Lubricant compositions comprising polymeric diphenylamine antioxidants

Abstract

Disclosed in certain embodiments is a lubricating oil composition comprising an antioxidant polymer (e.g., oligomer) composition comprising repeat units of diphenylamine monomers of formula I wherein R is H, C 1 -C 18 alkyl, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl, —C(O)C 1 -C 18 alkyl, —C(O)aryl and R 1 , R 2 , R 3 and R 4 are each independently H or a linear or branched C 1 -C 18 alkyl, C 1 -C 18 alkoxy, C 1 -C 18 alkylamino, C 1 -C 18 dialkylamino, C 1 -C 18 alkylthio, C 2 -C 18 alkenyl, C 2 -C 18 alkynyl or C 7 -C 21 aralkyl and wherein the number average molecular weight (Mn) of the polymer composition is from about 350 g/mol to about 5000 g/mol.

1 . A lubricating oil composition comprising
 a base oil; and   from about 0.01 wt % to about 20 wt %, based on the total weight of the lubricating oil composition, of an antioxidant polymer composition comprising repeat units of diphenylamine monomers of formula I   
       
         
           
           
               
               
           
         
         wherein 
         R is H, C 1 -C 18  alkyl, C 2 -C 18  alkenyl, C 2 -C 18  alkynyl, —C(O)C 1 -C 18  alkyl, —C(O)aryl and R 1 , R 2 , R 3  and R 4  are each independently H or a linear or branched C 1 -C 18  alkyl, C 1 -C 18  alkoxy, C 1 -C 18  alkylamino, C 1 -C 18  dialkylamino, C 1 -C 18  alkylthio, C 2 -C 18  alkenyl, C 2 -C 18  alkynyl or C 7 -C 21  aralkyl and 
         wherein 
         the number average molecular weight (Mn) of the polymer composition is from about 350 g/mol to about 5000 g/mol. 
       
     
     
         2 . The lubricating oil composition according to  claim 1 , comprising one or more components selected from the group consisting of other antioxidants, antiwear additives, viscosity index improvers, detergents, dispersants, pour point depressants, corrosion inhibitors, metal deactivators, seal compatibility additives, antifoam agents, inhibitors, antirust additives, and friction modifiers. 
     
     
         3 . The lubricating oil composition according to  claim 1 , wherein the Mn of the polymer composition is from about 400 g/mol to about 5000 g/mol. 
     
     
         4 . The lubricating oil composition according to  claim 1 , wherein R 1 , R 2 , R 3  and R 4  are each independently H or a linear or branched C 4 -C 10  alkyl. 
     
     
         5 . The lubricating oil composition according to  claim 1 , wherein R is H. 
     
     
         6 . The lubricating oil composition according to  claim 1 , wherein the polymer composition further comprises one or more monomers selected from the group consisting of other diphenylamines, phenothiazines, phenoxazines, aminodiphenylamines, methylenedianiline, toluenediamine, aminophenols, alkylphenols, thiophenols, phenylenediamines, quinolines, phenyl pyridinediamines, pyridinepyrimidinediamines and phenylpyrimidinediamines. 
     
     
         7 . The lubricating oil composition according to  claim 1 , wherein the polymer composition comprises from about 10 mol % to about 99 mol % diphenylamine monomers. 
     
     
         8 . The lubricating oil composition according to  claim 1 , wherein the polymer composition comprises <70 wt % residual monomers of formula I. 
     
     
         9 . The lubricating oil composition according to  claim 1 , wherein the polymer composition comprises from about 1 wt % to about 70 wt % residual monomers of formula I, based on the total weight of the polymer composition. 
     
     
         10 . The lubricating oil composition according to  claim 1 , wherein the viscosity of the polymer composition is from about 20 cSt to about 600 cSt. 
     
     
         11 . The lubricating oil composition according to  claim 1 , wherein the polymer composition is a solid. 
     
     
         12 . The lubricating oil composition according to  claim 1 , wherein the base oil comprises a natural oil or a synthetic oil. 
     
     
         13 . The lubricating oil composition according to  claim 1 , wherein the base oil comprises a mineral oil, a polyalphaolefin, an alkyl naphthalene or a gas-to-liquid base stock. 
     
     
         14 . The lubricating oil composition according to  claim 1 , comprising from about 50 wt % to about 90 wt % base oil, based on the total weight of the lubricating oil composition. 
     
     
         15 . The lubricating oil composition according to  claim 1 , which exhibits color of <about 5.5according to ASTM D1500. 
     
     
         16 . The lubricating oil composition according to  claim 1 , comprising an antioxidant combination of the polymer composition and one or more antioxidants selected from the group consisting of further aminic and phenolic antioxidants. 
     
     
         17 . The lubricating oil composition according to  claim 1 , comprising an antioxidant combination of the polymer composition and one or more further compounds selected from the group consisting of N,N-di-(p-tert-butylphenyl)amine, N,N-di-(p-tert-octylphenyl)amine, N-(p-tert-butylphenyl)-N-phenylamine, N-(p-tert-octylphenyl)-N-phenylamine and N-(p-tert-butylphenyl)-N-(p-tert-octylphenyl)amine, bis-nonylphenyldiphenylamine, N-(tert-C 1 -C 20 alkylphenyl)-1-naphthylamine and 3,5-di-tert-butyl-4-hydroxyhydrocinnamic acid octyl ester. 
     
     
         18 . A lubricating oil composition comprising
 a base oil; and   from about 0.01 wt % to about 20 wt %, based on the total weight of the lubricating oil composition, of a polymer composition comprising repeat units of diphenylamine monomers of formula I   
       
         
           
           
               
               
           
         
         wherein 
         R is H, C 1 -C 18  alkyl, C 2 -C 18  alkenyl, C 2 -C 18  alkynyl, —C(O)C 1 -C 18  alkyl, —C(O)aryl and R 1 , R 2 , R 3  and R 4  are each independently H or a linear or branched C 1 -C 18  alkyl, C 1 -C 18  alkoxy, C 1 -C 18  alkylamino, C 1 -C 18  dialkylamino, C 1 -C 18  alkylthio, C 2 -C 18  alkenyl, C 2 -C 18  alkynyl or C 7 -C 21  aralkyl, and 
         wherein the polymer composition comprises ≤70 wt % residual monomers of formula I. 
       
     
     
         19 . The lubrication oil composition according to  claim 18 , wherein the polymer composition comprises ≤30 wt % residual monomers of formula I. 
     
     
         20 . The lubricating oil composition according to  claim 18 , wherein the polymer composition comprises from about 1 wt % to about 70 wt % residual monomers of formula I, based on the total weight of the polymer composition. 
     
     
         21 . A method of reducing extending an oil drain interval, the method comprising adding to the engine the lubricating oil composition of  claim 1 . 
     
     
         22 . A method of improving oxidative stability of a lubricating oil in an engine, the method comprising adding to the engine the lubricating oil composition of  claim 1 . 
     
     
         23 . A process of providing a lubricating oil composition oxidative stability, deposits control and viscosity control, the process comprising incorporating a polymer composition comprising repeat units of diphenylamine monomers of formula I 
       
         
           
           
               
               
           
         
         wherein 
         R is H, C 1 -C 18  alkyl, C 2 -C 18  alkenyl, C 2 -C 18  alkynyl, —C(O)C 1 -C 18  alkyl, —C(O)aryl and R 1 , R 2 , R 3  and R 4  are each independently H or a linear or branched C 1 -C 18  alkyl, C 1 -C 18  alkoxy, C 1 -C 18  alkylamino, C 1 -C 18  dialkylamino, C 1 -C 18  alkylthio, C 2 -C 18  alkenyl, C 2 -C 18  alkynyl or C 7 -C 21  aralkyl and 
         wherein 
         the number average molecular weight (Mn) of the polymer composition is from about 350 g/mol to about 5000 g/mol; 
         into a base oil, 
         wherein the lubricating oil composition comprises from about 0.01 wt % to about 20 wt %, based on the total weight of the lubricating oil composition, of the polymer composition. 
       
     
     
         24 . The lubricating oil composition of  claim 1 , wherein the polymer composition is an oligomer composition. 
     
     
         25 . The lubricating oil composition of  claim 18 , wherein the polymer composition is an oligomer composition.