Functionalized polymer composition for grease

Abstract

A grease composition containing: (a) an esterified polymer derived from monomers comprising: (i) a vinyl aromatic monomer; (ii) an unsaturated dicarboxylic acid anhydride or derivatives thereof; (b) a thickening agent; and (c) an oil of lubricating viscosity, wherein the esterified polymer contains titratable acid groups with a total acid number of at least about 4. The invention further relates to the process to make the composition and its use in grease to increase water resistance.

1 . A grease composition comprising: 
 (a) an esterified polymer derived from monomers comprising: 
 (i) a vinyl aromatic monomer;  
 (ii) an unsaturated dicarboxylic acid anhydride or derivatives thereof;  
   (b) a thickening agent; and    (c) an oil of lubricating viscosity,    wherein the esterified polymer contains titratable acid groups with a total acid number of at least about 4.    
     
     
         2 . The grease composition of  claim 1 , wherein the titratable acid groups have a Total Acid Number (TAN) in the range from about 5 to about 100.  
     
     
         3 . The grease composition of  claim 1 , wherein the vinyl aromatic monomer is styrene, substituted styrene or mixtures thereof.  
     
     
         4 . The grease composition of  claim 1 , wherein the unsaturated dicarboxylic acid anhydride or derivatives thereof is derived from maleic anhydride, methyl maleic anhydride, ethyl maleic anhydride, dimethyl maleic anhydride or mixtures thereof.  
     
     
         5 . The grease composition of  claim 1 , wherein the conversion of dicarboxylic acid anhydride or derivatives thereof to ester groups is in the range of about 88% to about 99.5%.  
     
     
         6 . The grease composition of  claim 1 , wherein the esterified polymer is derived from alcohols containing about 6 to about 24 carbon atoms.  
     
     
         7 . The grease composition of  claim 1 , wherein the esterified polymer is derived from mixtures of alcohols containing at least one alcohol with about 6 to about 11 carbon atoms and at least one alcohol with about 12 to about 24 carbon atoms.  
     
     
         8 . The grease composition of  claim 1 , wherein the esterified polymer optionally contains at least one reacted amine.  
     
     
         9 . The grease composition of  claim 1 , wherein the esterified polymer is derived from a vinyl aromatic monomer present in the range from about 0.7 to about 1 mole equivalents relative to the amount of the of the dicarboxylic acid anhydride or derivatives thereof; and wherein the dicarboxylic acid anhydride or derivatives thereof is present in the esterified polymer in the range from about 0.7 to about 1 mole equivalents relative to the amount of the vinyl aromatic monomer.  
     
     
         10 . The grease composition of  claim 1 , wherein the esterified polymer is present in a grease composition in the range from about 0.01 to about 30 weight percent of the grease composition; wherein the thickener is present in the range from about 3 to about 40 weight percent of the grease composition; the oil of lubricating viscosity is present in the range from about 20 to about 97 weight percent of the grease composition; and wherein the other performance additives are present in the range from 0 to about 20 weight percent of the grease composition.  
     
     
         11 . A process for preparing a grease composition comprising the steps of: 
 (1) mixing an esterified polymer derived from monomers comprising (i) a vinyl aromatic monomer; (ii) an unsaturated dicarboxylic acid anhydride or derivatives thereof; with a solvent to form a solvated polymer;    (2) reacting the solvated polymer of step (1) with at least two alcohols containing (i) at least about 6 carbon atoms and (ii) the other containing less than about 6 carbon atoms to form a solvated polymer containing an ester or derivatives thereof;    (3) optionally, adding to the solvated polymer containing an ester or derivatives thereof an amine with primary functionality, secondary functionality or mixtures thereof to form an amidated polymer;    (4) adding the solvated polymer containing an ester or derivatives thereof of step (2) or the amidated polymer of step (3) to a thickening agent, an oil of lubricating viscosity or mixtures thereof; and    (5) optionally adding to the product of step (4) adding at least one other performance additive to form a grease composition.    
     
     
         12 . The use of the grease composition of  claim 1  for imparting at least one improved property include improved water repellence, improved water wash-off, improved thickening, increased longevity and decreased wear.