Antioxidant Combinations of Molybdenum Complexes and Organic Sulfur Compounds for Lubricating Oils

This invention relates to new lubricating oil additives and lubricating oil compositions prepared therefrom. More specifically, it relates to new lubricating oil compositions containing an antioxidant additive combination of a sulfur containing molybdenum compound and an organic sulfur compound.

Molybdenum disulfide has long been known as a desirable additive for use in lubricating oil compositions. However, one of its major detriments is its lack of oil solubility. Molybdenum disulfide is ordinarily finely ground and then dispersed in the lubricating oil composition to impart friction modifying and antiwear properties. Finely ground molybdenum disulfide is not an effective oxidation inhibitor in lubricating oils.

As an alternative to finely grinding the molybdenum disulfide, a number of different approaches involving preparing salts of molybdenum compounds have been tried. One type of compound which has been prepared is molybdenum dithiocarbamates. Representative compositions are described in U.S. Pat. Nos. 3,419,589, which teaches molybdenum (VI) dioxide dialkyldithiocarbamates; 3,509,051, which teaches sulfurized oxymolybdenum dithiocarbamates; and 4,098,705, which teaches sulfur containing molybdenum dihydrocarbyl dithiocarbamate compositions.

An alternative approach is to form dithiophosphates instead of dithiocarbamates. Representative of this type of molybdenum compound are the compositions described in U.S. Pat. No. 3,494,866, such as oxymolybdenum diisopropylphosphorodithioate.

U.S. Pat. No. 3,184,410 describes certain dithiomolybdenyl acetylacetonates for use in lubricating oils.

Braithwaite and Greene in Wear, 46 (1978) 405432 describe various molybdenum containing compositions for use in motor oils.

U.S. Pat. No. 3,349,108 teaches a molybdenum trioxide complex with diethylenetriamine for use as an additive for molten steel.

Russian Pat. No. 533,625 teaches lube oil additives prepared from ammonium molybdate and alkenylated polyamines.

Another way to incorporate molybdenum compounds in oil is to prepare a colloidal complex of molybdenum disulfide or oxysulfides dispersed using known dispersants. U.S. Pat. No. 3,223,625 describes a procedure in which an acidic aqueous solution of certain molybdenum compounds is prepared and then extracted with a hydrocarbon ether dispersed with an oil soluble dispersant and then freed of the ether. U.S. Pat. No. 3,281,355 teaches the preparation of a dispersion of molybdenum disulfide by preparing a mixture of lubricating oil, dispersant, and a molybdenum compound in water or C.sub.1-4 aliphatic alcohol, contacting this with a sulfide ion generator and then removing the solvent. Dispersants said to be effective in this procedure are petroleum sulfonates, phenates, alkylphenate sulfides, phosphosulfurized olefins and combinations thereof.

It has now been found that a lubricating oil additive which effectively stabilizes a lubricating oil against oxidation can be prepared by combining (a) a sulfur containing molybdenum compound prepared by reacting an acidic molybdenum compound, a basic nitrogen compound and a sulfur compound, preferably in the presence of a polar promoter, with (b) an organic sulfur compound.

More specifically, this invention is directed to a lubricating oil additive comprising a combination of

(a) an oil soluble sulfur containing molybdenum complex prepared by (1) reacting an acidic molybdenum compound and a basic nitrogen compound selected from the group consisting of a succinimide, carboxylic acid amide, Mannich base, phosphonamide, thiophosphonamide, phosphoramide, dispersant viscosity index improvers, or mixtures thereof to form a molybdenum complex wherein from 0.01 to 2 atoms of molybdenum are present per basic nitrogen atom, and (2) reacting said complex with a sulfur containing compound in an amount to provide 0.1 to 4 atoms of sulfur per atom of molybdenum, and

(b) an oil soluble organic sulfur compound or mixture thereof, wherein the organic sulfur compound of component (b) is present in an amount of from 0.02 to 10 parts by weight per part by weight of the sulfur containing molybdenum complex.

In U.S. Pat. Nos. 4,263,152 and 4,272,387, and of common inventive entity and assignee to this application, there is a teaching of a class of oil soluble sulfur containing molybdenum complexes prepared by reacting an acidic molybdenum compound, a basic nitrogen composition and a sulfur compound in the presence or absence of a polar promoter, respectively, to form molybdenum and sulfur containing complexes which are reported therein as useful for inhibiting oxidation, imparting antiwear and extreme pressure properties, and/or modifying the friction properties of a lubricating oil. It has now been discovered that lubricating oils are more effectively stabilized against oxidation when said complexes are used in combination with an organic sulfur compound. Lubricating oil compositions containing the additive combination prepared as disclosed herein are effective as either fluid and grease compositions (depending upon the specific additive or additives employed) for inhibiting oxidation, imparting antiwear and extreme pressure properties, and/or modifying the friction properties of the oil which may, when used as a crankcase lubricant, lead to improved mileage.

The precise molecular formula of the molybdenum compositions of component (a) of the combination is not known with certainty; however, they are believed to be compounds in which molybdenum, whose valences are satisfied with atoms of oxygen or sulfur, is either complexed by or the salt of one or more nitrogen atoms of the basic nitrogen containing composition used in the preparation of these compositions. These molybdenum complexes which are described in U.S. applications Ser. Nos. 52,696 and 52,699, both filed June 24, 1979 are incorporated herein by reference.

The molybdenum compounds used to prepare the sulfur containing molybdenum compounds of component (a) of this invention are acidic molybdenum compounds. By acidic is meant that the molybdenum compounds will react with a basic nitrogen compound as measured by ASTM test D-664 or D-2896 titration procedure. Typically these molybdenum compounds are hexavalent and are represented by the following compositions: molybdic acid, ammonium molybdate, molybdenum salts such as MoOCl.sub.4, MoO.sub.2 Br.sub.2, Mo.sub.2 O.sub.3 Cl.sub.6, molybdenum trioxide or similar acidic molybdenum compounds. Preferred acidic molybdenum compounds are molybdic acid, ammonium molybdate, and molybdenum trioxide. Particularly preferred are molybdic acid and ammonium molybdate.

The basic nitrogen compound must have a basic nitrogen content as measured by ASTM D-664 or D-2896. It is preferably oil-soluble. Typical of such compositions are succinimides, carboxylic acid amides, hydrocarbyl monoamines, hydrocarbon polyamines, Mannich bases, phosphonamides, thiophosphonamides, phosphoramides, dispersant viscosity index improvers, and mixtures thereof. These basic nitrogen containing compounds are described below (keeping in mind the reservation that each must have at least one basic nitrogen). Any of the nitrogen containing compositions may be after treated with e.g., boron, using procedures well known in the art so long as the compositions continue to contain basic nitrogen. These after treatments are particularly applicable to succinimides and Mannich base compositions.

The mono and polysuccinimides that can be used to prepare the lubricating oil additives described herein are disclosed in numerous references and are well known in the art. Certain fundamental types of succinimides and the related materials encompassed by the term of art "succinimide" are taught in U.S. Pat. Nos. 3,219,666; 3,172,892; and 3,272,746, the disclosures of which are hereby incorporated by reference. The term "succinimide" is understood in the art to include many of the amide, imide, and amidine species which are also formed by this reaction. The predominant product however is a succinimide and this term has been generally accepted as meaning the product of a reaction of an alkenyl substituted succinic acid or anhydride with a nitrogen containing compound. Preferred succinimides, because of their commercial availability, are those succinimides prepared from a hydrocarbyl succinic anhydride, wherein the hydrocarbyl group contains from about 24 to about 350 carbon atoms, and an ethylene amine, said ethylene amines being especially characterized by ethylene diamine, diethylene triamine, triethylene tetraamine, and tetraethylene pentamine. Particularly preferred are those succinimides prepared from polyisobutenyl succinic anhydride of 70 to 128 carbon atoms and tetraethylene pentaamine or triethylene tetraamine or mixtures thereof.

Also included within the term succinimide are the co-oligomers of a hydrocarbyl succinic acid or anhydride and a polysecondary amine containing at least one tertiary amino nitrogen in addition to two or more secondary amino groups. Ordinarily this composition has between 1,500 and 50,000 average molecular weight. A typical compound would be that prepared by reacting polyisobutenyl succinic anhydride and ethylene dipiperazine. Compositions of this type are disclosed in U.S. Ser. No. 816,063, filed July 15, 1977, now abandoned, the disclosure of which is hereby incorporated by reference.

Carboxylic amide compositions are also suitable starting materials for preparing the products of this invention. Typical of such compounds are those disclosed in U.S. Pat. No. 3,405,064, the disclosure of which is hereby incorporated by reference. These compositions are ordinarily prepared by reacting a carboxylic acid or anhydride or ester thereof, having at least 12 to about 350 aliphatic carbon atoms in the principal aliphatic chain and, if desired, having sufficient pendant aliphatic groups to render the molecule oil soluble with an amine or a hydrocarbyl polyamine, such as an ethylene amine, to give a mono or polycarboxylic acid amide. Preferred are those amides prepared from (1) a carboxylic acid of the formula R.sup.2 COOH, where R.sup.2 is C.sub.12-20 alkyl or a mixture of this acid with a polyisobutenyl carboxylic acid in which the polyisobutenyl group contains from 72 to 128 carbon atoms and (2) an ethylene amine, especially triethylene tetraamine or tetraethylene pentaamine or mixtures thereof.

Another class of compounds useful for supplying basic nitrogen are the Mannich base compositions. These compositions are prepared from a phenol of C.sub.9-200 alkylphenol, an aldehyde, such as formaldehyde or formaldehyde precursor such as paraformaldehyde, and an amine compound. The amine may be a mono or polyamine and typical compositions are prepared from an alkylamine, such as methylamine or an ethylene amine, such as, diethylene triamine, or tetraethylene pentaamine and the like. The phenolic material may be sulfurized and preferably is a C.sub.80-100 alkylphenol, dodecylphenol or a C.sub.8-10 alkylphenol. Typical Mannich bases which can be used in this invention are disclosed in U.S. Pat. Nos. 4,157,309 and 3,649,229; 3,368,972; and 3,539,663, the disclosures of which are hereby incorporated by reference. The last application discloses Mannich bases prepared by reacting an alkylphenol having at least 50 carbon atoms, preferably 50 to 200 carbon atoms with formaldehyde and an alkylene polyamine HN(ANH).sub.n H where A is a saturated divalent alkyl hydrocarbon of 2 to 6 carbon atoms and n is 1-10 and where the condensation product of said alkylene polyamine may be further reacted with urea or thiourea. The utility of these Mannich bases as starting materials for preparing lubricating oil additives can often be significantly improved by treating the Mannich base using conventional techniques to introduce boron into the composition.

Another class of composition useful for preparing the additives of this invention are the phosphoramides and phosphonamides such as those disclosed in U.S. Pat. Nos. 3,909,430 and 3,968,157 the disclosures of which are hereby incorporated by reference. These compositions may be prepared by forming a phosphorus compound having at least one P--N bond. They can be prepared, for example, by reacting phosphorus oxychloride with a hydrocarbyl diol in the presence of a monoamine or by reacting phosphorus oxychloride with a difunctional secondary amine and a monofunctional amine. Thiophosphoramides can be prepared by reacting an unsaturated hydrocarbon compound containing from 2 to 450 or more carbon atoms, such as polyethylene, polyisobutylene, polypropylene, ethylene, 1hexene, 1,3-hexadiene, isobutylene, 4-methyl-1-pentene, and the like, with phosphorus pentasulfide and nitrogen containing compound as defined above, particularly an alkylamine, alkyldiamine, alkylpolyamine, or an alkyleneamine, such as ethylene diamine, diethylene triamine, triethylene tetraamine, tetraethylene pentaamine, and the like.

Another class of nitrogen containing compositions useful in preparing the molybdenum compositions of this invention includes the socalled dispersant viscosity index improvers (VI improvers). These VI improvers are commonly prepared by functionalizing a hydrocarbon polymer, especially a polymer derived from ethylene and/or propylene, optionally containing additional units derived from one or more comonomers such as alicyclic or aliphatic olefins or diolefins. The functionalization may be carried out by a variety of processes which introduce a reactive site or sites which usually has at least one oxygen atom on the polymer. The polymer is then contacted with a nitrogen containing source to introduce nitrogen containing functional groups on the polymer backbone. Commonly used nitrogen sources include any basic nitrogen compound especially those nitrogen containing compounds and compositions described herein. Preferred nitrogen sources are alkylene amines, such as ethylene amines, alkyl amines, and Mannich bases.

Preferred basic nitrogen compounds for use in this invention ae succinimides, carboxylic acid amides, and Mannich bases.

The sulfur sources used to prepare the oil soluble sulfur containing molybdenum complexes of component (a) are sulfur compounds which are reactive with the intermediate molybdenum complex prepared from the acidic molybdenum compound and the basic nitrogen compound and capable of incorporating sulfur into the final product.

Representative sulfur sources used to prepare the molybdenum complexes of component (a) are sulfur, hydrogen sulfide, sulfur monochloride, sulfur dichloride, phosphorus pentasulfide, alkyl and aryl sulfides and polysulfides of the formula R.sub.2 S.sub.x where R is hydrocarbyl, preferably C.sub.1-40 alkyl, and x is at least 2, inorganic sulfides and polysulfides such as (NH.sub.4).sub.2 S.sub.x, where x is at least 1, thioacetamide, thiourea, and mercaptans of the formula RSH where R is as defined above. Also useful as sulfurizing agents are traditional sulfur-containing anti-oxidants such as wax sulfides and polysulfides, sulfurized olefins, sulfurized carboxylic acid esters, sulfurized ester-olefins, sulfurized alkylphenols and the metal salts thereof, and the reaction product of an olefin and sulfurized alkylphenol.

The sulfurized carboxylic acid esters are prepared by reacting sulfur, sulfur monochloride, and/or sulfur dichloride with an unsaturated ester under elevated temperatures. Typical esters include C.sub.1 -C.sub.20 alkyl esters of C.sub.3 -C.sub.24 unsaturated acids, such as palmitoleic, oleic, ricinoleic, petroselinic, vaccenic, linoleic, linolenic, oleostearic, licanic, paranaric, tariric, gadoleic, arachidonic, cetoleic, fatty acids, as well as the other unsaturated acids such as acrylic, crotonic, etc. Particularly good results have been obtained with mixed unsaturated fatty acid esters, such as are obtained from animal fats and vegetable oils, such as tall oil, linseed oil, olive oil, caster oil, peanut oil, grape oil, fish oil, sperm oil, and so forth.

Exemplary esters include lauryl tallate, methyl oleate, ethyl oleate, lauryl oleate, cetyl oleate, cetyl linoleate, lauryl ricinoleate, oleyl linoleate, lauryl acrylate, styryl acrylate, 2-ethylhexyl acrylate, oleyl stearate, and alkyl glycerides.

Cross-sulfurized ester olefins, such as a sulfurized mixture of C.sub.10 -C.sub.25 olefins with fatty acid esters of C.sub.10 -C.sub.25 fatty acids and C.sub.1 -C.sub.25 alkyl or alkenyl alcohols, wherein the fatty acid and/or the alcohol is unsaturated may also be used.

Sulfurized olefins are prepared by the reaction of the C.sub.3 -C.sub.6 olefins or a low-molecular-weight polyolefin derived therefrom or C.sub.8 -C.sub.24 olefins with a sulfur-containing compound such as sulfur, sulfur monochloride, and/or sulfur dichloride. Particularly preferred are the sulfurized olefins described in U.S. Pat. No. 4,132,659 which is incorporated herein by reference.

Particularly useful are the diparaffin wax sulfides and polysulfides, cracked wax-olefin sulfides and so forth. They can be prepared by treating the starting material, e.g., olefinically unsaturated compounds, with sulfur, sulfur monochloride, and sulfur dichloride. Most particularly preferred are the paraffin wax thiomers described in U.S. Pat. No. 2,346,156.

Sulfurized alkylphenols and the metal salts thereof include compositions such as sulfurized dodecylphenol and the calcium salts thereof. The alkyl group ordinarily contains from 9-300 carbon atoms. The metal salt may be preferably, a group I or group II salt, especially sodium, calcium, magnesium, or barium.

The reaction product of a sulfurized alkylphenol and cracked wax olefin is described in U.S. Pat. No. 4,228,022 which is incorporated herein by reference. The alkyl group present in the alkylphenol preferably contains from 8 to 35 carbon atoms and preferably the olefin contains from 10 to 30 carbon atoms.

Preferred sulfur sources for preparing the molybdenum complexes of component (a) of the combination are sulfur, hydrogen sulfide, phosphorus pentasulfide, R.sub.2 S.sub.x where R is hydrocarbyl, preferably C.sub.1-10 alkyl, and x is at least 3, mercaptans wherein R is C.sub.1-10 alkyl, inorganic sulfides and polysulfides, thioacetamide, and thiourea. Most preferred sulfur sources are sulfur, hydrogen sulfide, phosphorus pentasulfide, and inorganic sulfides and polysulfides.

The polar promoter which is preferably used to prepare the molybdenum complex of component (a) of this invention is one which facilitates the interaction between the acidic molybdenum compound and the basic nitrogen compound. A wide variety of such promoters are well known to those skilled in the art. Typical promoters are 1,3-propanediol, 1,4-butanediol, diethyleneglycol, butyl cellosolve, propylene glycol, 1,4-butyleneglycol, methyl carbitol, ethanolamine, diethanolamine, N-methyl-diethanol-amine, dimethyl formamide, N-methyl acetamide, dimethyl acetamide, methanol, ethylene glycol, dimethyl sulfoxide, hexamethyl phosphoramide, tetrahydrofuran and water. Preferred are water and ethylene glycol. Particularly preferred is water.

While ordinarily the polar promoter is separately added to the reaction mixture, it may also be present, particularly in the case of water, as a component of nonanhydrous starting materials or as water of hydration in the acidic molybdenum compound, such as (NH.sub.4).sub.6 Mo.sub.7 O.sub.24.4H.sub.2 O. Water may also be added as ammonium hydroxide.

A method for preparing the molybdenum complex of component (a) of this invention is to prepare a solution of the acidic molybdenum precursor and a basic nitrogen-containing compound preferably in the presence of a polar promoter with or without diluent. The diluent is used, if necessary, to provide a suitable viscosity for easy stirring. Typical diluents are lubricating oil and liquid compounds containing only carbon and hydrogen. If desired, ammonium hydroxide may also be added to the reaction mixture to provide a solution of ammonium molybdate. This reaction is carried out at a temperature from the melting point of the mixture to reflux temperature. It is ordinarily carried out at atmospheric pressure although higher or lower pressures may be used if desired. This reaction mixture is treated with a sulfur source as defined above at a suitable pressure and temperature for the sulfur source to react with the acidic molybdenum and basic nitrogen compounds. In some cases, removal of water from the reaction mixture may be desirable prior to completion of reaction with the sulfur source.

In the reaction mixture, the ratio of molybdenum compound to basic nitrogen compound is not critical; however, as the amount of molybdenum with respect to basic nitrogen increases, the filtration of the product becomes more difficult. Since the molybdenum component probably oligomerizes, it is advantageous to add as much molybdenum as can easily be maintained in the composition. Usually, the reaction mixture will have charged to it from 0.01 to 2.00 atoms of molybdenum per basic nitrogen atom. Preferably from 0.4 to 1.0, and most preferably from 0.4 to 0.7, atoms of molybdenum per atom of basic nitrogen is added to the reaction mixture.

The sulfur source is usually charged to the reaction mixture in such a ratio to provide 0.1 to 4.0 atoms of sulfur per atom of molybdenum. Preferably from 0.5 to 3.0 atoms of sulfur per atom of molybdenum is added, and most preferably, 1.0 to 2.6 atoms of sulfur per atom of molybdenum.

The polar promoter, which is optionally and preferably used, is ordinarily present in the ratio of 0.1 to 50 mols of promoter per mol of molybdenum compound. Preferably from 0.5 to 25 and most preferably 1.0 to 15 mols of the promoter is present per mol of molybdenum compound.

Representative of the organic sulfur compounds of component (b) which may be used in combination with the molybdenum complex of component (a) include the same type of organic sulfur compounds used to prepare the molybdenum complexes, as well as metal dihydrocarbyl dithiophosphates, metal dithiocarbamates, phosphosulfurized terpenes, and hydrocarbyl mono- and disulfides.

The metal hydrocarbyl dithiophosphates may be represented generally by the formula ##STR1## wherein R.sub.1 and R.sub.2 may be the same or different hydrocarbyl radicals containing from 1 to 18 carbon atoms and preferably 2 to 12 carbon atoms including radicals such as alkyl, alkenyl, aryl, aralkyl, alkaryl and cycloaliphatic radicals. Thus, the radicals R.sub.1 and R.sub.2 may, for example, be ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, n-hexyl, 2-ethylhexyl, octadecyl, phenyl, benzyl, butylphenyl, cyclohexyl, propenyl, butenyl, etc.

M is a Group I metal, a Group II metal, aluminum, tin, cobalt, lead, molybdenum, manganese or nickel, and m is an integer which is equal to the valence of the metal M. Preferably M is zinc.

These compounds can be prepared by the reaction of a suitable alcohol or mixture of alcohols with phosphorus pentasulfide followed by reaction with the appropriate metal compound. Methods to prepare these compounds are described in U.S. Pat. Nos. 3,083,850; 3,102,096; 3,293,181; and 3,489,682 and the disclosures thereof are incorporated herein by reference.

The phosphorosulfurized terpenes as represented by pinene, dipenene, allo-ocimene, etc., are another group of dithiophosphate diesters which are active sulfur donors. Of the terpenes, the bicyclic pinene is preferred. The phosphosulfurized terpene is readily obtained by reaction of about one mole of diester of thiophosphoric acid and one mole of pinene at a temperature of at least 100.degree. C., e.g. 100.degree. C. to 200.degree. C. The preferred active sulfur donor can be characterized as the bornyl ester of dihydrocarbyl (C.sub.2 -C.sub.20) dithiophosphoric acids (as shown in U.S. Pat. No. 2,689,258).

The metal dithiocarbamates made by methods well known in the art have the following general formula ##STR2## wherein R.sub.3 and R.sub.4 may be the same or different hydrocarbyl radicals containing 1 to 30 carbon atoms and preferably 1 to 12 carbon atoms, including such radicals as alkyl, alkenyl, aryl, aralkyl, and alkaryl, M is a metal of the group consisting of alkali and alkaline earth metals, aluminum, nickel, lead, cobalt, molybdenum, manganese and tin, and n is a subscript of corresponding to the valance M.

The hydrocarbyl sulfides may be represented generally by the formula

wherein R.sub.5 and R.sub.6 are the same or different hydrocarbyl radical each containing from 1 to 40 carbon atoms and preferably 1 to 20 carbon atoms, including radicals such as alkyl, alkenyl, aryl, aralkyl, alkaryl. Thus, the radicals R.sub.5 and R.sub.6 may, for example, be ethyl, propyl, n-hexyl, decyl, dodecyl, octadecyl, eicosyl, phenyl, benzyl, phenylethyl, butylphenyl, propenyl, butenyl, etc. and y is 1 or 2.

Preferred organic sulfur compounds which may be used in combination with the molybdenum complex of component (a) are metal dihydrocarbyl dithiophosphates, metal dithiocarbamates, sulfurized olefins, alkyl and aryl sulfides, alkyl and aryl polysulfides, sulfurized fatty acids, sulfurized alkylphenols, the reaction product of an olefin and sulfurized alkylphenol and phosphosulfurized terpenes. Most preferred are the alkyl and aryl sulfides and the reaction product of an olefin and sulfurized alkylphenol.

The lubricating oil compositions containing the additives of this invention can be prepared by admixing, by conventional techniques, the appropriate amount of the sulfur containing molybdenum complex of component (a) and the organic sulfur compound of component (b) with a lubricating oil. The selection of the particular base oil depends on the contemplated application of the lubricant and the presence of other additives. Generally, the amount of the combined additives of components (a) and (b) will vary from 0.05 to 15% by weight and preferably from 0.2 to 10% by weight.

The lubricating oil which may be used in this invention includes a wide variety of hydrocarbon oils, such as naphthenic bases, paraffin bases and mixed base oils as well as synthetic oils such as esters and the like. The lubricating oils may be used individually or in combination and generally have a viscosity which ranges from 50 to 5,000 SUS and usually from 100 to 15,000 SUS at 38.degree. C.

In many instances it may be advantageous to form concentrates of the combination of additives within a carrier liquid. These concentrates provide a convenient method of handling and transporting the additives before their subsequent dilution and use. The concentration of the additive combination within the concentrate may vary from 0.25 to 90% by weight although it is preferred to maintain a concentration between 1 and 50% by weight. The final application of the lubricating oil compositions of this invention may be in marine cylinder lubricants as in crosshead diesel engines, crankcase lubricants as in automobiles and railroads, lubricants for heavy machinery such as steel mills and the like, or as greases for bearings and the like. Whether the lubricant is fluid or a solid will ordinarily depend on whether a thickening agent is present. Typical thickening agents include polyurea acetates, lithium stearate and the like.

If desired, other additives may be included in the lubricating oil compositions of this invention. These additives include antioxidants or oxidation inhibitors, dispersants, rust inhibitors, anticorrosion agents and so forth. Also antifoam agents stabilizers, antistain agents, tackiness agents, antichatter agents, dropping point improvers, antisquawk agents, extreme pressure agents, odor control agents and the like may be included.

The following examples are presented to illustrate the operation of the invention and are not intended to be a limitation upon the scope of the claims.

To a 1-liter flask were added 290 grams of a solution of 45% concentration in oil of the succinimide prepared from polyisobutenyl succinic anhydride and tetraethylene pentaamine and having a number average molecular weight for the polyisobutenyl group of about 980, and 150 ml hydrocarbon thinner. The mixture was heated to 65.degree. C. and 28.8 grams molybdenum trioxide, and 50 ml water were added. The temperature was maintained at 65.degree. C. for 1/2 hour and increased to 150.degree. C. over a period of 55 minutes. To the mixture was added 7 grams elemental sulfur and 100 ml of hydrocarbon thinner. The reaction mixture was maintained at reflux at approximately 155.degree. C. for 45 minutes and then the temperature was increased to 165.degree. to 170.degree. C. and held there for two hours. To the mixture was added 50 ml of hydrocarbon thinner and the reaction mixture was filtered hot through diatomaceous earth. The filtrate was stripped to 160.degree. C. at 20 mm Hg to yield 316.5 grams of product containing 6.35% molybdenum, 3.57% oxygen, 1.86% nitrogen, 2.15% sulfur.

To a 3-liter flask were added 1160 grams of a polyamide prepared from a C.sub.18 carboxylic acid and tetraethylenepentaamine and containing 6.29% nitrogen and 800 ml hydrocarbon thinner. The mixture was heated to 65.degree. C. and 200 ml of water and 116 grams MoO.sub.3 was added. The temperature was raised to reflux, approximately 95.degree. C., and held at this temperature for 4 hours until the solution became clear green. The solvent was removed to 150.degree. C. maximum and the mixture was then cooled to 140.degree. C. and 28 grams sulfur was added. The temperature was raised to 155.degree. C. over a period of 1/4 hour and held at this temperature for 1/2 hour. The temperature was again increased to 175.degree. C. over a period of 20 minutes and then held at between 175.degree. C. and 180.degree. C. for 2 hours. The mixture was cooled and left overnight and then 200 ml hydrocarbon solvent was added. The mixture was heated to 130.degree. C., filtered through diatomaceous earth and then stripped to 180.degree. C. bottoms at 20 mm Hg to yield 1282 grams of product containing 5.45% nitrogen, 2.15% sulfur, 5.51% molybdenum, and 5.73% oxygen.

To a 1-liter flask were added 290 grams of a Mannich base prepared from dodecylphenol, methylamine and formaldehyde and having an alkalinity value of 110 and containing 2.7% nitrogen, and 200 ml of a hydrocarbon thinner. The mixture was heated to 65.degree. C. and 50 ml water and 29 grams of molybdenum trioxide were added. The mixture was stirred at reflux, 104.degree. to 110.degree. C., for 41/2 hours. The solution became a clear dark brown color and then was stripped to 175.degree. C. bottoms. The mixture was cooled to 140.degree. C. and 7 grams sulfur was added. The temperature was increased to 155.degree. C. over a period of 7 minutes and held at this temperature for 1/2 hour. The temperature was then increased to 180.degree. C. over a period of 10 minutes and held for 2 hours. The mixture was then cooled and left overnight. The next day 100 ml of hydrocarbon solvent was added. The mixture was heated to 100.degree. C. and filtered through diatomaceous earth and then stripped to 180.degree. C. at 20 mm Hg to yield 317 grams of product.

To a 1-liter flask containing 300 g of a borated Mannich base prepared from a C.sub.80-100 alkylphenol, formaldehyde and tetraethylene pentaamine or triethylene tetraamine, or mixtures thereof and containing urea (Amoco 9250) and 200 ml hydrocarbon thinner at 65.degree. C. were added 40 ml water and 25 g MoO.sub.3. The mixture was stirred at reflux for 4.5 hours and then stripped to 165.degree. C. After cooling to 140.degree. C., 7 g sulfur was added and the temperature was gradually increased to 185.degree. C. where it was held for 2 hours. Then, 75 ml hydrocarbon thinner was added and the mixture was filtered through diatomaceous earth and then stripped to 180.degree. C. at 20 mm Hg to yield 307 g product containing N, 1.04%; S, 2.53%; Mo, 4.68% Neutron Activation (N.A.), 4.99% X-Ray Fluorescence Spectroscopy (XRF); O, 2.53%; B, 0.22%.

To a 3-liter flask were added 500 g of a concentrate of polyisobutenyl succinic anhydride wherein the polyisobutenyl group had a number average molecular weight of about 980 and 36 g dimethyl aminopropylamine. The temperature of the reaction mixture was increased to 160.degree. C., held there for 1 hour and then stripped to 170.degree. C. at 20 mm Hg. To this mixture were added 350 ml hydrocarbon thinner, 50 ml water, and 29 g MoO.sub.3. This mixture was stirred at reflux for 2 hours and then stripped to 140.degree. C. to remove water. Then 7 g of sulfur was added and the mixture was held at 180.degree.-185.degree. C. for 2 hours. After cooling, additional hydrocarbon thinner was added and the mixture was filtered through diatomaceous earth, and then stripped to 180.degree. C. at 20 mm Hg to yield 336 g product containing N, 1.17%; S, 1.55%; Mo, 3.37% (N.A.), 3.31% (XRF); O, 2.53%.

To a 1-liter flask containing 290 g of the succinimide described in Example 1 and 200 ml of hydrocarbon thinner at 65.degree. C. were added 50 ml water and 29 g MoO.sub.3. The mixture was stirred at reflux for 1.5 hours and then stripped to 165.degree. C. to remove water. After cooling to 100.degree. C., 40 g butyldisulfide was added and the mixture was heated to 180.degree.-185.degree. C. for 2.5 hours. Then an additional 100 ml hydrocarbon thinner was added before filtering through diatomaceous earth and stripping to 180.degree. C. at 20 mm Hg to yield 305 g of product containing N, 1.90%; S, 0.47%; Mo, 6.21% (N.A.), 6.34% (XRF); O, 4.19 (N.A.).

To a 1-liter flask containing 290 g of the succinimide described in Example 1 and 200 ml hydrocarbon thinner at 75.degree. C. were added 50 ml water and 29 g MoO.sub.3. The mixture was refluxed for 1.5 hours and then stripped to 200.degree. C. to remove water. After cooling to 100.degree. C., 19 g thioacetamide was added and the mixture was gradually heated to 200.degree. C. where it was held for 0.75 hour. Then, 150 ml hydrocarbon thinner was added and the mixture was filtered through diatomaceous earth and stripped to 180.degree. C. at 20 mm Hg, to yield a product containing N, 1.46%; S, 2.05%; Mo, 4.57% (N.A.), 4.70% (XRF); O, 2.38%. Before testing, this product was diluted with 100 g neutral lubricating oil.

To a 1-liter flask containing 290 g of a solution of 45% concentrate in oil of the succinimide prepared from polyisobutenyl succinic anhydride and tetraethylene pentaamine and having a number average molecular weight for the polyisobutenyl group of about 980 and 200 ml hydrocarbon thinner at 75.degree. C. was added 50 ml water and 29 g MoO.sub.3. The mixture were stirred at reflux for 1.5 hours and then heated to 187.degree. C. to remove water. Then 100 ml hydrocarbon thinner was added and, at 75.degree. C., 34 g of aqueous ammonium polysulfide (31% free sulfur). This mixture was slowly heated to 180.degree. C. and held there for 2.25 hours. It was then filtered through diatomaceous earth and stripped to 180.degree. C. at 20 mm Hg to yield 318 g of product containing N, 1.89%; S, 4.07%; Mo, 6.16% (N.A.).

To a 1-liter flask containing 290 g of the succinimide described in Example 1 and 200 ml hydrocarbon thinner at 75.degree. C. were added 50 ml water and 29 g MoO.sub.3. The mixture was stirred at 96.degree.-98.degree. C. for 21/2 hours and then stripped at 191.degree. C. After cooling to 75.degree. C., 43 ml 1-butanethiol was added and the mixture was refluxed for 14 hours. The mixture was then stripped to 180.degree. C. at 20 mm Hg to yield 318 g product containing Mo, 6.17% (XRF); N, 1.97%; S, 1.05%.

The oxidation stability of lubricating oil compositions containing the additive combination prepared according to this invention were tested in an Oxidator B Test. According to this test, the stability of the oil is measured by the time in hours required for the consumption of 1 liter of oxygen by 100 grams of the test oil at 340.degree. F. In actual test, 25 grams of oil is used and the results are corrected to 100-gram samples. The catalyst which is used at a rate of 1.38 cc per 100 cc oil contains a mixture of soluble salts providing 95 ppm copper, 80 ppm iron, 4.8 ppm manganese, 1100 ppm lead and 49 ppm tin. The results of this test are reported as hours to consumption of 1 liter of oxygen and is a measure of the oxidative stability of the oil.

Formulation A tested contained in a neutral lubricating oil, 30 m moles/kg overbased magnesium sulfonate, 20 m moles/kg overbased sulfurized calcium alkyl phenate, 3.5% of a 50% concentrate of polyisobutenyl succinimide and 5.5% polymethacrylate V.I. improver.

Formulation B tested contained in a neutral lubricating oil, 1.5% of a 50% concentrate of a polyisobutenyl succinimide, 8 m moles/kg dialkyl zinc dithiophosphate from sec-butanol and methylisobutylcarbinol, 30 m moles/kg overbased magnesium sulfonate, 20 m moles/kg overbased sulfurized calcium alkyl phenate and 5.5% polymethacrylate V.I. improver.

Formulation C--contained only a heavy white oil.

In a similar manner, when the molybdenum complexes of Examples 2 through 9 are substituted for the molybdenum complex of Example 1 in the above test, the oxidation stability of the oil formulations containing the combinations of this invention are enhanced as compared to the oil formulations not containing the additive combination.

Formulated oil containing the additives shown in Table 2 were prepared and tested in a Sequence IIID test method (according to ASTM Special Technical Publication 315H). The Formulations were prepared by adding each of the components directly to the oil with stirring.

The purpose of the test is to determine the effect of the additives on the oxidation rate of the oil in an internal combustion engine at relatively high temperatures (about 149.degree. C. bulk oil temperature during testing).

In this test, an Oldsmobile 350 CID engine was run under the following conditions:

Runs at 3,000 RPM/max. run time for 64 hours and 100 lb load;

Air/fuel* ratio=16.5/1, using *GMR Reference fuel (leaded);

Timing=31.degree. BTDC;

Oil temperature=300.degree. F.;

Coolant temperature in=235.degree. F.--out 245.degree. F.;

30" of water of back pressure on exhaust;

Flow rate of jacket coolant=60 gal/min.;

Flow rate of rocker cover coolant=3 gal/min.;

Humidity must be kept at 80 grains of H.sub.2 O;

Air temperature controlled equal inlet equal 80.degree. F.;

Blowby Breather Heat exchanger at 100.degree. F.

The effectiveness of the additive is measured after 64 hours in terms of the viscosity increase.

The comparisons were made in a formulated base neutral oil containing 30 m moles/kg of a calcium sulfonate, 20 m moles/kg of a calcium phenate and 5.5% of a polymethacrylate V.I. improver.