GB2307916A - Lubricating compositions - Google Patents

Abstract

The compositions comprise a base oil and an additive selected from a multifunctional olefinic copolymer viscosity index improver with dispersant properties, Mg sulfonate and mixtures thereof and optionally and preferably a polymethacrylate demulsifier and high molecular weight dispersant. The lubricant compositions have particular utility in engines fueled by alcohol or gasoline/alcohol blends. Emulsion stabilising additives comprising the above components are also claimed.

Description

BACKGROUND OF THE INVENTION This invention relates to lubricating oil formulations useflil in internal combustion engines fueled by alcohol or gasoline/alcohol blend fuel compositions. The lubrication oil formulations used in engines using such fuel compositions must be capable of functioning efficiently in an environment wherein an appreciable quantity of alcohol and/or water eventually accumulates in the lubricating oil.

RELATED ART Alternate fuels for transportation, such as methanol, ethanol, natural gas, gasahol, etc. have been studied by the automotive industry for a number of years. While such fuels offer some advantages of reduced engine emissions, their use is accompanied by a number of deficiencies and limitations which must be addressed if they are to become viable alternatives to gasoline.

One of the most promising alternate fuels is M85, a blend of 85% methanol and 15% gasoline. This fuel takes advantage of the good reduced emissions performance of methanol, along with the higher octane number and higher latent heat of vaporization (resulting in greater volumetric efficiency) of methanol. It overcomes methanol's low volatility which, when coupled with its higher heat of vaporization, gives rise to driveability problems, by inclusion of gasoline into the blend.

The combustion of methanol, M85 or other alcohol or oxygenated fuels gives rise to a higher amount of water being formed per unit mass of feed burned as compared to just combusting gasoline.

This water formed during combustion, along with alcohol which bypasses the piston rings or is carried away by the blow-by gases, tends to accumulate in the oil.

This alcohol and excess water accumulating in the lubricating oil resulting from the use of such alternate fuels increase corrosion and wear problems in engines using such alternate fuels, especially alcohol or M85.

The presence of alcohol and/or water in the lubricating oil results in the formation of emulsions, especially under conditions of low temperatures/ short trip operation of the engine, conditions under which the water and alcohol, because of their lower boiling points as compared to the lubricating oil, are not simply evaporated from the oil USP 3,509,052 teaches that sludge forms on metal surfaces in areas of the engine where water vapor can condense in contact with lubricants containing various dispersants, especially succinic acid dispersants, and indicates that it is highly desirable to eliminate or reduce the amount of such sludge formed in the engine. The patent indicates that the sludge accumulation can be reduced or eliminated by incorporating demulsifiers for water and oil emulsions into the lubricating oil.

European Application 0330522 teaches improved demulsified lubricating oil compositions. The lube oil composition comprises a lube base oil and an additive mixture comprising (A) a lubricating oil dispersant additive comprising at least one of (1) ashless dispersant and/or (2) polymeric viscosity index improver dispersants and (B) a demulsifier additive comprising the reaction product of an alkylene oxide and an adduct obtained by reacting a bisepoxide with a polyhydric alcohol. Optionally, the additive may also contain (C) a compatibilizer additive for the demulsifier, which comprises a glycol ester or a hydroxy amide derivative of a carboxylic acid having a total of from 24 to 90 carbon atoms and at least one carboxylic group per molecule for enhanced solubility, versus stability, of the demulsifier in the oil solutions containing such dispersants.The application indicates that while emulsions in the lubricating oil would not necessarily be a matter of concern in themselves, condenser tubes can become partially blocked with emulsion leading to pressure drop across the condenser and pressure buildup in the crankcase. Emulsions are also of concern for fear that they would plug PCV valves and other crankcase ventilation lines and coat internal engine surfaces. Consequently, the application states it has become very important to prevent emulsion formation in modern lubricating oil formulations, despite the presence of additives such as dispersants and multifunctional viscosity improvers which are highly potent emulsion formers. The reference application teaches a formulation which inhibits emulsion formation.

Contrary to the above, however, the industry has now expressed concern about possible operational problems that might occur if water separates from the oil phase in vehicle sumps. In such instances, the moving metal parts would be bathed in water during startup, leading to unlubricated metal/metal contact and consequential metal surface damage and corrosion. It is now believed that emulsion formation is desirable as compared to phase separation, at least in those instances where appreciable amounts of water and/or alcohol will become unavoidably introduced into the oil, as in the case of alternate fuel vehicles.

DESCRIPTION OF THE FIGURES Figures IA- 1 D show fresh oil (no water) and the emulsion stability of oil samples containing 5, 10 and 20 cc water wherein one oil sample contained a multifunctional olefinic copolymer viscosity index modifier and one sample contained a monofunctional olefinic copolymer viscosity index modifier.

Figures 2A-2D show the emulsion stability characteristics of six oil samples containing from 10 to 40% v/v water but containing different viscosity index improvers.

Figures 3A-3C show the emulsion stability characteristics of six oil samples containing 20, 30 and 40% v/v of a 2/1 v/v water/methanol mixture, the oil samples containing different viscosity index improvers.

Figures 4A-4D show the emulsion stability characteristics of six oil samples containing 20, 30, 40 and 60% v/v of a 4/1 v/v water/methanol mixture the oil samples containing different viscosity index improvers.

Figures 5A-5D show the emulsion stability characteristics of six oil samples containing 10, 20, 30 and 40% v/v water, the oil samples containing different detergents and dispersants.

Figures 6A-6D show the emulsion stability characteristics of six oil samples containing 20, 30, 40 and 60% v/v of a 2/1 v/v water/methanol mixture, the oil samples containing different detergents and dispersants.

THE PRESENT INVENTION The present invention is directed to a lubricating composition containing additives which composition produces stable water and water/alcohol-oil emulsions in internal combustion engines run on alternate fuels to the additive package itself, and to a method for stabilizing the water and water/alcohol-oil emulsions formed in internal combustion engines run on alternate fuels which method comprises the use of said lubricating oil composition in said engine.The lubricating composition comprises a major portion of a base stock oil of lubricating viscosity, including mineral or synthetic base oil, and a minor portion of an emulsion stabilizing additive combination mixture, said emulsion stabilizing additive combination mixture containing components selected from the group consisting of magnesium sulfonate detergent, multi-functional olefinic copolymer viscosity index improver with dispersant properties and mixtures thereof, and optionally further including additional components selected from the group consisting of a demulsifier, preferably a polymethacrylate and a dispersant preferably a high molecular weight borated PIBSA/PAM and mixtures thereof.

The lubricating composition according to the invention requires a major amount of lubricating oil basestock. In general, the lubricating oil basestock will have a kinematic viscosity ranging from about 2 to about 1,000 cSt at 40"C. The lubricating oil basestock can be derived from natural lubricating oil stocks such as paraffinic or naphthenic petroleum hydrocarbons, synthetic lubricating oils, or mixtures thereof. Suitable lubricating oil basestocks include basestocks obtained by isomerization of synthetic wax and slack wax, as well as hydrocrackate basestocks produced by hydrocracking (rather than solvent extracting) the aromatic and polar components of the crude.

Natural lubricating oils include animal oils, vegetable oils (e.g., castor oils and lard oil), petroleum oils, mineral oils, and oils derived from coal or shale, and mixtures thereof.

Synthetic oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and interpolymerized olefins, alkylbenzenes, polyphenyls, alkylated diphenyl ethers, alkylated diphenyl ethers, alkylated diphenyl sulfides, as well as their derivatives, analogs, and homologs thereof, and the like. Synthetic lubricating oils also include alkylene oxide polymers, interpolymers, copolymers and derivatives thereof wherein the terminal hydroxyl groups have been modified by esterification, etherification, etc. Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids with a variety of alcohols. Esters useful as synthetic oils also include those made from C5 to C12 monocarboxylic aids and polyols and polyol ethers.

Silicon-based oils (such as the polyalkyl-, polyaryl-, polyalkoxy-, or polyaryloxy-siloxane oils and silicate oils) comprise another useful class of synthetic lubricating oils. Other synthetic lubricating oils include liquid esters of phosphorus-containing acids, polymeric tetrahydrofurans, polyalphaolefins, and the like.

The lubricating oil may be derived from unrefined, refined, rerefined oils, or mixtures thereof, Unrefined oils are obtained directly from a natural source or synthetic source (e.g., coal, shale, or tar sands bitumen) without further purification or treatment. Examples of unrefined oils include a shale oil obtained directly from a retorting operation, a petroleum oil obtained directly from distillation, or an ester oil obtained directly from an esterification process, each of which is then used without further treatment. Refined oils are similar to the unrefined oils except that refined oils have been treated in one or more purification steps to improve one or more properties. Suitable purification techniques include distillation, hydrotreating, dewaxing, solvent extraction, acid or base extraction, filtration, and percolation, all of which are known to those skilled in the art.Rerefined oils are obtained by treating refined oils in processes similar to those used to obtain the refined oils. These 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 emulsifying additive combination is selected from the group consisting of magnesium sulfonate used in an amount in the range 0.01 to 10 wt%, preferably 0.01 to 5 wtO/o, most preferably 0.01 to 3 wt%, a multi functional olefinic copolymer viscosity index improver with dispersant properties used in an amount in the range 0.001 to 10 wit%, preferably 0.01 to 5 wit%, most preferably 0.01 to 3 wit%, and mixtures thereof and, optionally additional components consisting of a demulsifier preferably polymethacrylate used in an amount in the range 0.01 to 3 wtO/o, preferably 0.01 to 2 wt%, most preferably 0.05 to 1 wt%, an auxiliary dispersant, preferably a high molecular weight borated PIBSA/PAM, used in an amount in the range 0.1 to 20 wit%, preferably 0.5 to 10 wtO/o, and mixtures thereof. All cited concentration ranges refer to the % weight active ingredients in the fully formulated oil.

It is envisioned that while the magnesium sulfonate can be used by itself as can be the multifunctional olefinic copolymer viscosity index improver, they will preferably be used in combination. Similarly, the aforesaid materials can be used individually or in combination with each other and further in combination with the polymethacrylate demulsifier. It is preferred that the emulsion stabilizing additives contain all three recited components, the magnesium sulfonate detergent, a multifunctional copolymeric viscosity index improver with dispersant properties or mixture of such multifunctional copolymeric viscosity index improver with dispersant properties, and the polymethyacrylate demulsifier.

It has been found that such mixtures added to lube oil base stock produce formulated lubricating oils exhibiting the most stable emulsions as compared to the use of other additive combinations of known composition having different combinations of demulsifiers, viscosity index improvers and detergents.

The multifunctional olefinic copolymer viscosity index modifier can be generally the material described as the polymeric viscosity index improver dispersant A-2 (ii) and (iii) recited in EP0330522.

That multifunctional olefinic copolymer viscosity index improver dispersant includes: (1) polymers of C2 to C20 olefin with unsaturated C3 to C10 mono- or dicarboxylic acid neutralized with amine, hydroxy amine or alcohols; and (2) polymers of ethylene with a C3 to C20 olefin further reacted either by grafting C4 to C20 unsaturated nitrogen containing monomers thereon or by grafting an unsaturated acid onto the polymer backbone and then reacting said carboxylic acid groups with amine, hydroxy amine or alcohol.

Amine compounds include mono- and (preferably) polyarnines, most preferably polyalkylene polyamines of about 2 to 60, preferably 2 to 40 (e.g., 3 to 20), total carbon atoms and about 1 to 12, preferably 3 to 12, and most preferably 3 to 8 nitrogen atoms in the molecule. These amines may be hydrocarbyl amines or may be hydrocarbyl amines including other groups, e.g. hydroxy groups, alkoxy groups, amide groups, nitriles, imidazoline groups, and the like. Hydroxy amines with 1 to 8 hydroxy groups, preferably 1 to 3 hydroxy groups are particularly useful. Preferred amines are aliphatic saturated amines.

Non-limiting examples of suitable amine compounds include: 1,2diamineoethane; 1,3-diaminopropane; 1,4-diaminobutane; 1,6-diaminohexane, polyethylene amines such as diethylene triamine; triethylene tetramine; tetraethylene pentamine; polypropylene amines such as 1,2-propylene diamine; di (1,2-propylene)triamine; di-(1,3- propylene) triamine; N,N-dimethyl-1,3diaminopropane; N,N-di(2- aminoethyl) ethylene diamine; N,N-di(2-hydroxyethyl)-1,3- propylene diamine; 3-do-decyloxypropylamine; N-dodecyl-1,3- propane diamine; tri hydroxymethylaminomethane (THAM); diisopropanol amine; diethanol amine; triethanol amine; mono-, di-, and tri-tallow amines; amino morpholines such as N-(3-aminopropyl) morpholine; and mixtures thereof.

Other useful amine compounds include: alicyclic diamines such as 1 ,4-di(aminomethyl)cyclohexane, and heterocyclic nitrogen compounds such as imidizolines, and N-aminoalkyl piperazines.

Hydroxyamines which can be used include 2-amino- l-butanol, 2 amino-2-methyl -1 -propanol, p-(beta-hydroxyethyl)-aniline, 2-amino- l-propanol, 3 -amino- 1 -propanol, 2-amino-2-methyl-1,3-propane-diol, 2-amino-2-ethyl-1,3- propanediol, N-(beta-hydroxy-propyl -N'-(beta- amino-ethyl-piperazine, tris(hydroxymethyl) amino-methane (also known as trismethylolaminomethane), 2-amino- 1 -butanol, ethanolamine, beta-(beta-hydroxyothoxy) ethylamine, and the like. Mixtures of these or similar amines can also be employed.

Monohydric and polyhydric alcohols may also be used, the polyhydric alcohols being the most preferred and preferably contain from 2 to about 10 hydroxy radicals, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and other alkylene glycols in which the alkylene radical contains from 2 to about 8 carbon atoms. Other useful polyhydric alcohols include glycerol, mono-oleate of glycerol, monostearate of glycerol, monomethyl ether of glycerol, pentaery-thritol, dipentaerythritol, and mixtures thereof.

Unsaturated alcohols may also be used such as alkyl alcohol, cinnamyl alcohol, propanyl alcohol, l-cyclohexane-3-ol, and oleyl alcohol. Still other classes of the alcohols comprise the ether-alcohols and amino-alcohols including, for example, the oxy-alkylene, oxy-arylene-, amino-alkylene-, and amino-arylene- substituted alcohols having one or more oxy-alkylene, aminoalkylene or amino-arylene oxy-arylene radicals. They are exemplified by Cellosolve, Carbital, N,N,N',N'-tetrahydroxy-trimethylene di-amine, and etheralcohols having up to about 150 oxy-aikylene radicals in which the alkylene radical contains from 1 to about 8 carbon atoms.

Examples of olefins which could be used to prepare the copolymers above include mono-olefins such as ethylene, propylene, l-butene, 1-pentene, l-benzene, 1-heptene, 1-decane, 1-dodacene, styrene, etc.

Representative non-limiting examples of diolefins that can be used include 1 -4-hexadiene, 1,5-heptadiene, 1,6-octadiene, 5-methyl- 1 -4 hexadiene, 1,4-dyclohexadiene, 1, 5-cyclo-octadiene, vinyl-cyclohexane, dicyclopentenyl and 4,4'-dicyclohexenyl such as tetrahydroindene, methyl tetrahydroindene, dicyclopentadiene, bicyclo(2,2,1)-hepta-2.5-diene, alkenyl, alkylidiene, 5-methylene- 2-norbornene, 5-ethylidene-2-norbornene.

It is preferred that the polymeric viscosity index improver dispersant have a number average molecular weight range as by vapor phase osmometry, membrane osmometry, or gel permeation chromatography, of 1000 to 2,000,000; preferably 5,000 to 250,000 and most preferably 10,000 to 200,000. It is also preferred that the polymers of group (1) comprises 0.1 to 10 moles of olefin, preferably 0.2 to 5 moles C2-C20 aliphatic or aromatic olefin moieties per mole of unsaturated carboxylic acid moiety and that from 50% to 100% of the acid moieties are neutralized.Preferably the polymer of group (2) comprises an ethylene copolymer of 25 to 60 wt% ethylene with 75 to 20 'wit% C3 to C20 mono- and/or diolefin, 100 parts by weight of ethylene copolymer being grafted with either 0.1 to 40, preferably 1 to 20 parts by weight unsaturated nitrogen containing monomer, or being grafted with 0.01 to 5 parts by weight of unsaturated C3 to C10 mono- or dicarboxylic acid, which acid is 50% or more neutralized.

The unsaturated carboxylic acids used above will preferably contain 3 to 10, more usually 3 or 4 carbon atoms, and may be mono carboxylic such as methacrylic and acrylic acids or dicarboxylic such as maleic acid, maleic anhydride, fumaric acid, etc.

Similarly, the ethylene copolymer viscosity index improverdispersant of U.S. Patent 4,517,104 also satisfies the definition of multifunctional olefins copolymer viscosity index modifiers dispersant as used in this specification.

The ethylene copolymer viscosity index improver-dispersant of U.S. Patent 4,517,104 is described as the reaction product of an oil soluble ethylene copolymer comprising within the range of about 15 to 90 wtO/o ethylene and about 10 to 85 wt% of one or more C3 to C28 alphaolefin, having a number average molecular weight within the range of about 5,000 to 500,000 and grafted with an ethylenically unsaturated carboxylic acid material having 1 to 2 carboxylic acid groups or anhydride groups; an alkylene or oxyalkylene amine having at least two primary amine groups selected from the group consisting of alkylene polyamines having alkylene groups of about 2 to 7 carbon atoms and 2 to 11 nitrogens and polyoxyalkylene polyamines wherein the alkylene groups contain 2 to 7 carbon atoms and the number of oxy alkylene groups will be about 3 to 70; and a long chain hydrocarbyl substituted succinic anhydride in acid having 50 to 400 carbon atoms.

The lubricating oil metal detergent additives are also frequently referred to as rust inhibitors and include the metal salts of sulphonic acids, alkyl phenols, sulphurized alkyl phenols, alkyl salicylates, naphthenates, and other oil soluble mono- and di- carboxylic acids. Highly basic, that is overbased metal salts, are frequently used as detergents and appear particularly prone to interaction with the ashless dispersant. Usually these metal containing rust inhibitors and detergents are used in lubricating oil in amounts of about 0.01 to 10, e.g., 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 of up to about 20 'wit%.

Highly basic alkaline earth metal sulfonates are frequently used as detergents. They are usually produced by heating a mixture comprising an oilsoluble sulfonate or alkaryl sulfonic acid, with an excess of alkaline earth metal compound above that required for complete neutralization of any sulfonic acid present and thereafter forming a dispersed carbonate complex by reacting the excess metal with carbon dioxide to provide the desired overbasing.The sulfonic acids are typically obtained by the sulfonation of alkyl substituted aromatic hydrocarbons such as those obtained from the fractionation of petroleum by distillation and/or extraction or by the alkylation of aromatic hydrocarbons as for example those obtained by alkylating benzene, toluene, xylene, naphthalene, diphenyl and the halogen derivatives such as chlorobenzene, chiorotuluene and chloronaphthalene. The alkylation may be carried out in the presence of a catalyst with alkylating agents having from about 3 to more than 30 carbon atoms. For example haloparaffins, olefins obtained by dehydrogenation of paraffins, polyolefins produced from ethylene, propylene, etc. are all suitable. The alkaryl sulfonates usually contain from about 9 to about 70 or more carbon atoms, preferably from about 16 to about 50 carbon atoms per alkyl substituted aromatic moiety.

The alkaline earth metal compounds which may be used in neutralizing these alkaryl sulfonic acids to provide the sulfonates includes the oxides and hydroxides, alkoxides, carbonates, carboxylate, sulfide, hydrosulfide, nitrate, borates and ethers of magnesium, calcium, and barium. Examples are calcium oxide, calcium hydroxide, magnesium acetate and magnesium borate.

As noted, the alkaline earth metal compound is used in excess of that required to complete neutralization of the alkaryl sulfonic acids. Generally, the amount ranges from about 100 to 220%, although it is preferred to use at least 125% of the atoichiometric amount of metal required for complete neutralization.

Various other preparations of basic alkaline earth metal alkaryl sulfonates are known, such as U.S. Patents 3,150,088 and 3,150,089 wherein overbasing is accomplished by hydrolysis of an alkoxide-carbonate complex with the alkaryl sulfonate in a hydrocarbon solvent-diluent oil.

Magnesium sulfonate detergent also acts as a rust inhibitor. The magnesium sulfonate is a magnesium salt of sulfonic acids. They are produced by heating a mixture comprising an oil-soluble sulfonate or alkaryl sulfonic acid with an excess of magnesium compound above that required for complete neutralization of any sulfonic acid present and thereafter forming a dispersed carbonate complex by reacting the excess magnesium with carbon dioxide to provide the desired overbasing.The sulfonic acids are typically obtained by the sulfonation of alkyl substituted aromatic hydrocarbons such as those obtained from the fractionation of petroleum by distillation and/or extraction or by the alkylation of aromatics hydrocarbons as for example those obtained by alkylating benzene, toluene, xylene naphthalene, diphenyl and the halogen derivatives such as chlorobenzene, chlorotoluene, and chloronaphthalene. The alkylation may be carried out in the presence of a catalyst with alkylating agents having from about 3 to more than 30 carbon atoms. For example haloparaffins, olefins obtained by dehydrogenation of paraffins, polyolefins produced from ethylene, propylene etc. are all suitable. The alkaryl sulfonates usually contain from about 9 to about 70 or more carbon atoms, preferably from about 16 to about 50 carbon atoms per alkyl substituted aromatic moiety.The magnesium compounds which may be used in neutralizing these alkaryl sulfonic acids to produce the sulfonates include oxides and hydroxides, alkoxides, carbonates, carboxylates, sulfides, hydrosulfides, nitrates, borates and ethers of magnesium. The magnesium compound is used in excess of that required to complete neutralization of the alkaryl sulfonic acids. Generally the amount ranges from about 100 to 220%, although it is preferred to use at least 125% of the stoichiometric amount of metal required for complete neutralization.

Various other preparations of basic magnesium alkaryl sulfonates are known, such as those recited in U.S. Patent 3,150,088 and U.S. Patent 3,150,089 wherein overbasing is accomplished by hydrolysis of an aLkoxide- carbonate complex with the alkylsulfonate in a hydrocarbon solvent-diluent oil.

A preferred magnesium sulfonate is magnesium alkyl aromatic sulfonate having a total base number (ASTM D2896) ranging from about 300 to 400.

The emulsion stabilizing additive combination will also optionally and preferably include a demulsifier, preferably a polymethacrylate, having a weight average molecular weight in the range 10,000 to 300,000, preferably 30,000 to 200,000.

Finally and optionally an auxiliary dispersant can also be included.

Ashless dispersants useful in this invention comprise nitrogen or ester containing dispersants selected from the group consisting of (i) oil soluble salts, amides, imides, oxazolines and esters, or mixtures thereof, of long chain hydrocarbon substituted mono and dicarboxylic acids or their anhydrides; (ii) long chain aliphatic hydrocarbon having a polyamine attached directly thereto; and (iii) Mannich condensation products formed by condensing about a molar proportion of a long chain substituted phenol with about 1 to 2.5 moles of formaldehyde and about 0.5 to 2 moles of polyalkylene polyamine; wherein said long chain hydrocarbon group in (i), (ii) and (iii) is a polymer of a C2 to C10, e.g., C2 to C5, monoolefin, said polymer having a number average molecular weight of at least about 1300. Dispersants are described in greater detail in U.S.Patent 4,938,880, incorporated herein by reference.

The nitrogen containing dispersant can be further treated by boration as generally taught in U.S. Patent Nos. 3,087,936 and 3,254,025 (incorporated herein by reference thereto). This is readily accomplished by treating said acyl nitrogen dispersant with a boron compound selected from the class consisting of boron oxide, boron halides, boron acids and esters of boron acids in an amount to provide from about 0.1 atomic proportion of boron for each mole of said acylated nitrogen composition to about 20 atomic proportions of boron for each atomic proportion of nitrogen of said acylated nitrogen composition. Useflilly the dispersants of the inventive combination contain from about 0.05 to 2.0 wt%, e.g., 0.05 to 0.7 wt% boron based on the total weight of said borated acyl nitrogen compound.The boron, which appears be in the product as dehydrated boric acid polymers (primarily (HBO2)3), is believed to attach to the dispersant imides and diimides as amine salts, e.g., the metaborate salt of said diimide.

Preferably, the auxiliary dispersant is a high molecular weight polyisobutylene succinic acid/anhydride (PIBSA) polyamine (PAM), such material being the reaction product of a polyisobutene succinic anhydride and polyamine that is post treated with boron. The polyisobutene moiety will usually have a number average molecular weight (Mn) within the range of from 1500 to 5000 preferably 2000 to 5000 or greater. The boron content ranges from 0.05 to 2wt%.

Other typical lube oil additives such as pour point depressants, other detergents, other viscosity index improvers, anti-wear additives, anti-foam agents, dispersants, antioxidants, friction modifiers, rust inhibitors, extreme pressure agents, etc., may also be present in the lubricating composition the amounts of these other additives used not being included in the loading weight %'s previously recited for the emulsion stabilizing additive combination.

Lubricating oil additives are described generally in "Lubricants and Related Products" by Dieter Klamann, Verlag Chemie, Deerfield, Florida, 1984, and also in "Lubricant Additives" by C. V. Smalheer and R. Kennedy Smith, 1967, pages 1-11, the disclosures of which are incorporated herein by reference and in U.S. Patent 4,938,880, incorporated herein by reference.

EXPERIMENTAL To understand the effect of additive composition on emulsion stability, several oil blends were prepared using different viscosity index improvers, demulsifiers, and detergents. The oils were heated at 800C and water was added while stirring until homogeneous emulsions formed. In the case of emulsions formed using water/methanol mixtures, the temperature was held at 52"C because of the lower boiling point of methanol. The water/methanol mixtures added to the oil contain water/methanol at ratios of 4/1 and 2/1 v/v.

The emulsions were transferred to graduated cylinders and observed over several weeks. When phase separation occurred, samples from the two phases were analyzed for water content and elemental composition of Mg, Ca, Zn, P and B.

EXAMPLE 1 The effect of type of viscosity index improver and demulsifier used on emulsion stability was evaluated in a series of seven (7) oil samples. These seven (7) samples are described compositionally in Table 1.

The physical property characteristics ofthe oils are reported in Table 2. The oils were blended to have the same viscometric properties at 100"C.

TABLE 2 - Formulation Details (% W/W) of the Oils Tested for Effect of Viscosity Modifier on Emulsion Stability Component Oil 1 Oil 2 Oil 3 Oil 4 Oil 5/B Oil 6 Oil B-1 S100N LP 44.0 44.0 41.0 46.0 42.7 46.7 48.5 S150N 36.0 36.0 35.0 31.0 34.7 31.1 28.7 DI Package I* 16.5 16.5 16.5 16.5 16.4 DI Package II* 17.4 DI Package III* 16.3 VI Improver AC 702 (PMA)# 3.5 AC954 (MF PMA) # 3.5 Shell Vis 40 (SICP) # 7.5 Lz 7342 (SBCP) # 6.5 ECA 8899 (MF OCP) # 6.2 4.8 ECA 13112 (OCP) # 6.5 Total % w/w 100.0 100.0 100.0 100.0 100.0 100.0 100.0 # Polymethacrylate - commercially available from Rohm & Haas.

# Multifunctional polymethacrylate - commercially available from Rohm & Haas.

# Styrene isoprene copolymer - commercially available from Shell Chemical.

# Monofunctional styrene butadiene copolymer - commercially available from Lubrizol.

# Multifunctional olefinic copolymer viscosity index modifier - commercially available from Exxon Chemical (active ingredient is 23% w/w).

# Monofunctional olefinic copolymer viscosity index modifier - commercially available from Exxon Chemical.

* Addpack5 DI Package I and DI Package II both contained non-borated PIBSA/PAM dispersant, magnesium sulfonate detergent, anti-wear additives, antioxidants, pour point depressants, rust inhibitors, demulsifiers, anti-foaming agents and diluent oil. They differed in that DI Package I contained 0.114% w/w rust inhibitor and 0.011% w/w ester of dimer acid as demulsifier (from Emery) whereas DI Package II contained 0.228% w/w rust inhibitor and 1.028% w/w polymethacrylate as demulsifier (from Rohm). DI package III was similar to DI Package I but contained 0.7% w/w rust inhibitor.

TABLE 2 Oil 1 Oil 2 Oil 3 Oil 4 Oil 5/B Oil 6 Oil B-1 KV @ 100 C (cSt) 10.05 10.10 9.70 8.36 10.79 10.74 10.50 KV @ 40 C (cSt) 59.10 59.50 60.80 48.93 69.49 51.82 CCS @ -20 C (cp) 2696 2736 2591 2405 3231 3190 Surface Tension, air 31.5 29.3 29.5 29.7 32.0 31.9 (dyne/cm) Interfacial Tension, water 10.8 11.2 12.05 10.8 10.4 9.83 (dyne/cm) Interfacial Tension, 6.55 6.75 7.1 7.15 6.55 8.33 water/methanol (4/1 v/v) (dyne/cm) in a first experiment, water was added to oil samples 5/B and B- 1.

To 50 cc of each oil sample were added 5, 10, and 20 cc of water (9 /O, 17%, and 28.5% v/v water respectively).

The resulting emulsions were permitted to stand until phase separation was observed. Severe, distinct phase separation occurred in the oil sample containing the monofunctional olefinic copolymer viscosity index improver after less than 10 days of standing (Oil B-l). See Figures lA-lD.

In a second experiment various amounts of water and water/methanol (2/1 and 4/1 v/v ratio) were added to oil samples 1-6 and the resulting emulsions permitted to stand for 64 days, then evaluated for phase separation. See Figures 2A-2D, 3A-3C, and 4A-4D. The concentrations of oil blend, water and water/methanol mixtures are shown on the Figures.

In all cases the oil sample containing the styrene-butadiene and styrene-isoprene copolymer viscosity index improvers (oil blends 3 and 4) exhibited severe phase separation. Oil samples 5 and 6 containing the multifunctional olefinic copolymer VI improver with dispersant properties uniformly, in all cases, showed superior emulsion stabilizing behavior. Oil Sample 2 showed emulsion stabilizing behavior when employed in oil-water/alcohol emulsions. Visual observation of phase separation, however, does not constitute an end to the inquiry.

Additional information regarding additive behavior is presented in Tables 3 and 4 below.

Tables 3 and 4 present compositional analysis of the separated layers observed in the emulsibility study of the six (6) oil samples listed. It is seen that the separated phases recovered from the emulsion using oil 6, the oil system containing multifunctional olefinic copolymer viscosity index modifier with dispersant properties and polymethacrylate demulsifier, exhibited the smallest difference in the water content between the top layer (oil phase) and the lower layer (aqueous phase) as well as the smallest differences in the additive distribution between the top and bottom layers in the presence of methanol (see Table 3).

Consequently, from this it is seen that, in general for water- and water/alcohol (methanol)-oil emulsions, the lubricating oil containing multifunctional olefinic copolymeric viscosity index modifier with dispersant properties resulted in stable emulsions in both systems (oils 5/B and 6). The most preferred lubricating oil contained the system containing both multifunctional olefinic copolymer viscosity index improver with dispersant properties and polymethacrylate demulsifier (oil 6).

All of the additive systems evaluated above contained magnesium sulfonate detergent (about 1.9% w/w).

EXAMPLE 2 The effect of detergent type on emulsion stability was evaluated in another series of oil samples (oils 6-12) which contained different detergents.

The composition of these oil samples is present in Table 5. The amount of detergent added was varied in oils 7- 11 so that the total base number (TBN) of the resulting formulated oil was essentially the same. Water was added to each sample in amounts of 10, 20, 30 and 40 'wit%. Similarly water/methanol (2/1 v/v) was added to fresh samples in amounts of 20, 30, 40 and 60 wtO/o.

TABLE 3 Compositional Analysis of the Fresh Oils and the Separated Layers in the Emulsibility Study: Viscosity Index Improver Effects; 70% v/v Oil, 30% v/v Water Mg Zn Water Mg Zn Water ppm ppm % w/w ppm ppm % w/w Oil 5/B 1880 1270 - Oil 6 1850 1240 - Top Layer Bottom Layer Oil 1 + water 1140 946 0.8 1220 607 67 Oil 2 + water 1130 891 2.3 1210 539 70.2 Oil 3 + water 1010 894 0.6 1450 722 58.5 Oil 4 + water 1120 958 0.7 1320 861 50 Oil 5/B + water 1210 1040 5 622 120 56.3 Oil 6 + water 1310 961 12.2 1140 509 69.5 TABLE 4 Compositional Analysis of the Fresh Oils and the Separated Layers in the Emulsibility Study: Viscosity Index Improver Effects; 70% v/v Oil, 30% v/v Water/Methanol (2/1 v/v) Mg Zn Water Mg Zn Water ppm ppm % w/w ppm ppm % w/w Oil 5/B 1880 1270 - Oil 6 1850 1240 - Top Layer Bottom Layer Oil 1 + water/methanol 1550 1210 1.3 853 320 60 Oil 2 + water/methanol 1510 1050 2.8 873 379 36.7 Oil 3 + water/methanol 1560 1190 0.6 405 2.62 70.5 Oil 4 + water/methanol N/A N/A N/A N/A N/A N/A Oil 5/B + water/methanol 1500 1090 2.1 433 2.93 71.3 Oil 6 + water/methanol 1430 988 9.7 1046 556 43 TABLE 5 - Composition (% w/w) of the Oil Blends Tested for Detergent Effects on Emulsion Stability

Designation Oil 6 Oil 7 Oil 8 Oil 9 Oil 10 Oil 11 Oil 12 S100N LP 46.709 52.342 53.342 51.520 52.144 51.809 51.809 S150N RP 31.068 28.119 28.119 27.667 28.012 27.833 27.833 Multifunctional olefinic copolymer VI 4.847 2.177 2.177 2.177 2.177 2.177 2.177 improver Low mole weight non-borated PIBSA/PAM 10.452 -- -- -- -- -- -dispersant High mole weight borated PIBSA/PAM -- 10.434 10.434 10.434 10.434 10.434 10.434 (0.23 wt% B, 0.88 wt% N) (Mg Sulfonate, 400 TBN) 1.910 1.911 -- -- -- -- - (Ca Sulfonate, 400 TBN) -- -- 1.911 -- -- -- - (Mg Phenate, 240 TBN) -- -- -- 3.185 -- -- - (Mg Salicylate, 345 TBN) -- -- -- -- 2.216 -- - (Ca Salicylate, 280 TBN) -- -- -- -- -- 2.730 - (Ca Salicylate, 64 TBN) -- -- -- -- -- -- 2.730 Other Additives * 3.986 3.987 3.987 3.987 3.987 3.987 3.987 Polymethacrylate Demulsifier 1.028 1.029 1.029 1.029 1.029 1.029 1.029 TOTAL (% w/w) 100.000 100.000 100.000 100.000 100.000 100.000 100.000 TBN (mg KOH/g) 12.30 10.99 10.95 10.81 10.69 10.52 4.85 KV @ 100 C (cSt) 10.71 10.56 10.69 11.18 11.04 10.67 10.69 * Additives included anti-wear agents, antioxidants, pour point depressants, rust inhibitors, anti-foaming agents and diluent oil.

TABLE 5 - Composition (% w/w) of the Oil Blends Tested for Detergent Effects on Emulsion Stability (continued)

Designation Oil 6 Oil 7 Oil 8 Oil 9 Oil 10 Oil 11 Oil 12 KV &commat; 40 C (cSt) 70.39 68.44 69.05 72.83 70.49 68.56 68.97 CCS &commat; -25 C (cp) 3212 3380 3717 3973 3598 3598 3687 Surface Tension, air (dyne/cm) 31.9 32.0 29.0 29.0 28.4 29.9 31.7 Interf. Tension, water (dyne/cm) 9.83 10.5 N/A 14.3 14.4 13.65 15.0 Interf. Tension, water/methanol (2/1 v/v) 8.3 9.0 N/A 10.3 10.0 9.7 10.9 (dyne/cm) ICP Analysis (ppm) B 8.6 207 213 210 203 209 210 Ca 7.3 6.7 3100 (5.6) 41.1 2750 629 Mg 1850 1960 (11) 1790 1720 19 ND < 9 P 1010 1030 1030 1100 1030 1030 1020 Zn 1240 1250 1220 1290 1220 1240 1200 Figures 5A-5D and 6A-6D provide visual evidence of the effects on emulsion stability of the different detergents tested. It is clear that the magnesium sulfonate detergent was the best performer and resulted in the most stable emulsion (oil 7).The interfacial tensions of oils 9-12 were considerably higher than those of oils 6 and 7 and 9, consistent with the pronounced instabilities observed with the oils. Inductively Coupled Plasma (ICP) elemental analysis and water concentration results from the top and bottom layers in the graduated cylinders are reported in Tables 6 and 7. The distribution of oil additives and water was more homogeneous in oils 6 and 7 which contained the magnesium sulfonate detergent and was especially apparent in oil sample 7 which contained the high molecular wt borated PIBSA/PAM (0.23 wtO/o B, 0.88 wtO/o N) dispersant.

The amount of "other additives" used was essentially identical in each sample, varying at most by 1 unit in the third decimal place.

TABLE 6 Compositional Analysis of the Separated Layers in the Emulsibility Study: Detergent Effects; 70% v/v Oil, 30% v/v Water

Top Layer Bottom Layer B Ca Mg P Zn Water B Ca Mg P Zn Water ppm ppm ppm ppm ppm % w/w ppm ppm ppm ppm ppm % w/w Oil 6 16 -- 1510 820 1120 8.09 -- -- 742 528 657 60.67 Oil 7 82 -- 1560 842 1180 11.99 96 -- 1280 772 941 22.37 Oil 8 103 2770 -- 864 1220 3.27 46 453 -- 230 195 84 Oil 9 105 -- 1190 720 1200 8.34 86 -- 943 708 1070 82 Oil 10 48 32 981 785 1090 3.52 54 34 939 763 1050 31.84 Oil 11 45 1620 -- 874 1180 0.31 66 1210 -- 558 609 40.64 Oil 12 38 344 -- 858 1230 1.99 -- 130 -- 422 409 78.21 TABLE 7 Compositional Analysis of the Separated Layers in the Emulsibility Study: Detergent Effects; 70% v/v Oil, 30% v/v Water/Methanol (2/1 v/v)

Top Layer Bottom Layer B Ca Mg P Zn Water % B Ca Mg P Zn Water % ppm ppm ppm ppm ppm w/w ppm ppm ppm ppm ppm w/w Oil 6 38 13 1420 752 1090 12.66 -- 66 1220 655 709 35.05 Oil 7 107 -- 1430 769 1110 16.01 196 -- 746 568 527 41.57 Oil 8 106 2810 -- 881 1210 0.99 161 899 -- 441 365 54.05 Oil 9 80 -- 1350 663 1290 1.26 164 -- 529 583 445 51.47 Oil 10 47 37 1290 745 1210 1.20 149 -- 249 378 214 56.51 Oil 11 38 1490 -- 807 1100 0.32 166 435 -- 461 345 53.22 Oil 12 12 355 -- 796 1220 0.29 172 174 -- 551 432 69.53 From this it can be concluded, therefore, that to achieve emulsion stability in oil/water and oil/water-alcohol environments it is preferred that an emulsion stabilizing additive combination be used consisting of magnesium sulfonate detergent in combination with multifunctional olefinic copolymeric viscosity index improver with dispersant properties, and polymethacrylate demulsifier. Optimally a high molecular weight borated PIBSA/PAM dispersant may also be included but is not essential.

Claims (6)

CLAIMS:

1. A lubricating composition comprising a major portion of a base oil of lubricating viscosity and a minor portion of an emulsion stabilizing additive mixture containing components selected from the group consisting of magnesium sulfonate detergent, a multifunctional olefinic copolymer viscosity index improver with dispersant properties and mixtures thereof and with or without a demulsifier, a dispersant and mixtures thereof, and with or without other conventional additives.

2. The lubricating composition of claim 1 wherein the magnesium sulfonate is present in an amount in the range 0.01 to 10 wt%, based on active ingredient.

3. The lubricating composition of claim 1 wherein the multifunctional olefinic copolymer viscosity index improver with dispersant properties is present in an amount in the range 0.001 to 10 wtO/o, based on active ingredient.

4. The lubricating composition of claim 1 wherein the demulsifier is a polymethacrylate demulsifier present in an amount in the range 0.01 to 3 wtO/o, based on active ingredient.

5. The lubricating composition of claim 1 wherein auxiliary dispersant is a high molecular weight borated PIBSA/PAM present in an amount in the range 0. I to 20 wtO/o, based on active ingredient.

6. An emulsion stabilizing additive mixture containing components selected from the group consisting of magnesium sulfonate detergent, a multifunctional olefinic copolymer viscosity index improver with dispersant properties and mixtures thereof, and with or without a demulsifier, a high molecular weight dispersant and mixtures thereof and with or without other conventional additives.