Patent ID: 12203045

BEST MODE FOR CARRYING OUT THE INVENTION

Additives in the Additive Blend According to the Present Invention

The additive blend (or additive package) according to the present invention is a blend for treatment of industrial and automotive lubricants, which comprises—in addition to the base oil—a combination of different additives such as antioxidants, antiwear additives, dispersants, ashless (metal free) polymeric materials, detergents, antifoam additives, viscosity index improvers, copper passivators, rust inhibitors, pour point depressants, demulsifiers and friction modifiers. The mixture of alkylated diphenylamines of the structural formula (I), (II), (III), and (IV) according to the present invention, preferably the mixture of alkylated diphenylamines of the structural formula (I), (II), (III), and (IV) in which R is a branched residue having the formula —C9H19, may thus by a part of such an additive package.

Suitable antioxidants in the additive blend which can be present in addition to the mixture of alkylated diphenylamines of the structural formula (I); (II), (III), and (IV), preferably in addition to the mixture alkylated diphenylamines of the structural formula (I), (II), (III), and (IV) in which R is a branched residue having the formula —C9H19, are selected from:1) Alkylated monophenols, for example 2,6-di-tert-butyl-4-methylphenol, 2-butyl-4,6-di-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-iso-butylphenol, 2,6-di-cyclopentyl-4-methylphenol, 2-(a-methyl-cyclo-hexyl)-4,6-dimethylphenol, 2,6-di-octadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, linear or side chain-branched nonylphenols, for example 2,6-dinonyl-4-methylphenol, 2,4-dimethyl-6-(1′-methyl-undec-1′-yl)phenol, 2,4-dimethyl-6-(1′-methylheptadec-1′-yl)phenol, 2,4-dimethyl-6-(1′-methyltridec-1′-yl)-phenol or mixtures thereof;2) Alkylthiomethylphenols, for example 2,4-di-octylthiomethyl-6-tert-butylphenol, 2,4-di-octylthiomethyl-6-methylphenol, 2,4-di-octylthiomethyl-6-ethylphenol or 2,6-di-dode-cylthiomethyl-4-nonylphenol;3) Hydroquinones and alkylated hydroquinones, for example 2,6-di-tert-butyl-4-methoxy-phenol, 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octadecyloxyphenol, 2,6-di-tert-butyl-hydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenyl stearate or bis(3,5-di-tert-butyl-4-hydroxyphenyl)adipate;4) Tocopherols, for example a-, b-, γ-or δ-tocopherol or mixtures thereof (vitamin E);5) Hydroxylated thiodiphenyl ethers, for example 2,2′-thiobis(6-tert-butyl-4-methylphe-nol), 2,2′-thiobis(4-octylphenol), 4,4′-thiobis(6-tert-butyl-3-methylphenol), 4,4′-thiobis-(6-tert-butyl-2-methylphenol), 4,4′-thiobis(3, 6-di-sec.-amylphenol) or 4,4′-bis(2,6-di-methyl-4-hydroxyphenyl)disulfide;6) Alkylidenebisphenols, for example 2,2′-methylenebis (6-tert-butyl-4-methylphenol), 2,2′-methylenebis(6-tert-butyl-4-ethylphenol), 2,2′-methylenebis(4-methyl-6-(a-methyl-cyclohexyl)-phenol), 2,2′-methylenebis(4-methyl-6-cyclohexylphenol), 2,2′-methylene-bis-(6-nonyl-4-methylphenol), 2,2′-methylenebis(4,6-di-tert-butylphenol), 2,2′-ethylidene-bis(4,6-di-tert-butylphenol), 2,2′-ethylidenebis(6-tert-butyl-4-isobutylphenol), 2,2′-methylenebis(6-(a-methylbenzyl)-4-nonylphenol), 2,2′-methylene-bis(6-(a,a-dimethylben-zyl)-4-nonylphenol), 4,4′-methylenebis(2,6-di-tert-butylphenol), 4,4′-methylene-bis(6-tert-butyl-2-methylphenol), 1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-butane, 2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-3-n-dodecylmercaptobutane, ethylene glycol bis(3,3-bis(3′-tert-butyl-4′-hydroxyphenyl)butyrate), bis(3-tert-butyl-4-hydroxy-5-methylphenyl)dicyclopentadiene, bis(2-(3′-tert-butyl-2′-hydroxy-5′-methylbenzyl)-6-tert-butyl-4-methylphenyl)terephth alate, 1,1-bis(3,5-dimethyl-2-hydroxyphenyl)butane, 2,2-bis(3,5-di-tert-butyl-4-hydroxyphenyl)propane, 2,2-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmercaptobutane or 1,1,5,5-tetra(5-tert-butyl-4-hydroxy-2-methylphenyl)-pentane;7) O—, N— and S-benzyl compounds, for example 3,5,3′,5′-tetra-tert-butyl-4,4′-dihydroxy-dibenzyl ether, octadecyl 4-hydroxy-3,5-dimethylbenzylmercaptoacetate, tridecyl 4-hydroxy-3,5-di-tert-butylbenzylmercaptoacetate, tris(3,5-di-tert-butyl)amine, bis(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate, bis(3,5-di-tert-butyl-4-hydroxy-benzyl)sulfide or isooctyl 3,5-di-tert-butyl-4-hydroxy-benzylmercaptoacetate;8) Hydroxybenzylated malonates, for example dioctadecyl 2,2-bis(3,5-di-tert-butyl-2-hy-droxybenzyl)malonate, dioctadecyl 2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)-malo-nate, d-dodecyl mercaptoethyl-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-malonate, or di(4-(1,1,3,3-tetramethylbutyl)phenyl)-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malo nate;9) Aromatic hydroxybenzyl compounds, for example 1,3,5-tris(3,5-di-tert-butyl-4-hydroxy-benzyl)-2,4,6-trimethylbenzene, 1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene or 2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol;10) Triazine compounds, for example 2,4-bisoctylmercapto-6-(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,3,5-triazine, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,2,3-triazine, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris(4-tert-butyl-3-hydroxy-2, 6-dimethylbenzyl)isocyanurate, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenylethyl)-1,3,5-triazine, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hexahydro-1,3,5-triazine or 1,3,5-tris-(3,5-dicyclohexyl-4-hydroxybenzyl)-isocyanurate;11) Benzylphosphonates, for example dimethyl 2,5-di-tert-butyl-4-hydroxybenzyl-phosphonate, diethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl 5tert-butyl-4-hydroxy-3-methylbenzyl-phosphonate, or the calcium salt of the monoethyl ester of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid;12) Acylaminophenols, for example 4-hydroxylauranilide, 4-hydroxystearanilide, or octyl N-(3, 5-di-tert-butyl-4-hydroxyphenyl) carbamate;13) Esters of b-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid, b-(5-tert-butyl)-4-hydroxy-3-methylphenyl) propionic acid, b-(3, 5-dicyclohexyl-4-hydroxyphenyl)-propionic acid, 3,5-di-tert-butyl-4-hydroxyphenylacetic acid, or b-(5-tert-butyl)-4-hydroxypheny))-3-thiabutyric acid with mono- or polyhydric alcohols, e. g. with methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl) isocyanurate, N,N′-bis(hydroxyethyl) oxalamide, 3-thiaundecanol, 3-thiapentadecanol, trimethyl-hexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo(2.2.2)octane, glycerol, or transesterification products based on natural triglycerides of, for example, coconut oil, rape seed oil, sunflower oil, or colza oil;14) Amides of b-(3, 5-di-tert-butyl-4-hydroxyphenyl)propionic acid, e. g. N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hexamethylenediamine, N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)trimethylenediamine, or N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazine;15) Ascorbic acid (vitamin C);16) Amine-type antioxidants, for example N,N′-diisopropyl-p-phenylenediamine, N,N′-di-sec-butyl-p-phenylenediamine, N,N′-bis(1,4-dimethylpentyl)-p-phenylenediamine, N,N′-bis(1-ethyl-3-methyl-pentyl)-p-phenylenediamine, N,N′-bis(1-methyl-heptyl)-p-pheny-lenediamine, N,N′-dicyclohexyl-p-phenylenediamine, N,N′-diphenyl-p-phenylenediamine, N,N′-di-(naphth-2-yl)-p-phenylenediamine, N-isopropyl-N′-phenyl-p-phenylene-diamine, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, N-(1-methylheptyl)-N′-phenyl-p-phenylenediamine, N-cyclohexyl-N′-phenyl-p-phenylenediamine, 4-(p-toluenesulfonamido)diphenylamine, N,N′-dimethyl-N,N′-di-sec-butyl-p-phenylenediamine, diphenylamine, N-allyldiphenylamine, 4-isopropoxy-diphenylamine, N-phenyl- 1-naphthylamine, N-(4-tert-octylphenyl)-1-naphthylamine, N-phenyl-2-naphthylamine, octylated diphenylamine, e. g. p,p′-di-tert-octyldiphenylamine, 4-n-butylaminophenol, 4-butyrylaminophenol, 4-nonanoylaminophenol, 4-dodecanoylaminophenol, 4-octadecanoylaminophenol, di-(4-methoxyphenyl)-amine, 2,6-di-tert-butyl-4-dimethylamino-me-thylphenol, 2,4′-diamino-diphenylmethane, 4,4′-diamino-diphenylmethane, N,N,N′,N′-tetramethyl-4,4′-diamino-diphenylmethane, 1,2-di-((2-methyl-phenyl)-amino)ethane, 1,2-di-(phenylamino)propane, (o-tolyl)biguanide, di(4-(1′,3′-dimethyl-butyl)-phenyl)amine, tert-octylated N-phenyl-1-naphthylamine, a mixture of mono- and dialkylated tert-butyl/tert-octyldiphenylamines, a mixture of mono- and dialkylated nonyldiphenylamines, a mixture of mono- and dialkylated dodecyldiphenylamines, a mixture of mono- and dialkylated isopropyl/isohexyldiphenylamines, mixtures of mono- and dialkylated tert-butyldiphenylamines, 2,3-dihydro-3,3-dimethyl-4H-1,4-benzothiazine, phenothiazine, a mixture of mono- and dialkylated tert-butyl/tert-octylphenothiazines, a mixture of mono- and dialkylated tert-butyl/tert-octyl-phenothiazines, N-allylphenothiazine, N,N,N′,N″-tetraphenyl-1,4-diaminobut-2-ene, N,N-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexamethylenediamine, bis-(2,2,6,6-tetramethylpiperidin-4-yl)sebacate, 2,2,6,6-tetramethylpiperidin-4-one, or 2,2,6,6-tetramethylpiperidin-4-ol; and17) Aliphatic or aromatic phosphites, esters of thiodipropionic acid, or of thiodiacetic acid, or salts of dithiocarbamic or dithiophosphoric acid, 2,2,12,12-tetramethyl-5,9-dihydroxy-3,7,1-trithiatridecane, or 2,2,15,15-tetramethyl-5,12-dihydroxy-3,7,10,14-tetrathiahexadecane.

Suitable antiwear additives are selected from:1) Dihydrocarbyl dithiophosphate metal salts where the metal is aluminum, lead, tin manganese, cobalt, nickel, zinc or copper, but most often zinc. The zinc salt (zinc dialkyl dithiophosphate) is represented as

where R and R′ are independently represent C1-C20alkyl, C3-C20alkenyl, C5-C12cycloalkyl, C7-C13aralkyl or C6-C10aryl, for example R and R′ are independently, C1-C12alkyl; and2) Sulfur-and/or phosphorus-and/or halogen-containing compounds, such as sulfurized olefins and vegetable oils, tritolyl phosphate, tricresyl phosphate, chlorinated paraffins, alkyl and aryl di-and trisulfides, amine salts of mono- and dialkyl phosphates, amine salts of methylphosphonic acid, diethanolaminomethyltolyltriazole, di(2-ethylhexyl)aminomethyltolyltriazole, derivatives of 2, 5-dimercapto-1,3, 4-thiadiazole, ethyl((bisisopropyloxyphosphinothioyl)thio) propionate, triphenyl thiophosphate(triphenyl phosphorothioate), tris(alkylphenyl)phosphorothioates and mixtures thereof (for example tris(isononylphenyl)phosphorothioate), diphenyl-monononylphenylphosphorothioate, isobutylphenyldiphenylphosphorothioate, the dodecylamine salt of 3-hydroxy-1,3-thiaphosphetan-3-oxide, trithiophosphoric acid 5,5,5-tris(isooctyl 2-acetate), derivatives of 2-mercaptobenzothiazole, such as 1-(N,N-bis(2-ethylhexyl) aminomethyl)-2-mercapto-1H-1, 3-benzothiazole, or ethoxycarbonyl 5-octyldithiocarbamate.

Suitable dispersants are selected from:1) Mannich bases that are condensation reaction products of a high molecular weight phenol, an allylene polyamine, and an aldehyde, such as formaldehyde;2) Succinic-based dispersants that are reaction products of a olefin polymer, and succinic acylating agent (acid, anhydride, ester or halide), further reacted with an organic hydroxy compound and/or an amine; and3) High molecular weight amides and esters, such as reaction products of a hydrocarbyl acylating agent and a polyhydric aliphatic alcohol (such as glycerol, pentaerythritol or sorbitol).

Ashless (metal-free) polymeric materials that usually contain an oil soluble high molecular weight backbone linked to a polar functional group that associates with particles to be dispersed are typically used as dispersants. Commonly used hydrocarbon backbone materials are olefin polymers and copolymers, i.e.-ethylene, propylene, butylene, isobutylene, styrene; there may or may not be further functional groups incorporated into the backbone of the polymer. Polar materials, such as amines, alcohols, amides or esters are attached to the backbone via a bridge.

Suitable detergents are selected from: calcium, magnesium, barium, sodium or lithium salts of organic acids, for example, sulphonates, alkylphenates, sulfurized alkyl phenates, carboxylates, salicylates, phosphonates, thiophosphonates, and phosphinates. The salts may be neutral or may be overbased by, for example, metal hydroxides or carbonates.

Suitable antifoam additives are selected from: silicone oils, polysiloxanes, and polyethylene glycol ethers.

Suitable viscosity index improvers are selected from: polyisobutylene, co- polymers of ethylene and propylene, polyacrylates, polymethacrylates, vinylpyrrolidone/methacrylate copolymers, polyvinylpyrrolidones, polybutenes, olefin copolymers, styrene/ acrylate copolymers, styrene/isoprene copolymers, styrene/isobutadiene copolymers, isoprene/butadiene copolymers and polyethers.

Suitable copper passivators are selected from:1) Benzotriazoles and their derivatives, for example 4-or 5-alkylbenzotriazoles (e. g. tolutriazole) and derivatives thereof, 4,5,6,7-tetrahydrobenzotriazole, 5,5′-methylenebisbenzotriazole; Mannich bases of benzotriazole or tolutriazole, such as 1-(di(2-ethylhexyl)aminomethyl)tolutriazole and 1-(di-(2-ethylhexyl)aminomethyl)-benzotriazole; alkoxyalkylbenzotriazoles, such as 1-(nonyloxymethyl)-benzotriazole, 1-(1-butoxyethyl)-benzotriazole, or 1-(1-cyclohexyloxybutyl)-tolutriazole;2) Imidazole derivatives, for example 4,4′-methylenebis(2-undecyl-5-methyl-imidazole), bis((N-methyl)imidazol-2-yl)carbinol octyl ether;3) Sulfur-containing heterocyclic compounds, for example, 2-mercaptobenzothiazole, 2,5-dimercapto-1,3,4-thiadiazole, 2,5-dimercaptobenzothiadiazole and derivatives thereof, or 3,5-bis(di(2-ethylhexyl) aminomethyl)-1,3,4-thiadiazolin-2-one; and4) Amino compounds, for example, salicylidenepropylenediamine, salicylaminoguanidine or salts thereof.

Suitable rust inhibitors are selected from:1) Nonionic polyoxyalkylene polyols and their esters, polyoxyalkylene phenols, organic acids, their esters, metal salts, amine salts and anhydrides, for example alkyl- and alkenylsuccinic acids and the partial esters thereof with alcohols, diols or hydroxycarboxylic acids, partial amides of alkyl-and alkenyisuccinic acids, 4-nonylphenoxyacetic acid, alkoxy- and alkoxyethoxycarboxylic acids, such as dodecyloxyacetic acid, dodecyloxy(ethoxy) acetic acid and the amine salts thereof, or N-oleoylsarcosine, sorbitan monooleate, lead naphthenate and alkenylsuccinic anhydrides, for example dodecenylsuccinic anhydride, 2-(2-carboxyethyl)-1-dodecyl-3-methylglycerol and its salts, for example, sodium and triethanolamine salts;2) Nitrogen-containing compounds selected from: i) Primary, secondary, or tertiary aliphatic or cycloaliphatic amines and amine salts of organic and inorganic acids, for example oil-soluble alkylammonium carboxylates, and also 1-(N,N-bis(2-hydroxyethyl) amino)-3-(4-nonylphenoxy)propan-2-ol, or ii) Heterocyclic compounds, for example: substituted imidazolines or oxazolines, for example, 2-heptadecenyl-1-(2-hydroxyethyl)-imidazoline;3) Phosphorus-containing compounds, for example amine salts of phosphoric acid, phosphoric acid partial esters or phosphonic acid partial esters, or zinc dialkyldithiophosphates;4) Sulfur-containing compounds, for example barium dinonylnaphthalene-sulfonates, calcium petroleumsulfonates, alkylthio-substituted aliphatic carboxylic acids, esters of aliphatic 2-sulfocarboxylic acids, or salts thereof; and5) Glycerol derivatives, for example glycerol monooleate, 1-(alkylphenoxy)-3-(2-hydroxyethyl)glycerols, 1-(alkylphenoxy)-3-(2,3-dihydroxypropyl)glycerols, or 2-carboxyalkyl-1,3-dialkylglycerols.

Suitable pour point depressants are selected from polymethacrylates and alkylated naphthalene derivatives.

Suitable demulsifiers are selected from polyetherpolyols and dinonyinaphthalenesulfonates.

Suitable friction modifiers are selected from fatty acids and their derivatives, e. g. natural esters of fatty acids, such as glycerol monooleate, amides, imides and amines, e. g. oleylamine, sulfur containing organomolybdenum dithiocarbamates, sulfurphosphorus containing organomolybdenum dithiophosphates, sulfur-nitrogen containing or—ganomolybdenum compounds based on dispersants, molybdenum carboxylate salts, molybdenum-amine complexes, molybdenum amine/alcohol/amid complexes, and molybdenum cluster compounds, Teflon® and molybdenum disulfide.

Base Oils in the Engine Oil According to the Present Invention

The engine oil according to the present invention comprises at least one base oil (i. e. a lubricant of lubricating viscosity) and the mixture of alkylated diphenylamines of the structural formula (I), (II), (III), and (IV) according to the present invention, preferably the mixture of alkylated diphenylamines of the structural formula (I), (II), (III), and (IV) in which R is a branched residue having the formula —C9H19, preferably the additive blend defined in embodiments 12 to 14.

Suitable base oils are mineral and synthetic base oils chosen from Group I to V. These base oils are broadly specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines.

The base oils can be oils and greases, for example, based on mineral oil or vegetable and animal oils, fats, tallow and wax or mixtures thereof. Vegetable and animal oils, fats, tallow and wax are, for example, palm kernel oil, palm oil, olive oil, colza oil, rapeseed oil, linseed oil, soy bean oil, cotton wool oil, sunflower oil, coconut oil, maize oil, castor oil, walnut oil, and mixtures thereof, fish oils, and chemically modified, e.g. epoxidized or sulphoxidezed, forms or forms prepared by genetic engineering, for example soy bean oil prepared by genetic engineering.

Examples of synthetic base oils include lubricants based on aliphatic or aromatic carboxylic esters, polymeric esters, polyalkylene oxides, phosphoric acid esters, poly-a-olefins, silicones, alkylated benzene, alkylated naphthalenes or the diester of a di basic acid with a monohydric alcohol, e.g. dioctyl sebacate or dinonyl adipate, of a triester of trimethylolpropane with a monobasic acid or with a mixture of such acids, e.g. trimethylolpropane tripelargonate, trimethylolpropane tricaprylate, or mixtures thereof, of a tetra ester of pentaerythritol with a monobasic acid or with a mixture of such acids, e.g. pentaerythrityl tetracaprylate, or of a complex ester of monobasic and dibasic acids with polyhydric alcohols, e.g. a complex ester of trimethylolpropane with caprylic and sebacic acid or of a mixture thereof. Particularly suitable in addition to mineral oils are, for example, poly-a-olefins, ester-based lubricants, phosphates, glycols, polyglycols, and polyalkylene glycols, and mixtures thereof with water.

When in addition to the mixture of alkylated diphenylamines of the structural formula (I), (II), (III), and (IV) according to the present invention, preferably in addition to the mixture of alkylated diphenylamines of the structural formula (I), (II), (III), and (IV) in which R is a branched residue having the formula —C9H19, other additives are employed, it may be desirable, although not necessary, to prepare additive concentrates in the form of the above described additive blend (or additive package) comprising concentrated solutions or dispersions of the mixture of alkylated diphenylamines of the structural formula (I), (II), (III), and (IV) according to the present invention together with one or more of said other additives, whereby several additives can be added simultaneously to the base oil to form a lubricating oil composition. Dissolution of the additive concentrate into the lubricating oil can be facilitated by solvents and by mixing accompanied by mild heating, but this action is not essential. The concentrate or additive blend will typically be formulated to contain the additives in proper amounts to provide the desired concentration in the final formulation when the additive blend is combined with a predetermined amount of the base oil. Thus, the mixture of alkylated diphenylamines of the structural formula (I), (II), (III), and (IV) according to the present invention can be added to small amounts of base oil or other compatible solvents along with other desirable additives to form an additive blend containing active ingredients in collective amounts of, typically, from about 2.5 to about 90 wt. %, preferably from about 15 to about 75 wt. %, and more preferably from about 25 percent to about 60 wt. % additives in the appropriate proportions with the remainder being base oil. The final formulations can typically employ about 1 to 20 wt. % of the additive blend the remainder being base oil.

Thermoplastic Polymers in the Polymer Composition According to the Present Invention

The polymer composition according to the present invention comprises, in addition to the mixture of alkylated diphenylamines of the structural formula (I), (II), (III), and (IV) according to the present invention, preferably in addition to the mixture of alkylated diphenylamines of the structural formula (I), (II), (III), and (IV) in which R is a branched residue having the formula —C9H19, a polymer, preferably a thermoplastic polymer.

The thermoplastic polymers that can be stabilized against oxidative degradation employing the mixture of alkylated diphenylamines of the structural formula (I), (II), (III), and (IV) include resins derived from ethylene including low density polyethylene (LDPE), linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), or other ethylene derived resins that have densities from 0.85 to 1.4 gm/cm3; homopolymers derived from mono- and diethylenically unsaturated hydrocarbon monomers of C3 and above, such as, polypropylene, polyisobutylene, polymethylbutene-1, polymethylpentene-1, polybutene-1, polyisobutylene, and the like; copolymers derived from two or more monomers, such as, ethylene-propylene copolymers, preferably having at least a majority of propylene, propylene-butene-1 copolymers, propylene-isobutylene copolymers, and the like, and blends thereof, polystyrenes; polyvinylhalides; and engineering thermoplastics, for example, polyamides, polyesters, polyphenyleneoxides, polyphenylenesulfides, polyacetals, aliphatic polyketone co- or terpolymers, poly(ethersulfones), polycarbonates, liquid crystalline polymers, poly(etheretherketones), polyurethanes and poly(arylates). It is preferred that the thermoplastic resin that is protected by the composition according to the present invention be a polyurethane or a polypropylene.

The invention is now described in more detail by reference to test methods and non-limiting examples.

MODE FOR THE INVENTION

Test Methods

Determination of Oxidative Stability

The oxidative stability was evaluated by means of a pressurized differential scanning calorimetry (PDSC) apparatus.

The PDSC examines an oil's oxidative stability under thin-film oxidation conditions. In the isothermal mode where PDSC temperature is maintained at a predetermined value, a test oil's oxidation stability is ranked according to the oxidation induction time (OIT), corresponding to an exothermic release of heat caused by the onset of oxidation of the oil. Oil giving longer OIT is generally considered more resistant to oxidation. Each blend was tested in duplicate using the following instrumental conditions and the average OIT was determined. The PDSC test temperature was 185° C.

The following measuring conditions have been selected:Temperature ramp: 40° C./minPressures: 500 psi0 2 flow: 100 ml/minSample size: ˜1.5 mgPan: Aluminum, open

Determination of Lead Corrosion

The corrosion of lead was determined according to ASTM D 6594.

EXAMPLE

A commercially available mixture of alkylated diphenylamines of the structural formula (I), (II), (III) in which R represents a branched alkyl group having the formula —C9H19was supplemented with different amounts of the corresponding alkylated diphenylamine of the structural formula (IV), subsequently referred to as “TN-DPA” (tetranonyl diphenylamine). Samples in Table 1 have been obtained and analyzed:

TABLE 1nonyl-DPAdi-nonyl-DPATri-nonyl-DPATN-DPASample[wt. %][wt. %][wt. %][wt. %]120.4-24.964.4-78.85.0-6.10.19221.0-25.765.0-79.53.7-4.50.32321.0-25.765.0-79.43.7-4.40.42420.0-24.564.9-79.43.6-4.40.60520.5-25.163.8-78.03.8-4.62.13620.3-24.963.0-77.03.8-4.73.12720.0-24.461.5-75.25.0-6.15.16

Using the above described samples of a mixture comprising mono-, di, tri- and tetranonyl diphenylamine a fully finished engine oil was prepared. For that purpose, the sample was added separately to an antioxidant-free fully finished engine oil in an amount of 1.0 wt. %. The engine oil was formulated with API Group III base oils which consisted of a mixture of Yubase 4 and Yubase 6 obtained from SK Lubricants Co. Ltd., Seoul, Korea. From the thus obtained lubricants the oxidative stability and the lead corrosion have been determined (by means of the PDSC- and the ASTM D 6594-test). The results of the PDSC-test are shown in Table 2, and the results of the ASTM D 6594-test are shown in Table 3:

TABLE 2TN-DPAoxidative stability1)Sample[wt. %]determined by PDSC [min]10.1919.6820.3220.1830.4220.4340.6020.4552.1320.3863.1220.4075.1619.951)average value of two measurements

TABLE 3lead corrosion1)TN-DPAdetermined according to ASTM D 6594Sample[wt. %][DPb in ppm]]10.191740.60452.13463.12375.1681)average value of two measurementsAs can be seen from the results shown in tables 2 and 3, adjusting the content of tetra-alkylated diphenylamines of the structural formula (IV) in a composition comprising alkylated diphenylamines of the structural formulas (I), (II), (III), and (IV) to the very narrow range of 0.2 to 3.5 wt. % leads to compositions which, when added to a base oil for the formation of an engine oil, provide an optimum performance of the engine oil with respect to both, the oxidative stability and the resistance towards the corrosion of lead.