Oil-based graphite lubricant composition

Abstract

The lubricant composition comprises graphite, an oil, and a dispersant selected from the group consisting of a sulfosuccinate, a polyalkylene glycol comprising propylene oxide and butylene oxide, and combinations thereof, wherein the combination of sulfosuccinate dispersant and polyalkylene glycol dispersant comprises up to 80 wt.% polyalkylene glycol, based on the total weight of the combined sulfosuccinate and polyalkylene glycol dispersants.

Description

[Technical Field]

[0001] The present disclosure relates to lubricant compositions, and more particularly to lubricant compositions comprising oil-based graphite lubricant compositions. [Background technology]

[0002] Introduction Graphite is used as a lubricant in a variety of applications. For example, automotive, household, and industrial applications all utilize graphite as a lubricant. One example of an industrial application is hot forging. Hot forging is an industrial process in which a metal workpiece is placed in a die and deformed under pressure. The energy applied to the metal workpiece to plastically deform it is converted into heat. The repeated forging of the workpiece and the generation of heat increases the temperature of the die. Lubricants are used at the interface between the workpiece and the die during forging to reduce friction and ensure the workpiece can be removed from the die. Good lubrication improves workpiece deformation, favors accurate filling of the die cavity, reduces tool wear at points with free-flowing motion and high specific pressures, and can reduce forging forces. These characteristics reduce stresses induced in the forging tool and prevent direct contact between the tool and the workpiece, which contributes to longer tool life and better quality control.

[0003] One option for hot forging lubricants is oil-based lubricants. Oil-based lubricants typically contain oil as a carrier and lubricating particles, such as graphite. Oil-based lubricants adhere graphite to the die to form a coating. Oil-based lubricants are disadvantageous compared to water-based lubricants because they tend to run off the die surface and be squeezed out of the workpiece / die interface under pressure. Additional problems exist. For example, graphite dispersions in oil are not stable and require continuous stirring. Otherwise, gelation and caking can occur in the graphite-rich portions of the dispersion. Caking in the lubricant holding tank can lead to inaccurate application of graphite to the die, thereby reducing the die's useful life. Agglomeration and settling can also clog pipes and spray nozzles intended to apply the lubricant to the forging die. Gelling is particularly disadvantageous because it renders the precipitated graphite indispersible. Ideally, an oil-based graphite dispersion should not gel and remain dispersible within 31 days (ie, 1 month) ("Gelation Test").

[0004] The gelation test is difficult to pass because of the existence of various competing theories to explain graphite dispersion. For example, one hypothesis is that dispersants accumulate on the surface of graphite particles and act as spacers that prevent their steric proximity, but it is unknown which moiety influences this property. In contrast, Chinese Patent Application Publication No. 111925697(A) ("'697 Publication") provides graphene and polymer dispersant composites. '697 Publication explains that improved graphene dispersions can be obtained by including a water-soluble polymer dispersant containing an aromatic ring structure and a hydrophilic group, because the dispersant improves the miscibility between surface-inert graphene and the water-soluble polymer due to π-π interactions between the dispersant and graphene. '697 Publication does not mention how the arrangement or amount of the aromatic structure affects dispersion.

[0005] Given the competing theories behind the effectiveness of graphite dispersants, the unclear influence of different molecular moieties on dispersion performance, and the complexity of intermolecular forces present in oil-based graphite dispersions, it is surprising to find a dispersant that can pass the gelation test. Summary of the Invention

[0006] The inventors of the present application have discovered lubricant compositions containing oil-based graphite dispersions that are capable of passing the gelation test.

[0007] This disclosure is the result of the discovery that a dispersant selected from the group consisting of sulfosuccinate, polyalkylene glycols containing propylene oxide and butylene oxide, and combinations thereof, can enable a lubricant composition to pass the gel test. Without being bound by theory, it is believed that the dispersant not only interacts with the surface of the graphite to improve dispersion of the graphite in the oil, but also remains attached to the graphite after settling. It is believed that the retention of the dispersant on the surface of the graphite after settling from the oil prevents gelation from occurring, thereby keeping the graphite redispersible upon agitation, thereby passing the gel test.

[0008] The present disclosure is particularly useful in formulating lubricants that utilize graphite.

[0009] According to a first aspect of the present disclosure, a lubricant composition comprises graphite, oil, and a dispersant selected from the group consisting of sulfosuccinates, polyalkylene glycols comprising propylene oxide and butylene oxide, and combinations thereof, with the proviso that the combination of sulfosuccinate dispersant and polyalkylene glycol dispersant comprises no more than 80 wt.% polyalkylene glycol, based on the total weight of the combined sulfosuccinate and polyalkylene glycol dispersants.

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

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

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

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

[0014] According to a sixth aspect 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 eighth feature of the present disclosure, the dispersant includes a polyalkylene glycol, and the polyalkylene glycol includes 30 wt % to 70 wt % of propylene oxide based on the total weight of propylene oxide and butylene oxide in the polyalkylene glycol.

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

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

[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 used by itself, or any combination of two or more of the listed items can be used. 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] Unless otherwise stated, all ranges are inclusive of the endpoints.

[0021] As used herein, the term weight percent ("wt. %") refers to the weight percentage that a component represents of the total weight of the lubricant composition, unless otherwise specified.

[0022] As used herein, Chemical Abstract Services Registry Number ("CAS Number") refers to the unique numeric identifier most recently assigned to a chemical compound by the Chemical Abstracts Service as of the priority date of this document.

[0023] Lubricant composition The present disclosure relates to a lubricant composition comprising graphite, an oil, and a dispersant. The lubricant composition may also contain one or more other additives designed to modify the characteristics of the lubricant composition.

[0024] graphite The lubricant composition includes graphite. The graphite may have a spherical, platelet, ellipsoidal, and / or irregular shape. The graphite particles may have a D90 of 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 linear dimension smaller than the specified value and 10% of the particles have a diameter or longest linear dimension larger than the specified value. The graphite may have a particle size of 0.5 μm or more, or 1.0 μm or more, or 1.5 μm or more, or 2.0 μm or more, or 2.5 μm or more, or 3.0 μm or more, or 3.5 μm or more, or 4.0 μm or more, or 4.5 μm or more, or 5.0 μm or more, or 5.5 μm or more, or 6.0 μm or more, or 6.5 μm or more, or 7.0 μm or more, or 7.5 μm or more, or 8.0 μm or more, or 8.5 μm or more, or 9.0 μm or more, or 9.5 μm or more, while simultaneously The graphite may have a D90 particle size of 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.% graphite, based on the total weight of the lubricant composition. For example, the lubricant composition may comprise 1 wt.% or more, or 5 wt.% or more, or 10 wt.% or more, or 15 wt.% or more, or 20 wt.% or more, or 25 wt.% or more, or 30 wt.% or more, or 35 wt.% or more, or 40 wt.% or more, or 45 wt.% or more, or 50 wt.% or more, or 55 wt.% or more graphite, while simultaneously comprising 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 graphite, based on the total weight of the lubricant composition.

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

[0027] The lubricant composition may comprise 50% to 98% by weight of oil, based on the total weight of the lubricant composition. For example, the lubricant composition may comprise 50% or more, or 55% or more, or 60% or more, or 65% or more, or 70% or more, or 75% or more, or 80% or more, or 85% or more, or 90% or more, or 95% or more by weight, while simultaneously comprising 98% or less, or 95% or less, or 90% or less, or 85% or less, or 80% or less, or 75% or less, or 70% or less, or 65% or less, or 60% or less, or 55% or less by weight of oil, based on the total weight of the lubricant composition.

[0028] Dispersants The lubricant composition includes a dispersant. As explained above, the dispersant functions to disperse the graphite and prevent gelation after extended periods of non-mixing. The dispersant is selected from the group consisting of sulfosuccinates, polyalkylene glycols including propylene oxide ("PO") and butylene oxide ("BO"), and combinations thereof.

[0029] Sulfosuccinates have the general formula shown in structure (I):

[0030] [ka] [In the formula, R1 and R2 each independently represent a C4 to C 16 is alkyl, and M + is a cation. Each of R1 and R2 can independently be linear or branched. Each of R1 and R2 can 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 C 10 Alkyl or C 11 Alkyl or C 12 Alkyl or C 13 Alkyl or C 14 Alkyl or C 15 Alkyl or C 16 M can be alkyl.+ 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.

[0031] The polyalkylene glycol is a copolymer of PO and BO ("PO / BO copolymer") and is an oil-soluble polyalkylene glycol (OSP). The PO / BO copolymer can be a block copolymer or a random copolymer. The polyalkylene glycol contains an average of 10% to 90% by weight of PO, based on the total weight of PO and BO in the polyalkylene glycol. For example, the polyalkylene glycol contains 10% by weight or more, or 20% by weight or more, or 30% by weight or more, or 40% by weight or more, or 50% by weight or more, or 60% by weight or more, or 70% by weight or more, or 80% by weight or more, while simultaneously containing 90% by weight or less, or 80% by weight or less, or 70% by weight or less, or 60% by weight or less, or 50% by weight or less, or 40% by weight or less, or 30% by weight or less, or 20% by weight or less of PO, based on the total weight of PO and BO in the polyalkylene glycol. The polyalkylene glycol contains an average of 10% to 90% by weight of BO, based on the total weight of PO and BO in the polyalkylene glycol. For example, the polyalkylene glycol contains 10% by weight or more, or 20% by weight or more, or 30% by weight or more, or 40% by weight or more, or 50% by weight or more, or 60% by weight or more, or 70% by weight or more, or 80% by weight or more, based on the total weight of PO and BO in the polyalkylene glycol, while simultaneously containing 90% by weight or less, or 80% by weight or less, or 70% by weight or less, or 60% by weight or less, or 50% by weight or less, or 40% by weight or less, or 30% by weight or less, or 20% by weight or less of BO.

[0032] The polyalkylene glycol may be an alcohol-initiated polyalkylene glycol. The alcohol initiator may be a primary or secondary alcohol. The alcohol may have 8 or more carbon atoms, or 9 or more carbon atoms, or 10 or more carbon atoms, or 11 or more carbon atoms, or 12 or more carbon atoms, or 13 or more carbon atoms, or 14 or more carbon atoms, or 15 or more carbon atoms, or 16 or more carbon atoms, or 17 or more carbon atoms, or 18 or more carbon atoms, or 19 or more carbon atoms, while simultaneously having 20 or fewer carbon atoms, or 19 or fewer carbon atoms, or 18 or fewer carbon atoms, or 17 or fewer carbon atoms, or 16 or fewer carbon atoms, or 15 or fewer carbon atoms, or 14 or fewer carbon atoms, or 13 or fewer carbon atoms, or 12 or fewer carbon atoms, or 11 or fewer carbon atoms, or 10 or fewer carbon atoms, or 9 or fewer carbon atoms. The number of carbon atoms in the alcohol initiator is determined by the number of carbon atoms in the end groups of the polyalkylene glycol. In a specific example, the alcohol initiator can be dodecanol (ie, a 12 carbon alcohol).

[0033] The polyalkylene glycol can 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 can be 500 g / mol or more, or 600 g / mol or more, or 700 g / mol or more, or 800 g / mol or more, or 900 g / mol or more, or 1000 g / mol or more, or 1100 g / mol or more, or 1200 g / mol or more, or 1300 g / mol or more, or 1400 g / mol or more, or 1500 g / mol or more, or 1600 g / mol or more, or 1700 g / mol or more, or 1800 g / mol or more, or 1900 g / mol or more, or 2000 g / mol or more, or 2100 g / mol or more, or 2200 g / mol or more, or 2300 g / mol or more, as measured by gel permeation chromatography. or above, or 2400 g / mol or above, while simultaneously being 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.

[0034] The polyalkylene glycol used in the lubricant composition may comprise a dodecanol-initiated random copolymer containing 50% by weight PO and 50% by weight BO, based on the total weight of PO and BO in the dispersant. Such copolymers are commercially available under the tradenames 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) from The Dow Chemical Company, Midland, Michigan.

[0035] The lubricant composition comprises 0.01 wt % to 5.0 wt % of a dispersant, based on the total weight of the lubricant composition. For example, the lubricant composition may comprise 0.01 wt % or more, or 0.05 wt % or more, or 0.1 wt % or more, or 0.5 wt % or more, or 1.0 wt % or more, or 1.5 wt % or more, or 2.0 wt % or more, or 2.5 wt % or more, or 3.0 wt % or more, or 3.5 wt % or more, or 4.0 wt % or more, or 4.5 wt % or more, while simultaneously comprising 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 a dispersant, based on the total weight of the lubricant composition.

[0036] The dispersant may include both a succinate and a polyalkylene glycol. In such examples, the dispersant combination includes 80% or less by weight of polyalkylene glycol based on the total weight of the combined sulfosuccinate and polyalkylene glycol dispersant. For example, the combined dispersant may include 80% or less by weight, or 75% or less by weight, or 70% or less by weight, or 65% or less by weight, or 60% or less by weight, or 55% or less by weight, or 50% or less by weight, or 45% or less by weight, or 40% or less by weight, or 35% or less by weight, or 30% or less by weight, or 25% or less by weight, or 20% or less by weight, or 15% or less by weight, or 10% or less by weight, or 5% or less by weight, or 1% or less by weight of polyalkylene glycol dispersant based on the total weight of the combined sulfosuccinate and polyalkylene glycol dispersant. [Example]

[0037] material The following materials were used in the examples:

[0038] The graphite was a powder of graphite particles having a D90 of 5.0 μm and was commercially available from Molygraph Lubricants (Mumbai, India).

[0039] PIBSA is polyisobutylene succinic anhydride with CAS number 67762-77-0 and is commercially available from Transasia Petrochem Pvt Ltd. (Mumbai, India).

[0040] The oil is a Group (II) oil obtained by dewaxing and hydrotreating the vacuum distillate of certain crude oil fractions. The oil has a minimum viscosity index of 85, as measured in accordance with ASTM D227, and a density of 0.875 g / cc to 0.89 g / cc, as measured in accordance with ASTM D4052-18. Exemplary oils are available from Sigma Aldrich (St. Louis, Missouri).

[0041] DISP1 is composed of 95% by weight or more of structure (II)

[0042] [ka] where x is 31 and R is C4H9OH. DISP1 is commercially available from The Dow Chemical Company (Midland, Michigan).

[0043] DISP2 is a mixture of up to 65.5% by weight of di-2-ethylhexyl sodium C and other ingredients, and is commercially available as TRITON™ GR-7M from The Dow Chemical Company, Midland, Michigan.

[0044] DISP3 is a mixture of 56% to 60% by weight di-2-ethylhexyl sodium sulfosuccinate, 20% by weight isopropanol, and 20% by weight water, and is commercially available as TRITON™ GR-5M from The Dow Chemical Company (Midland, Michigan).

[0045] DISP4 is 18mm at 40℃ 2 DISP5 is a dodecanol-initiated random copolymer (PO / BO, 50 / 50 by weight) with a typical kinematic viscosity of 10 ...

[0046] DISP5 is 32mm at 40℃ 2 DISP5 is a dodecanol-initiated random copolymer (PO / BO, 50 / 50 by weight) with a typical kinematic viscosity of 1000 kJ / s (cSt). Its average Mn is 760 g / mol. DISP5 is commercially available as UCON™ OSP-32 from The Dow Chemical Company (Midland, Michigan).

[0047] DISP6 is a dodecanol-initiated random copolymer (PO / BO, 50 / 50 by weight) with a typical kinematic viscosity of 150 mm / s (cSt) at 40°C. Its average molecular weight (Mn) is 1900 g / mol. DISP6 is commercially available as UCON™ OSP-150 from The Dow Chemical Company (Midland, Michigan).

[0048] DISP7 is 680mm at 40℃ 2 DISP6 is a butylene oxide homopolymer having a typical kinematic viscosity of 1000 kJ / 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.

[0049] Sample preparation 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, graphite was slowly added to the mixture while continuing to stir. The mixture was then stirred at 700 RPM for an additional 15 minutes using the same overhead stirrer. Finally, the mixture was transferred to a clear graduated cylinder, capped, and the mixture's stability was observed. The mixture was allowed to stand at approximately 23°C for 31 days and then observed.

[0050] result Table 1 shows the results for comparative examples ("CE") and inventive examples ("IE").

[0051] [Table 1]

[0052] Referring now to Table 1, it can be seen that lubricant compositions containing graphite, oil, and a dispersant selected from the group consisting of sulfosuccinate, polyalkylene glycols containing propylene oxide, and butylene oxide can pass the gelation test. CE1 demonstrates that the absence of dispersant causes graphite gelation. Similarly, the addition of PIBSA and other dispersants in CE2-CE5 cannot prevent graphite gelation in the oil. CE6 demonstrates that an 80:20 weight ratio of DISP5 and DISP2 (i.e., polyalkylene glycol DISP5 active approximately 86 wt%) also fails to prevent graphite gelation. In contrast to CE6, IE5, in which DISP5 and DISP2 are present in equal weight amounts (i.e., polyalkylene glycol DISP5 active approximately 61 wt%), successfully prevents graphite gelation. Similarly, by using succinate and polyalkylene glycol alone in IE1 to IE4, it is possible to prevent the graphite from gelling and to maintain the graphite in a dispersible form.

Claims

1. Graphite and Oil and a dispersant selected from the group consisting of sulfosuccinates, polyalkylene glycols comprising propylene oxide and butylene oxide, and combinations thereof, with the proviso that the combination of sulfosuccinate dispersant and polyalkylene glycol dispersant comprises no more than 80 wt.% of said polyalkylene glycol, based on the total weight of said combined sulfosuccinate and polyalkylene glycol dispersants.

2. 10. The lubricant composition of claim 1, wherein the lubricant composition comprises 1 to 60 weight percent graphite, based on the total weight of the lubricant composition.

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

4. The lubricant composition of any one of claims 1 to 3, wherein the lubricant composition comprises 50 to 98 wt% oil, based on the total weight of the lubricant composition.

5. The lubricant composition of any one of claims 1 to 4, wherein the lubricant composition comprises 0.01 wt% to 5.0 wt% of the dispersant, based on the total weight of the lubricant composition.

6. The lubricant composition of any one of claims 1 to 5, wherein the dispersant comprises a sulfosuccinate.

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

8. 6. The lubricant composition of claim 1, wherein the dispersant comprises the polyalkylene glycol, and the polyalkylene glycol comprises 30% to 70% by weight of propylene oxide, based on the total weight of propylene oxide and butylene oxide in the polyalkylene glycol.

9. 9. The lubricant composition of claim 8, wherein the polyalkylene glycol comprises 40 to 60 weight percent propylene oxide, based on the total weight of propylene oxide and butylene oxide in the polyalkylene glycol.

10. 6. The lubricant composition of any one of claims 1 to 5, wherein the dispersant comprises di-2-ethylhexyl sodium sulfosuccinate and a dodecanol-initiated polyalkylene glycol comprising 50 wt% propylene oxide, based on the total weight of propylene oxide and butylene oxide in the polyalkylene glycol.

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