Lubricating Composition Including Esterified Copolymer And Diene Rubber Polymer

Abstract

A lubricating composition includes (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) a diene rubber copolymer comprising at least a first block (B1) derived from a conjugated diene monomer and at least a second block (B2) derived from a vinyl aromatic monomer. A ratio of the diene rubber copolymer to the esterified copolymer in the lubricating composition (B:A) is from 0.01 to 0.9, by weight.

1 . 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, wherein a majority of the vinyl monomer units of A1 are derived from a vinyl aliphatic monomer, and wherein the carboxylic acid monomer comprises an ethylenically unsaturated carboxylic acid or derivative thereof, esterified with a primary alcohol; and   B. a diene rubber copolymer comprising at least a first block (B1) derived from a conjugated diene monomer and at least a second block (B2) derived from a vinyl aromatic monomer; and   wherein a ratio of the diene rubber copolymer to the esterified copolymer in the lubricating composition (B:A) is from 0.01 to 0.9, by weight.   
     
     
         2 . The lubricating composition of  claim 1 , wherein the ratio (B:A) of the diene rubber copolymer to the esterified copolymer in the lubricating composition is from 0.2 to 0.85. 
     
     
         3 . The lubricating composition of  claim 2 , wherein the ratio (B:A) of the diene rubber copolymer to the esterified copolymer in the lubricating composition is from 0.3 to 0.8. 
     
     
         4 . The lubricating composition of  claim 1 , wherein the ratio (B:A) of the diene rubber copolymer to the esterified copolymer in the lubricating composition is at least 0.4. 
     
     
         5 . The lubricating composition of  claim 1 , wherein the esterified copolymer is from 1 to 22 wt. % of the composition, or from 2 to 15 wt. %., or 3-10 wt. %. 
     
     
         6 . The composition of  claim 1 , wherein the diene rubber copolymer is from 0.01 to 18 wt. % of the composition. 
     
     
         7 . The lubricating composition of  claim 1 , wherein the diene monomer from which the at least a first block (B1) of the diene rubber copolymer is derived comprises at least one of butadiene or isoprene. 
     
     
         8 . The lubricating composition of  claim 1 , wherein the vinyl aromatic monomer from which the at least a second block (B2) of the diene rubber copolymer is derived comprises at least one of styrene, alpha-methylstyrene, nuclear methylstyrenes, ethylstyrene, isopropylstyrene, tert-butylstyrene, chlorostyrenes, dichlorostyrenes, or vinylnaphthalene. 
     
     
         9 . The lubricating composition of  claim 1 , wherein the diene rubber copolymer (B) has a weight average molecular weight of at least 30,000. 
     
     
         10 . The lubricating composition of  claim 1 , wherein the at least first block (B1) derived from the conjugated diene monomer has a weight average molecular weight of at least 10,000. 
     
     
         11 . The lubricating composition of  claim 1 , wherein the at least second block (B2) derived from the vinyl aromatic monomer has a weight average molecular weight of at least 3,000. 
     
     
         12 . The lubricating composition of  claim 1 , wherein the diene rubber copolymer (B) comprises at least one of poly(styrene-co-butadiene), poly(styrene-co-butadiene-co-isoprene), or poly(styrene-co-isoprene). 
     
     
         13 . The lubricating composition of  claim 1 , wherein the esterified copolymer (A) has a weight average molecular weight of at least 5000, or up to 50,000. 
     
     
         14 . The lubricating composition of  claim 1 , wherein the units (A1) derived from a vinyl monomer further comprise units derived from a vinyl aromatic monomer. 
     
     
         15 . The lubricating composition of  claim 1 , wherein the vinyl aliphatic monomer comprises an alpha-olefin. 
     
     
         16 . The lubricating composition of  claim 15 , wherein the alpha-olefin has at least 6 carbon atoms. 
     
     
         17 . The lubricating composition of  claim 1 , 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. 
     
     
         18 . The composition of  claim 1 , wherein the esterified copolymer is esterified with a primary alcohol branched at the β- or higher position. 
     
     
         19 . The composition of  claim 1 , wherein the carboxylic acid monomer comprises maleic anhydride. 
     
     
         20 . The lubricating composition of  claim 1 , wherein the esterified copolymer (A) comprises a nitrogen-containing group. 
     
     
         21 . The lubricating composition of  claim 1 , 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. 
     
     
         22 . The lubricating composition of  claim 20 , 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. 
     
     
         23 . The lubricating composition of  claim 1 , wherein the lubricating oil comprises a polyalphaolefin API Group IV oil having a kinematic viscosity at 100° C. of at least 3 cSt. 
     
     
         24 . The lubricating composition of  claim 1 , wherein the lubricating composition has a kinematic viscosity at 100° C. of at least 9.3 cSt or up to 12.5 cSt. 
     
     
         25 . The lubricating composition of  claim 1 , wherein the lubricating composition has a kinematic viscosity at 100° C. of at least 6.1 cSt or up to 9.3 cSt. 
     
     
         26 . The use of the lubricating composition of  claim 1  as an engine oil. 
     
     
         27 . A process for preparing a lubricating composition comprising:
 admixing (A) an esterified copolymer with (B) a diene rubber copolymer, (C) an oil of lubricating viscosity and (D) optionally one or more other performance additives;   the 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;   the diene rubber copolymer comprising at least a first block (B1) derived from a conjugated diene monomer and at least a second block (B2) derived from a vinyl aromatic monomer; and   a ratio, by weight, of the diene rubber copolymer to the esterified copolymer in the lubricating composition (B:A) being from 0.01 to 0.9.   
     
     
         28 . The process of  claim 27 , further comprising:
 forming the esterified copolymer, comprising:   (1) reacting (i) a vinyl monomer, and (ii) a carboxylic acid monomer comprising an ethylenically unsaturated carboxylic acid or derivative thereof, to form a copolymer;   (2) reacting the copolymer of step (1) with an alcohol or mixture of alcohols under esterifying conditions to form an esterified copolymer; and   (3) optionally, reacting the copolymer of step (1) or (2) with an nitrogen-containing compound in an amount to provide an esterified copolymer with at least 0.01 wt. % nitrogen.