Lubricant grease compositions comprising polymeric diphenylamine antioxidants

Abstract

Disclosed in certain embodiments is a lubricating grease 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 grease composition comprising a base oil;
 a thickener; and   from about 0.01 wt % to about 20 wt %, based on the total weight of the lubricating grease 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 grease composition according to  claim 1 , wherein the thickener is selected from the group consisting of simple lithium soap, lithium complex soap, polyurea, calcium sulfonate, aluminum soap, calcium soap, mixed aluminum/calcium, clay, polymer and a combination thereof. 
     
     
         3 . The lubricating grease composition according to  claim 2 , wherein the thickener comprises a lithium complex soap. 
     
     
         4 . The lubricating grease composition according to  claim 1 , comprising one or more components selected from the group consisting of other antioxidants, antiwear additives, polymers, detergents, dispersants, pour point depressants, corrosion inhibitors, metal deactivators, complexing agents, antifoam agents, inhibitors, antirust additives, and friction modifiers. 
     
     
         5 . The grease composition of  claim 1 , wherein the base oil comprises at least one of a Group I oil, a Group II oil, a Group III oil, a Group IV oil, a Group V oil, a gas-to-liquid oil, or combinations thereof. 
     
     
         6 . The lubricating grease composition according to  claim 1 , having an ISO Viscosity grades of about 100 to about 680. 
     
     
         7 . The lubricating grease composition according to  claim 1 , having an NLGI consistency grade of 000 to 6. 
     
     
         8 . The lubricating grease composition according to  claim 1 , wherein the Mn of the antioxidant antioxidant polymer composition is from about 400 g/mol to about 5000 g/mol. 
     
     
         9 . The lubricating grease 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. 
     
     
         10 . The lubricating grease composition according to  claim 1 , wherein R is H. 
     
     
         11 . The lubricating grease composition of  claim 1 , wherein the antioxidant polymer composition is an oligomer composition. 
     
     
         12 . A lubricating grease composition comprising a base oil;
 a water insoluble thickener; and   from about 0.01 wt % to about 20 wt %, based on the total weight of the lubricating grease 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. 
       
     
     
         13 . A lubricating grease composition comprising
 a base oil; and   from about 0.01 wt % to about 20 wt %, based on the total weight of the lubricating grease 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. 
       
     
     
         14 . A method of improving the high temperature performance of a bearing comprising adding to the bearing the lubricating grease composition of  claim 1 .