Lubricant comprising a mixture of an olefin-ester copolymer with an ethylene alpha-olefin copolymer

Abstract

A lubricant composition comprising an oil of lubricating viscosity having a kinematic viscosity at 100° C. of less than 15 mm 2 /s; and an esterified copolymer with a backbone comprising units derived from (i) an α-olefin monomer of at least 6 carbon atoms and (ii) an ethylenically unsaturated carboxylic acid or derivative thereof, optionally containing nitrogen functionality; and an ethylene α-olefin copolymer comprising greater than 5 weight percent ethylene monomer units, exhibits good operating efficiency when used to lubricate a mechanical device.

1 . A lubricant composition comprising:
 (a) an oil of lubricating viscosity having a kinematic viscosity at 100° C. of less than about 15 mm 2 /s and   (b) an esterified copolymer with a backbone comprising units derived from (i) an α-olefin monomer of at least about 6 carbon atoms and (ii) an ethylenically unsaturated carboxylic acid or derivative thereof, wherein the mole ratio of (i) α-olefin monomer to (ii) carboxylic acid or derivative monomer is about 1:3 to about 3:1, said copolymer having a weight average molecular weight of about 5,000 to about 20,000 and optionally containing nitrogen functionality; and   (c) an ethylene α-olefin copolymer comprising ethylene monomer units and one or more α-olefin monomer units other than ethylene monomer, wherein the amount of ethylene monomer units is greater than 5 weight percent, wherein the α-olefin monomer units contain 3 to about 20, or 3 to about 6, or 3 to 4, or 3 carbon atoms or mixtures thereof.   
     
     
         2 . The lubricant composition of  claim 1  wherein the polymers (b) and (c) are present in a weight ratio (b):(c) of about 1:10 to about 10:1 and wherein the total amount of polymer (b) plus (c) is about 3 to about 60 percent by weight of the lubricant composition. 
     
     
         3 - 4 . (canceled) 
     
     
         5 . The lubricant composition of  claim 1  wherein the copolymer (b) comprises an esterified copolymer of an α-olefin of 8 to 16 carbon atoms and maleic anhydride, in a mole ratio of about 1:2 to about 1.5:1. 
     
     
         6 . The lubricant composition of  claim 1  wherein the ester functionality of copolymer (b) is derived from a mixture of alcohols comprising a primary alcohol that is branched at the β- or higher position and a linear primary alcohol. 
     
     
         7 - 8 . (canceled) 
     
     
         9 . The lubricant composition of  claim 1  wherein the copolymer (b) contains nitrogen functionality derived from reaction with an amine. 
     
     
         10 . The lubricant composition of  claim 9  wherein the amine is one or more of morpholines, imidazolinones, aminoamides, β-alanine alkyl esters, aliphatic amines, aromatic amines, aliphatic polyamines, aromatic polyamines, or and mixtures thereof. 
     
     
         11 . The lubricant of  claim 10  wherein the amine comprises an aliphatic monoamine or an aliphatic polyamine. 
     
     
         12 . The lubricant of  claim 10  wherein the amine comprises N,N-dimethylaminopropylamine, 1-(2-amino-ethyl)imidazolidin-2-one, 4-(3-aminopropyl)morpholine, or 1-(3-aminopropyl)imidazole. 
     
     
         13 . The lubricant composition of  claim 10  wherein the amine comprises a coupled product of 4-aminodiphenylamine. 
     
     
         14 . The lubricant of  claim 1  wherein the polymer of (b) contains about 0.01 to about 1.5 weight percent nitrogen. 
     
     
         15 - 16 . (canceled) 
     
     
         17 . The lubricant of  claim 1  wherein the amount of the polymer of (b) is about 2 to about 50 weight percent. 
     
     
         18 . The lubricant of  claim 1  wherein the polymer of (c) comprises an ethylene propylene copolymer. 
     
     
         19 . The lubricant of  claim 1  wherein the α-olefin monomer units of the ethylene α-olefin copolymer comprise propylene units and monomer units containing 4 to about 20 carbon atoms. 
     
     
         20 . (canceled) 
     
     
         21 . The lubricant of  claim 1  wherein the polymer of (c) has a number average molecular weight of about 1,300 to about 13,000. 
     
     
         22 . The lubricant of  claim 1  wherein the amount of the polymer of (c) is about 1 to about 20 weight percent. 
     
     
         23 . (canceled) 
     
     
         24 . The lubricant of  claim 1  further comprising at least one of a detergent, a dispersant, an antioxidant, a viscosity improver, an antiwear agent, and anti-scuffing agent, an extreme-pressure agent, a corrosion inhibitor, a foam inhibitor, a pour point depressant, or a friction modifier. 
     
     
         25 . The lubricant of  claim 1  wherein the lubricant contains 0.01 to 2.5 weight percent sulfur and 0.005 to 0.2 weight percent phosphorus. 
     
     
         26 . A process for preparing a lubricating composition comprising:
 (A) forming an esterified copolymer comprising
 (1) reacting (i) an α-olefin of at least about 6 carbon atoms and (ii) an ethylenically unsaturated carboxylic acid or derivative thereof, to form a copolymer; wherein the mole ratio of (i) α-olefin monomer to (ii) carboxylic acid or derivative monomer is about 1:3 to about 3:1; 
 (2) esterifying the copolymer of step (1) to form an esterified copolymer; and 
 (3) optionally reacting the copolymer of step (2) with a nitrogen-containing compound in an amount to provide an esterified copolymer with at least about 0.01 weight percent nitrogen; and 
   (B) mixing the esterified copolymer from (A) with (i) an oil of lubricating viscosity having a kinematic viscosity at 100° C. of less than about 15 mm 2 /s and (ii) an ethylene α-olefin copolymer comprising greater than 5 weight percent ethylene monomer units, wherein the olefin monomer units contain 3 to about 20, or 3 to about 6, or 3 to 4, or 3 carbon atoms;   wherein the polymers of (A)) and (B)(ii) are present in a weight ratio (A):(B)(ii) of about 1:10 to about 10:1 and wherein the total amount of polymer (A) plus (B)(ii) is about 2 to about 60 percent by weight of the lubricant composition.   
     
     
         27 . A process for preparing a lubricating composition comprising:
 (A) forming an esterified copolymer comprising
 (1) reacting (i) an α-olefin of at least about 6 carbon atoms and (ii) an ester of an ethylenically unsaturated carboxylic acid, to form a copolymer; wherein the mole ratio of (i) α-olefin monomer to (ii) ester of unsaturated carboxylic acid is about 1:3 to about 3:1; 
 (2) optionally reacting the copolymer of step (1) with a nitrogen-containing compound in an amount to provide an esterified copolymer with at least about 0.01 weight percent nitrogen; and 
   (B) mixing the esterified copolymer from (A) with (i) an oil of lubricating viscosity having a kinematic viscosity at 100° C. of less than about 15 mm 2 /s and (ii) an ethylene α-olefin copolymer comprising greater than 5 weight percent ethylene monomer units, wherein the α-olefin monomer units contain 3 to about 20, or 3 to about 6, or 3 to 4, or 3 carbon atoms;   wherein the polymers of (A)) and (B)(ii) are present in a weight ratio (A):(B)(ii) of about 1:10 to about 10:1 and wherein the total amount of polymer (A) plus (B)(ii) is about 2 to about 60 percent by weight of the lubricant composition.   
     
     
         28 . A method for lubricating a mechanical device, comprising supplying thereto the lubricant of  claim 1 . 
     
     
         29 - 32 . (canceled)