WO1994010269A1

WO1994010269A1 - Novel antiwear-antioxidant additives for lubricating oils

Info

Publication number: WO1994010269A1
Application number: PCT/EP1993/003042
Authority: WO
Inventors: Jack Ryer; Abhimanyu Onkar Patil
Original assignee: Exxon Chemical Ltd; Exxon Chemical Patents Inc
Current assignee: ExxonMobil Chemical Ltd; ExxonMobil Chemical Patents Inc
Priority date: 1992-11-02
Filing date: 1993-10-30
Publication date: 1994-05-11
Anticipated expiration: 1995-05-02
Also published as: AU5339194A

Abstract

The present invention provides for an improved lubricating oil composition for automatic transmissions and internal combustion engines, as well as novel oil soluble or oil dispersible compounds which are useful as antiwear/antioxidant additives when incorporated in such oils. The additives of this invention comprise substituted quinones which are the reaction product of a benzoquinone and a thio compound having the formula RSH or (R?1-0) (R2¿-0) PSSH wherein R, R?1 and R2¿ are hydrocarbyl radicals. These additives have been found to impart good antiwear and antioxidant properties to such oils and fluids, particularly when used in combination with other conventional oil additive components.

Description

NOVEL ANTI EAR-ANTIOXIDANT ADDITIVES FOR LUBRICATING OILS

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to hydrocarbon soluble or dispersible adducts of benzoquinone and a thioalcohol or a phosphorodithioic acid, their method of preparation, and their utility as antiwear/antioxidant additives for oleaginous compositions such as fuel oils, lubricating oils, including power transmitting fluids and engine lubricating oils, and to the oleaginous compositions in which they are contained.

2. Description of Related Art

There are many instances, as is well known, particularly under boundary lubrication conditions where two moving surfaces in contact with each other must be lubricated or otherwise protected to prevent wear and to insure continued movement. There are other instances where friction between two rubbing surfaces is sought to be modified but not necessarily minimized. By controlling friction between two surfaces, the power required to impart movement from one surface to another is also controlled. For example, a specialized property sought to be imparted to certain lube oil compositions adapted for use as an automatic transmission fluid is the friction modification characteristic of the fluid. This property distinguishes automatic transmission fluids (ATF) from other lubricants, and in fact between types of ATF as well. Such characteristic quality has received the most attention by both the transmission manufacturers and fluid producers for many years. This attention stems from the fact that the friction requirements of an ATF are unique and depend on the transmission and clutch design, as well as on the type of clutch plate material used.

Another property sought to be imparted to lubricating oil compositions including automatic transmission fluids is reduced wear such as bearing and power component wear. As is well known, both wear and friction modification can be controlled through the addition of suitable additives with varying degrees of success.

While there are many known additives which may be classified as antiwear, or friction modifying agents, it is also known that many of these additives act in a different physical or chemical manner and often compete with one another, e.g. they may compete for the surface of the moving metal parts which are subjected to lubrication. Accordingly, extreme care must be exercised in the selection of these additives to insure compatibility and effectiveness. The metal dihydrocarbyl dithiophosphates are one of the additives which are known to exhibit anti- oxidant and anti-wear properties. The most commonly used are materials such as disclosed in U.S. Patent 4,938,880 and represented by the following formula:

wherein R and R' may be the same or different hydrocarbyl radicals containing from 1 to 18, preferably 2 to 12 carbon atoms and including radicals such as alkyl, alkenyl, aryl, aralkyl, alkaryl and cycloaliphatic radicals. Particularly preferred as R and R' groups are alkyl groups of 2 to 8 carbon atoms. Thus, the radicals, may, for example, be ethyl, n-propyl, i-propyl, n-butyl, i- butyl, sec-butyl, a yl, n-hexyl, i-hexyl, n-octyl, decyl, dodecyl, octadecyl, 2-ethylhexyl, phenyl, butylphenyl, cyclohexyl, methylcyclopentyl, propenyl, butenyl etc. In order to obtain oil solubility, the total number of carbon atoms (i.e. R and R' in the above formula) in the dithiophosphoric acid will generally be about 5 or greater. While such zinc compounds afford excellent oxidation resistance and exhibit superior anti-wear properties, it has heretofore been believed that they significantly limit the ability to control the friction modification properties of the lubricant compositions in which they are contained.

Both anti-wear and friction modifying agents function by forming a coating on the surface of the moving metal parts. The coating bonds are generally effected physically and/or chemically. Consequently, if the bonding between the anti-wear agent and the metal part is stronger than the bonding between the friction modifying agent and the metal part, the anti-wear agent will displace the friction modifying agent at the metal surface, i.e. at the metal/fluid lubrication boundary interface. This results in a loss in the ability of the friction modifying agent to exert its intended effect.

Unfortunately, while ZDDP is recognized as an industry wide standard for imparting anti-wear properties to lubricating compositions, it has been found that it also exhibits a greater affinity for the metal surface than available friction modifying agents.

A number of chemically different additives have been proposed for inclusion in lube oils as antioxidants. For example, U.S. patents 2,969,378 and 3,071,548 disclose dithiophosphate esters of stilbene quinone for such purposes. These materials are prepared by reacting stilbene quinone and a dialkyl dithiophosphoric acid. The alkyl groups may contain 3 to 20 carbon atoms and the addition of the thiophosphoric acid occurs at the stilbene double bond and not in the ring.

Reaction products of quinone and hydroquinone as well as ring substituted versions thereof, and thiophosphoric acid ester compounds having the structure (RO)₂P(S)SH wherein R is C_, to C₄ alkyl are also known in the art, as disclosed in UK Patent Specification 952,294. These compounds preferably contain alkyl or halo substituent groups on the quinone ring. The preferred method of synthesis employs a halogen substituted p-quinone as a starting material wherein ring halogens are displaced in forming the ester. Monoalkylthiophosphonate esters of hydroquinone prepared by reacting the thioester with p- benzoquinone in alcoholic medium are also disclosed. The utility of such materials as pesticides or pharmaceutical intermediates is disclosed.

SUMMARY OF THE INVENTION

The present invention provides for an improved lubricating oil composition for automatic transmissions and internal combustion engines, as well as novel oil soluble or oil dispersible compounds which are useful as antiwear/antioxidant additives when incorporated in such oils. The additives of this invention comprise substituted quinones which are the reaction product of a benzoquinone and a thio compound having the formula RSH or (R¹-0) (R²-0) PSSH wherein R,R¹ and R² are hydrocarbyl radicals as defined below. These additives have been found to impart good antiwear and antioxidant properties to such oils and fluids, particularly when used in combination with other conventional oil additive components.

DETAILED DESCRIPTION OF THE INVENTION

The substituted quinones useful as antiwear antioxidant additives may have the general formula 1:

wherein R is a straight or branched chain organic radical containing from 5 to about 28 carbon atoms, inclusive of alkyl, alkenyl, alkoxy, aryloxy, oxygen or sulfur-containing heteroalkyl, cycloalkyl, aryl, alkaryl and aralkyl, as well as such radicals which contain substituent groups such as hydroxy, halogen or nitro, and n is 1 or 2. Most preferably R is an alkyl group and contains from about 5 to about 13 carbon atoms and n is 2. In the more preferred embodiment, the substituted quinones have the formula 2:

wherein R¹ and R² are each independently selected from straight or branched chain alkyl, alkenyl, alkoxy, aryloxy, oxygen or nitrogen-containing heteroalkyl, cycloalkyl, aryl, alkaryl and aralkyl radicals containing from 5 to about 28 carbon atoms, as well as such radicals containing halogen, nitro or hydroxy substituent groups, and n is 1 or 2. Most preferably R¹ and R² contain from about 5 to about 13 carbon atoms, and n is 2.

By the term oxygen or sulfur-containing heteroalkyl as used above is meant groups containing one or more recurring groups of the structure R—X-R⁶)_m wherein X is oxygen or sulfur, R is as defined above, R⁶ is an alkylene group containing from 2 to 5 carbon atoms, preferably 2 or 3 carbon atoms, and m is 1 to 5.

Adducts having the structure of formula 1 or 2 may be prepared by heating a mixture of the appropriate RSH thioalcohol compound or (R¹-0) (R²-0) PSSH phosphorodithioic acid compound with benzoquinone in the presence of a suitable reaction solvent such as a lower alcohol (methanol or ethanol) , acetone, methyl ethyl ketone, benzene and the like. The reaction usually proceeds at room temperature up to about 50°C.

The use of an approximate stoichiometric amount of the thioalcohol or thioacid reactant will give rise to compounds of formulas 1 and 2 above wherein n averages close to 1 and wherein the substituent groups are located at the 2-position on the quinone ring; the use of a larger excess of such reactants will give rise to compounds of formulas 1 and 2 above wherein n averages close to 2 and two substituent groups are located at the 2,5-positions on the quinone ring. In effect, the reaction product may comprise a mixture of mono and di- substituted quinones (along with some unreacted quinone) , with the bulk of the reaction product being either the mono or disubstituted product as a function of the quantity of thioalcohol or thioacid used in the reaction.

The phosphorodithioic acids used to prepare compounds of formula 2 are prepared by the reaction of phosphorus pentasulfide with an alcohol or phenol or mixtures of alcohols, mixtures of phenols or mixtures of alcohols and phenols. The reaction involves four moles of the alcohol or phenol per mole of phosphorus pentasulfide, and may be carried out within the temperature range from about 50°C to about 200°C, preferably from about 50°C to about 150°C. Thus the preparation of 0,0-di-n-hexyl phosphorodithioic acid involves the reaction of phosphorus pentasulfide with four moles of n-hexyl alcohol at about 100°C for about two hours. Hydrogen sulfide is liberated and the residue is the defined acid.

Suitable alcohols which may be reacted with phosphorous pentasulfide are R^H, R²OH or mixed R¹OH/R²OH alcohols wherein the R¹ and R² groups are selected from phenyl and alkyl substituted phenyl, amyl, n-hexyl, methylisobutyl, carbinyl, heptyl, 2- ethylhexyl, diisobutyl, octyl, isooctyl, nonyl, behenyl, decyl, dodecyl, tridecyl, etc. Illustrative lower alkylphenyl groups include xylyl, cresyl, butylphenyl, amylphenyl, heptyl- phenyl, etc. Cycloalkyl groups likewise are useful and these include chiefly cyclohexyl and the lower alkyl-cyclohexyl radicals. Many substituted hydrocarbon groups may also be used, e.g., chloropentyl, dichlorophenyl, and dichlorodecyl.

Generally speaking, the R, R¹ and R² groups should be of sufficient chain length such that the quinone adduct is soluble or readily dispersible in the lubricating oil formulation into which it is incorporated.

The base lubricating oil into which the additive of this invention may be incorporated includes automotive crankcase and transmission oils of lubricating viscosity for both diesel and gasoline engines, including natural and synthetic lubricating oils and mixtures thereof, as well as gear oils and industrial oils.

Natural oils include animal oils and vegetable oils such as castor oil or lard oil, liquid petroleum oils and hydrorefined oils, solvent-treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic and mixed paraffinic- naphthenic types. Oils of lubricating viscosity derived from coal or shale are also useful base oils.

Synthetic lubricating oils include hydrocarbon and halo-substituted hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes, propylene- isobutylene copolymers, chlorinated polybutylenes, poly(l-hexenes) , poly(l-octenes) , poly(l-decenes) ; alkylbenezenes (e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di(2- ethylhexyl) benzenes); and polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenols) .

Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification or etherification constitute another class of known synthetic lubricating oils. These are exemplified by polyoxylalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide, and include the alkyl and aryl ethers of these polyoxyalkylene polymers such as methyl- polyisopropylene glycol ether having an average molecular weight of 1000, diphenyl ether of poly¬ ethylene glycol having a molecular weight of 500- 1000, diethyl ether of polypropylene glycol having a molecular weight of 1000-1500, and ono-and polycarboxylic esters thereof such as acetic acid esters, mixed C^ to C₆ fatty acid esters and the C₁₃ Oxo acid diester of tetraethylene glycol.

Another suitable class of synthetic lubricating oils comprises one or more esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebasic acid, fu aric acid, adipic acid, linoleic acid dimer, malonic acid, alkylmalonic acids and alkenyl malonic acids) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2- ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether and propylene glycol) . Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, dodecyl phthalate, dieicosyl sebacate, the 3-ethylhexyl diester of linoleic acid dimer, and the complex ester formed by reacting one mole of sebasic acid with two moles of tetraethylene glycol and two moles of 2- ethylhexanoic acid.

Esters useful as synthetic oils also include those made from C₅ to C₁₂ monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipenta- erythritol and tripentaerythritol.

Silicon-based oils such as the polyalkyl, polyaryl- polyalkoxy, or polyaryloxysiloxane oils and silicate oils comprise another useful class of synthetic lubricants. These include tetraethyl silicate, tetraisopropyl silicate, tetra-(2- ethylhexyl) silicate, tetra-4 (4-methyl-2- ethylhexyl) silicate, tetra-(p-tert-butyl-phenyl) silicate, hexa-(4-methyl-2-pentoxy) disiloxane, poly(methyl)siloxanes and poly(methylphenyl) siloxanes. Other synthetic lubricating oils include liquid esters of phosphorus-containing acids (e.g., tricresyl phosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid) and polymeric tetrahydrofurans.

Unrefined, refined and rerefined oils can be used in the lubricants of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from distillation or ester oil obtained directly from an esterification process and used without further treatment would be an unrefined oil. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques, such as distillation, solvent extraction, acid or base extraction, filtration and percolation are known to those skilled in the art. Rerefined oils are obtained by processes similar to those used to obtain refined oils, but applied to refined oils which have been already used in service. Such rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques for removal of spent additives and oil breakdown products.

The quinone adduct of this invention is blended into the lube oil base stock in amounts which are effective to enhance the anti-wear and antioxidant properties of the oil. Generally speaking, such effective amounts range from about 0.1 to about 2% by weight, more preferably from about 0.3 to 1.0% by weight, based on the weight of the oil.

The benefits of the additive of the present invention are particularly significant when employed in a lubricating oil adapted for use as an automatic transmission fluid.

Power transmitting fluids, such as automatic transmission fluids, as well as lubricating oils in general, are typically compounded from a number of additives each useful for improving chemical and/or physical properties of the same. The additives are usually sold as a concentrate package in which mineral oil or some other base oil is present. The mineral lubricating oil in automatic transmission fluids typically is refined hydrocarbon oil or a mixture or refined hydrocarbon oils selected according to the viscosity requirements of the particular fluid, but typically would - have a viscosity range of 2.5-9, e.g. 3.5-9 cst. at 100°C. Suitable base oils include a wide variety of light hydrocarbon mineral oils, such as naphthenic base oils, paraffin base oils, and mixtures thereof.

Representative additives which can be present in such packages as well as in the final formulation include viscosity index (V.I.) improvers, corrosion inhibitors, oxidation inhibitors, friction modifiers, lube oil flow improvers, dispersants, anti-foa ants, other supplemental anti-wear agents, detergents, metal rust inhibitors and seal swellants.

Suitable dispersants which may be employed are known in the art. A preferred class of dispersant are the ashless dispersants which are normally nitrogen-containing, oil-soluble salts, amides, i ides or esters of mono or dicarboxylic acids. A particularly preferred dispersant is the reaction product of a polyolefin-substituted succinic anhydride such as polyisobutenyl succinic anhydride and an alkylene polyamine, which can be further treated with a source of boron or copper. Such a material is disclosed in U.S. Patent 4,938,880, the complete disclosure of which is incorporated herein by reference. Such dispersants are generally added to the oil in amounts ranging from about 0.1 to about 10% by weight.

Metal containing rust inhibitors and/or detergents are frequently used with ashless dispersants. Such detergents and rust inhibitors include the metal salts of sulphonic acids, fatty acid esters such as glycerol mono and/or di stearate (which also function as friction modifiers) , alkyl phenols, sulfurized alkyl phenols, alkyl salicylates, naphthenates, and other oil soluble mono- and di¬ carboxylic acids. Highly basic, that is overbased metal salts, which are frequently used as detergents include calcium or magnesium phenates, sulfurized phenates and/or sulfonates. Usually these metal containing inhibitors and detergents are used in lubricating oil in amounts of about 0.01 to 10 wt.%, more preferably about 0.1 to 5 wt.%, based on the weight of the total lubricating composition. Marine diesel lubricating oils typically employ such metal-containing rust inhibitors and detergents in amounts up to about 20 wt.%.

The oil may also contain one or more supplemental antioxidants and/or oxidation inhibitors. Suitable antioxidants include phenols, hindered phenols, bis-phenols, sulfurized phenols, catechol, alkylated and sulfurized alkylated catechols, diphenylamine, alkylated diphenylamines and phenyl- 1-naphthylamines and alkyl and aryl borates, phosphites and phosphates.

Other antioxidants include oil soluble copper compounds. The copper compound may be in the cuprous and cupric form. The copper may be in the form of copper dihydrocarbyl thio- or dithio- phosphates. Alternatively the copper may be added as the copper salt of a synthetic or natural carboxylic acid. Examples include C₁₀ to c₁₈ fatty acids such as stearic or palmitic. Unsaturated acids such as oleic or branched carboxylic acids such as napththenic acids of molecular weight from 200 to 500 or synthetic carboxylic acids are preferred because of the improved handling and solubility properties of the resulting copper carboxylates. Also useful are oil soluble copper dithiocarbamates. Copper sulphonates, phenates, and acetylacetonates may also be used. The copper antioxidant can comprise a copper salt of a hydrocarbyl substituted C to C₁₀ monounsaturated dicarboxylic acid producing reaction product, which reaction product is formed by reacting a polymer of a C₂ to C₁₀ monolefin having a number average molecular weight of 900 to 1400 (e.g., 700 to 1200) substituted with a C₄ to C₁₀ monounsaturated acid material. Exemplary are copper salts of a hydrocarbyl substituted C₄ to C₁₀ monounsaturated dicarboxylic acid producing reaction product, which reaction product is formed by reacting a polymer of C₂ to C₁₀ monolefin having a number average molecular weight of from 900 to 1400 substituted with succinic moieties selected from the group consisting of acid, anhydride and ester groups, wherein there is an average of about 0.8 to 1.6 molar proportions of succinic moieties per molar proportion of the polymer.

The copper antioxidants will generally be added to the oil in an amount of from about 50-500 ppm by weight of the metal. Corrosion inhibitors, also known as anti-corrosive agents, reduce the degradation of the metallic parts contacted by the lubricating oil composition. Illustrative of corrosion inhibitors are phosphosulfurized hydrocarbons and the products obtained by reaction of a phosphosulfurized hydrocarbon with an alkaline earth metal oxide or hydroxide, preferably in the presence of carbon dioxide. Phosphosulfurized hydrocarbons are prepared by reacting a suitable hydrocarbon such as a terpene, a heavy petroleum fraction of a C₂ to C₆ olefin polymer such as polyisobutylene, with from 5 to 30 weight percent of a sulfide of phosphorus for 0.5 to 15 hours, at a temperature in the range of 150° to 600° C. Neutralization of the phosphosulfurized hydrocarbon may be effected in the manner taught in U.S. Patent 1,969,324.

Oxidation inhibitors reduce the tendency of mineral oils to deteriorate in service which deterioration can be evidenced by the products of oxidation such as sludge and varnish-like deposits on the metal surfaces and viscosity growth. Such oxidation inhibitors include alkaline earth metal salts of alkylphenolthioesters having preferably C₅ to C₁₂ alkyl side chains, calcium nonylphenol sulfide, barium t-octylphenyl sulfide, dioctylphenylamine, phenylalphanaphthylamine, phosphosulfurized or sulfurized hydrocarbons, etc.

Pour point depressants lower the temperature at which the oil will flow or can be poured. Such depressants are well known. Typical of those additives which usefully optimize the low temperature fluidity of the oil are ₈-C₁₈ dialkylfumarate/vinyl acetate copolymers, polymethacrylates, and wax naphthalene.

Foam control can be provided by an antifoa ant of the polysiloxane type, e.g. silicone oil and polydimethyl siloxane.

The oil of the present invention may also contain one or more alkoxylated amine friction modifier components as are known in the art. Preferred additives have the general formula:

( R "θ)_α H

R^"'-N

wherein R³ is a branched or straight chain hydrocarbyl or oxyhydrocarbyl group having from about 8 to about 30 carbon atoms, R⁴ and R⁵ are independently the same or different alkylene radicals containing from 2 to 4 carbon atoms and (a) and (b) are independently integers ranging from 1 to 4. Both (a) and (b) are preferably 1.

Illustrative of the most preferred alkoxylated amines are those of the formula and wherein R⁴ and R⁵ each have 2 carbon atoms and include:

N,N-bis(2-hydroxyethyl) tallow-amine N,N-bis(2-hydroxyethyl)-n-dodecylamine

N,N-bis(2-hydroxyethyl)-1-methyl-tridecenylamine

N,N-bis(2-hydroxyethyl)-hexadecylamine

N,N-bis(2-hydroxyethyl)-octadecylamine

N,N-bis(2-hydroxyethy1)-octadecenylamine

N,N-bis(2-hydroxyethyl)-oleylamine

N,N-bis(2-hydroxyethy1)-stearylamine

N,N-bis(2-hydroxyethyl)-undecylamine and boronated derivatives thereof.

The hydroxyl amine compounds may be used as such. However they may also be used in the form of an adduct or reaction product with a boron compound, such as a boric oxide, a boron halide, a metaborate, boric acid, or a mono-, di-, or triorgano borate, such as a mono-, di-, and .-rialkyl borate. Such adducts or derivatives may be prepared by contacting the above amines with a boronating agent. Preferred boronation agents include boric acid and boric acid esters, e.g., tributyl borate.

Anti-wear agents, as their name implies, reduce wear of moving metallic parts. Representative of conventional anti-wear agents which may be used to supplement the present thioquinone adducts are the zinc dialkyl-dithiophosphates and the zinc diaryldithiophosphates. However, it is an important advantage of the present invention that supplemental anti-wear agents do not have to be employed and, in fact, can be excluded from the compositions of this invention. Viscosity modifiers impart high and low temperature operability to the lubricating oil and permit it to remain relatively viscous at elevated temperatures and also exhibit acceptable viscosity or fluidity at low temperatures. Viscosity modifiers are generally high molecular weight polymers, including polyesters, polyacrylates and polyolefins. The viscosity modifiers may also be derivatized to include other properties or functions, such as the addition of dispersancy properties. These oil soluble viscosity modifying polymers will generally have number average molecular weights of from 10³ to 10⁶, preferably 10⁴ to 10⁶, e.g., 20,000 to 250,000, as determined by gel permeation chromotography or osmometry.

Examples of suitable hydrocarbon polymers include homopolymers and copolymers of two or more C₂ to C~_Q olefin monomers, e.g. C₂ to C₈ olefins, including both alpha olefins and internal olefins, which may be straight or branched, aliphatic, aromatic, alkyl-aromatic, cycloaliphatic, etc. Particularly preferred polymers are polyisobutylenes, homopolymers and copolymers of C₂ and higher alpha olefins, atactic polypropylene, hydrogenated polymers and copolymers and terpolymers of styrene, e.g. with isoprene and/or butadiene and hydrogenated derivatives thereof. The polymer may be degraded in molecular weight, for example by mastication, extrusion, oxidation or thermal degradation, and may contain oxygen.

These viscosity modifiers are normally added to the oil composition at a level within the range of from about 0.1 to about 10% by weight.

Seal swellants include mineral oils of the type that provoke swelling, including aliphatic alcohols of 8 to 13 carbon atoms such as tridecyl alcohol, with a preferred seal swellant being characterized as an oil-soluble, saturated, aliphatic or aromatic hydrocarbon ester of from 10 to 60 carbon atoms and 2 to 4 linkages, e.g. dihexylphthalate, as are described in U.S. Patent 3,974,081.

Compositions, when containing these additives, typically are blended into the base oil in amounts which are effective to provide their normal attendant function. Representative effective amounts of such additives are illustrated as follows:

Compositions

V.I. Improver

Corrosion Inhibitor

Oxidation Inhibitor

Dispersant

Lube Oil Flow Improver

Detergents and Rust

Inhibitors Anti-Foaming Agents Anti-wear Agents Seal Swellant Friction Modifiers Mineral Oil Base

In broad sense therefore, the additive of the present invention, when employed in a lubricating oil composition, typically in a minor amount, is effective to impart enhanced anti-wear and friction stability properties thereto relative to the same composition in the absence of the present additive. Additional conventional additives, particularly dispersants and friction modifiers, selected to meet the particular requirements of a selected type of lubricating oil composition also can be included as desired.

The following Examples are illustrative of the invention.

Example 1

In this example, an adduct of benzoquinone and dioctyl thiophosphoric acid ester having the following structure was prepared:

In a 500 ml flask was added 54.8g (.155mol) of dioctyl thiophosphoric acid ester. 8.36g (0.077mol) of benzoquinone (half equivalent) was dissolved in 100 ml methanol and was slowly added to the above stirred solution. Reaction was slightly exothermic as the temperature of the reaction increased from 25°C to 40°C. The solution was allowed to stir at room temperature for 12 more hours. Methanol was removed with nitrogen stripping.

Example 2

Example 1 was repeated except that 61.Og (.172mol) of the ester and 18.61g (.172mol) of benzoquinone were used in the reaction mixture. The reaction product was primarily the 1:1 aduct having the structure:

Example 3

This example shows the preparation of an adduct having the structure of formula 1 above wherein n is 1, substitution occurs at the 2 position on the quinone ring and R has 12 carbon atoms.

21.6g (0.05mol) of benzoquinone was dissolved in 500ml of methanol in a round bottom flask. 40.4g (0.05mol) of 1-dodecanethiol was then added slowly to this solution. The solution was stirred for 2.5 hours at room temperature yielding a red solid. The solid was separated, washed with methanol and dried. Yield = 10.6g.

Example 4

An ATF base fluid, designated hereinafter as the Control Test Base, was formulated with conventional amounts of a seal swell additive, an antioxidant and a viscosity index improver. The composition of the Test Base is as follows:

e ormulation

The Control Test Base of Example 4 was further formulated by thoroughly admixing it with 0.4% by weight of the anti-wear/antioxidant additive prepared in Example 1.

The formulations of Examples 4 and 5 were then tested for antiwear properties using the FZG Gear Test and for antioxidant properties using the LMOT Test by the following procedures. FZG Gear Test

This test employs a gear box containing a wheel gear engaged with a pinion gear. The pinion gear is connected by an axle to a motor. The motor turns the pinion gear through the axle and the pinion gear serves to drive the wheel gear. The wheel gear is connected to a different axle which extends out of the gear box. A load is applied to the wheel gear during the test which creates resistance to the turning of the wheel gear by the pinion gear. This load is applied in several stages and increases in each stage. The load is expressed as torque (N.m) at the pinion gear.

Thus, the load of each load stage can be expressed as follows:

Prior to the start of each run, the test gear box is carefully flushed twice with a suitable solvent (non-flammable) . The solvent is filled above the center of the shaft axles. The machine is then turned one full rotation by hand to remove waste oil from the bearings assemblies. The complete housing is then dried thoroughly.

The test gears are likewise washed. The tooth flanks are visually inspected from a fixed viewing distance of 25 cm. Existing irregularities are noted. Test wheels with any signs of rusting or corrosion are discarded.

The pinion and wheel gears are marked in such a way that when the test pieces are reassembled, the same teeth mesh as before. After installing the pinion gear on its shaft and the wheel gear on its shaft, the test gear box is filled with the oil formulation to be tested up to the center of the shafts. A preliminary run is made at the first load stage while heating until the temperature has reached 90 + 3°C. The motor and rig are turned off until the next load stage is run.

The pinion and wheel gears are disassembled at the end of each load stage, washed in solvent, allowed to cool to room temperature, washed again and this time dried with an air gun.

The test gears are then separately examined at the fixed viewing distance for changes in appearance of the flanks. Thus, smoothing of the grinding marks, scratches, scoring, seizure marks, discoloration of the tooth flanks, corrosion symptoms, deposits, the natural position, and extent of the change of the tooth flanks are all noted.

The inspected gears are then re-mounted on the shafts for the next load stage. The same oil is used and the load stages are increased until a marked deviation (e.g. increase) in deterioration of the visible appearance of the gears is observed relative to the progressive deterioration observed in previous load stages. When such deterioration is observed, the oil fails that load stage and the test is completed. The load stage at failure is reported as the FZG value.

The following is a summary of the test conditions of the FZG test.

TEST CONDITIONS

Complete Revolutions of Wheel Gear per Load Stage 21,700 Pinion Speed 2,170 RMP Drive Gear Pinion Lubrication Splash or Dip Oil Temp, at Beginning of Test Run 90 + 3°C. Amount of Oil Needed

(Center of Shaft) 1.25L Running Time Per Load Stage 15 min. LMOT Test

The lubricant-multiple oxidation test (LMOT) is designed to measure the resistance to oxidation of lubricant materials. 50 grams of oil, 2.0 grams of iron filings and 0.5 gram of copper naphthenate are placed in a 100ml test tube. The tube with the contents is then placed in an aluminum heating block and heated to 150°C. Air is then continuously bubbled through the oil sample at a rate of about 25cc per minute while maintaining the temperature at 150°C. One drop of the oil sample is placed on a blotter strip every twenty four hours. When the oil spot becomes black, the test has failed. The number of days required to reach this point of failure is then recorded.

The results for testing the Control formulation of Example 4 and the formulation of this invention (Example 5) were as follows:

Test results show that the oil formulation containing the additive of the present invention provides enhanced antiwear and antioxidant properties when compared with an identical formulation but without the additive.

Claims

CLAIMSWhat is claimed is:

1. A hydrocarbon soluble or dispersible compound which enhances the antiwear and antioxidant properties of lubricating oil compositions comprising a substituted quinone compound having a structure selected from the group consisting of:

wherein R, R¹ and R² are the same or different branched or straight chain, substituted or unsubstituted, hydrocarbyl radicals containing from about 5 to about 28 carbon atoms selected from the group consisting of alkyl, alkenyl, oxygen or sulfur-containing heteroalkyl, alkoxy, aryloxy, cycloalkyl, aryl, alkaryl and aralkyl, and n is 1 or 2.

2. The compound of claim 1 having the structure;

3. The compound of claim 2 wherein R¹ and

R² are alkyl groups.

4. The compound of claim 3 wherein R and

R² are octyl.

5. The compound of claim 1 having the structure:

O

6. The compound of claim 5 wherein R is an alkyl group.

7. The compound of claim 6 wherein R is dodecyl.

8. An oleagenous composition comprising an oil selected from the group consisting of fuels and lubricating oils and an amount of the compound of claim 1 dissolved or dispersed therein effective to improve the antiwear and antioxidant properties of said composition.

9. The composition of claim 8 wherein said oil is a lubricating oil.

10. The composition of claim 9 which also contains an effective amount of an ashless dispersant.

11. The composition of claim 10 wherein said ashless dispersant comprises a borated, aminated, long chain hydrocaryl-substituted dicarboxylic acid material.

12. The composition of claim 9 wherein the compound dispersed or dissolved in said oil has the structure:

13. The composition of claim 12 wherein R¹ and R² are alkyl groups.

14. The composition of claim 9 wherein the compound dispersed or dissolved in said oil has the structure:

O

15. The composition of claim 14 wherein R is an alkyl group.

16. The composition of claim 9 wherein said compound is dissolved or dispersed in said oil at a level of from about 0.1 to about 2% by weight.

17. A process for enhancing the properties of a lubricating oil comprising blending with said oil an amount of the compound of claim 1 sufficient to improve the antiwear and antioxidant properties of said oil.

18. The process of claim 17 wherein said compound has the structure:

wherein R and R² are alkyl groups containing from about 5 to about 13 carbon atoms.

19. The process of claim 18 wherein said compound is blended with said oil at a level of from about 0.1 to about 2% by weight.