EP2773731A2

EP2773731A2 - Oil soluble polyalkylene glycol lubricant compositions

Info

Publication number: EP2773731A2
Application number: EP12784827.3A
Authority: EP
Inventors: Martin R. Greaves
Original assignee: Dow Global Technologies LLC
Current assignee: Dow Global Technologies LLC
Priority date: 2011-11-01
Filing date: 2012-10-25
Publication date: 2014-09-10
Also published as: JP2014534316A; US20140303053A1; CN103890154A; WO2013066702A3; WO2013066702A2

Abstract

A lubricant composition comprising at least 90 wt% of at least one oil soluble polyalkylene glycol (OSP), wherein the OSP comprises at least 40 wt% units derived from butylene oxide and at least 40 wt% units derived from propylene oxide, initiated by one or more initiators selected from monols, diols, and polyols; and at least 0.05 wt% of at least one anti-wear additive; wherein the lubricant composition exhibits a four ball anti-wear of less than or equal to 0.35 mm and an air release value at 50 °C of less than or equal to 1 minute is provided.

Description

OIL SOLUBLE POLYALKYLENE GLYCOL LUBRICANT COMPOSITIONS

Field of Invention

The instant invention relates to oil soluble polyalkylene glycol lubricant compositions.

Background of the Invention

Three important performance properties of hydraulic fluids are anti-wear performance, air release, and deposit control.

Commercially available hydraulic fluids include those based on mineral oils,

polyalphaolefms (PAOs), synthetic esters, phosphate esters, vegetable oils, and polyalkylene glycols (PAGs). The different types of hydraulic fluids offer varying wear, air release and deposit control properties. Formulated hydraulic fluids which combine all three properties in which the air release and anti-wear values are low but deposit control is excellent are highly desired.

Summary of the Invention

The instant invention is a lubricant composition and methods of using same in hydraulic fluids, compressor oils and engine oils.

In one embodiment, the instant invention provides a lubricant composition comprising at least 90 wt% of at least one oil soluble polyalkylene glycol (OSP), wherein the OSP comprises at least 40 wt% units derived from butylene oxide and at least 40 wt% units derived from propylene oxide, initiated by one or more initiators selected from monols, diols, and polyols; and at least 0.05 wt% of at least one anti-wear additive; wherein the lubricant composition exhibits a four ball anti- wear of less than or equal to 0.35 mm and an air release value at 50 °C of less than or equal to 1 minute.

Detailed Description of the Invention

It has been discovered that new oil soluble PAGs derived from butylene oxide (BO) derivatives and formulated with an anti-wear additive can provide very low anti-wear values and excellent low air release values. In addition these products offer excellent deposit control.

The instant invention is a lubricant composition. The composition according to the instant invention comprises at least 90 wt% of at least one oil soluble polyalkylene glycol (OSP), wherein the OSP comprises at least 40 wt% units derived from butylene oxide and at least 40 wt% units derived from propylene oxide (PO), initiated by one or more initiators selected from monols, diols, and polyols; and at least 0.05 wt% of at least one anti-wear additive; wherein the lubricant composition exhibits a four ball anti-wear of less than or equal to 0.35 mm and an air release value at 50 °C of less than or equal to 1 minute.

Oil soluble polyalkylene glycols (OSPs) useful in embodiments of the lubricant composition comprise at least 40 weight percent units derived from butylene oxide. All individual values and subranges from at least 40 weight percent units derived from butylene oxide are included herein and disclosed herein; for example, the amount of units derived from butylene oxide can be from a lower limit of 40, 45, 50, 55 or 60 weight percent. Oil soluble polyalkylene glycols useful in embodiments of the lubricant composition comprise at least 40 weight percent units derived from propylene oxide. All individual values and subranges from at least 40 weight percent units derived from propylene oxide are included herein and disclosed herein; for example, the amount of units derived from propylene oxide can be from a lower limit of 40, 45, 50, 55 or 60 weight percent.

The lubricant composition comprises at least 90 weight percent (wt%) of such oil soluble PAG. All individual values and subranges from at least 90 weight percent oil soluble PAG are included herein and disclosed herein; for example, the amount of oil soluble PAG in the lubricant composition can be from a lower limit of 90, 92, 94, 95, 96, 98 or 100 weight percent.

OSPs useful in embodiments of the lubricant composition are initiated by one or more initiators selected from group consisting of alcohols (i.e., monols), diols, and polyols. Exemplary alcohol (i.e., monol) initiators include methanol, ethanol, propanol, butanol, pentanol, hexanol, neopentanol, isobutanol, decanol, 2-ethylhexanol, and the like, as well as higher acyclic alcohols derived from both natural and petrochemical sources with from 11 carbon atoms to 22 carbon atoms alcohols Exemplary diol initiators include monoethylene glycol, monopropylene glycol, butylene glycol, diethylene glycol or dipropylene glycol. Exemplary polyol initiators include neopentyl glycol, trimethyolpropane and pentaerythritiol.

Embodiments of the lubricant compositions comprise at least 0.05 wt% of at least one anti- wear additive. All individual values and subranges from at least 0.05 weight percent anti-wear additive are included herein and disclosed herein; for example, the amount of anti-wear additive in the lubricant composition can be from a lower limit of 0.05, 0.15, 0.25, 0.5, 0.8 or 1 weight percent

Embodiments of the lubricant composition exhibit a four ball anti-wear of less than or equal to 0.35 mm. All individual values and subranges from less than or equal to 0.35 mm are included herein and disclosed herein; for example, the lubricant composition can exhibit a four ball anti-wear of less than or equal to 0.35, 0.34, 0.33, 0.32, 0.31, 0.30, or 0.29 mm.

Embodiments of the lubricant composition exhibit an air release value at 50 °C of less than or equal to 1 minute. All individual values and subranges from less than or equal to 1 minute are included herein and disclosed herein; for example, the lubricant composition can exhibit an air release value at 50 °C of less than or equal to 15 seconds, 30 seconds, 45 seconds, or 1 minute.

Certain embodiments of the lubricant composition further exhibit an air release value at 75 °C of less than or equal to 1 minute. All individual values and subranges from less than or equal to 1 minute are included herein and disclosed herein; for example, the lubricant composition can exhibit an air release value at 75 °C of less than or equal to 15 seconds, 30 seconds, 45 seconds, or 1 minute.

In some embodiments of the lubricant composition, the at least one OSP exhibits an aniline point of less than -20 °C. All individual values and subranges from less than -20 °C are included herein and disclosed herein; for example, the aniline point of the at least one OSP can be from an upper limit of -30, -28, -24, or -20 °C.

In some embodiments of the lubricant composition, the at least one OSP exhibits a kinematic viscosity at 40 °C from 15 to 250 cSt. All individual values and subranges from 15 to 250 cSt are included herein and disclosed herein; for example, the kinematic viscosity at 40 °C of the at least one OSP can be from a lower limit of 15, 20, 50, 80, 110, 130, 170, 210, or 240 cSt to an upper limit of 30, 60, 90, 120, 150, 180, 220 or 250 cSt. For example, the kinematic viscosity may be in the range of from 15 to 250 cSt, or from 15 to 220 cSt, or from 100 to 180 cSt.

Anti-wear additives useful in the lubricant composition include, for example, one or more additives selected from the group consisting of zinc dialkyldithiophosphates, amine phosphates, dithiocarbamates, alkylphosphate esters, ashless dithiocarbamates, combinations thereof and blends thereof.

Some embodiments of the lubricant composition may further comprise one or more additives selected from the group consisting of extreme pressure additives, yellow metal passivators, and antioxidants. Exemplary extreme pressure additives include ashless dithiophosphates, triaryl

phosphothionates, alkyl diphenylphosphites, amine phosphates, dithiophosphates and triaryl phosphothionates. Examples of yellow metal passivators include tolyltriazole, benzotriazole and N- alkylated toyltriazole. Examples of antioxidants include octylated diphenylamine, alkylated phenyl alpha napthylamine, octylated/butylated diphenylamine and phenolic types antioxidant. The lubricant composition may be used as a hydraulic fluid, compressor oil or engine oil.

Without being limited by any particular theory, it is believed that polar base oils, such as PAG based oils, provide good deposit control. The polarity of a base oil is generally related to its aniline point. Polar base oils generally have low aniline points (<50 °C). Aniline points for API (American Petroleum Institute) Group I-IV hydrocarbon base oils are typically greater than or equal to 100 °C. The aniline point generally increases from Group I to II to III and IV base oils, as is shown in Table 1.

Table 1

In an alternative embodiment, the instant invention provides a lubricant composition, hydraulic fluid, compressor oil or engine oil, in accordance with any of the preceding embodiments, each of the at least one OSP exhibits an aniline point of less than -20 °C.

In an alternative embodiment, the instant invention provides a lubricant composition, hydraulic fluid, compressor oil or engine oil, in accordance with any of the preceding embodiments, except that each of the at least one OSPs has a kinematic viscosity at 40 °C between 15 and 250 cSt.

In an alternative embodiment, the instant invention provides a lubricant composition, hydraulic fluid, compressor oil or engine oil, in accordance with any of the preceding embodiments, each of the at least one anti-wear additives is present in an amount from 0.1 to 0.25 wt%.

In an alternative embodiment, the instant invention provides a lubricant composition, hydraulic fluid, compressor oil or engine oil, in accordance with any of the preceding embodiments, the anti-wear additives are selected from the group consisting of zinc dialkyldithiophosphates, amine phosphates, dithiocarbamates, alkylphosphate esters, ashless dithiocarbamates, combinations thereof and blends thereof. In an alternative embodiment, the instant invention provides a lubricant composition, hydraulic fluid, compressor oil or engine oil, in accordance with any of the preceding embodiments, each of the at least one OSP exhibits an aniline point of less than -25 °C.

In an alternative embodiment, the instant invention provides a lubricant composition, hydraulic fluid, compressor oil or engine oil, in accordance with any of the preceding embodiments, the lubricant composition further comprises one or more additives selected from the group consisting of extreme pressure additives, yellow metal passivators, and anti-oxidants.

In an alternative embodiment, the instant invention provides a lubricant composition, hydraulic fluid, compressor oil or engine oil, in accordance with any of the preceding embodiments, the lubricant composition further exhibits an air release value at 75 °C of less than or equal to 1 minute.

In an alternative embodiment, the instant invention provides a lubricant composition, hydraulic fluid, compressor oil or engine oil, in accordance with any of the preceding embodiments, the lubricant composition exhibits a four ball anti-wear value of less than or equal to 0.32 mm.

In an alternative embodiment, the lubricant composition consists essentially of an oil soluble polyalkylene glycol (OSP), wherein the OSP comprises from 40 to 60 wt% units derived from butylene oxide and from 40 to 60 wt% units derived from propylene oxide, initiated by one or more initiators selected from alcohols and diols; and at least 0.05 wt% of at least one anti-wear additive; wherein the lubricant composition exhibits a four ball anti-wear value of less than or equal to 0.35 mm and an air release value at 50 °C of less than or equal to 1 minute.

In another aspect, the invention further provides a gear lubricant composition comprising at least 95 wt% of at least one oil soluble polyalkylene glycol (OSP), wherein the OSP is a polymer selected from the group consisting of copolymers comprising units derived from propylene oxide and butylene oxide, polybutylene oxide homopolymer, and combinations thereof and wherein the OSP exhibits a kinematic viscosity at 40 °C of greater than or equal to 100 cSt; and from 0.25 to 2 wt% of at least one extreme pressure additive; wherein the lubricant composition exhibits a four ball EP weld load of at least 160 kg and an air release value at 75 °C of less than or equal to 3 minutes.

All individual values and subranges of at least 90 wt% are included herein and disclosed herein; for example, the OSP may be present from a lower limit of 90, 92, 94, 95, 96, 98, or 99 wt%. In an alternative embodiment, the OSP of the gear lubricant composition is a polymer selected from the group consisting of copolymers comprising units derived from propylene oxide and butylene oxide, polybutylene oxide homopolymer, and combinations thereof.

In yet another embodiment of the gear lubricant composition, the OSP comprises from 30 to 70 percent by weight units derived from propylene oxide and from 70 to 30 percent by weight units derived from butylene oxide. All individual values and subranges from 30 to 70 percent by weight units derived from propylene oxide are included herein and disclosed herein; for example, the amount of units derived from propylene oxide may range from a lower limit of 30, 40, 50, or 60 percent by weight to an upper limit of 35, 45, 55, 65, or 70 percent by weight. For example, the amount of units derived from propylene oxide may range from 30 to 70 percent by weight, or in the alternative, the amount of units derived from propylene oxide may range from 40 to 60 percent by weight, or in the alternative, the amount of units derived from propylene oxide may range from 40 to 70 percent by weight, or in the alternative, the amount of units derived from propylene oxide may range from 45 to 55 percent by weight, or in the alternative, the amount of units derived from propylene oxide may be 50 percent by weight. All individual values and subranges from 30 to 70 percent by weight units derived from butylene oxide are included herein and disclosed herein; for example, the amount of units derived from butylene oxide may range from a lower limit of 30, 40, 50, or 60 percent by weight to an upper limit of 35, 45, 55, 65, or 70 percent by weight. For example, the amount of units derived from butylene oxide may range from 30 to 70 percent by weight, or in the alternative, the amount of units derived from butylene oxide may range from 40 to 60 percent by weight, or in the alternative, the amount of units derived from butylene oxide may range from 30 to 60 percent by weight, or in the alternative, the amount of units derived from butylene oxide may range from 45 to 55 percent by weight, or in the alternative, the amount of units derived from butylene oxide may be 50 percent by weight.

In an alternative embodiment, the OSP of the gear lubricant composition exhibits a kinematic viscosity at 40 °C of greater than or equal to 100 cSt. All individual values and subranges are included herein and disclosed herein; for example, the kinematic viscosity at 40 °C can be from a lower limit of 100, 200, 300, 400, 500, or 600 cSt.

The gear lubricant composition comprises from 0.25 to 2 wt% of at least one extreme pressure additive. All values and subranges from 0.25 to 2 percent by weight are included herein and disclosed herein; for example, the amount of extreme pressure additive can range from a lower limit of 0.25, 0.5, 0.75, 1, 1.25, 1.5, or 1.75 percent by weight to an upper limit of 0.5, 0.75, 1, 1.25, 1.5, 1.75, or 2 percent by weight. For example, the amount of one or more extreme pressure additives may be from 0.25 to 2 percent by weight, or in the alternative, the amount of one or more extreme pressure additives may be from 0.25 to 1 percent by weight, or in the alternative, the amount of one or more extreme pressure additives may be from 1 to 2 percent by weight, or in the alternative, the amount of one or more extreme pressure additives may be from 0.75 to 1.75 percent by weight, or in the alternative, the amount of one or more extreme pressure additives may be from 0.5 to 1 percent by weight.

The gear lubricant composition exhibits a four ball EP weld load of at least 160 kg. All individual values and subranges of at least 160 kg are included herein and disclosed herein; for example, the four ball EP weld load may be from a lower limit of 160, 170, 180, 190 or 200 kg.

The gear lubricant composition exhibits an air release value at 75 °C of less than 3 minutes. All individual values and subranges of less than 3 minutes are included herein and disclosed herein; for example, the air release value at 75 °C may be from an upper limit of 3, 2.5, 2, 1.5 or 1 minutes.

While the foregoing discussion refers to a gear lubricant composition, it is not intended to limit the use of such composition to solely geared mechanisms. Rather, the gear lubricant composition is particularly suited to certain applications due to its excellent air release and extreme pressure properties. However, the gear lubricant composition may be used in any situation in which its properties would be useful or beneficial.

Examples

The following examples illustrate the present invention but are not intended to limit the scope of the invention. Table 2 provides a listing of base oils, anti-wear additives, antioxidants, extreme pressure additives and yellow metal passivators, their compositions, properties and commercial suppliers, used in the inventive and comparative examples.

Table 2

IRGANOX L57 BASF The benzeneamine and N-phenyl-reaction products with 2,4,4-trimethylpentene diphenylamine

IRGANOX L101 BASF a high molecular weight phenolic antioxidant

EXTREME PRESSURE ADDITIVE

DURAD 310M Chemtura a mixed organophosphate ester having a

Corporation viscosity at 40 °C of 51 cSt

YELLOW METAL PASSIVATOR

TOLYTRIAZOLE BASF 5 -methyl benzotriazole

The compositions of Inventive Examples 1-6 are shown in Tables 3- 7.

Table 3 (Composition of Inventive Example 1)

Table 4 (Compositions of Inventive Examples 2 and 3)

Table 5 (Composition of Inventive Example 4)

Table 6 (Composition of Inv. Ex. 5)

Comparative Examples 1-5 were 100 wt% (with no additives) of each of PAG- A, PAG-B, PAG-C, PAG-D, and UCON 50-HB-260, respectively.

Comparative Example 6 was 99.75 wt% UCON 50-HB-260 plus 0.25 wt% NALUBE AW6110.

Comparative Example 7 was a formulated commercial oil, available under the name QUINTOLUBRIC 888-46, which is a synthetic polyol ester-based hydraulic fiuid available from Quaker Chemical Corporation.

Comparative Example 8 was a formulated commercial oil, available under the name QUINTOLUBRIC 855, which is a natural ester (rapeseed oil)-based hydraulic fluid, available from Quaker Chemical Corporation.

Comparative Example 9 was a formulated commercial oil, available under the name QUINTOLUBRIC 703, which is a fire resistant water glycol-based hydraulic fluid, available from Quaker Chemical Corporation.

Comparative Example 10 was a formulated commercial oil, available under the name HYSPIN AWH-M32, which is a mineral oil-based hydraulic fluid, available from Castrol Ltd.

Comparative Example 11 was a formulated commercial oil, available under the name HYSPIN AWH-M46, which is a mineral oil-based hydraulic fluid, available from Castrol Ltd. Comparative Example 12 was a formulated commercial oil, available under the name HYSPIN AWH-M68, which is a mineral oil-based hydraulic fluid, available from Castrol Ltd.

Comparative Example 13 was a formulated commercial oil, available under the name HYSPIN AWH-M100, which is a mineral oil-based hydraulic fluid, available from Castrol Ltd.

Comparative Example 14 was a formulated commercial oil, available under the name HYSPIN AWH-M150, which is a mineral oil-based hydraulic fluid, available from Castrol Ltd.

Comparative Example 15 was a formulated biodegradable commercial oil, available under the name 112B-32, which is a high oleic vegetable oil and synthetic ester-based hydraulic fluid, available from Schaeffer Manufacturing Co. (St. Louis, MO, USA).

Comparative Example 16 was a formulated biodegradable commercial oil, available under the name 112B-46, which is a high oleic vegetable oil and synthetic ester-based hydraulic fluid, available from Schaeffer Manufacturing Co. (St. Louis, MO, USA).

Comparative Example 17 was a formulated biodegradable commercial oil, available under the name 112B-68, which is a high oleic vegetable oil and synthetic ester-based hydraulic fluid, available from Schaeffer Manufacturing Co. (St. Louis, MO, USA).

Comparative Example 18 was a formulated synthetic commercial oil, available under the name NATURELLE HF-E32, which is a synthetic ester-based hydraulic fluid, available from Shell Oil Company.

Comparative Example 19 was a formulated synthetic commercial oil, available under the name NATURELLE HF-E46, which is a synthetic ester-based hydraulic fluid, available from Shell Oil Company.

Comparative Example 20 was a formulated biodegradable commercial oil, available under the name CAT BIO HYDO, which is a synthetic ester-based hydraulic fluid, available from

Caterpillar Corporation

Comparative Example 21 was a formulated biodegradable commercial oil, available under the name BIO-46 HYD, which is an ester-based hydraulic fluid, available from Renewable Lubricants, Inc. (Hartville, OH, USA).

Comparative Example 22 was a formulated biodegradable commercial oil, available under the name SYMBIO Bio-hydraulic Fluid, which is a high oleic vegetable oil and PAG (based on a butanol initiated propoxylate)-based hydraulic fluid containing 0.5 wt% amine phosphate and 1 wt% antioxidant package, from The Dow Chemical Company. Comparative Example 23 was a synthetic PAG hydraulic fluid, an EO/PO random copolymer with 0.25 wt% amine phosphate anti-wear additive, available under the name UCON TRIDENT AW-46, from The Dow Chemical Company.

Comparative Example 24 was a fire resistant hydraulic fluid, available under the name ECOSAFE FR-46, a PAG based on a butanol initiated propoxylate, from American Chemical Technologies, Inc. (Fowlerville, MI, USA).

Comparative Example 25 was a Group II mineral oil-based hydraulic fluid (ISO 46), obtained from King Industries, Inc. (Norwalk, CT, USA).

Comparative Example 26 was a Group II mineral oil-based (ISO 46) hydraulic fluid formulated with 0.1 wt% NALUBE AW-6110, obtained from King Industries, Inc. (Norwalk, CT, USA).

Inventive Examples 1-6 and Comparative Examples 1-26 were tested for kinematic viscosity, viscosity index, air release, four ball anti-wear, aniline point and/or pour point. The results are shown in Table 8.

Table 8

Comp. Ex. 5 52 11 211 NA 0.59 <-30 -38

Comp. Ex. 6 53 11 211 NA 0.40 <-30 NA

Comp. Ex. 7 49 9.6 185 7 0.36 20-30 -39

Comp. Ex. 8 ** 55 NA 220 8 NA NA NA

Comp. Ex. 9 ** 46 NA 178 20 NA NA NA

Comp. Ex. 10 ** 32 6.3 >150 4 NA >100 NA

Comp. Ex. 11 ** 46 8.1 >150 8 NA >100 NA

Comp. Ex. 12 ** 68 10.9 >140 8 NA >100 NA

Comp. Ex. 13 ** 100 13.3 >130 12 NA >100 NA

Comp. Ex. 14 ** 150 17.7 >130 24 NA >100 NA

Comp. Ex. 15 ** 32 6.9 205 <0.5 0.36 0-30 NA

Comp. Ex. 16 ** 46 9.8 206 <0.5 0.36 0-30 NA

Comp. Ex. 17 ** 68 14 218 <0.5 0.36 0-30 NA

Comp. Ex. 18 ** 31.6 6.3 156 4 NA NA NA

Comp. Ex. 19 ** 46.1 9.2 182 9 NA NA NA

Comp. Ex. 20 ** 44 NA 176 1 0.35 0-30 NA

Comp. Ex. 21 ** 47.5 NA 194 NA 0.4 0-30 NA

Comp. Ex. 22 46 9.5 195 8.5 0.4 NA NA

Comp. Ex. 23 46 9.7 200 9 0.81 <-30 NA

Comp. Ex. 24 46 9.2 190 8 NA <-30 NA

Comp. Ex. 25 ** 46 NA NA NA 0.75 NA NA

Comp. Ex. 26 ** 46 NA NA NA 0.5 NA NA

* Due to its high viscosity the air release value was measured at 75 °C (per ASTM D3427).

** Values provided in manufacturers' literature. Inventive Examples 7-14 and Comparative Example 27-28 illustrate the effect of certain OSPs as base oils to yield lubricant compositions having improved extreme pressure and air release properties. Table 9 provides the composition and properties of Comparative Examples 27-28 and Inventive Examples 7-9. Table 10 provides the composition and properties of Inventive Examples 10-14.

Table 9

* Air release value measured at 50 °C. Table 10

Test Methods

Test methods include the following:

Kinematic viscosities at 40 °C and at 100 °C were measured in accordance with ASTM

D445.

Viscosity index was measured in accordance with ASTM 2272.

Pour point was measured in accordance with ASTM D97.

Four ball anti-wear was measured in accordance with ASTM D4172 under test conditions of 75 °C, 1200 rpm, load of 40 kg and test time of 60 minutes. Air release was measured in accordance with ASTM D3427. For hydraulic fluids which are typically low viscosity fluids and in the range 22 to 150 cSt at 40 °C, air release measurements were made at 50 °C. For higher viscosity fluids, (i.e., Inv. Ex. 6) measurements were made at higher temperatures such as 75 °C.

Extreme pressure welding load was measured using ASTM D2783 at a temperature of 18- 36oC, speed 1760 +/-40 rpm, duration 10 seconds with increasing load.

Unless otherwise stated, implicit from the context or conventional in the art, all parts and percentages are based on weight. All applications, publications, patents, test procedures, and other documents cited, including priority documents, are fully incorporated by reference to the extent such disclosure is not inconsistent with the disclosed compositions and methods and for all jurisdictions in which such incorporation is permitted.

The present invention may be embodied in other forms without departing from the spirit and the essential attributes thereof, and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.

Claims

We Claim:

1. A lubricant composition comprising

at least 90 wt% of at least one oil soluble polyalkylene glycol (OSP), wherein the OSP comprises at least 40 wt% units derived from butylene oxide and at least 40 wt% units derived from propylene oxide, initiated by one or more initiators selected from monols, diols and polyols; and

at least 0.05 wt% of at least one anti-wear additive;

wherein the lubricant composition exhibits a four ball anti-wear of less than or equal to 0.35 mm and an air release value at 50 °C of less than or equal to 1 minute.

2. The lubricant composition according to Claim 1, wherein each of the at least one OSP exhibits an aniline point of less than -20 °C.

3. The lubricant composition according to any one of the preceding Claims, wherein each of the at least one OSPs has a kinematic viscosity at 40 °C between 15 and 250 cSt.

4. The lubricant composition according to any one of the preceding Claims, wherein each of the at least one anti-wear additives is present in an amount from 0.1 to 0.25 wt%.

5. The lubricant composition according to any one of the preceding Claims, wherein the anti- wear additives are selected from the group consisting of zinc dialkyldithiophosphates, amine phosphates, dithiocarbamates, alkylphosphate esters, ashless dithiocarbamates, ashless

ditiophosphate, combinations thereof, and blends thereof.

6. The lubricant composition according to any one of the preceding Claims, wherein each of the at least one OSP exhibits an aniline point of less than -25 °C.

7. The lubricant composition according to any one of the preceding Claims, further comprising one or more additives selected from the group consisting of extreme pressure additives, yellow metal passivators, and anti-oxidants.

8. The lubricant composition according to any one of the preceding Claims, wherein the lubricant composition further exhibits an air release value at 75 °C of less than or equal to 1 minute.

9. The lubricant composition according to any one of the preceding Claims, wherein the lubricant composition exhibits a four ball anti-wear of less than or equal to 0.32 mm.

10. A lubricant composition comprising

at least 90 wt% of at least one oil soluble polyalkylene glycol (OSP), wherein the OSP is a polymer selected from the group consisting of copolymers comprising units derived from propylene oxide and butylene oxide, polybutylene oxide homopolymer, and combinations thereof and wherein the OSP exhibits a kinematic viscosity at 40 °C of greater than or equal to 100 cSt; and

from 0.25 to 2 wt% of at least one extreme pressure additive;

wherein the lubricant composition exhibits a four ball EP weld load of at least 160 kg and an air release value at 75 °C of less than or equal to 3 minutes.

12. The lubricant composition according to Claim 10, further comprising an extreme pressure additive selected from the group consisting of ashless dithiophosphates, triaryl phosphothionates, alkyl diphenylphosphites, amine phosphates, dithiophosphates, triaryl phosphothionates, blends thereof and combinations thereof.

13. A hydraulic fluid comprising the lubricant composition of any one of the preceding Claims.