Oil-based graphite lubricant compositions

Abstract

A lubricant composition includes graphite, oil and a dispersant selected from the group consisting of a sulfosuccinate, a polyalkylene glycol comprising propylene oxide and butylene oxide, and combinations thereof. Combinations of sulfosuccinate and polyalkylene glycol dispersants comprise 80 wt % or less of the polyalkylene glycol based on the total weight of the combined sulfosuccinate and polyalkylene glycol dispersants.

Description

BACKGROUNDField of the Disclosure

[0001] The present disclosure is directed to lubricant compositions and more specifically to lubricant compositions comprising oil-based graphite lubricant compositions.INTRODUCTION

[0002] A variety of applications utilize graphite as a lubricant. For example, automotive applications, household applications and industrial applications all can utilize graphite as a lubricant. One example of an industrial application is hot forging. Hot forging is an industrial process where a metal workpiece is placed in a die and is deformed under pressure. The energy applied to the metal workpiece to plastically deform it is converted into heat. Repeated forging of workpieces and generation of heat raises the temperature of the of the die. A lubricant is used during forging at the interface between workpiece and die to reduce friction and to ensure the workpiece can be removed from the die. Good lubrication can improve the workpiece deformation, favor accurate filling of the die cavities, reduce tool wear at those points with free flow movement and high specific pressures, and reduce the forging force. Such features will lessen the stresses induced in the forging tool and prevent direct tool to workpiece contact, which contributes to longer tool life and better-quality control.

[0003] One available choice for hot forging lubricant has been oil-based lubricants. Oil-based lubricants typically include an oil as a carrier and a lubricating particle such as graphite. Oil-based lubricants adhere the graphite to the die to form a coating. Oil-based lubricants are disadvantaged relative to water-based lubricants as oil-based lubricants tend to run off the die surface and be squeezed out of the work piece / die interface under pressure. Additional issues exist as well. For example, graphite dispersions in oil are not stable and require continuous agitation otherwise gelling and caking occur in the graphite rich portion of the dispersion. Caking occurring in lubricant holding tanks can result in an incorrect amount of graphite being applied to the die thereby decreasing the useful life of the die. Flocculation and sedimentation can also result in clogged pipes and spray nozzles intended to apply the lubricant to the forging die. Gelling is particularly disadvantageous as it renders settled graphite non-dispersible. Ideally, an oil-based graphite dispersion should not gel and remain dispersible within 31 days (i.e., one month) (“The Gelling Test”).

[0004] The Gelling Test is hard to pass as a variety of competing theories exist to explain the dispersion of graphite. For example, one hypothesis theorizes that the dispersants act as spacers which accumulate at the surface of graphite particles and prevent their steric approach, but it is not known which moieties affect such properties. In contrast, Chinese patent application publication number CN111925697A (“the '697 publication”) provides a graphene and polymer dispersant composite material. The '697 publication explains that an enhanced graphene dispersion can be obtained by the inclusion of water-soluble polymer dispersant containing an aromatic ring structure and a hydrophilic group because the dispersant improves the compatibility between the surface inert graphene and the water-soluble polymer due to pi-pi interaction between the dispersant and the graphene. The '697 publication is silent with regard to how placement or quantity of aromatic structures affects the dispersion.

[0005] In view of the competing theories behind graphite dispersant efficacy, the unclear affect different molecular moieties have on dispersion performance, and the complexity of the intermolecular forces present in oil-based graphite dispersions, it would be surprising to discover a dispersant that is able to pass the Gelling Test.SUMMARY OF THE DISCLOSURE

[0006] The inventors of the present application have discovered a lubricant composition comprising an oil-based graphite dispersion that is able to pass the Gelling Test.

[0007] The present disclosure is a result of discovering that a dispersant selected from the group consisting of a sulfosuccinate, a polyalkylene glycol comprising propylene oxide and butylene oxide, and combinations thereof can render a lubricant composition able to pass the Gelling Test. Without being bound by theory, it is believed that the above-described dispersants not only interact with the surface of the graphite to enhance dispersion of the graphite in the oil, but also remain adhered to the graphite after settling. It is believed that the persistence of the dispersants on the surface the graphite, even when settled out of the oil, prevents the gelling from occurring and thereby keeps the graphite in a condition to be redispersed when agitated thereby passing The Gelling Test.

[0008] The present disclosure is particularly useful for the formation of lubricants utilizing graphite.

[0009] According to a first feature of the present disclosure, a lubricant composition, comprises graphite, oil, and a dispersant selected from the group consisting of a sulfosuccinate, a polyalkylene glycol comprising propylene oxide and butylene oxide, and combinations thereof with the proviso that combinations of sulfosuccinate and polyalkylene glycol dispersants comprise 80 wt % or less of the polyalkylene glycol based on the total weight of the combined sulfosuccinate and polyalkylene glycol dispersants.

[0010] According to a second feature of the present disclosure, the lubricant composition comprises 1 wt % to 60 wt % of graphite based on a total weight of the lubricant composition.

[0011] According to a third feature of the present disclosure, the graphite has a D90 particle diameter of from 0.5 μm to 5.0 μm.

[0012] According to a fourth feature of the present disclosure, the lubricant composition comprises 50 wt % to 98 wt % oil based on a total weight of the lubricant composition.

[0013] According to a fifth feature of the present disclosure, the lubricant composition comprises 0.01 wt % to 5.0 wt % of the dispersant based on a total weight of the lubricant composition.

[0014] According to a sixth feature of the present disclosure, the dispersant comprises a sulfosuccinate.

[0015] According to a seventh feature of the present disclosure, the sulfosuccinate dispersant comprises di-2-ethylhexyl sodium sulfosuccinate.

[0016] According to an eight feature of the present disclosure, the dispersant comprises the polyalkylene glycol and the polyaklylene glycol comprises from 30 wt % to 70 wt % propylene oxide based on the combined weight of propylene oxide and butylene oxide in the polyalkylene glycol.

[0017] According to a ninth feature of the present disclosure, the polyaklylene glycol comprises from 40 wt % to 60 wt % propylene oxide based on the combined weight of propylene oxide and butylene oxide in the polyalkylene glycol.

[0018] According to a tenth feature of the present disclosure, the dispersant comprises di-2-ethylhexyl sodium sulfosuccinate and a dodecanol initiated polyalkylene glycol comprising 50 wt % propylene oxide based on the combined weight of propylene oxide and butylene oxide in the polyalkylene glycol.DETAILED DESCRIPTION

[0019] As used herein, the term “and / or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

[0020] All ranges include endpoints unless otherwise stated.

[0021] As used herein, the term weight percent (“wt %”) designates the percentage by weight a component is of a total weight of the lubricant composition unless otherwise specified.

[0022] As used herein, Chemical Abstract Services registration numbers (“CAS #”) refer to the unique numeric identifier as most recently assigned as of the priority date of this document to a chemical compound by the Chemical Abstracts Service.Lubricant Composition

[0023] The present disclosure is directed to a lubricant composition. The lubricant composition comprises graphite, oil, and a dispersant. The lubricant composition may comprise one or more other additives designed to alter a property of characteristic of the lubricant composition.Graphite

[0024] The lubricant composition comprises graphite. The graphite may have spherical shape, a plate like shape, an oblong shape and / or an irregular shape. The particles of the graphite may have a D90 of from 0.5 microns (“μm”) to 10 μm. As used herein, the term “D90” means that 90% of the graphite particles have a diameter or longest length dimension smaller than the indicated value and 10% of the particles have a diameter or longest length dimension greater than the indicated value. The graphite may have a D90 particle size of 0.5 μm or greater, or 1.0 μm or greater, or 1.5 μm or greater, or 2.0 μm or greater, or 2.5 μm or greater, or 3.0 μm or greater, or 3.5 μm or greater, or 4.0 μm or greater, or 4.5 μm or greater, or 5.0 μm or greater, or 5.5 μm or greater, or 6.0 μm or greater, or 6.5 μm or greater, or 7.0 μm or greater, or 7.5 μm or greater, or 8.0 μm or greater, or 8.5 μm or greater, or 9.0 μm or greater, or 9.5 μm or greater, while at the same time, 10 μm or less, or 9.5 μm or less, or 9.0 μm or less, or 8.5 μm or less, or 8.0 μm or less, or 7.5 μm or less, or 7.0 μm or less, or 6.5 μm or less, or 6.0 μm or less, or 5.5 μm or less, or 5.0 μm or less, or 4.5 μm or less, or 4.0 μm or less, or 3.5 μm or less, or 3.0 μm or less, or 2.5 μm or less, or 2.0 μm or less, or 1.5 μm or less, or 1.0 μm or less. The D90 particle size of the graphite is determined using a Malvern Mastersizer™ laser diffraction particle size analyzer.

[0025] The lubricant composition may comprise from 1 wt % to 60 wt % of graphite based on a total weight of the lubricant composition. For example, the lubricant composition may comprise 1 wt % or greater, or 5 wt % or greater, or 10 wt % or greater, or 15 wt % or greater, or 20 wt % or greater, or 25 wt % or greater, or 30 wt % or greater, or 35 wt % or greater, or 40 wt % or greater, or 45 wt % or greater, or 50 wt % or greater, or 55 wt % or greater, while at the same time, 60 wt % or less, or 55 wt % or less, or 50 wt % or less, or 45 wt % or less, or 40 wt % or less, or 35 wt % or less, or 30 wt % or less, or 25 wt % or less, or 20 wt % or less, or 15 wt % or less, or 10 wt % or less, or 5 wt % or less of graphite based on a total weight of the lubricant composition.Oil

[0026] The medium in which the graphite and the dispersant are dissolved is the oil. The oil may be a group (I) oil, a group (II) oil, or a group (III) oil as defined by the American Petroleum Institute. As used herein, a group (I) oil is one which satisfies one of the two following criteria: (i) the oil is composed of less than 90 wt % saturates and / or greater than 0.03 wt % sulfur. As used herein, a group (II) oil is one which is both over 90 wt % saturates and less than 0.03 wt % sulfur. As used herein, a group (III) oil meets the same criteria as group (II) oils, but also has a viscosity index of greater than 120 as measured according to ASTM D2270. The oil may be derived from petroleum and / or may be derived from a biological source (e.g., plants, beans, seeds, nuts, fruits, etc.). In a specific example, the oil used can be a mineral oil (i.e., a colorless and odorless mixture of alkanes and cycloalkanes) distilled from crude oil. The oil may have a density from 0.70 grams per cubic centimeter (“g / cc”) to 0.95 g / cc. Any oil may be used in the lubricant composition.

[0027] The lubricant composition may comprise from 50 wt % to 98 wt % oil based on a total weight of the lubricant composition. For example, the lubricant composition may comprise 50 wt % or greater, or 55 wt % or greater, or 60 wt % or greater, or 65 wt % or greater, or 70 wt % or greater, or 75 wt % or greater, or 80 wt % or greater, or 85 wt % or greater, or 90 wt % or greater, or 95 wt % or greater, while at the same time, 98 wt % or less, or 95 wt % or less, or 90 wt % or less, or 85 wt % or less, or 80 wt % or less, or 75 wt % or less, or 70 wt % or less, or 65 wt % or less, or 60 wt % or less, or 55 wt % or less of the oil base on the total weight of the lubricant composition.Dispersant

[0028] The lubricant composition comprises the dispersant. As explained, above, the dispersant functions to disperse the graphite and prevent gelling after prolonged periods of no mixing. The dispersant is selected from the group consisting of a sulfosuccinate, a polyalkylene glycol comprising propylene oxide (“PO”) and butylene oxide (“BO”), and combinations thereof.

[0029] The sulfosuccinate can have the general formula provided in Structure (I)wherein R1 and R2 are each independently a C4-C16 alkyl and M+ is a cation. Each one of R1 and R2 may independently be linear or branched. Each one of R1 and R2 may independently be a C4 alkyl, or a C5 alkyl, or a C6 alkyl, or a C7 alkyl, or a C8 alkyl, or a C9 alkyl, or a C10 alkyl, or a C11 alkyl, or a C12 alkyl, or a C13 alkyl, or a C14 alkyl, or a C15 alkyl, or a C16 alkyl. M+ may be selected from the group consisting of Li, Na, K, Rb and other cations. In a specific example, the sulfosuccinate may be di-2-ethylhexyl sodium sulfosuccinate, dicotylsulfosuccinate or other succinates.The polyalkylene glycol is a copolymer of PO and BO (“PO / BO copolymer”) is an oil soluble polyalkylene glycol (OSP). The PO / BO copolymer can be a block copolymer or a random copolymer. The polyalkylene glycol comprises, on average, from 10 wt % to 90 wt % PO based on the combined weight of PO and BO in the polyalkylene glycol. For example, the polyalkylene glycol comprises 10 wt % or greater, or 20 wt % or greater, or 30 wt % or greater, or 40 wt % or greater, or 50 wt % or greater, or 60 wt % or greater, or 70 wt % or greater, or 80 wt % or greater, while at the same time, 90 wt % or less, or 80 wt % or less, or 70 wt % or less, or 60 wt % or less, or 50 wt % or less, or 40 wt % or less, or 30 wt % or less, or 20 wt % or less PO based on the combined weight of PO and BO in the polyalkylene glycol. The polyalkylene glycol comprises, on average, from 10 wt % to 90 wt % BO based on the combined weight of PO and BO in the polyalkylene glycol. For example, the polyalkylene glycol comprises 10 wt % or greater, or 20 wt % or greater, or 30 wt % or greater, or 40 wt % or greater, or 50 wt % or greater, or 60 wt % or greater, or 70 wt % or greater, or 80 wt % or greater, while at the same time, 90 wt % or less, or 80 wt % or less, or 70 wt % or less, or 60 wt % or less, or 50 wt % or less, or 40 wt % or less, or 30 wt % or less, or 20 wt % or less BO based on the combined weight of PO and BO in the polyalkylene glycol.

[0031] The polyalkylene glycol may be alcohol initiated. The alcohol initiator can be a primary or secondary alcohol. The Alcohol may have 8 carbons or greater, or 9 carbons or greater, or 10 carbons or greater, or 11 carbons or greater, or 12 carbons or greater, or 13 carbons or greater, or 14 carbons or greater, or 15 carbons or greater, or 16 carbons or greater, or 17 carbons or greater, or 18 carbons or greater, or 19 carbons or greater, while at the same time, 20 carbons or less, or 19 carbons or less, or 18 carbons or less, or 17 carbons or less, or 16 carbons or less, or 15 carbons or less, or 14 carbons or less, or 13 carbons or less, or 12 carbons or less, or 11 carbons or less, or 10 carbons or less, or 9 carbons or less. The number of carbons in the alcohol initiator is evident from the number of carbons in the end group of the polyalkylene glycol. In a specific example, the alcohol initiator may be dodecanol (i.e., a 12 carbon alcohol).

[0032] The polyalkylene glycol may have a number average molecular weight (“Mn”) of 500 grams per mole (“g / mol”) to 2500 g / mol. For example, the Mn of the polyalkylene glycol may be 500 g / mol or greater, or 600 g / mol or greater, or 700 g / mol or greater, or 800 g / mol or greater, or 900 g / mol or greater, or 1000 g / mol or greater, or 1100 g / mol or greater, or 1200 g / mol or greater, or 1300 g / mol or greater, or 1400 g / mol or greater, or 1500 g / mol or greater, or 1600 g / mol or greater, or 1700 g / mol or greater, or 1800 g / mol or greater, or 1900 g / mol or greater, or 2000 g / mol or greater, or 2100 g / mol or greater, or 2200 g / mol or greater, or 2300 g / mol or greater, or 2400 g / mol or greater, while at the same time, 2500 g / mol or less, or 2400 g / mol or less, or 2300 g / mol or less, or 2200 g / mol or less, or 2100 g / mol or less, or 2000 g / mol or less, or 1900 g / mol or less, or 1800 g / mol or less, or 1700 g / mol or less, or 1600 g / mol or less, or 1500 g / mol or less, or 1400 g / mol or less, or 1300 g / mol or less, or 1200 g / mol or less, or 1100 g / mol or less, or 1000 g / mol or less, or 900 g / mol or less, or 800 g / mol or less, or 700 g / mol or less, or 600 g / mol or less as measured according to gel permeation chromatography.

[0033] The polyalkylene glycol used in the lubricant composition may comprise dodecanol initiated random copolymers comprising 50 wt % PO and 50 wt % BO based on the total weight of the PO and BO in the dispersant. Such copolymers are commercially available under the commercial name of UCON™ OSP-18, UCON™ OSP-32, UCON™ OSP-46, UCON™ OSP-68, UCON™ OSP-150, and UCON™ OSP-220 (UCON™ is a trademark of Union Carbide Corporation) and are commercially available form The Dow Chemical Company, Midland, Michigan.

[0034] The lubricant composition comprises 0.01 wt % to 5.0 wt % of the dispersant based on a total weight of the lubricant composition. For example, the lubricant composition may comprise 0.01 wt % or greater, or 0.05 wt % or greater, or 0.1 wt % or greater, or 0.5 wt % or greater, or 1.0 wt % or greater, or 1.5 wt % or greater, or 2.0 wt % or greater, or 2.5 wt % or greater, or 3.0 wt % or greater, or 3.5 wt % or greater, or 4.0 wt % or greater, or 4.5 wt % or greater, while at the same time, 5.0 wt % or less, or 4.5 wt % or less, or 4.0 wt % or less, or 3.5 wt % or less, or 3.0 wt % or less, or 2.5 wt % or less, or 2.0 wt % or less, or 1.5 wt % or less, or 1.0 wt % or less, or 0.5 wt % or less, or 0.1 wt % or less, or 0.05 wt % or less of the dispersant based on a total weight of the lubricant composition.

[0035] The dispersant may comprise both a succinate and a polyalkylene glycol. In such examples, the dispersant combination comprises 80 wt % or less of the polyalkylene glycol based on the total weight of the combined sulfosuccinate and polyalkylene glycol dispersants. For example, the combined dispersant can comprise 80 wt % or less, or 75 wt % or less, or 70 wt % or less, or 65 wt % or less, or 60 wt % or less, or 55 wt % or less, 50 wt % or less, or 45 wt % or less, 40 wt % or less, or 35 wt % or less, 30 wt % or less, or 25 wt % or less, 20 wt % or less, or 15 wt % or less, 10 wt % or less, or 5 wt % or less, 1 wt % or less of the polyalkylene glycol dispersant based on the combined weight of the combined sulfosuccinate and polyalkylene glycol dispersants.EXAMPLESMaterials

[0036] The following materials were used in the examples.

[0037] Graphite is a powder of graphite particles having a D90 of 5.0 μm and is commercially available from Molygraph Lubricants, Mumbai, India.

[0038] PIBSA is polyisobutylene succinic anhydride having a CAS # of 67762-77-0 and is commercially available from Transasia Petrochem Pvt Ltd., Mumbai, India.

[0039] Oil is a group (II) oil derived from refining of vacuum distillates of specific crude oil fractions by dewaxing and hydro-processing. The Oil has a minimum viscosity index of 85 as measured according to ASTM D 227 and a density of 0.875 g / cc to 0.89 g / cc as measured according to ASTM D 4052-18. Examples of the Oil may be obtained from Sigma Aldrich, St. Louis, Missouri.

[0040] DISP1 is 95 wt % or greater Structure (II)

[0041] wherein x is 31 and R is C4H9OH. DISP 1 is commercially available from The Dow Chemical Company, Midland, Michigan.

[0042] DISP2 is a mixture of 65.5 wt % or less of di-2-ethylhexyl sodium C and other components and is commercially available as TRITON™ GR-7M from The Dow Chemical Company, Midland, Michigan.

[0043] DISP3 is a mixture of 56 wt % to 60 wt % Di-2-ethylhexyl sodium sulfosuccinate, 20 wt % isopropanol and 20 wt % water and is commercially available as TRITON™ GR-5M from The Dow Chemical Company, Midland, Michigan.

[0044] DISP4 is a dodecanol initiated random copolymer (PO / BO, 50 / 50 by wt) with a typical kinematic viscosity at 40° C. of 18 mm2 / s (cSt). Its average Mn is 500 g / mol. DISP5 is commercially available as UCON™ OSP-18 from The Dow Chemical Company, Midland, Michigan.

[0045] DISP5 is a dodecanol initiated random copolymer (PO / BO, 50 / 50 by wt) with a typical kinematic viscosity at 40° C. of 32 mm2 / s (cSt). Its average Mn is 760 g / mol. DISP5 is commercially available as UCON™ OSP-32 from The Dow Chemical Company, Midland,Michigan.

[0046] DISP6 is a dodecanol initiated random co-polymer (PO / BO, 50 / 50 by wt) with a typical kinematic viscosity at 40° C. of 150 mm / s (cSt). Its average molecular weight (Mn) is 1900 g / mol. DISP6 is commercially available as UCON™ OSP-150 from The Dow Chemical Company, Midland, Michigan.

[0047] DISP7 is a butylene oxide homopolymer with a typical kinematic viscosity at 40° C. of 680 mm2 / s (cSt) and a number average molecular weight of 5100 g / mol. DISP6 is commercially available as UCON™ OSP-680 from The Dow Chemical Company, Midland, Michigan.Sample Preparation

[0048] The samples were prepared by adding the indicated dispersant to the oil and stirring the mixture at 700 revolutions per minute (“RPM”) for 15 minutes using an overhead stirrer. Next, the graphite was slowly added to the mixture while stirring continued. Next, the mixture was stirred for an additional 15 minutes at 700 RPMs using the same overhead stirrer. Finally, the mixture was transferred to transparent graduated cylinders and covered to observe the stability of the mixture. The mixtures were left undisturbed at approximately 23° C. for 31 days and then observed.Results

[0049] Table 1 provides the results of the comparative examples (“CE”) and the inventive examples (“IE”).TABLE 1GraphiteDispersantOilExampleDispersant(wt %)(wt %)(wt %)ResultCE1None12288GelledCE2PIBSA12288GelledCE3DISP112288GelledIE1DISP212288No gellingIE2DISP312288No gellingIE3DISP412288No gellingIE4DISP512288No gellingCE4DISP612288GelledCE5DISP712288GelledCE6DISP5:DISP212288Gelled(80:20 by weight)IE5DISP5:DISP212288No gelling(50:50 by weight)

[0050] Referring now to Table 1, it can be seen that lubricant compositions comprising a graphite, oil and a dispersant selected from the group consisting of a sulfosuccinate, a polyalkylene glycol comprising propylene oxide and butylene oxide are able to pass the Gelling Test. CE1 demonstrates that the lack of a dispersant causes gelling of the graphite. Similarly, the addition of PIBSA and other dispersants in CE2-CE5 are unable to prevent gelling of the graphite within the oil. CE6 demonstrates that an 80:20 amount by weight of the DISP5 and DISP2 (i.e., about 86 wt % actives of the polyalkylene glycol DISP5) is also unable to prevent gelling of graphite. Contrary to CE6, IE5 which has equal weights of DISP5 and DISP2 (i.e., about 61 wt % actives of the polyalkylene glycol DISP5) is able to successfully prevent gelling of the graphite. Similarly, the use of the succinate and the polyalkylene glycols alone in IE1-IE4 are able to prevent the graphite from gelling and keep the graphite in a dispersible form.

Claims

1. A lubricant composition, comprising:graphite;oil; anda dispersant selected from the group consisting of a sulfosuccinate, a polyalkylene glycol comprising propylene oxide and butylene oxide, and combinations thereof with the proviso that combinations of sulfosuccinate and polyalkylene glycol dispersants comprise 80 wt % or less of the polyalkylene glycol based on the total weight of the combined sulfosuccinate and polyalkylene glycol dispersants.

2. The lubricant composition of claim 1, wherein the lubricant composition comprises 1 wt % to 60 wt % of graphite based on a total weight of the lubricant composition.

3. The lubricant composition of claim 1, wherein the graphite has a D90 particle diameter of from 0.5 μm to 5.0 μm.

4. The lubricant composition of claim 1, wherein the lubricant composition comprises 50 wt % to 98 wt % oil based on a total weight of the lubricant composition.

5. The lubricant composition of claim 1, wherein the lubricant composition comprises 0.01 wt % to 5.0 wt % of the dispersant based on a total weight of the lubricant composition.

6. The lubricant composition of claim 1, wherein the dispersant comprises a sulfosuccinate.

7. The lubricant composition of claim 6, wherein the sulfosuccinate dispersant comprises di-2-ethylhexyl sodium sulfosuccinate.

8. The lubricant composition of claim 1, wherein the dispersant comprises the polyalkylene glycol and the polyaklylene glycol comprises from 30 wt % to 70 wt % propylene oxide based on the combined weight of propylene oxide and butylene oxide in the polyalkylene glycol.

9. The lubricant composition of claim 8, the polyaklylene glycol comprises from 40 wt % to 60 wt % propylene oxide based on the combined weight of propylene oxide and butylene oxide in the polyalkylene glycol.

10. The lubricant composition of claim 1, wherein the dispersant comprises di-2-ethylhexyl sodium sulfosuccinate and a dodecanol initiated polyalkylene glycol comprising 50 wt % propylene oxide based on the combined weight of propylene oxide and butylene oxide in the polyalkylene glycol.

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