range of such elements between the amounts noted herein.

The second dispersant used in the dispersant system includes a polyisobutenyl moiety having a number average molecular weight less than <NUM>, or <NUM> to <NUM>, and is present in the lubricating and cooling fluid an amount sufficient to deliver less than <NUM> ppm nitrogen, or less than <NUM> ppm nitrogen, less than <NUM> ppm nitrogen, less than <NUM> ppm nitrogen, less than <NUM> ppm nitrogen, or less than <NUM> ppm nitrogen. In other approaches, the second dispersant includes, more than <NUM> ppm nitrogen, more than , <NUM> ppm nitrogen, more than <NUM> ppm nitrogen, more than <NUM> ppm nitrogen, or more than <NUM> ppm nitrogen (or any other ranges of such amounts herein). In embodiments herein, the second dispersant is preferably not borated and/or phosphorylated and does not provide such elements to the fluid.

As shown in the examples herein, when the first dispersant having a relatively high molecular weight is present in the lubricating and cooling fluid in an amount to deliver less than <NUM> ppm boron, less than <NUM> ppm phosphorus, and less than <NUM> ppm nitrogen (or other ranges noted above) and combined with the second dispersant in the lubricating and cooling fluid in an amount to deliver less than <NUM> ppm nitrogen (or other ranges noted above) and no boron or phosphorus, the resulting composition has decreased electric conductivity and maintain suitable wear and friction performance. If a single dispersant having a relatively low molecular weight is used to deliver boron and/or phosphorus to the lubricating and cooling fluid, the resulting composition has increased electric conductivity.

In yet other approaches or embodiments, the combined dispersant system of the fluids herein is balanced to provide high levels of boron and phosphorus relative to the total molecular weight of the combined polyisobutenyl moiety within the dispersant system. For instance, unexpectedly good conductivity was achieved when at least one of the first dispersant and the second dispersant is borated and phosphorylated such that a total amount of boron and phosphorus in the dispersant system relative to the nitrogen in the dispersant system is from <NUM> to <NUM> and wherein the first and second dispersants deliver up to <NUM> ppm of total boron and phosphorus per <NUM> number average molecular weight of the combined polyisobutylene moieties used in the dispersant system.

Such unique dispersant system combination unexpectedly achieves low conductivity together with the other desired fluid performance characteristics. <FIG>, as explained further in the Examples below, shows the dramatic effect of such dispersant system on the conductivity of the fluids herein.

THE FRICTION MODIFIER SYSTEM: The lubricating and cooling fluid described herein also contains a friction modifier system comprising at least two friction modifiers, such as an alkoxylated aliphatic amine and ether amine in specific amounts to provide suitable friction performance and decreased electrical conductivity.

The alkoxylated aliphatic amine useful in the present invention include, but are not limited to bis[<NUM>-hydroxyethyl]-coco-amine, polyoxyethylene cocoamine, (bis[<NUM>-hydroxyethyl] soyamine, bis[<NUM>-hydroxyethyl]allow-amine, polyoxyethylene-tallowamine, bis[<NUM>-hydroxyethyl] oleyl-amine, bis[<NUM>-hydroxyethyl]octadecylamine, and polyoxyethylene octadecylamine. In one embodiment, the alkoxylated aliphatic amine is a di(hydroxyalkyl) aliphatic tertiary amine in which the hydroxyalkyl groups, being the same or different, each contain from <NUM> to <NUM> carbon atoms, and in which the aliphatic group is an acyclic hydrocarbyl group containing from <NUM> to <NUM> carbon atoms. The alkoxylated aliphatic amine may be present in the lubricating and cooling fluid in an amount sufficient to deliver up to <NUM> ppm nitrogen, or up to <NUM> ppm of nitrogen.

The ether amine useful in the present invention include primary ether amines and ether diamines. More specifically, these can include but are not limited to one or more of: isohexyloxypropylamine, <NUM>-ethylhexyloxypropylamine, octyl/decyloxypropylamine, isodecyloxypropylamine, isododecyloxypropylamine, isotridecyloxypropylamine, C<NUM>-<NUM> alkyloxypropylamine, isodecyloxypropyl-<NUM>,<NUM>-diaminopropane, isododecyloxypropyl-<NUM>,<NUM>-diaminopropane, Isotridecyloxypropyl-<NUM>,<NUM>-diaminopropane, isohexyloxypropylamine, <NUM>-ethylhexyloxypropylamine, octyl/decyloxypropylamine, isodecyloxypropylamine, isopropyloxypropylamine, tetradecyloxypropylamine, dodecyl/tetradecyloxypropylamine, tetradecyl/dodecyloxypropylamine, octadecyl/hexadecyloxypropylamine. The ether amine may be present in the lubricating and cooling fluid in an amount sufficient to deliver up to <NUM> ppm nitrogen, or up to <NUM> ppm of nitrogen.

In one embodiment, the alkoxylated aliphatic amine and ether amine may be present in the lubricating and cooling fluid in an amount sufficient to deliver up to <NUM> ppm of nitrogen, or up to <NUM> ppm of nitrogen. In another embodiment, the alkoxylated aliphatic amine is a di(hydroxyalkyl) aliphatic tertiary amine and the ether amine is isodecyloxy- propylamine and the combination of both amines is present in an amount sufficient deliver up to <NUM> ppm of nitrogen, or up to <NUM> ppm of nitrogen.

In another embodiment, the lubricating and cooling fluid described herein further comprises an optional third friction modifier, such as a fatty diamine. Examples of suitable fatty diamines are mono- or dialkyl, symmetrical or asymmetrical ethylenediamines, propanediamines (<NUM>, <NUM>, or <NUM>,<NUM>), and polyamine analogs of the above, n-coco-<NUM>,<NUM>-diaminopropane, n-soya-<NUM>,<NUM>-diaminopropane, n-tallow-<NUM>,<NUM>-diaminopropane, and n-oleyl-<NUM>,<NUM>-diaminopropane. The fatty diamine may be present in the lubricating and cooling fluid in an amount sufficient to deliver up to <NUM> ppm nitrogen or up to <NUM> ppm of nitrogen.

In one embodiment, the lubricating and cooling fluid described herein includes an alkoxylated aliphatic amine, an ether amine, and a fatty diamine and the combination of these components may be present in the lubricating and cooling fluid in an amount sufficient to deliver up to <NUM> ppm of nitrogen. In another embodiment, the lubricating and cooling fluid includes a di(hydroxyalkyl) aliphatic tertiary amine, isodecyloxypropylamine, n-oleyl-<NUM>,<NUM>-diaminopropane and the combination of these compounds present in an amount sufficient deliver up to <NUM> ppm of nitrogen.

The lubricating and cooling fluid described herein may also include other additives of the type used in transmission fluid compositions in addition to the components described above. Such additives include, but are not limited to, antioxidant(s), viscosity modifier(s), phosphorus-containing components, detergent(s), corrosion inhibitor(s), antirust additives, antifoam agent(s), demulsifier(s), pour point depressant(s), seal swell agent(s), and additional dispersant(s), additional friction modifier(s), and additional sulfur-containing component(s).

ANTIOXIDANTS: In some embodiments, the lubricating and cooling fluid contains one more antioxidants. Suitable antioxidants include phenolic antioxidants, aromatic amine antioxidants, sulfur containing antioxidants, and organic phosphites, among others.

Examples of phenolic antioxidants include <NUM>,<NUM>-di-tert-butylphenol, liquid mixtures of tertiary butylated phenols, <NUM>,<NUM>-di-tert-butyl-<NUM>-methylphenol, <NUM>,<NUM>'-methylenebis(<NUM>,<NUM>-di-tert-butylphenol), <NUM>,<NUM>'-methylenebis(<NUM>-methyl-<NUM>-ter-t-butylphenol), and mixed methylene-bridged polyalkyl phenols, and <NUM>,<NUM>'-thiobis(<NUM>-methyl-<NUM>-tert-butylphenol), N,N'-di-sec-butyl-phenylenediamine,.

<NUM>-iisopropylaminodiphenylamine, phenyl-alpha-naphthyl amine, phenyl-alpha-naphthyl amine, and ring-alkylated diphenylamines. Examples include the sterically hindered tertiary butylated phenols, bisphenols and cinnamic acid derivatives and combinations thereof.

Aromatic amine antioxidants include, but are not limited to diarylamines having the formula:
<CHM>
wherein R' and R" each independently represents a substituted or unsubstituted aryl group having from <NUM> to <NUM> carbon atoms. Illustrative of substituents for the aryl group include aliphatic hydrocarbon groups such as alkyl having from <NUM> to <NUM> carbon atoms, hydroxy groups, halogen radicals, carboxylic acid or ester groups, or nitro groups.

The aryl group is preferably substituted or unsubstituted phenyl or naphthyl, particularly wherein one or both of the aryl groups are substituted with at least one alkyl having from <NUM> to <NUM> carbon atoms, preferably from <NUM> to <NUM> carbon atoms, most preferably from <NUM> to <NUM> carbon atoms. It is preferred that one or both aryl groups be substituted, e.g. mono-alkylated diphenylamine, di-alkylated diphenylamine, or mixtures of mono- and di-alkylated diphenylamines.

Examples of diarylamines that may be used include, but are not limited to: diphenylamine; various alkylated diphenylamines, <NUM>-hydroxydiphenylamine, N-phenyl-<NUM>,<NUM>-phenylenediamine, N-phenyl-<NUM>,<NUM>-phenylenediamine, monobutyldiphenyl-amine, dibutyldiphenylamine, monooctyldiphenylamine, dioctyldiphenylamine, monononyldiphenylamine, dinonyldiphenylamine, monotetradecyldiphenylamine, ditetradecyldiphenylamine, phenyl-alpha-naphthylamine, monooctyl phenyl-alpha-naphthylamine, phenyl-beta-naphthylamine, monoheptyldiphenylamine, diheptyl-diphenylamine, p-oriented styrenated diphenylamine, mixed butyloctyldi-phenylamine, and mixed octylstyryldiphenylamine.

The sulfur containing antioxidants include, but are not limited to, sulfurized olefins that are 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 <NUM> to <NUM>/mole, are preferred. Examples of olefins that may be used include alpha-olefins, isomerized alpha-olefins, branched olefins, cyclic olefins, and combinations of these.

Alpha-olefins include, but are not limited to, any C4 to C25 alpha-olefins. Alpha-olefins may be isomerized before the sulfurization reaction or during the sulfurization reaction. Structural and/or conformational isomers of the alpha olefin that contain internal double bonds and/or branching may also be used. For example, isobutylene is a branched olefin counterpart of the alpha-olefin <NUM>-butene.

Sulfur sources that may be used in the sulfurization reaction of olefins include: elemental sulfur, sulfur monochloride, sulfur dichloride, sodium sulfide, sodium polysulfide, and mixtures of these added together or at different stages of the sulfurization process.

Unsaturated oils, because of their unsaturation, may also be sulfurized and used as an antioxidant. Examples of oils or fats that may be used include corn oil, canola oil, cottonseed oil, grapeseed oil, olive oil, palm oil, peanut oil, coconut oil, rapeseed oil, safflower seed oil, sesame seed oil, soybean oil, sunflower seed oil, tallow, and combinations of these.

The total amount of antioxidant in the lubricating and cooling fluid described herein may be present in an amount to deliver up to <NUM> ppm nitrogen, or up to <NUM> ppm nitrogen, or up to <NUM> ppm nitrogen, or <NUM> to <NUM> ppm nitrogen.

ADDITIONAL FRICTION MODIFIERS: In some embodiments, the lubricating and cooling fluid contains additional friction modifiers other than those contained in the friction modifier system described above. Suitable additional friction modifiers may comprise metal containing and metal-free friction modifiers and may include, but are not limited to, imidazolines, amides, amines, succinimides, alkoxylated amines, alkoxylated ether amines, amine oxides, amidoamines, nitriles, betaines, quaternary amines, imines, amine salts, amino guanidine, alkanolamides, phosphonates, metal-containing compounds, glycerol esters, sulfurized fatty compounds and olefins, sunflower oil other naturally occurring plant or animal oils, dicarboxylic acid esters, esters or partial esters of a polyol and one or more aliphatic or aromatic carboxylic acids.

Suitable friction modifiers may contain hydrocarbyl groups that are selected from straight chain, branched chain, or aromatic hydrocarbyl groups or mixtures thereof, and such hydrocarbyl groups may be saturated or unsaturated. The hydrocarbyl groups may be composed of carbon and hydrogen or hetero atoms such as sulfur or oxygen. The hydrocarbyl groups may range from <NUM> to <NUM> 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 di-ester, 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.

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 a polar terminal group (e.g. carboxyl or hydroxyl) covalently bonded to an oleophilic hydrocarbon chain. An example of an organic ashless nitrogen-free friction modifier is known generally as glycerol monooleate (GMO) which may contain mono-, di-, and tri-esters of oleic acid. Other suitable friction modifiers are described in <CIT>.

Aminic friction modifiers may include amines or polyamines. Such compounds can have hydrocarbyl groups that are linear, either saturated or unsaturated, or a mixture thereof and may contain from <NUM> to <NUM> carbon atoms. Further examples of suitable friction modifiers include alkoxylated amines and alkoxylated ether amines. Such compounds may have hydrocarbyl groups that are linear, either saturated, unsaturated, or a mixture thereof. They may contain from <NUM> to <NUM> carbon atoms. Examples include ethoxylated amines and ethoxylated ether amines.

The amines and amides may be used as such or in the form of an adduct or reaction product with a boron compound such as a boric oxide, boron halide, metaborate, boric acid or a mono-, di- or tri-alkyl borate. Other suitable friction modifiers are described in <CIT>.

If the additional friction modifiers contain nitrogen, such additional friction modifiers may be present in the lubricating and cooling fluid in an amount to deliver up to <NUM> ppm nitrogen, or up to <NUM> ppm nitrogen, or <NUM> to <NUM> ppm nitrogen.

DETERGENTS: Metal detergents that may be included in the lubricating and cooling fluid described herein may generally comprise a polar head with a long hydrophobic tail where the polar head comprises a metal salt of an acidic organic compound. The salts may contain a substantially stoichiometric amount of the metal, in which case they are usually described as normal or neutral salts, and would typically have a total base number or TBN (as measured by ASTM D2896) of from <NUM> to less than <NUM>. Large amounts of a metal base may be included by reacting an excess of a metal compound such as an oxide or hydroxide with an acidic gas such as carbon dioxide. The resulting overbased detergent comprises micelles of neutralized detergent surrounding a core of inorganic metal base (e.g., hydrated carbonates). Such overbased detergents may have a TBN of <NUM> or greater, such as from <NUM> to <NUM> or more.

Detergents that may be suitable for use in the present embodiments include oil-soluble overbased, low base, and neutral sulfonates, phenates, sulfurized phenates, and salicylates of a metal, particularly the alkali or alkaline earth metals, e.g., sodium, potassium, lithium, calcium, and magnesium. More than one metal may be present, for example, both calcium and magnesium. Mixtures of calcium and/or magnesium with sodium may also be suitable. Suitable metal detergents may be overbased calcium or magnesium sulfonates having a TBN of from <NUM> to <NUM> TBN, overbased calcium or magnesium phenates or sulfurized phenates having a TBN of from <NUM> to <NUM> TBN, and overbased calcium or magnesium salicylates having a TBN of from <NUM> to <NUM>. Mixtures of such salts may also be used.

The metal-containing detergent may be present in the lubricating and cooling fluid in an amount sufficient to improve the anti-rust performance of the fluid. The metal-containing detergent may be present in the fluid in an amount sufficient to provide up to <NUM> ppm alkali and/or alkaline earth metal based on a total weight of the lubricating and cooling fluid. In one example, the metal-containing detergent may be present in an amount sufficient to provide from <NUM> to <NUM> ppm alkali and/or alkaline earth metal. In another embodiment, the metal-containing detergent may be present in an amount sufficient to provide from <NUM> to <NUM> ppm alkali and/or alkaline earth metal.

CORROSION INHIBITORS: Rust or corrosion inhibitors may also be included in the lubricating compositions described herein. Such materials include monocarboxylic acids and polycarboxylic acids. Examples of suitable monocarboxylic acids are octanoic acid, decanoic acid and dodecanoic acid. Suitable polycarboxylic acids include dimer and trimer acids such as are produced from such acids as tall oil fatty acids, oleic acid, linoleic acid.

Another useful type of rust inhibitor may be alkenyl succinic acid and alkenyl succinic anhydride corrosion inhibitors such as, for example, tetrapropenylsuccinic acid, tetrapropenylsuccinic anhydride, tetradecenylsuccinic acid, tetradecenylsuccinic anhydride, hexadecenylsuccinic acid, hexadecenylsuccinic anhydride. Also useful are the half esters of alkenyl succinic acids having <NUM> to <NUM> carbon atoms in the alkenyl group with alcohols such as the polyglycols. Other suitable rust or corrosion inhibitors include ether amines, acid phosphates, amines, polyethoxylated compounds such as ethoxylated amines, ethoxylated phenols, and ethoxylated alcohols, imidazolines, aminosuccinic acids or derivatives thereof. Mixtures of such rust or corrosion inhibitors may be used. The total amount of corrosion inhibitor, when present in the lubricating composition described herein may range up to <NUM> wt% or from <NUM> to <NUM> wt% based on the total weight of the lubricating composition.

VISCOSITY MODIFIERS: The lubricating and cooling fluid may optionally contain one or more viscosity modifiers. Suitable viscosity modifiers may include polyolefins, olefin copolymers, ethylene/propylene copolymers, polyisobutenes, hydrogenated styreneisoprene polymers, styrene/maleic ester copolymers, hydrogenated styrene/butadiene copolymers, hydrogenated isoprene polymers, alpha-olefin maleic anhydride copolymers, polymethacrylates, polyacrylates, polyalkyl styrenes, hydrogenated alkenyl aryl conjugated diene copolymers, or mixtures thereof. Viscosity modifiers may include star polymers and suitable examples are described in <CIT>.

The lubricating and cooling fluid described herein also may optionally contain one or more dispersant viscosity modifiers in addition to a viscosity modifier or in lieu of a viscosity modifier. Suitable dispersant viscosity modifiers may include functionalized polyolefins, for example, 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 an amine, or esterified maleic anhydride-styrene copolymers reacted with an amine.

The total amount of viscosity modifier and/or dispersant viscosity modifier, when present, may be up to <NUM> wt%, or up to <NUM> wt%, or up to <NUM> wt% based on the total weight of the lubricating and cooling fluid.

DEMULSIFIERS: Demulsifiers include trialkyl phosphates, and various polymers and copolymers of ethylene glycol, ethylene oxide, propylene oxide, or mixtures thereof, including polyethylene oxides, polypropylene oxides and (ethylene oxide-propylene oxide) polymers. When present, the amount of demulsifier in the lubricating and cooling fluid may be up <NUM> wt, or up to <NUM> wt%, or below <NUM> wt% based on the total weight of the lubricating and cooling fluid.

ANTIFOAM AGENTS: Antifoam agents used to reduce or prevent the formation of stable foam include silicones, polyacrylates, or organic polymers. Foam inhibitors that may be useful in the compositions of the disclosed invention include polysiloxanes, copolymers of ethyl acrylate and <NUM>-ethylhexylacrylate and optionally vinyl acetate. When present, the amount of antifoam in the lubricating and cooling fluid may be up <NUM> wt, or up to <NUM> wt%, or below <NUM> wt% based on the total weight of the lubricating and cooling fluid.

POUR POINT DEPRESSANTS: The lubricating and cooling fluid may optionally contain one or more pour point depressants. Suitable pour point depressants may include esters of maleic anhydride-styrene, polymethacrylates, polymethylmethacrylates, polyacrylates or polyacrylamides or mixtures thereof. Pour point depressants, when present, may be present in amount from <NUM> wt% to <NUM> wt%, based upon the total weight of the lubricating and cooling fluid.

In general terms, a lubricating and cooling fluid described herein may include additive components in the ranges listed in Table <NUM>.

The percentages of each component above represent the weight percent of each component, based upon the total weight of the lubricating and cooling fluid containing the recited component. Additives used in formulating the compositions described herein may be blended into the base oil individually or in various sub-combinations. However, it may be suitable to blend all of the components concurrently using an additive concentrate (i.e., additives plus a diluent, such as a hydrocarbon solvent). The use of an additive concentrate takes advantage of the mutual compatibility afforded by the combination of ingredients when in the form of an additive concentrate. Also, the use of a concentrate reduces blending time and lessens the possibility of blending errors.

Electric motor systems including a single fluid that provides not only lubrication to gears, clutches, and other mechanical parts but also cooling to the electric motor should provide good wear and friction performance, low copper corrosion, and relatively low electrical conductivity. However, the elevated temperatures in the electric motor pose challenges for developing this type of fluid. In the sump of the electric motor, the lubricating and cooling fluid can reach temperatures greater than <NUM> or greater than <NUM> and, in some instances, <NUM> to <NUM>. Likewise, the temperature of the copper windings in the stator of the motor may reach at least <NUM>, and in some instances up to <NUM>. Additives that provide elements like sulfur, boron, or phosphorus to achieve good wear performance, but can lead to excessive copper corrosion and higher conductivity. Moreover, these negative effects are exacerbated at higher temperatures. Thus, it was unexpected that the combination of selected additives providing amounts of sulfur, phosphorus, and boron herein provided acceptable wear and friction performance while also providing low copper corrosion and low conductivity at elevated temperatures.

In any of the embodiments herein, fluids including the sulfurized component, the dispersant system, and the friction modifier systems as described herein and when used with an oil of lubricating viscosity including an API Group III base oil, an API Group IV base oil, or mixtures thereof may exhibit one or more of the following: (i) a torque when using a clutch rig test applying a maximum force of about <NUM> kN and at a fluid temperature of about <NUM>, as measured at <NUM>% of maximum RPM, <NUM>% of maximum RPM, and <NUM>% of maximum RPM over <NUM> shifts; (ii) a torque when using a clutch rig test applying a maximum force of about <NUM> kN and at a fluid temperature of about <NUM>, as measured after a dynamic shift over <NUM> shifts and after breakaway over <NUM> shifts; (iii) a µV-behavior evidencing a controllable shift performance when using a clutch rig test applying a maximum force of about 2kN, a fluid temperature of about <NUM>, and a ramp speed n of <NUM> to <NUM> where the µV-behavior exhibits a positive shape characteristic from <NUM> to <NUM> RPM; (iv) a synchronization friction value when using a SSP180 synchro test rig (ZF Friedrichshafen AG) with a maximum force of about <NUM> kN, a fluid temperature of about <NUM>, and a double carbon synchro ring for up to <NUM> shifts at <NUM> rpm with an average friction coefficient (µavg) of approximately <NUM> for up to <NUM> shifts and a minimum friction coefficient (µmin) of approximately <NUM> for up to <NUM> shifts; (v) a resistance pursuant to DIN EN <NUM> at a frequency of <NUM> using a Flucon or equivalent conductivity meter of at least <NUM> MΩ*m in a temperature range of <NUM> to <NUM> and, in particular, from <NUM> to <NUM>, and a resistance of at least <NUM> MΩ*m at <NUM>, a resistance of approximately <NUM> MΩ*m at <NUM>, and a resistance of approximately <NUM> MΩ*m at <NUM>; and/or (vi) a dissipation factor (tan δ) pursuant to DIN EN <NUM> at a frequency of <NUM> using the Flucon or equivalent conductivity meter of <NUM> or less from a temperature of <NUM> to <NUM> and, in particular, from <NUM> to <NUM>.

The following non-limiting examples illustrate the features and advantages of one or more embodiments of the disclosure. In these examples, as well as elsewhere in this application, all ratios, parts, and percentages are by weight unless otherwise indicated. To demonstrate how the sulfurized component, dispersant system, and friction modifier systems affected the wear, oxidation, copper compatibility, and conductivity of the fluid, exemplary finished fluids were formulated and tested.

The formulations were evaluated in the FZG Scuffing Test, DKA Oxidation Test, a copper corrosion test, and measured for initial electrical conductivity.

FZG Scuffing Test is wear test used to evaluate the scuffing load capacity of lubricants and is performed according to ASTM D5182-<NUM> (<NUM>). Results are reported in load stage pass, and better results are obtained for samples with a higher load stage pass.

DKA Oxidation Test is carried out according to the CEC L-<NUM>-A-<NUM> with operating conditions of <NUM> or <NUM> for <NUM> hours. The results obtained are the percentage increase in kinematic viscosity at <NUM>. Lower values suggest improved performance.

It is beneficial for electric motor fluids to exhibit low conductivity, and thus act somewhat as an insulator. The conductivity of fluids was measured according to a modified version of ASTM D2624-<NUM> (testing of a lubricant, rather than of a fuel using a Flucon Epsilon+ at <NUM> V).

The copper corrosion test is a modified version of ASTM D130-<NUM> in which copper strips are immersed in the lubricant at <NUM> for <NUM> hours. At the end of the test, the oil was evaluated for levels of copper. Higher levels of copper in the oil indicate the corrosiveness of the lubricant to copper.

The formulations were also tested for thermal conductivity to ensure they exhibit appropriate cooling ability. The thermal conductivity of each formulation was measured at <NUM> using one measurement according to ASTM D7896-<NUM> and all formulations exhibited a thermal conductivity between <NUM> and <NUM> mW/(m-K), and thus had suitable cooling ability.

The formulations tested in Table <NUM> below all contained the same additive base pack containing antioxidant, friction modifiers, antifoam and demulsifier. The formulations also contained varying amounts of sulfurized components, additional friction modifiers, dispersants, and base oil as set forth in Table <NUM>. The formulations were tested in a broad range of base oils to obtain finished fluids having kinematic viscosities at <NUM> of between <NUM> and <NUM> cSt. The inventive formulations contain similar additives to the comparative formulations but balanced the delivery of sulfur, friction modifiers and dispersants differently to achieve surprisingly improved wear, oxidation stability, copper compatibility, and low conductivity even with high levels of sulfur, boron, and phosphorus not expected to perform in the context of lubricants for electric motor systems. Details of these components are described below:.

All the inventive formulations contain the first sulfurized component, in this case, <NUM>,<NUM>-dimercapto-<NUM>,<NUM>,<NUM>-thiadiazole and hydrocarbyl-substituted derivatives thereof, at a treat rate to deliver between <NUM> ppm to <NUM> pm sulfur to the lubricant. Two of the inventive formulations also contained the optional second sulfurized component, in this case, sulfurized synthetic sperm oil, in an amount up to <NUM> ppm sulfur to the lubricant. All inventive examples exhibited improved wear performance and improved copper protection compared to the comparative examples that delivered too little or too much sulfur from the first sulfurized component and/or delivered too much sulfur from the second sulfurized component.

In both the inventive and comparative formulations, the friction modifier system comprised the following friction modifiers: alkoxylated aliphatic amine, ether amine, and fatty diamine. The inventive formulations contain these components in amounts to provide suitable friction performance and decreased electrical conductivity.

In the comparative formulations, the dispersant system included one phosphorylated and borated succinimide dispersant obtained from <NUM> MW polyisobutylene. In the inventive samples, the dispersant system included two dispersants. The first dispersant was a phosphorylated and borated succinimide dispersant obtained from <NUM> Mn polyisobutylene. The second dispersant was a succinimide dispersant obtained from <NUM> Mn polyisobutylene. Without being bound by any particular theory, it is believed that the inclusion of the first and second dispersants in the inventive formulations improves lubricant conductivity and maintains suitable wear and friction performance. The surprising effect of the dispersant system is shown in Tables <NUM> and <NUM> and <FIG> with a ratio of boron and phosphorus relative to the total molecular weight of the polyisobutylene chains in the dispersant system.

<FIG> shows the improvement of inventive samples over comparative samples in the context of how the dispersant system boron and phosphorus are provided relative to the number average molecular weight of total polyisobutylene moiety or moieties in the dispersant system. Surprisingly, this factor exhibits an effect on conductivity with inventive samples showing a much lower conductivity suitable for fluids for electric motor systems.

Inventive Fluids including the sulfurized component, dispersant system, and friction modifier systems of Inventive Sample <NUM> of Example <NUM> used with an oil of lubricating viscosity including an API Group III base oil, an API Group IV base oil, or mixtures thereof were further evaluated for torque using a clutch rig test applying a maximum force of <NUM> kN and a fluid temperature of <NUM>. As shown in <FIG>, <FIG>, the torque was measured as N·m at <NUM>% of maximum RPM, <NUM>% of maximum RPM, and <NUM>% of maximum RPM respectively over <NUM> shifts. If the torque measurement deviates significantly from the graphed values, poor shift quality may occur.

The Inventive fluid from Example <NUM> was further evaluated for torque after a dynamic shift and after breakaway using the clutch rig test of Example <NUM> applying a maximum force of <NUM> kN and a fluid temperature of <NUM>. <FIG>illustrates the torque measurements after a dynamic shift over <NUM> shifts. <FIG> illustrates the torque measurements after breakaway over <NUM> shifts. If the torque values deviates significantly from the graphed values, poor shift quality may occur, and torque transmission may not be optimal.

The Inventive fluid from Example <NUM> was further evaluated for controllable shift behavior (Torque -V Behavior) using the clutch rig test of Example <NUM> applying a maximum force of 2kN, a fluid temperature of <NUM>, and a ramp speed n of <NUM> to <NUM>. In <FIG>, the torque -V measurements are plotted over <NUM>/min [X] and have a positive shape characteristic from <NUM> to <NUM> RPM. If the torque-V measurements deviate from the plotted values, then poor shift quality with noise and vibration may occur.

The Inventive fluid from Example <NUM> was further evaluated for synchronization friction values using a SSP180 synchro test rig (ZF Friedrichshafen AG) applying a maximum force of 600N, a fluid temperature of <NUM>, a double carbon synchro ring, and at <NUM> rpm. As shown in <FIG>, the fluid exhibited an average friction coefficient (µavg) of approximately <NUM> for up to <NUM> shifts. <FIG> shows that the fluid exhibited a minimum friction coefficient (µmin) of approximately <NUM> for up to <NUM> shifts.

The Inventive fluid from Example <NUM> was further evaluated for specific resistance pursuant to DIN EN <NUM> at a frequency of <NUM> using a Flucon conductivity meter. As shown in <FIG>, the specific resistance of fresh and used inventive fluids was at least <NUM> MΩ*m in a temperature range of <NUM> to <NUM>. The specific resistance of fresh and used inventive fluids was at least <NUM> MΩ*m at <NUM>. For the Worldwide Harmonized Light Vehicle Test (WLTP) laboratory test, the oil temperature is around <NUM> and for the usual consumer drive program around <NUM>. As shown in <FIG>, the inventive fluid (both fresh and used) had a specific resistance of approximately <NUM> MΩ*m (at <NUM>) and approximately <NUM> MΩ*m (at <NUM>), which were much higher than either the fresh or used comparison ATF and DCT gear oils shown in <FIG>.

The Inventive fluid from Example <NUM> was further evaluated for dissipation factor (tan δ) pursuant to DIN EN <NUM> at a frequency of <NUM> using the Flucon conductivity meter. As shown in <FIG>, the dissipation factor (tan δ) was at <NUM> or less from a temperature of <NUM> to <NUM>. For the usual consumer drive program with a temperature of <NUM> to <NUM>, the dissipation factor was at <NUM> or less for the inventive fluid (both fresh and used), but fresh and used comparative ATF and DCT gear oil were all higher than <NUM> at temperatures above <NUM>.

It is to be understood that while the lubricating composition and compositions of this disclosure have been described in conjunction with the detailed description thereof and summary herein, the foregoing description is intended to illustrate and not limit the scope of the disclosure, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the claims. It is intended that the specification and examples be considered as exemplary only.

Other embodiments of the present disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. As used throughout the specification and claims, "a" and/or "an" may refer to one or more than one. Unless indicated to the contrary, the numerical parameters set forth in the specification are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

Thus, a range of from <NUM> to <NUM> is to be interpreted as an express disclosure of the values <NUM>, <NUM>, <NUM> and <NUM> as well as any range of such values such as <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>, <NUM> to <NUM>.

Claim 1:
A lubricating and cooling fluid for an electric motor system comprising:
a majority base oil of lubricating viscosity comprising an API Group III base oil, an API Group IV base oil, or mixtures thereof;
at least one thiadiazole or hydrocarbyl-substituted derivatives thereof delivering <NUM> to <NUM> ppm sulfur to the lubricating and cooling fluid; an optional sulfurized ester delivering up to <NUM> ppm sulfur to the lubricating and cooling fluid;
a dispersant system including (i) a first dispersant obtained from polyisobutylene having a number average molecular weight of <NUM> to <NUM> and delivering nitrogen in amounts of <NUM> ppm or less nitrogen to the lubricating and cooling fluid and (ii) a second dispersant obtained from polyisobutylene having a number average molecular weight of <NUM> or less and delivering nitrogen in amounts of <NUM> ppm or less nitrogen to the lubricating and cooling fluid;
an alkoxylated aliphatic amine delivering up to <NUM> ppm nitrogen to the lubricating and cooling fluid;
an ether amine delivering up to <NUM> ppm nitrogen to the lubricating and cooling fluid;
wherein at least one of the first dispersant and the second dispersant is borated and phosphorylated such that a total amount of boron and phosphorus in the dispersant system relative to the nitrogen in the dispersant system is from <NUM> to <NUM> and wherein the first and second dispersants deliver up to <NUM> ppm of total boron and phosphorus per <NUM> number average molecular weight of the combined polyisobutylene moieties used in the dispersant system;
wherein the average number molecular weight is determined by gel permeation chromatography using a polystyrene standard with a Mn of <NUM> to <NUM>,<NUM> as the calibration reference;
wherein the lubricating and cooling fluid has an electrical conductivity of <NUM> nS/M or less, as measured by ASTM D2624-<NUM> at <NUM> and at <NUM>.