HIGH VISCOSITY LUBRICANTS WITH POLYETHER

Abstract

Disclosed is a method of treating a used hydrocarbon lubricant of ISO Viscosity Grade 46 or higher comprising oxidation products that adversely affect lubricant performance. The hydrocarbon lubricant has a Group II hydrocarbon oil or Group III hydrocarbon oil, optionally one or more lubricant additives, and an amount of varnish. The hydrocarbon lubricant is free of zinc-containing additives. The method comprises adding to the used hydrocarbon lubricant from about 2 percent by weight to about 20 percent by weight of a polyhydroxy polypropylene oxide homopolymer that has a hydroxyl number of from about 12 mg KOH/g to about 58 mg KOH/g as measured according to ASTM D4274.

Claims

1. A method, comprising: adding to a hydrocarbon lubricant comprising a Group II or Group III oil and sludge or varnish from about 2 percent by weight to about 20 percent by weight of a polyhydroxy polypropylene oxide homopolymer having a hydroxyl number of from about 12 mg KOH/g to about 58 mg KOH/g, based on the weight of the used hydrocarbon lubricant, wherein the hydrocarbon lubricant has an ISO Viscosity Grade of at least 46 and is free of zinc dialkylthiophosphate and other zinc coordination compounds.

2. A method according to claim 1, wherein the hydrocarbon lubricant has a Varnish Potential Rating of Elevated or higher.

3. A method according to claim 1, wherein the hydrocarbon lubricant has an ISO Viscosity Grade of from 46 to 220 and the polyhydroxy polypropylene oxide homopolymer has a hydroxyl number of from about 25 mg KOH/g to about 58 mg KOH/g.

4. A method according to claim 1, wherein the hydrocarbon lubricant has an ISO Viscosity Grade of from 100 to 220 and the polyhydroxy polypropylene oxide homopolymer has a hydroxyl number of from about 25 mg KOH/g to about 32 mg KOH/g.

5. A method according to claim 1, wherein the hydrocarbon lubricant has an ISO Viscosity Grade of from 220 to 1500 and the polyhydroxy polypropylene oxide homopolymer has a hydroxyl number of from about 12 mg KOH/g to about 20 mg KOH/g.

6. A method according to claim 1, wherein from about 3 percent by weight to about 17 percent by weight of the polyhydroxy polypropylene oxide homopolymer is added.

7. A method according to claim 1, wherein from about 5 percent by weight to about 14 percent by weight of the polyhydroxy polypropylene oxide homopolymer is added.

8. A method according to claim 1, wherein the hydrocarbon lubricant is free of detergent and dispersant additives.

9. A method according to claim 1, wherein the hydrocarbon lubricant is free of additives dispersed with surfactants and/or dispersants.

10. A method according to claim 1, further comprising adding to the hydrocarbon lubricant a member selected from the group consisting of antioxidants, antifoam additives, corrosion inhibitors, and combinations thereof.

11. A method, comprising: adding to a used hydrocarbon lubricant comprising a Group II or Group III oil, in which atomic oxygen has changed by at least about 0.3 weight percent compared to the weight percent of atomic oxygen of the hydrocarbon lubricant as originally formulated, from about 2 percent by weight to about 20 percent by weight of a polyhydroxy polypropylene oxide homopolymer, based on the weight of the used hydrocarbon lubricant, wherein the hydrocarbon lubricant has an ISO Viscosity Grade of at least 46; wherein the hydrocarbon lubricant is free of zinc lubricant additives; wherein the polyhydroxy polypropylene oxide homopolymer has a hydroxyl number of from about 12 mg KOH/g to about 58 mg KOH/g.

12. A method according to claim 11, wherein atomic oxygen has changed by at least about 0.5 weight percent compared to the weight percent of atomic oxygen of the hydrocarbon lubricant as originally formulated.

13. A method according to claim 11, wherein the hydrocarbon lubricant has an ISO Viscosity Grade of from 46 to 220 and the polyhydroxy polypropylene oxide homopolymer has a hydroxyl number of from about 25 mg KOH/g to about 58 mg KOH/g.

14. A method according to claim 11, wherein the hydrocarbon lubricant has an ISO Viscosity Grade of from 100 to 220 and the polyhydroxy polypropylene oxide homopolymer has a hydroxyl number of from about 25 mg KOH/g to about 32 mg KOH/g.

15. A method according to claim 11, wherein the hydrocarbon lubricant has an ISO Viscosity Grade of from 220 to 1500 and the polyhydroxy polypropylene oxide homopolymer has a hydroxyl number of from about 12 mg KOH/g to about 20 mg KOH/g.

16. A method according to claim 11, wherein from about 3 percent by weight to about 17 percent by weight of the polyhydroxy polypropylene oxide homopolymer is added.

17. A method according to claim 11, wherein from about 3 percent by weight to about 14 percent by weight of the polyhydroxy polypropylene oxide homopolymer is added.

18. A method according to claim 11, wherein the hydrocarbon lubricant is free of detergent and dispersant additives.

19. A method according to claim 11, wherein the hydrocarbon lubricant is free of additives dispersed with surfactants and/or dispersants.

20. A method according to claim 11, further comprising adding to the hydrocarbon lubricant a member selected from the group consisting of antioxidants, antifoam additives, corrosion inhibitors, and combinations thereof.

21. A method, comprising: adding to a used hydrocarbon lubricant comprising a Group II or Group III oil, which has an increase in E of at least about 25 in the Membrane Patch Colorimetry test compared to the hydrocarbon lubricant as originally formulated, from about 2 percent by weight to about 20 percent by weight of a polyhydroxy polypropylene oxide homopolymer, based on the weight of the used hydrocarbon lubricant, wherein the hydrocarbon lubricant has an ISO Viscosity Grade of at least 46; wherein the hydrocarbon lubricant is free of zinc lubricant additives; wherein the polypropylene oxide is linear and terminated on both ends with hydroxyl groups and has a hydroxyl number of from about 12 mg KOH/g to about 58 mg KOH/g.

22. A method according to claim 21, wherein the hydrocarbon lubricant has an ISO Viscosity Grade of from 46 to 220 and the polyhydroxy polypropylene oxide homopolymer has a hydroxyl number of from about 25 mg KOH/g to about 58 mg KOH/g.

23. A method according to claim 21, wherein the hydrocarbon lubricant has an ISO Viscosity Grade of from 100 to 220 and the polyhydroxy polypropylene oxide homopolymer has a hydroxyl number of from about 25 mg KOH/g to about 32 mg KOH/g.

24. A method according to claim 21, wherein the hydrocarbon lubricant has an ISO Viscosity Grade of from 220 to 1500 and the polyhydroxy polypropylene oxide homopolymer has a hydroxyl number of from about 12 mg KOH/g to about 20 mg KOH/g.

Description

DETAILED DESCRIPTION

[0029] A detailed description of exemplary, nonlimiting embodiments follows.

[0030] The used hydrocarbon lubricant that is treated in the disclosed method comprises either a Group II hydrocarbon oil or a Group III hydrocarbon oil according to API 1509, Appendix E. Group II hydrocarbon oils are defined as containing more than 90 percent saturates, containing less than 0.03 percent sulfur, and having a viscosity index of 80 to 120. Group III hydrocarbon oils contain greater than 90 percent saturates, contain less than 0.03 percent sulfur, and have a viscosity index above 120. Both Group II and Group III hydrocarbon oils may be manufactured by hydrocracking, while Group III oils are generally severely hydrocracked at higher pressure and heat to obtain a higher purity. Group II and Group III hydrocarbon oils are widely available commercially. The used hydrocarbon lubricant may optionally contain one or more lubricant additives.

[0031] The used hydrocarbon lubricant has an ISO Viscosity Grade of 46 or higher or a viscosity as measured according to ASTM D445 of 40 or higher. The used hydrocarbon lubricant's ISO Viscosity Grade may be, for example, from 46 to 1500. In various embodiments, the used hydrocarbon lubricant's ISO Viscosity Grade may be one of ISO Viscosity Grades 46, 68, 100, 150, 220, 320, 460, 680, 1000, and 1500. Such hydrocarbon lubricants find use, for example, as hydraulic pump oils, industrial gear lubricants and greases. Industrial gear lubricants are specifically distinguished from automotive gear oils, which are subject to operating challenges distinct from industrial gear lubricants and are therefore formulated differently. The used hydrocarbon lubricants treated in the present method are free of zinc dialkylthiophosphate and other zinc coordination compounds and may preferably be free of additives dispersed with surfactants and/or dispersants. In particular, the used hydrocarbon lubricants treated in the present method are free of zinc dialkylthiophosphate and other zinc coordination compounds.

[0032] A hydrocarbon lubricant is exposed to oxidative conditions during use, and over time the amount of varnish in the hydrocarbon lubricant increases to a point at which it negatively affects performance of the apparatus containing the hydrocarbon lubricant. The used hydrocarbon lubricant is then advantageously treated according to the method now disclosed. In various embodiments, the used hydrocarbon lubricant is subjected to the presently disclosed method when it contains varnish detectable by ASTM D7843. In various embodiments, the used hydrocarbon lubricant is subjected to the presently disclosed method when it contains varnish: (1) that manifests as sludge or agglomerated varnish that causes an increase in hydrocarbon lubricant viscosity compared to viscosity of the hydrocarbon lubricant as originally formulated (i.e., new or unused hydrocarbon lubricant) or (2) that is determined by at least one of: a change in amount of atomic oxygen of at least 0.3 wt %, or an increase in Varnish Potential Rating to Elevated or higher, or an increase in E of at least about 25 in the Membrane Patch Colorimetry test, wherein each of these is determined by comparison to the hydrocarbon lubricant as originally formulated (properties of an unused hydrocarbon lubricant of the lubricant's formulation). A Varnish Potential Rating of Elevated or higher as determined by ASTM D7843 is an increase in E of at least about 25 in the Membrane Patch Colorimetry test. Still another method of determining when a used hydrocarbon lubricant should be treated is by monitoring the increase in color determined by Membrane Patch Colorimetry (ASTM D7843). An increase in E of at least about 25, for example from about 25 to about 60, should be treated with the polyhydroxy polypropylene oxide homopolymer having a hydroxyl number of from about 12 mg KOH/g to about 58 mg KOH/g.

[0033] When a used hydrocarbon lubricant has an increase or decrease in weight percent atomic oxygen by weight, for example when atomic oxygen has increased or decreased at least about 0.3 weight percent or at least about 0.4 weight percent or at least about 0.5 weight percent as compared to the weight percent of atomic oxygen of the lubricant as originally formulated (that is, the weight percent of atomic oxygen that can be accounted for by the additives used in formulating the lubricant) it typically includes a level of varnish that detrimentally affects lubricant properties or operation of the lubricated machinery and should be treated with the polyhydroxy polypropylene oxide homopolymer having a hydroxyl number of from about 12 mg KOH/g to about 58 mg KOH/g, as measured according to ASTM D4274. The method may be used to treat used hydrocarbon lubricant in which atomic oxygen is changed, for example, from 0.3 weight percent or from about 0.4 weight percent or from about 0.5 weight percent to about 0.7 weight percent or to about 0.8 weight percent or to about 0.9 weight percent or to about 1 weight percent compared to the weight percent of atomic oxygen of the lubricant as formulated.

[0034] The method of treating the used hydrocarbon lubricant comprises adding to the used hydrocarbon lubricant from about 2 percent by weight to about 20 percent by weight of the polyhydroxy polypropylene oxide homopolymer having a hydroxyl number of from about 12 mg KOH/g to about 58 mg KOH/g, based on weight of the used hydrocarbon lubricant. That is, for every 100 parts by weight of the used hydrocarbon lubricant, 2 to 20 parts by weight of polyhydroxy polypropylene oxide homopolymer having a hydroxyl number of from about 12 mg KOH/g to about 58 mg KOH/g is added. In general, a lesser amount of the polyhydroxy polypropylene oxide homopolymer can be used as the used hydrocarbon lubricant's ISO Viscosity Grade increases. In general, it may be advantageous to use a polyhydroxy polypropylene oxide homopolymer having a viscosity within about about 80% to about |300|.sub.[BAM1]% of the used hydrocarbon lubricant viscosity, although addition of a higher viscosity polyhydroxy polypropylene oxide homopolymer tends to have much less of an effect on viscosity than expected theoretically due to its action in re-dissolving the varnish in the used hydrocarbon lubricant. In various embodiments, the polyhydroxy polypropylene oxide homopolymer may have a hydroxyl number of from about 12 mg KOH/g or from about 13 mg KOH/g or from about 14 mg KOH/g or from about 15 mg KOH/g or from about 16 mg KOH/g or from about 17 mg KOH/g or from about 18 mg KOH/g or from about 19 mg KOH/g or from about 20 mg KOH/g or from about 21 mg KOH/g or from about 22 mg KOH/g to about 58 mg KOH/g or to about 56 mg KOH/g or to about 53 mg KOH/g or to about 50 mg KOH/g or to about 47 mg KOH/g or to about 44 mg KOH/g or to about 42 mg KOH/g or to about 40 mg KOH/g or to about 38 mg KOH/g or to about 36 mg KOH/g or to about 34 mg KOH/g or to about 32 mg KOH/g or to about 31 mg KOH/g or to about 30 mg KOH/g or to about 29 mg KOH/g or to about 28 mg KOH/g or to about 27 mg KOH/g or to about 26 mg KOH/g or to about 25 mg KOH/g as measured according to ASTM D4274.

[0035] Suitable polyhydroxy polypropylene oxide homopolymers may be prepared from polypropylene oxide using water, diols such as ethylene glycol and polypropylene glycol, or polyols such as glycerine, trimethylolpropane, or pentaerythritol as an initiator compound. Preferably, the initiator compound is water or a polyol having two to four carbon atoms, more preferably two or three carbon |atoms|.sub.[BAM2]. Polyhydroxy polypropylene oxide homopolymers having a hydroxyl number of from about 12 mg KOH/g to about 58 mg KOH/g are commercially available, for example under the VORANOL trademark from The Dow Chemical Company of Midland, Mich.

[0036] The optimum amount of the polyhydroxy polypropylene oxide homopolymer to be added to the used hydrocarbon lubricant can be determined in a straightforward fashion by adding the polyhydroxy polypropylene oxide homopolymer to the used hydrocarbon lubricant in incremental amounts and observing the effect on Membrane Patch Colorimetry (E). Typically, the improvement in Membrane Patch Colorimetry (E) is accompanied by loss of cloudiness in the used oil. When the lubricant was formulated with emulsifiers, relatively more of the polyhydroxy polypropylene oxide homopolymer may need to be added to the used hydrocarbon |lubricant|.sub.[BAM3].

[0037] In various embodiments, at least about 2 percent by weight or at least about 3 percent by weight or at least about 4 percent by weight or at least about 5 percent by weight or at least about 6 percent by weight or at least about 7 percent by weight or at least about 8 percent by weight or at least about 9 percent by weight or at least about 10 percent by weight of the polyhydroxy polypropylene oxide homopolymer is added to the used hydrocarbon lubricant and up to about 20 percent by weight or up to about 19 percent by weight or up to about 18 percent by weight or up to about 17 percent by weight or up to about 16 percent by weight or up to about 15 percent by weight or up to about 14 percent by weight or up to about 13 percent by weight or up to about 12 percent by weight or up to about 11 percent by weight or up to about 10 percent by weight of the polyhydroxy polypropylene oxide homopolymer may be added to the used hydrocarbon lubricant, in each case based on the weight of the used hydrocarbon lubricant. For example, from about 2 percent by weight to about 19 percent by weight or from about 2 percent by weight to about 18 percent by weight or from about 2 percent by weight to about 17 percent by weight or from about 2 percent by weight to about 16 percent by weight or from about 2 percent by weight to about 15 percent by weight or from about 2 percent by weight to about 14 percent by weight or from about 2 percent by weight to about 13 percent by weight or from about 2 percent by weight to about 12 percent by weight or from about 2 percent by weight to about 11 percent by weight or from about 2 percent by weight to about 10 percent by weight of the polyhydroxy polypropylene oxide homopolymer may be added to the used hydrocarbon lubricant, in each case based on the weight of the used hydrocarbon lubricant.

[0038] By way of further examples, from about 3 percent by weight to about 20 percent by weight or from about 3 percent by weight to about 19 percent by weight or from about 3 percent by weight to about 18 percent by weight or from about 3 percent by weight to about 17 percent by weight or from about 3 percent by weight to about 16 percent by weight or from about 3 percent by weight to about 15 percent by weight or from about 3 percent by weight to about 14 percent by weight or from about 3 percent by weight to about 13 percent by weight or from about 3 percent by weight to about 12 percent by weight or from about 3 percent by weight to about 11 percent by weight or from about 3 percent by weight to about 10 percent by weight of the polyhydroxy polypropylene oxide homopolymer may be added to the used hydrocarbon lubricant, in each case based on the weight of the used hydrocarbon lubricant.

[0039] By way of further examples, from about 4 percent by weight to about 20 percent by weight or from about 4 percent by weight to about 19 percent by weight or from about 4 percent by weight to about 18 percent by weight or from about 4 percent by weight to about 17 percent by weight or from about 4 percent by weight to about 16 percent by weight or from about 4 percent by weight to about 15 percent by weight or from about 4 percent by weight to about 14 percent by weight or from about 4 percent by weight to about 13 percent by weight or from about 4 percent by weight to about 12 percent by weight or from about 4 percent by weight to about 11 percent by weight or from about 4 percent by weight to about 10 percent by weight of the polyhydroxy polypropylene oxide homopolymer may be added to the used hydrocarbon lubricant, in each case based on the weight of the used hydrocarbon lubricant.

[0040] By way of further examples, from about 5 percent by weight to about 20 percent by weight or from about 5 percent by weight to about 19 percent by weight or from about 5 percent by weight to about 18 percent by weight or from about 5 percent by weight to about 17 percent by weight or from about 5 percent by weight to about 16 percent by weight or from about 5 percent by weight to about 15 percent by weight or from about 5 percent by weight to about 14 percent by weight or from about 5 percent by weight to about 13 percent by weight or from about 5 percent by weight to about 12 percent by weight or from about 5 percent by weight to about 11 percent by weight or from about 5 percent by weight to about 10 percent by weight of the polyhydroxy polypropylene oxide homopolymer may be added to the used hydrocarbon lubricant, in each case based on the weight of the used hydrocarbon lubricant.

[0041] By way of further examples, from about 6 percent by weight to about 20 percent by weight or from about 6 percent by weight to about 19 percent by weight or from about 6 percent by weight to about 18 percent by weight or from about 6 percent by weight to about 17 percent by weight or from about 6 percent by weight to about 16 percent by weight or from about 6 percent by weight to about 15 percent by weight or from about 6 percent by weight to about 14 percent by weight or from about 6 percent by weight to about 13 percent by weight or from about 6 percent by weight to about 12 percent by weight or from about 6 percent by weight to about 11 percent by weight or from about 6 percent by weight to about 10 percent by weight of the polyhydroxy polypropylene oxide homopolymer may be added to the used hydrocarbon lubricant, in each case based on the weight of the used hydrocarbon lubricant.

[0042] By way of further examples, from about 7 percent by weight to about 20 percent by weight or from about 7 percent by weight to about 19 percent by weight or from about 7 percent by weight to about 18 percent by weight or from about 7 percent by weight to about 17 percent by weight or from about 7 percent by weight to about 16 percent by weight or from about 7 percent by weight to about 15 percent by weight or from about 7 percent by weight to about 14 percent by weight or from about 7 percent by weight to about 13 percent by weight or from about 7 percent by weight to about 12 percent by weight or from about 7 percent by weight to about 11 percent by weight or from about 7 percent by weight to about 10 percent by weight of the polyhydroxy polypropylene oxide homopolymer may be added to the used hydrocarbon lubricant, in each case based on the weight of the used hydrocarbon lubricant.

[0043] By way of further examples, from about 8 percent by weight to about 20 percent by weight or from about 8 percent by weight to about 19 percent by weight or from about 8 percent by weight to about 18 percent by weight or from about 8 percent by weight to about 17 percent by weight or from about 8 percent by weight to about 16 percent by weight or from about 8 percent by weight to about 15 percent by weight or from about 8 percent by weight to about 14 percent by weight or from about 8 percent by weight to about 13 percent by weight or from about 8 percent by weight to about 12 percent by weight or from about 8 percent by weight to about 11 percent by weight or from about 8 percent by weight to about 10 percent by weight of the polyhydroxy polypropylene oxide homopolymer may be added to the used hydrocarbon lubricant, in each case based on the weight of the used hydrocarbon lubricant.

[0044] By way of further examples, from about 9 percent by weight to about 20 percent by weight or from about 9 percent by weight to about 19 percent by weight or from about 9 percent by weight to about 18 percent by weight or from about 9 percent by weight to about 17 percent by weight or from about 9 percent by weight to about 16 percent by weight or from about 9 percent by weight to about 15 percent by weight or from about 9 percent by weight to about 14 percent by weight or from about 9 percent by weight to about 13 percent by weight or from about 9 percent by weight to about 12 percent by weight or from about 9 percent by weight to about 11 percent by weight or from about 9 percent by weight to about 10 percent by weight of the polyhydroxy polypropylene oxide homopolymer may be added to the used hydrocarbon lubricant, in each case based on the weight of the used hydrocarbon lubricant.

[0045] By way of further examples, from about 10 percent by weight to about 20 percent by weight or from about 10 percent by weight to about 19 percent by weight or from about 10 percent by weight to about 18 percent by weight or from about 10 percent by weight to about 17 percent by weight or from about 10 percent by weight to about 16 percent by weight or from about 10 percent by weight to about 15 percent by weight or from about 10 percent by weight to about 14 percent by weight or from about 10 percent by weight to about 13 percent by weight or from about 10 percent by weight to about 12 percent by weight or from about 10 percent by weight to about 11 percent by weight of the polyhydroxy polypropylene oxide homopolymer may be added to the used hydrocarbon lubricant, in each case based on the weight of the used hydrocarbon lubricant.

[0046] In various embodiments, the used hydrocarbon lubricant comprises a Group II hydrocarbon oil or Group III hydrocarbon oil and one or more lubricant additives and has a kinematic viscosity at 40 C. of from about 40 centistokes to about 352 centistokes or is one of ISO Viscosity Grades 46, 68, 100, 150, 220, or 320, wherein the method comprises adding to the used hydrocarbon lubricant at least about 2 percent by weight or at least about 3 percent by weight or at least about 4 percent by weight or at least about 5 percent by weight or at least about 6 percent by weight or at least about 7 percent by weight or at least about 8 percent by weight or at least about 9 percent by weight or at least about 10 percent by weight and up to about 20 percent by weight or up to about 19 percent by weight or up to about 18 percent by weight or up to about 17 percent by weight or up to about 16 percent by weight or up to about 15 percent by weight or up to about 14 percent by weight or up to about 13 percent by weight or up to about 12 percent by weight or up to about 11 percent by weight or up to about 10 percent by weight, based on the weight of the used hydrocarbon lubricant, of a polyhydroxy polypropylene oxide homopolymer having a hydroxyl number of from about 25 mg KOH/g to about 58 g KOH/g as measured according to ASTM D4274. The used hydrocarbon lubricant has varnish or sludge or has a Varnish Potential Rating of Elevated or higher or has a change in weight percent of atomic oxygen of at least about 0.3 weight percent more than the weight percent of atomic oxygen of the lubricant as formulated or has an increase in E of at least about 25 determined by Membrane Patch Colorimetry (ASTM D7843). In various embodiments, the polyhydroxy polypropylene oxide homopolymer may have a hydroxyl number of from about 25 mg KOH/g or from about 26 mg KOH/g or from about 27 mg KOH/g or from about 28 mg KOH/g to about 58 mg KOH/g or to about 56 mg KOH/g or to about 54 mg KOH/g or to about to about 52 mg KOH/g or to about 50 mg KOH/g or to about 48 mg KOH/g or to about 46 mg KOH/g or to about 44 mg KOH/g or to about 42 mg KOH/g or to about 40 mg KOH/g or to about 38 mg KOH/g or to about 36 mg KOH/g or to about 34 mg KOH/g or 32 mg KOH/g or to about 31 mg KOH/g or to about 30 mg KOH/g or to about 29 mg KOH/g or to about 28 mg KOH/g as measured according to ASTM 4274. For example, the polyhydroxy polypropylene oxide homopolymer may have a hydroxyl number of from about 25 mg KOH/g to about 56 mg KOH/g; or from about 25 mg KOH/g to about 50 mg KOH/g; or from about 25 mg KOH/g to about 46 mg KOH/g; or from about 25 mg KOH/g to about 40 mg KOH/g; or from about 25 mg KOH/g to about 36 mg KOH/g; or from about 25 mg KOH/g to about 32 mg KOH/g; or from about 25 mg KOH/g to about 30 mg KOH/g; or from about 25 mg KOH/g to about 28 mg KOH/g. In other embodiments, the polyhydroxy polypropylene oxide homopolymer may have a hydroxyl number of from about 26 mg KOH/g to about 58 mg KOH/g; or from about 26 mg KOH/g to about 54 mg KOH/g; or from about 26 mg KOH/g to about 50 mg KOH/g; or from about 26 mg KOH/g to about 46 mg KOH/g; or from about 26 mg KOH/g to about 40 mg KOH/g; or from about 26 mg KOH/g to about 36 mg KOH/g or from about 26 mg KOH/g to about 32 mg KOH/g; or from about 26 mg KOH/g to about 30 mg KOH/g or from about 26 mg KOH/g to about 28 mg KOH/g. In still other embodiments, the polyhydroxy polypropylene oxide homopolymer may have a hydroxyl number of from about 27 mg KOH/g to about 58 mg KOH/g; or from about 27 mg KOH/g to about 54 mg KOH/g; or from about 27 mg KOH/g to about 50 mg KOH/g or from about 27 mg KOH/g to about 46 mg KOH/g; or from about 27 mg KOH/g to about 40 mg KOH/g; or from about 27 mg KOH/g to about 36 mg KOH/g; or from about 27 mg KOH/g to about 32 mg KOH/g; or from about 27 mg KOH/g to about 30 mg KOH/g. In other embodiments, the polyhydroxy polypropylene oxide homopolymer may have a hydroxyl number of from about 28 mg KOH/g to about 58 mg KOH/g; or from about 28 mg KOH/g to about 54 mg KOH/g; or from about 28 mg KOH/g to about 50 mg KOH/g; or from about 28 mg KOH/g to about 46 mg KOH/g; or from about 28 mg KOH/g to about 40 mg KOH/g; or from about 28 mg KOH/g to about 36 mg KOH/g; or from about 28 mg KOH/g to about 32 mg KOH/g; or from about 28 mg KOH/g to about 30 mg KOH/g.

[0047] In various embodiments, the used hydrocarbon lubricant comprises a Group II hydrocarbon oil or Group III hydrocarbon oil and one or more lubricant additives, and has a kinematic viscosity at 40 C. of from about 288 centistokes to about 1650 centistokes or has an ISO Viscosity Grade of from |320|.sub.[BAM4] to 1500, measured according to ISO 3448, wherein the method comprises adding to the used hydrocarbon lubricant at least about 2 percent by weight or at least about 3 percent by weight or at least about 4 percent by weight or at least about 5 percent by weight or at least about 6 percent by weight or at least about 7 percent by weight or at least about 8 percent by weight or at least about 9 percent by weight or at least about 10) percent by weight and up to about 20 percent by weight or up to about 19 percent by weight or up to about 18 percent by weight or up to about 17 percent by weight or up to about 16 percent by weight or up to about 15 percent by weight or up to about 14 percent by weight or up to about 13 percent by weight or up to about 12 percent by weight or up to about 11 percent by weight or up to about 10 percent by weight, based on the weight of the used hydrocarbon lubricant, of a polyhydroxy polypropylene oxide homopolymer having a hydroxyl number of from about 12 mg KOH/g to about 20 mg KOH/g as measured according to ASTM D4274. The used hydrocarbon lubricant has varnish or sludge or has a Varnish Potential Rating of Elevated or higher or has a change in weight percent of atomic oxygen of at least about 0.3 weight percent more than the weight percent of atomic oxygen of the lubricant as formulated or has an increase in E of at least about 25 determined by Membrane Patch Colorimetry (ASTM D7843). In various embodiments, the polyhydroxy polypropylene oxide homopolymer may have a hydroxyl number of from about 12 mg KOH/g or from about 13 mg KOH/g or from about 14 mg KOH/g or from about 15 mg KOH/g to about 20 mg KOH/g or to about 19 mg KOH/g or to about 18 mg KOH/g or to about 17 mg KOH/g or to about 16 mg KOH/g or to about 15 mg KOH/g as measured according to ASTM D4274. For example, the polyhydroxy polypropylene oxide homopolymer may have a hydroxyl number of from about 12 mg KOH/g to about 19 mg KOH/g; or from about 12 mg KOH/g to about 18 mg KOH/g; or from about 12 mg KOH/g to about 17 mg KOH/g; or from about 12 mg KOH/g to about 16 mg KOH/g; or from about 12 mg KOH/g to about 15 mg KOH/g. In other examples, the polyhydroxy polypropylene oxide homopolymer may have a hydroxyl number of from about 13 mg KOH/g to about 20 mg KOH/g; or from about 13 mg KOH/g to about 19 mg KOH/g; or from about 13 mg KOH/g to about 18 mg KOH/g; or from about 13 mg KOH/g to about 17 mg KOH/g; or from about 13 mg KOH/g to about 16 mg KOH/g; or from about 13 mg KOH/g to about 15 mg KOH/g. In still other examples, the polyhydroxy polypropylene oxide homopolymer may have a hydroxyl number of from about 14 mg KOH/g to about 20 mg KOH/g; or from about 14 mg KOH/g to about 19 mg KOH/g; or from about 14 mg KOH/g to about 18 mg KOH/g; or from about 14 mg KOH/g to about 17 mg KOH/g; or from about 14 mg KOH/g to about 16 mg KOH/g; or from about 14 mg KOH/g to about 15 mg KOH/g. In still further examples, the polyhydroxy polypropylene oxide homopolymer may have a hydroxyl number of from about 15 mg KOH/g to about 20 mg KOH/g or from about 15 mg KOH/g to about 19 mg KOH/g; or from about 15 mg KOH/g to about 18 mg KOH/g; or from about 15 mg KOH/g to about 17 mg KOH/g; or from about 15 mg KOH/g to about 16 mg KOH/g.

[0048] The polyhydroxy polypropylene oxide homopolymer is not amphiphilic and does not form micelles as would a surfactant. Rather, it is understood that the polyhydroxy polypropylene oxide homopolymer changes the characteristics of the lubricant to permit the varnish to dissolve in the lubricant. Testing for Varnish Potential Rating shows the used lubricant returned to good working condition by the disclosed method of treating the used hydrocarbon lubricant with the polyhydroxy polypropylene oxide homopolymer.

[0049] The used hydrocarbon lubricant includes one or more additives suited for the particular use to which the lubricant is put. The used hydrocarbon lubricant is free of zinc dialkylthiophosphate and other zinc coordination compounds and preferably free of additives dispersed with surfactants and/or dispersants. Nonlimiting examples of additives with which the lubricant may be formulated include extreme pressure and antiwear additives antioxidants, friction-reducing agents, metal inactivating agents such as benzotriazoles, viscosity modifiers, pour point depressants, stabilizers, corrosion inhibitors, and flammability suppressants. Such additives may be present singly or in any combination of two or more. There are no particular restrictions on the inclusion of such additives in the used hydrocarbon lubricant. Generally, additives such as these may be present at less than or equal to about 10% by weight of the lubricant composition. Various embodiments of the used hydrocarbon lubricant may include about 0.1 to about 5% by weight of an additive or a combination of additives or about 0.2 to about 2% by weight of an additive or a combination of additives.

[0050] Nonlimiting examples of the antioxidants that can be used include phenolic antioxidants such as 2,6-di-t-butyl-4-methylphenol and 4,4-methylenebis(2,6-di-t-butylphenol), and bisphenol A; amine and thiazine antioxidants such as p,p-dioctylphenylamine, monooctyldiphenylamine, phenothiazine, 3,7-dioctylphenothiazine, N,N-di(2-naphthyl)-p-phenylenediamine, phenyl-1-naphthylamine, phenyl-2-naphthylamine, alkylphenyl-1-naphthylamines, and alkylphenyl-2-naphthylamines; and sulfur-containing antioxidants such as alkyl disulfide, thiodipropionic acid esters and benzothiazole. The lubricant composition may comprise up to about 5.0 weight % antioxidants, about 0.1 to about 5 weight %, about 0.1 to about 2.0 weight %, or about 0.2 to about 0.8 weight % antioxidants. The lubricant compositions may include one or a combination of two or more antioxidant compounds.

[0051] In certain embodiments, the used hydrocarbon lubricant may include one or more extreme pressure or anti-wear additives. Nonlimiting examples of suitable extreme pressure/antiwear additives include sulfur- and phosphorous-containing types such as phosphoric acid esters, acidic phosphoric acid esters, branched alkyl amine phosphates containing 5 to 20 carbon atoms, thiophosphoric acid esters, acidic phosphoric acid ester amine salts, and chlorinated phosphoric acid esters and phosphorous acid esters that are esters of phosphoric acid or phosphorous acid with alkanols or polyether alcohols. Specific, nonlimiting examples of phosphoric acid esters include tributyl phosphate, tripentyl phosphate, trihexyl phosphate, triheptyl phosphate, trioctyl phosphate, trinonyl phosphate, tridecyl phosphate, triundecyl phosphate, tridodecyl phosphate, tritridecyl phosphate, tritetradecyl phosphate, tripentadecyl phosphate, trihexadecyl phosphate, triheptadecyl phosphate, trioctadecyl phosphate, trioleyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyldiphenyl phosphate, and xylenyldiphenyl phosphate. Specific, nonlimiting examples of acidic phosphoric acid esters there may be mentioned monobutyl acid phosphate, monopentyl acid phosphate, monohexyl acid phosphate, monoheptyl acid phosphate, monooctyl acid phosphate, monononyl acid phosphate, monodecyl acid phosphate, monoundecyl acid phosphate, monododecyl acid phosphate, monotridecyl acid phosphate, monotetradecyl acid phosphate, monopentadecyl acid phosphate, monohexadecyl acid phosphate, monoheptadecyl acid phosphate, monooctadecyl acid phosphate, monooleyl acid phosphate, dibutyl acid phosphate, dipentyl acid phosphate, dihexyl acid phosphate, diheptyl acid phosphate, dioctyl acid phosphate, dinonyl acid phosphate, didecyl acid phosphate, diundecyl acid phosphate, didodecyl acid phosphate, ditridecyl acid phosphate, ditetradecyl acid phosphate, dipentadecyl acid phosphate, dihexadecyl acid phosphate, diheptadecyl acid phosphate, dioctadecyl acid phosphate and dioleyl acid phosphate. Specific, nonlimiting examples of thiophosphoric acid esters include tributyl phosphorothionate, tripentyl phosphorothionate, trihexyl phosphorothionate, triheptyl phosphorothionate, trioctyl phosphorothionate, trinonyl phosphorothionate, tridecyl phosphorothionate, triundecyl phosphorothionate, tridodecyl phosphorothionate, tritridecyl phosphorothionate, tritetradecyl phosphorothionate, tripentadecyl phosphorothionate, trihexadecyl phosphorothionate, triheptadecyl phosphorothionate, trioctadecyl phosphorothionate, trioleyl phosphorothionate, triphenyl phosphorothionate, tricresyl phosphorothionate, trixylenyl phosphorothionate, cresyldiphenyl phosphorothionate, and xylenyldiphenyl phosphorothionate. Specific, nonlimiting examples of amine salts of acidic phosphoric acid esters include salts of acidic phosphoric acid esters with amines such as methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, and trioctylamine. Specific, nonlimiting examples of chlorinated phosphoric acid esters include tris(dichloropropyl) phosphate, tris(chloroethyl) phosphate, tris(chlorophenyl) phosphate, and polyoxyalkylene bis[di(chloroalkyl)]phosphate. As phosphorous acid esters there may be mentioned dibutyl phosphite, dipentyl phosphite, dihexyl phosphite, diheptyl phosphite, dioctyl phosphite, dinonyl phosphite, didecyl phosphite, diundecyl phosphite, didodecyl phosphite, dioleyl phosphite, diphenyl phosphite, dicresyl phosphite, tributyl phosphite, tripentyl phosphite, trihexyl phosphite, triheptyl phosphite, trioctyl phosphite, trinonyl phosphite, tridecyl phosphite, triundecyl phosphite, tridodecyl phosphite, trioleyl phosphite, triphenyl phosphite, and tricresyl phosphite. The extreme pressure/antiwear additives may be present individually or in any combination, in any desired amount. In various embodiments, the used hydrocarbon lubricant may include about 0.01 weight % to about 5.0 weight %, about 0.01 weight % to about 4.0 weight %, about 0.02 weight % to about 3.0 weight %, or 0.1 weight % to about 5.0 weight % each of extreme pressure additives and antiwear additives.

[0052] In various embodiments, the used hydrocarbon lubricant may include one or more corrosion inhibitors, such as those selected from isomeric mixtures of N,N-bis(2-ethylhexyl)-4-methyl-1H-benzotriazole-1-methylamine and N,N-bis(2-ethylhexyl)-5-methyl-1H-benzotriazole-1-methylamine. The used hydrocarbon lubricant may include about 0.01 to about 1.0 weight % of one or more corrosion inhibitors, about 0.01 to about 0.5 weight % of one or more corrosion inhibitors, or about 0.05 to about 0.15 weight % of one or more corrosion inhibitors.

[0053] Viscosity modifiers (or viscosity index improvers) are polymeric materials, typical examples of these being polyolefins, such as ethylene-propylene copolymers, hydrogenated styrene-isoprene block copolymers, hydrogenated copolymers of styrene-butadiene, acrylic polymers produced by polymerization of acrylate and methacrylate esters, hydrogenated isoprene polymers, polyalkyl styrenes, hydrogenated alkenyl arene conjugated diene copolymers, polyolefins, esters of maleic anhydride-styrene copolymers, and polyisobutylene.

[0054] Nonlimiting examples of pour point depressants include polyalkyl methacrylates, polyalkyl acrylates, polyvinyl acetate, polyalkylstylenes, polybutene, condensates of chlorinated paraffin and naphthalene, and condensates of chlorinated paraffin and phenol.

[0055] Nonlimiting examples of flammability suppressants include trifluorochloromethane, trifluoroiodomethane, phosphate esters and other phosphorous compounds, and iodine- or bromine-containing hydrocarbons, hydroflorocarbons, or fluorocarbons.

[0056] A composition comprising the polyhydroxy polypropylene oxide homopolymer and at least one additive other than zinc dialkylthiophosphate and other zinc coordination compounds and dispersed (solid) additives may be added to the used hydrocarbon lubricant in the disclosed method. In various embodiments, the additive is selected from antioxidants, anti-wear agents, extreme-pressure agents, friction-reducing agents, metal inactivating agents such as benzotriazoles, viscosity modifiers, pour point depressants, stabilizers, corrosion inhibitors, flammability suppressants, and combinations of these. In particular embodiments, the composition used to treat the used hydrocarbon lubricant may comprise the polyhydroxy polypropylene oxide homopolymer and an antioxidant. The composition used to treat the used hydrocarbon lubricant may comprise up to about 1.5 weight percent of one or more antioxidant additives, up to 0.75 weight percent of one or more lubricity additives, up to 0.5 weight percent of one or more corrosion inhibitor additives, or any combination thereof.

[0057] The hydrocarbon lubricant may be formulated with dispersed (solid) additives and dispersed additives may have been added to the hydrocarbon lubricant during use but before treatment by the presently disclosed method. While not wishing to be bound by theory, it is believed that such dispersed additives become entrained in the varnish and sludge of used hydrocarbon lubricant. It is often necessary to add a larger amount of the polyhydroxy polypropylene oxide homopolymer than would be needed if dispersed additives had not been added to the hydrocarbon lubricant

[0058] It is observed that the polyhydroxy polypropylene oxide homopolymer may have a higher viscosity that the hydrocarbon lubricant while keeping the treated hydrocarbon lubricant within 10% of the kinematic viscosity at 40 C. of the ISO Viscosity Grade for the hydrocarbon lubricant, which is believed to be due to reincorporation of material from the sludge and varnish.

EXAMPLES

[0059] Amounts are given in parts by weight unless specifically indicated to be in a different unit.

[0060] The polyhydroxy polypropylene oxide homopolymer compositions were prepared using the materials shown in the following table. The ingredients were combined, then heated with mixing to homogenize. Each example composition was then evaluated for the properties shown in the following table.

Examples 4-7

[0061] A sample of a used hydrocarbon lubricant was obtained and divided into four portions to make Examples 4-7. Example 4 is a first portion of the used hydrocarbon lubricant that was not treated. Example 5 was prepared by adding to a second portion of the used hydrocarbon lubricant 10% by weight of Example 1. Example 6 was prepared by adding to a second portion of the used hydrocarbon lubricant 10% by weight of Example 2. Example 7 was prepared by adding to a second portion of the used hydrocarbon lubricant 10% by weight of Example 3. Properties of the Examples were measured and are provided in the table below.

TABLE-US-00001 Property Example 4 Example 5 Example 6 Example 7 Visual Clear Cloudy- Cloudy- Cloudy Appearance Orange Orange Orange Orange Viscosity (cSt) 63.50 69.41 68.95 75.08 Total Acid 0.20 0.15 0.24 0.15 Number (mg KOH/g) Water (ppm) 630 682 507 921 Tramp Oil % (T) No No No No Membrane Patch 48.5 4.7 13.2 24.0 Colorimetry (E) Atomic Oxygen 4.5 5.5 5.1 4.6 wt % Density at 15 C. 0.8764 0.8819 0.8798 0.8773 (g/cm.sup.3)

[0062] The testing shows that as the amount of hydroxyl content of the polyhydroxy polypropylene oxide homopolymer composition decreases, the Membrane Patch Colorimetry value (E) rises. Example 5 shows that the Example 1 polyhydroxy polypropylene oxide composition was the most effective for treating this used hydrocarbon lubricant. Reduction in the Membrane Patch Colorimetry value to 4.7 without a substantial change in viscosity indicates that the agglomerated varnish has been dissolved into the liquid phase of the lubricant Example 1 also has a viscosity that is closest to the used lubricant viscosity of the three polyhydroxy polypropylene oxide compositions tested.

Examples 8-10

[0063] A sample of a used hydrocarbon lubricant was obtained and divided into three portions to make Examples 8-10. Example 8 is a first portion of the used hydrocarbon lubricant that was not treated. Example 9 was prepared by adding to a second portion of the used hydrocarbon lubricant 5% by weight of Example 3. Example 10 was prepared by adding to a second portion of the used hydrocarbon lubricant 10% by weight of Example 3. Properties of the Examples were measured and are provided in the table below. The same properties are given for Example 3 itself. Also given in the table are the properties that would theoretically be expected by adding 5% by weight and 10% by weight of the Example 3 linear, dihydroxy-terminated polypropylene oxide composition if the Example 3 linear, dihydroxy-terminated polypropylene oxide composition were to have no effect on varnish contained in the used hydrocarbon oil.

TABLE-US-00002 Theoretical Theoretical result for result for Property Ex. 3 Ex. 8 Ex. 9 Ex. 9 Ex. 10 Ex. 10 Visual Clear- SltHazy- Clear-Colorless Clear-LtYellow Appearance Colorless Yellow Viscosity (cSt) 1502.69 44.70 45.93 117.60 54.29 190.50 Total Acid 0.14 0.21 0.20 0.21 0.17 0.20 Number (mg KOH/g) Water (ppm) 2471 277 1065 386.7 367 496.4 Tramp Oil % No No No No No No (T) Membrane 5.0 18.2 17.8 17.5 16.1 16.9 Patch Colorimetry (E) Atomic 33.4 0.6 1.3 2.3 2.2 3.9 Oxygen wt % Density at 15 C. 1.0057 0.8408 0.8440 0.8490 0.8488 0.8573 (g/cm.sup.3)

[0064] The testing of Examples 8-10 demonstrate that, due to the effect of the polyhydroxy polypropylene oxide composition on varnish in the used lubricant, the addition of the polyhydroxy polypropylene oxide composition has less effect on lubricant viscosity that is predicted theoretically. Addition of Example 3 would be expected to significantly increase the viscosity of the used lubricant because its viscosity is much higher than that of the used lubricant, but it does not. The reduction in Total Acid Number demonstrates that the Example 3 composition has dissolved varnish agglomerations and re-dissolved entrained antioxidants into the used lubricant.

Example 11

[0065] A composition of a polyalkylene oxides having at least one hydrocarbyl end group according to Kovanda et al., U.S. Pat. No. 8,685,905 was prepared by combining the ingredients listed in the table below properties of Example 11 were measured and are provided in the following

Examples 12-14

[0066] A sample of a used hydrocarbon lubricant was obtained and divided into three portions to make Examples 12-14. Example 12 is a first portion of the used hydrocarbon lubricant that was not treated. Example 13 was prepared by adding to a second portion of the used hydrocarbon lubricant 10% by weight of the Example 11. Example 14 was prepared by adding to a second portion of the used hydrocarbon lubricant 10% by weight of the Example 1 polypropylene oxide composition. Properties of the Examples were measured and are provided in the table below.

TABLE-US-00003 Property Example 12 Example 13 Example 14 Visual Hazy-Brown Hazy-Brown Clear-Brown Appearance Viscosity (cSt) 61.81 53.70 76.16 Total Acid 0.91 0.51 0.49 Number (mg KOH/g) Water (ppm) 96 204 442 Tramp Oil % (T) No No No Membrane Patch 41.84 48.59 19.50 Colorimetry (E) Atomic Oxygen 5.6 7.2 7.8 wt % Density at 15 C. 0.8824 0.8903 0.8936 (g/cm.sup.3)

[0067] Example 13 has a reduced viscosity that is below the viscosity range for an ISO VG 68 lubricants according to ISO 3448. Example 13 also remains hazy; the total acid number is decreased, but the Membrane Patch Colorimetry (E) measurement is not reduced, indicating that varnish agglomerations remain in the lubricant. In contrast, the total acid number of Example 14 has been reduced, the lubricant is clear, and the Membrane Patch Colorimetry (E) measurement has been sharply reduced to less than half of the value for the untreated lubricant.

[0068] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.