CA1058150A

CA1058150A - Molybdenum disulphide-containing petroleum lubricant composition and method of preparing same

Info

Publication number: CA1058150A
Application number: CA177,854A
Authority: CA
Inventors: Joseph J. Silverstein
Original assignee: ORE-LUBE Corp (THE)
Current assignee: ORE-LUBE Corp (THE)
Priority date: 1972-08-04
Filing date: 1973-08-01
Publication date: 1979-07-10
Also published as: GB1451922A; CA1101829B; DE2339423A1; FR2194769B1; NL7310794A; JPS4945909A; FR2194769A1; IT992813B

Abstract

ABSTRACT

A lubricating fluid comprising a refined petroleum base stock containing minor controlled amounts of each of a finely-divided, particulate molybdenum disulfide, a viscosity index improver, an anti-wear agent and a corrosion inhibitor.

Description

, ~150 BACKGROUND

What with ecologists beating the drums for purer atmospheric conditions and what with manufacturers of internal combustion engines locked in life or death struggles for superior engine horsepower, it is small wonder that lubricant producers and suppliers feel threatened by the jaws of a vise.
To their credit, however, they have expended untold energies to meet the challenge; to their dismay, on the other hand, many have met with limited success .
This is not too surprising when one considers the stringent specifications and the many requirements imposed on them. Typical of these requirements for today's lubricant are: reduced evaporative emissions; high temperature stability; reduced carbon emission; reduced blow-by; all seasons performance; reduced carbon, sludge and gum buildup; extreme pressure resistance; long life; stable viscosity; increased power output; increased gas mileage; better resistance to deterioration; good pumpability and fluidity at low temperatures; etc.; etc.
Of course, owners of buses, taxi fleets, racing cars, conventional automobiles, heavy duty equipment (including on and off the road vehicles), all are insisting upon the better lubricant. Environmental protection agencies, legislators and concerned citizens are not only casting a jaundiced eye at pollution sources, vehicular or otherwise, but they are doing something about it.

-2-~05t~50 It is therefore and object of the present invention to meet the challenge of today with a superior motor oil for, say, diesel and gasoline engines, for heavy duty and touring vehicles, et., under a wide variety of demanding conditions. Another object of the present invention is to provide an ecologically and economically desirable motor oil with significantly enhanced properties in sludge, carbon and gum buildup, much longer life, reduced engine wear and fuel consumption, excellent stability. These and many-other advantages and objects will be apparent from the description, infra, of the present invention.

INVENTION

The present invention relates to a superior, long life lubricating fluid comprising a petroleum base stock, e.g., a naphthenic base oil, containing controlled amounts of each of a finely-divided, particulate molybdenum disulfide and a viscosity index improver and minor amounts of an anti-wear agent and corrosion inhibitor. According to certain preferred embodiments, minor proportions of any or all of the following may be added: an antifoam agent, an extreme pressure ~E.P.) agent, a pour point depressant, a detergent, a dispersant, and other like additives for general or specific end 1058~5 uses intended for the oil. Certain individual additives provide several of the functions desired; for instance, an additive may act as both an E.P. and an anti-wear agent. Likewise, several different anti-wear or corrosion inhibitors may comprise the total concentration herein contemplated for each of these additives.
According to the instant discovery, the petroleum base stock is present in the concentration of at least about 62 percent, by volume, preferably at least about 76 percent; finely-divided molybdenum disulfide having a particulate size in the range of about 0.15 to about 0.9 micron, preferably from about 0.2 to about 0.55 micron, is present in the concentration range of about 0.25 to about 1.25 percent, by volume, preferably from about 0.45 to about 1.10; the viscosity index improver, e.g., linear polyisobutylene, polymethacrylate, or the like, in the concentration range of about n . 60 to about 1. 75 percent, by volume, preferably from about 0. 75 to about 1.40; the anti-wear agent is in the concentration of about 0.75 to about 3.00 percent, by volume, preferably from about 0.95 to about 2.50;
and the corrosion inhibitor in the concentration range of about 0.25 and about 2.00, preferably from about 0.50 to about 1.75.
The base oil contemplated herein is a lubricating oil fraction of petroleum, either naphthenic or paraffinic base, unrefined, acid refined or solvent refined. Typical and preferred are the naphthenlc base oils, e.g., alicyclic or cycloaliphatlc saturated hydrocarbon having, generally, five (5) ll 1o5~15U

or six (6) carb~n atoms in the ring. The C5 or C6 saturated cyclic hydrocarbon may be substituted with alkly moieties, e . g., a lower alkyl .
Naphthenic fractions from Gulf Coast or California naphthenic base crudes, for example, are very suitable, as well as blends of these fractions.
l~e SAE 10 through 40 oils are preferred. The more desirable viscositites at 210F. (99C.), kinematic, centlstokes, evaluated according to the American Society for Testing and Materials standard test method ASTM D-445, are, for example, minimum to maximum: from about 5.7 to less than about 7.5 for SAE 10; from about 7.5 to less than about 9.6 for SAE 20; from about 9.6 to less than about 12.9 for SAE 30 and from about 12.9 to less than about 16.8 for SAE 40.
Other properties of the SAE 10 to 40 oils contemplated herein are: a minimum viscosity index lASTM D-2270) of about 70 and a maximum viscosity index of about 150, preferably from about 85 to about 125; a flash point (ASTM D-92) in F from about 250 to about 550, preferably from about 400 to about 500; a pour point maximum in F ~STM D-97) from about -30 to about 20, preferably from about -20 to about 7; a (ASTM D-287) gravity, API, from about 24.5 to about 32.5, preferably from about 26.0 to about 30;
and, preferably, the oils should contain less than about one (1) percent sulfated ash (residue) as measured by ASTM D-874.
The concentration of viscosity index improver, such as an oil-soluble linear polyisobutylene having a relatlvely high molecular welght, is important to the lubricant of the present invention. If desired, a blend of ~058150 different viscosity index improvers may be used, including oil-soluble isobutylene polymers of different molecular weight. Preferably, however, the molecular weight of the linear polyisobutylene viscosity index (V.I.) improver is in the range of 120,000 to 250,000, preferably between about 190,000 and 230,000.
As suggested above, other V.I. improvers, such as poly-methacrylates, are herein contemplated. Typical polymethacrylates are those having general formula COOR
C - C
¦ H2 \ CH3 wherein R is an alkyl moiety having from about 4 to about 20 carbon atoms, the R moieties being the same of there being a mixture of R moieties in any given polymer, and n is a number to provide an average molecular weight of the polymer of about 100,000 to about 750,000, preferably from about 150,000 to about 400,000. Various polymethacrylates of this type are known which possess viscosity index improving properties. A
very satisfactory material of this type is a polymer of alkyl (C4 - C14) methacrylate monomers. A commercial polymethacrylate, of the formual just above, which is primarily a viscosity index improver~ is sold under the trademark "Acryloid 710"

(Rohm & Haas Co., Philadelphia, Penna.), wherein R comprises about 50 percent lauryl and 50 percent octyl moieties and the average molecular weight of the polymethacrylate is about 560,000. Another commercially available polymethacrylate of the formula just above is "Acryloid 615"
wherein the alkyl moieties are a mixture of alkyls derived fromOxo alcohols and the polymer likewise has an average molecular weight of about 560,000.
Still another suitable polymethacrylate of the formula just above is available under the trademark "Acryloid 150", in which the alkyl moieties are predominantly a mixture of 50% cetyl, 25% lauryl and 25% octyl, and the polymethacrS~late has an average molecular weight of about 650,000. Other suitable commercial "Acryloid" polymethacrylate viscosity index improvers are the following: "Acryloid 772", average molecular weight 700,000;
"Acryloid 953", average molecularweight 660,000; "Acryloid 954", average molecular weight 500,000; "Acryloid 955 ", average molecular weight 350,000;
and "Acryloid 956", average molecular weight 210,000.
A small particle size of the finely-divided molybdenum disulfide (MoS2) solids contemplated herein is very important in order to achieve the very desirable properties hereinabove described. Quite surprisingly, it has been found according to the present invention that the MoS2 particulates may be uniformly dispersed throughout the base oil without the heretofore cumbersome necessity of, for example, reacting an aqueous or alcohol molybdenum salt solution, such as an aqueous molybdenum halide solution, 1058~50 with hydrogen sulfide in the presence of a lubricating oil detergent additive, such as a petroleum sulfonate, thus preparing the molybdenum sulfide in situ. The water in the resulting blend is subsequently removed.
Another cumbersome process heretofore employed involved reacting H2S with an aqueous molybdenum salt solution and dispersing the resulting molyWenum sulfide precipitate in the H2O by the use of a lyophilic (protecting) colloid, e.g., gelatin. The resulting sol is, in turn, mixed with alcohol and a lubricating oil solution containing, say, a metal sulfonate, such as calcium sulfonate. The effect of this is that colloidal metal sulfide is extracted from said sol and redispersed in the lubricating oil. Residual water and alcohol are then removed from the mixture to isolate the colloidal dispersion of metal sulfide in lubricating oil.
Pursuant to the present invention, the aforedescribed onerous processes, intended to overcome the metal sulfide precipitation curse, have been supplanted. According to one embodiment of the instant discovery, the MoS2 particulates in finely-divided form, i.e., having a critical particle size in the range of about 0.15 to about 0.9 micron, preferably about 0.2 to about 0 . 55 micron, are first thoroughly blended with viscosity index improver and base oil, both of the type contemplated herein, and the resulting homogeneous dispersion admixed with the balance of the components.
Typlcally, from about 5 to about 15 percent by volume, preferably from about 6.5 to about 12 percent by volume of (a) MoS2 particulates, say, lOS8~50 about 0.33 micron average particle size, are mixed with ~om about 5 to about 15 percent, by volume, preferably from about 6.5 to about 12 percent, of (b) viscosity index improver, such as a polymethacrylate of the type herein-before described, and from about 70 to about 90 percent, preferably from about 75 to about 87.5 percent of (c) base oil, likewise of the type herein described.
The resulting dispersion is then intimately blended with the balance of the components to provide the product of the present invention containing the balance of the base oil, viscosity inde~s improver, MoS2, antiwear asent, corrosion inhibitor, and any other conventional additives, including antifoam agents, pour point depressants, extreme pressure (EP.) agents, detergents, and the like.
Another embodiment wlthin the purview of the present discovery involves preparing concentrates from the aforedescribed dispersion of MoS2 in viscosity index improver and base oil, which concentrates have the advantage of being blended into end use solutions at the place of use, thus avoidins~ high freight or shipping costs. Surprisingly enough, according to the present invention, neither the final solutions nor the concentrates suffer from the intolerable precipitation curse described in the prior art.
One oi the preferred concentrates comprises, by volume, from about 20 to about 42%, preferably from about 25 to about 38.5 percent, of the above dispersion with from about 4 to about 10% corrosion inhibitor, preferably from about 5 to about 8%, from about 4 to about 11.5% antiwear agent, preferably from about 6 to about 9 .5% .
_g_ iO5~31SO

and the balance base oil. Preferably up to about 2.5% antifoam agent is present.
¦ Alternatively, the concentrate may comprise, by volume, from about 65 to about 88% of the above dispersion, preferably from about 75 to about 85%, rom about 7 to about 13% corrosion inhibitor, preferably from about 8.5 to about 11.5%, from about 6.75 to about 11% anti-wear agent, preferably from about 7.75 to about 10.2%, and the balance base oil. Again, up to about 2 . 5% antifoam agent, generally about 1%, is desirable . Further, the dispersion and the remaining components are best heated to effect intimate blending and a homogeneous mixture.
While the latter two are preferred embodiments, concentrations intermediate the ranges given may be used providing broad ranges of about 20 to about 88% dispersion, about 4 to about 13% corrosion inhibitor and about 4 to about 11.5% anti-wear agent, the balance being base oil.
In addition to significantly enhancing the lubricant of the present invention in the manner suggested hereinbefore, the colloidal molybdenum disulfide protects against corrosion and wear.
Particularly desirable corrosion iIhibitors, pursuant to the present invention, are the so-called hindered phenols. These are compounds having one or more phenolic fings with at least one tertiary alkyl (lower) group, usually tertiary butyl, per ring located ortho to a phenolic hydroxyl moiety to sterically hinder its reactivity. Hindered phenols as a class are well known. 111ustrative examples thereof include 4,4'-thio-bis(6-tertiary butyl-m-cresol); 4,4'-thio-bis(6-tertiary butyl-o-cresol); '2-6-di(tertiary butyl)-p-cresol;
4, 4 ' -methylene bis (2, 6 -di -tertlary butyl phenol); 2, 6 -di -tertlary butyl -alpha -dimethylamino-p-cresol; 2, 6-di-tertiary butyl-alpha-methoxy-p-cresol;

lo58150 2, 6-di-tertiary butyl phenol; and mixed tertiary butyl-phenols such as those containing at least 75% of 2,6-di-tertiary butyl phenol; 4,4'-methylene bis (6-tertiary butyl-o-cresol); 2, 2 ' -methylene bis (4-methyl-6 -tertiary butyl-phenol); and 2,2'-methylene bis(4-ethyl-6-tertiary butyl-phenol); and the like.
Other contemplated oxidation and rust inhibitors within the purview of the present invention include the oil-soluble polyvalent metal salts derived from a wide variety of diester dithiophosphoric acids conventionally prepared by reacting a sulfide of phosphorus, such as phosphorous pentasulfide, with an alcohol, phenol or mercaptan. These salts have antl-wear properties as well and have the structure . Rl-O S S o_R3 . \,~

R2_o S - M - S o-R4 wherein Rl to R in the acid esters each represents substituted or unsubstituted aryl (e.g., phenyl), alkyl, aralkyl, cycloalkyl or other monovalent hydrocarbon moieties which contain from about 3 to 20 carbon atoms, preferably about 3 to 12 carbon atoms, R through R4 being the same or different. Of the poly-valent metals designated M in the above structure, zinc is preferred but other metals of 28 to 30 atomic number, such as nickel or copper, are suitable.
Alcohols which may be employed in preparing the acid esters include primary and secondary alcohols, such as 4-methyl-pentanol-2, 2-methylpentanol-1, 105~i150 2-ethylhexanol, di-isopropyl carbinol, cyclohexanol, butanol-l, isopropanol and octadecanol-l, or mixtures of high and low molecular weight alcohols.
The preferred compounds are the zinc dialkyl dithiophosphates wherein the alkyl group contains about 3 to 12 carbon atoms, preferably about 3 to 8 carbon atoms. More specifically, the preferred dialkyl dithiophosphates include, for instance, dihexyl dithiophosphate, diheptyl dithiophosphate, di-2-methylamyl dithiophosphate, di-2-ethylhexyl dithiophosphate, and the like .
Still other anti-oxidants and anti-corrosion additives suitable for use herein are the oil-soluble alkaline earth metal thiophenates having the structural formula:

;~,~~~ S - M - S ~L R (r~) wherein M Is an alkaline earth metal, R and R6 each represent a monovalent hydrocarbon moiety containing from about 3 to 20, preferably about 3 to 12 carbon atoms, and n is an integer of 0 to 3, R and R6 being the same or different. Of the alkaline earth metals, calcium is preferred, but other divalent metals belonging to Group II of the Periodic Table, such as beryllium, barium, strontium and magnesium may be used. As in the case of the metal dialky dithiophosphates discus sed above, the monovalent hydrocarbon moleUe~ R R6 may be aryl (e.g., phenyl), alkyl, aralkyl, cyclralkyl, ~05~150 and the like, and may be further substituted in the organic portlon. Preferably, R5 and R6 each represent an alkyl group of 3 to 12 carbon atoms, such as n-propyl, isopropyl, butyl, amyl, hexyl, cyclohexyl, octyl, nonyl, decyl, undecyl, dodecyl, and the like. Some examples of the preferred aikaline earth metal thiophenates useful as antioxidants in the compositions of the present invention are the calcium salts of amyl thiophenate, cyclohexyl thiophenate, 2,4-dioctyl thiophenate, 2,4-ethylhexyl thiophenate, and the like.
Of course, the person skilled in the art will appreciate the fact that other corrosion inhibitors may be used alone or conjolntly with the above, including p, p' -dioctyldiphenylamine, phenyl-beta-naphthylamine, and the like.
Particularly desirable anti-wear agents within the purview of the lnstant discovery are the antimony dialkyl dithlocarbamates wherein the alkyl moiety has from two (2) to fourteen (14) carbons, e.g., ethyl, n-butyl, amyl, hexyl, octyl, decyl, dodecyl, and the like. Generally, as indicated herein-before, from about 1.10 to about 3.0 percent by volume, based upon the total volume of the lubricant composition, is used. While the aforementioned antimony dialkyl dithiocarbamates are preferred as anti-wear agents, other well-known anti-wear agents soluble in petroleum hydrocarbons may be used in lieu thereof or in combination therewith, including the metal salts of diorgano-dithiophosphates likewlse herelnbefore discussed, particularly the antimony O,O-dialkyl phosphorodlthioates, such alkyl moleties being, say, n-propyl, lsopropyl, isobutyl, amyl, hexyl and 2-ethylhexyl, and other like antiwear agents .
If desired, as suggested hereinbefore, conventional antifoam agents, .P. agents, pour point depressants, detergents, dispersants, and antioxidants may be incorporated herein in conventional concentrations. Typical of the antifoam agents are the well-known, commercially available liquid silicone polymers, such as dimethyl silicone polymer, diethyl silicone polymer, methyl ethyl silicone polymer, diphenyl silicone polymer, phenyl ethyl silicone polymer, methyl phenyl silicone polymer, and other dihydrocarbon silicone polymers, such as disclosed in U.S. Patent No. 2,373,007.
If desired, minor amounts of basic aromatic sulfonates may be added, generally less than about one (1) percent, by volume, usually less than 0.25 percent, based upon the total volume of the lubricant composition. The sulfo-nates are effective, among other things, in neutralizing sulfur and nitrogen compounds present during lubrication.
The basic sulfonates can be prepared by neutralizing aromatic sulfonic acids with a theoretical excess of the hydroxides, chlorides, oxides or other inorganic compounds of the alkaline earth metals so as to obtain a product whlch contains an amount of alkaline earth metal in excess of that theoretically required to replace the acidic hydrogens of the sulfonic acids.
The preferred alkaline earth metal is barium. Generally preferred aromatic sulfonic acids are the oil-soluble mahogany sulfonlc acids which can be derived from the treatment of a suitablè petroleum oil, such as a liquid .. _ ., ., . . .

1058~50 petroleum distillate boiling in the range of about 600 to 1000 F., with fuming sulfuric acid or sulfur trioxide, separating the resulting acid sludge from the acid treated oil and recovering the mahogany acids contained in the acid treated oil. The useful mahogany acids generally have a molecular weight of from about 300 to 500 or more, and although their exact chemical structures may vary, it appears that such acids are composed to a large extent of sulfonated aro~atic hydrocarbons having either one or two aromatic rings per molecule, possibly with one or more long chain alkyl groups containing from about 8 to 30 carbons atoms attached to the ring nuclei.
From about 5 to about 25%, preferably about 9 to about 16%, based upon the total volume of final ready-to-use oil compositions of the present invention may comprise a synthetic diester lubricant base, to provide a wider thermal operating range. Typical organic diesters are the dialkyl (lower) and glycol d~pelargonates and azelates, i.e., the C9 nonanoic and nonanedioic acid esters .
Of course, other conventional additives of the type herein describe may be present in likewise conventional concentrations. Typical are the pour point depressants, such as hydrocarbon wax-naphthalene condensates of the Friedel-Crafts type having, typically, the following properties:
Yiscosity at 210F, SSU 308 Flash point, F 450 Pour polnt, F ~55 Conradson carbon, wt per cent 1.9 Density, lb/gal at 60F 7,5 A suitable detergent/dispersant, for instance, is Santolube 801 (Trade Mark of Monsanto Company) which has the following properties:
Specific gravity 60/600F. 1.03 Viscosity 2100F., SUS ca. 180 Pour point, oF (max.)30 Barium, % wt., min 11.8 Phosphorus, ~ wt., min. 1.3 Sulfur, ~ wt., min 0.7 A

105~1S0 EXA~IPLES
The examples which follow are illustrative only and not intended to unfuly limit the scope of the present invention.
Example I
A mixture of base oil, molybdenum disulfide solids and polymethacrylate viscosity index improver is prepared by preliminarily blending a high shear mixer the following components until a homogeneous dispersion results:
Component Percent by Volume Naphthenic oil base (SAE 30) 80 Viscosity, kinematic, centistokes at 210 F (ASTM D-445) = 12.6 Viscosity index (ASTM D-2270) =104.0 ~lash point, F (ASTM D-92) =460.0 Pour point, F (ASTM D-97) = -5.0 Gravity, API (ASTM D-2~7) = 27.1 Sulfated ash (by weight) = 1%
MoS2 - finely divided - 0.33 micron 10 particle size Acryloid 710 (trade mark) polymethacrylate viscosity index improver 10 (Rohm & Haas Co.); polymethacrylate wherein R comprises about 50 percent l~uryl and 50% octyl moities; average molecular weight about ~60,000 /

~05~50 To this homogeneous disperson ~which can be called component (A)]
is then added, while agitating (stirring), more of the same naphthenic oil base (SAE 30), as well as the following components in sufficient concentrations to form a concentrate blend having the following makeup:
Com~onent Percent bv Volume Component (A) 35.00 . Antimony dihexyl dithiocarbamate . 8.00 Viscosity, SSU at 210 F. 65 Flash polnt, COC, F. 350 Specific gravity 1.04 - Antimony, weight per cent 6 . 8 Sulfur, weight per cent 10 . 9 2, 6 -Di(tertiary butyl) -p-cresol 7 .00 Vlscosi~ at 100F., SSU 59 Flash point, F. 285 Pour point, F. -30 Specific gravity, 60/60F. 0.876 Density, lb./gal. at 60F. 7.3 Zinc, weight per cent 0.22 Ash, we~ght per cent 0.33 Conradson carbon, wt per cent 0.40 10~15o Liquid dimethyl silicone 1.0 Silicone content wt. per cent 100.0 Specific gravity 2 5/2 5 C . 1 .0 Viscoslty, centipoise at 25C. 500 (max.) Flash point, F. open cup600 (min.) Naphthenic oil base~ ~49.0 (same oil as in homogeneous dispersion above) Exam~le II
Example I is repeated in every essential respect with the exception that component ~A) and the remaining components are blended in the following higher concentrations:
Coml)onent Percent bY Volume Component (A) 80.00 Antimony dihexyl dithiocarbamate .......... 9. 00 2,6-Di(tertiary butyl)-p-cresol .. .. 10. 00 Llquid dimethyl silicone . . . . 1. 00 Blending is enhanced by applylng heat to the mixture while mixing.

ExamDle III
The product concentrate of Example I, which contains 77% of the naphthenic oil base, by volume, is diluted before use as a motor oil, for instance,with additional of the same naphthenic oil base to provide the following final concentrations:

~)5t3~50 Component Percent by Volume Antimony dihexyl dithiocarbamate............ 2.00 Acryloid 710 (Trade Mark)................... 0.875 MoS2 ....................................... 0.875 2,6 Di (tertiary butyl)-p-cresol............ 1.75 Liquid dimethyl silicone.................... 0.25 Naphthenic oil base......................... 94.27 Example IV
The product concentrate of Example II, which contains 64~ of the naphthenic oil base, by volume, is diluted before use as a motor oil, for instance, with additional of the same anphthenic oil base to provide the following final concentrations:
Component Percent by Volume Antimony dihexyl dithiocarbamate.... 1.125 Acryloid 710 (Trade Mark) polymethacrylate. 1.00 MS2 1.00 2,6 Di (tertiary butyl)-p-cresol............ 1.25 Liquid dimethyl silicone.................... 0.125 Naphthenic oil base......................... 95.50 Example V
Example III is repeated in every essential with the exception that the polymethacrylate viscosity index improver has an ave. molecular weight of 210,000 (Acryloid 956-a Trade Mark at Rohm & Haas Co., Philadelphia, Pennsylvania).

"~

~058150 Example VI
Example IV repeated in every essential respect with exception that the polymethacrylate viscosity index improver has an average molecular weight of 210,000 (Acryloid 956, a Trade Mark of Rohm ~ Haas Co.) Example VII
Example III is repeated in every essential respect with the exception that the viscosity index improver is a linear isobutylene polymer having the following properties:
Molecular weight about 200,000 Viscosity at 2100F., cs 645 Specific gravity, 60~60OF. 0.875 Density, lb./gal. at 60OF. 7.30 Example VIII
Example IV is repeated in every essential respect with the exception that the viscosity index improver of Example VII is substitutea for the polymethacrylate.
Example IX
Example III is repeated in every essential respect with the exception that antimony dibutyl dithiocarbamate is used in lieu of antimony dihexyl dithiocarbamate.

Example X
Example IV is repeated in every essential respect with the exception that the zinc di-2-methylamyl dithiophosphate is used in lieu of 2,6-di(tertiary butyl)-p-cresol.

,.,j Example XI ~0581S0 Example V is repeated in every essential respect with the exception that the calcium salt of cyclohexyl thiophenate is present in the concent5ation of 0.95%, by volume, as an oxidation and rust inhibitor and all concentrations modified accordingly.
Example XII
Example VI is repeated in every essential respect with the exception that the naphthenic oil base is present in the concentration of 91.00 percent by volume, and 0.30 percent by volume of a polymeric pour point depressant is added, all other concentrations being increased proportionately, pour point depressant being Santopour C (trade mark o~ Monsanto Company) which has the following properties:
Gravity, API 24 Specific Gravity, 60/60F. 0.91 Flash Point (COC) 300F.
Viscosity 210F., SUS 811 Neutralization Number 7 Example XIII
Example V is repeated in every essential respect with the execution that naphthenic oil base (SAE 20) is used having the following properties:
Viscosity, kinematic, centistokes, at 210F (ASTM D-445) = 9 30 Viscosity index (ASTM D-2270) = 109.00 Flash point, F (ASTM D-92) = 445O00 Pour point, F (ASTM D-97) = -5.0 Gravity, API (ASTM D-287) = 28.3 Sulfated ash (by weight) = ~1 1o58l5o Example XIV
Example V is repeated in every essential respect with the exception that the concentration of napthenic oil base in the final oil composition is 76.27%, by volume, and the difference of 18% is substituted by the diester lubricant base di-2-ethyl-hexyl azelate (pour point - 100F., Emery Indus~ies, Cincinnati, Ohio) to widen thermal operating range.
~ ' ' .
ExamDle XV
- Example VI is repeated in every essential respect with the exception that the following naphthenic oil base is substituted for the SAE 30:
Naphthenic oil base (SAE 10) Viscosity, ki nematic, centistokes, at 210 F (ASTM D-445) =6.8 Viscosity index (ASTM D-2270) = 116.0 Flash point, F (ASTM D-92) =435.0 Pour point, F (A$TM D-97) =- 20.0 Gravity, oAPr (ASTM D-287) =29.6 Sulfated ash (by weight) = ~1%
. , , .

.ample XVI
Examp~e V is repeated in evely essential respect with the exception that the following naphthenic oll base ls substituted for the SAE 30:
Vlscoslty, kinematic, centistokes, at 210 F (ASTM D-445) =14.4 Vlscosity index (ASTM D-2 2 70) = 103 . 0 Flash point, F (ASTM D-92) = 490.0 Pour point, F (ASTM D-97) =5.0 Gravity, oAPr (ASTM D-287) = 26.7 Sulfated ash (by weight) =<1%

Examl)le XVII
Example I is repeated in every essential respect with the exception that 6 . 7% MoS2 and 11 .0% viscosity index improver are employed, the balance (to 100%) being the naphthenic oil base (SAW 30).

Exam~le XVIII
Example VI is repeated in every essential respect with the exception that the hindered phenol is 2, 6-ditertiary butyl phenol .
The lubricants illuskated in the above examples exhibit much long life, reduced engine wear and fuel consumption, excellent stability, low evaporative emission, low sludge, carbon and gum buildup, and many other very desirable properties of the type herebefore discussed.
Pursuant to statutory requirements, there are described above the invention and what are now considered its best embodiments. It should be ulderstood, however, that the invenUon can be practiced otherwise than as specifically described within the scope of the appended claims.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A lubricant composition which comprises at least about 62 percent, by volume, of a petroleum-based oil as a base oil; about 0.25 to about 1.25 percent, by volume, of molybdenum disulfide particulates having a particle size in the range of about 0.15 to about 0.9 micron; about 0.60 to about 1.75 percent, by volume, of an oil-soluble, viscosity index improver selected from one or more linear polyiso-butylenes and a polymethacrylate of the general formula n in which R is an alkyl group of from 4 to 20 carbon atoms and n is a number to provide a molecular weight in the range 100,000 to 750,000; about 0.75 to about 3.00 percent by volume, of an anti-wear agent; and about 0.25 to about 2.00 percent, by volume, corrosion inhibitor, all of the above percentages being based upon the total volume of the lubricant composition.

2. A lubricant composition as claimed in claim 1 in which the petroleum based oil is a lubricating oil fraction of petroleum having a naphthenic or paraffinic base, unrefined, acid refined or solvent refined.

3. The lubricant composition of claim 1 wherein the concentrations are, by volume, at least about 76 percent base oil; about 0.45 to about 1.10 percent, by volume, of the molybdenum disulfide; about 0.75 to about 1.40 percent, by volume, of oil-soluble viscosity index improver; about 0.95 to about 2.50 percent, by volume, anti-wear agent; and about 0.50 to about 1.75 percent, by volume, corrosion inhibitor.

4. The lubricant composition of claim l wherein the base oil is selected from SAE 10 through SAE 40.

5. The lubricant composition of claim 4 wherein the viscosity index improver is a polymethacrylate having a molecular weight in the range of about 150,000 to about 400,000.

6. The lubricant composition of claim 5 wherein the corrosion inhibitor is 2,6-di(tertiary butyl)-p-cresol.

7. The lubricant composition of claim 5 which contains a small but effective amount of silicone polymer foam inhibitor.

8. The lubricant composition of claim 7 wherein the anti-wear agent is antimony dihexyl dithiocarbamate.

9. The lubricant composition of claim 4 wherein the base oil has a viscosity at 210°F. (99°C.), kinematic, centistokes (ASTM D-445) in the range of about 5.7 to less than about 16.8; a viscosity index (ASTM D-2270) from about 70 to about 150; a flash point (ASTM D-92) in °F.from about 250 to about 550; a pour point in °F. (ASTM D-97 from about -30 to about 20; and a (ASTM D-287) gravity, °API, from about 24.5 to about 32.5.

10. A concentrate suitable for preparing a lubricant composition by the addition of base oil, the concentrate comprising, by volume, from about 20 to about 88 percent dispersion, from about 4 to about 13 percent corro-sion inhibitor and from about 4 to about 11.5 percent anti-wear agent, said dispersion comprising, by volume, from about 5 to about 15 percent MoS2 particulates having a particle size in the range of about 0.15 to about 0.9 micron, from about 5 to about 15 percent viscosity index improver selected from one or more linear polyisobutylenes and a polymethacrylate of the general formula n in which R is an alkyl group of from 4 to 20 carbon atoms and n is a number to provide a molecular weight in the range 100,000 to 750,000 and from about 70 to about 90 percent petroleum-based oil as a base oil.

11. A concentrate as claimed in claim 10 in which the petroleum-based oil is a lubricating oil fraction of petroleum having a naphthenic of paraffinic base, unrefined, acid refined or solvent refined.

12. The concentrate of claim 10 wherein the base oil has a viscosity at 210°F. (99°C.), kinematic, centistokes (ASTM D-455) in the range of about 5.7 to less than about 16.8; a viscosity index (ASTM D-2270)from about 70 to about 150: a flash point (ASTM D-92) in °F. from about 250 to about 550; a pour point in °F. (ASTM D-97) from about -30 to about 20; and a (ASTM D-287) gravity, °API, from about 24.5 to about 32.5.

13. The concentrate of claim 12 wherein the viscosity index improver is a polymethacrylate having an average molecular weight in the range of about 150,000 to about 400,000.

14. The concentrate of claim 13 wherein the corrosion inhibitor is a hindered phenol.

15. The concentrate of claim 14 containing, in addition, up to 2.5 percent, by volume, silicone antifoam agent.

16. A composition suitable for making a lubricant which comprises, by volume, a dispersion of from about 5 to about 15 percent MoS2 particulates having a particle size in the range of about 0.15 to about 0.9 micron, from about 5 to about 15 percent oil-soluble viscosity index improver selected from one or more linear polyisobutylenes and a polymethacrylate of the general formula in which R is an alkyl group of from 4 to 20 carbon atoms and n is a number to provide a molecular weight in the range 100,000 tO 750,000, and from about 70 to about 90 percent petroleum-based oil as a base oil.

17. A composition as claimed in claim 16 in which the petroleum based oil is a lubricating oil fraction of petroleum having a naphthenic or paraffinic base, unrefined, acid refined or solvent refined.

18. The composition of claim 16 wherein the base oil has a viscosity at 210°F. (99°C.), kinematic, centi-stokes (ASTM D-445) in the range of about 5.7 to less than about 16.8; a viscosity index (ASTM D-2270) from about 70 to about 150; a flash point (ASTM D-92) in °F.

from about 250 to about 550; a pour point in °F. (ASTM D-97) from about -30 to about 20; and a (ASTM D-287) gravity, °API, from about 24.5 to about 32.5.

19. A method of making an improved lubricant composition which comprises subjecting to high shear mixing the components of claim 14 and intimately blending therewith from about 20 to about 88% of the resulting dispersion with about 4 to about 13 percent corrosion inhibitor, from about 4.0 to about 11.5% anti-wear agent, and the balance (to 100%) base oil.

20. The method of claim 19 wherein the concen-trates having high disperson volume percentages are heated while mixing in order to enhance blending.