Lubricating Composition Including Esterified Copolymer And Method

Abstract

A lubricating composition includes an (A) esterified copolymer comprising units (A1) derived from a vinyl monomer and units (A2) derived from a carboxylic acid monomer, the vinyl monomer comprising a vinyl aliphatic monomer, the carboxylic acid monomer comprising an ethylenically unsaturated carboxylic acid or derivative thereof, esterified with a primary alcohol; and (B) an oil of lubricating viscosity. The lubricating composition can provide a lubricant with at least one (or at least two, or all) of acceptable or improved HTHS, KV, shear stability, acceptable or improved viscosity index control, and acceptable or improved low temperature viscosity.

What is claimed is: 
     
         1 . The use of an esterified copolymer, comprising units (A1) derived from a vinyl monomer and units (A2) derived from a carboxylic acid monomer, the vinyl monomer comprising a vinyl aliphatic monomer, the carboxylic acid monomer comprising an ethylenically unsaturated carboxylic acid or derivative thereof, esterified with a primary alcohol, in a lubricating oil for a driveline device. 
     
     
         2 . The use according to  claim 1  to improve high-temperature high-shear (HTHS) performance of the lubricating oil. 
     
     
         3 . The use according to any previous claim to improve kinematic viscosity performance of the lubricating oil as temperature increases 
     
     
         4 . The use according to any previous claim to improve kinematic viscosity performance of the lubricating oil as shear rate increases. 
     
     
         5 . A lubricating composition comprising:
 A. an esterified copolymer comprising units (A1) derived from a vinyl monomer and units (A2) derived from a carboxylic acid monomer, the vinyl monomer comprising a vinyl aliphatic monomer, the carboxylic acid monomer comprising an ethylenically unsaturated carboxylic acid or derivative thereof, esterified with a primary alcohol; and   B. an oil of lubricating viscosity.   
     
     
         6 . The lubricating composition of  claim 5 , wherein the esterified copolymer is from 1 to 22 wt. % of the composition, or from 2 to 15 wt. %, or 3-10 wt. %. 
     
     
         7 . The lubricating composition of  claim 5 , wherein the esterified copolymer (A) has a weight average molecular weight of at least 5000, or up to 50,000. 
     
     
         8 . The lubricating composition of  claim 5 , wherein the units (A1) derived from a vinyl monomer further comprise units derived from a vinyl aromatic monomer. 
     
     
         9 . The lubricating composition of  claim 5 , wherein the vinyl aliphatic monomer comprises an alpha-olefin. 
     
     
         10 . The composition of  claim 9 , wherein the α-olefin has at least 6 carbon atoms. 
     
     
         11 . The lubricating composition of  claim 5 , wherein a molar ratio of the vinyl monomer units to the carboxylic acid monomer units in the copolymer is from 1:3 to 3:1, or from 1:2 to 2:1 or 0.6:1 to 1:1, or from 0.7:1 to 1:1.1. 
     
     
         12 . The composition of  claim 5 , wherein the esterified copolymer is esterified with a primary alcohol branched at the β- or higher position. 
     
     
         13 . The composition of  claim 5 , wherein the carboxylic acid monomer comprises maleic anhydride. 
     
     
         14 . The lubricating composition of  claim 5 , wherein the esterified copolymer (A) comprises a nitrogen-containing group. 
     
     
         15 . The lubricating composition of  claim 5 , wherein at least some of the units (A2) derived from the carboxylic acid monomer are at least one of aminated, amidated, and imidated with a nitrogen-containing compound. 
     
     
         16 . The lubricating composition of  claim 15 , wherein the nitrogen-containing compound is an amine-containing compound selected from the group consisting of morpholines, imidazolidinones, amino amides, β-alanine alkyl esters, aliphatic amines, aromatic amines, aliphatic polyamines, aromatic polyamines, and mixtures thereof. 
     
     
         17 . The lubricating composition of  claim 5 , wherein the lubricating composition has a viscosity at 100° C. of at least 9.3 cSt or up to 12.5 cSt.