Lubricant composition comprising a bi-modal side-chain distribution lofi

Abstract

A lubricant composition is disclosed. The lubricant composition is made up of (a) an API Group III base stock; (b) one or more semi-crystalline viscosity modifier; and (c) one or more LOFIs having a side-chain distribution which satisfies the following requirements: (1) the distribution contains side chains ranging from C 8 to C 18 with an average carbon number ranging from 12.4 to 14.4; (2) the side chain distribution is bi-modal with a lower portion of the bi-modal distribution made up primarily of C 12 and an upper portion of the distribution made up primarily of C 16 , C 18 or combinations thereof (3) the total mole % of the upper portion of the distribution must be less than that of the lower portion of the distribution; and (4) the amount of C 12 on the side chain must be at least 40 mole % of the total side chain distribution.

1 . A lubricant composition comprising:
 (a) an API Group III base stock;   (b) one or more semi-crystalline viscosity modifier; and   (c) one or more LOFIs having a side-chain distribution which satisfies the following requirements:
 (1) the distribution contains side chains ranging from C 8  to C 18  with an average carbon number ranging from 12.4 to 14.4; 
 (2) the side chain distribution is bi-modal with a lower portion of the bi-modal distribution made up primarily of C 12  and an upper portion of the distribution made up primarily of C 16 , C 18  or combinations thereof; 
 (3) the total mole % of the upper portion of the distribution must be less than that of the lower portion of the distribution; and 
 (4) the amount of C 12  on the side chain must be at least 40 mole % of the total side chain distribution. 
   
   
   
       2 . The lubricant composition according to  claim 1  wherein the semi-crystalline viscosity modifier includes an amorphous viscosity modifier. 
   
   
       3 . The lubricant composition according to  claim 1  wherein the LOFI is a dialkyl fumarate-vinyl acetate copolymer. 
   
   
       4 . The lubricant composition according to  claim 1  wherein the distribution contains side chains ranging from C 8  to C 18  with an average carbon number ranging from 12.8 to 14.0. 
   
   
       5 . The lubricant composition according to  claim 1  wherein the semi-crystalline viscosity modifier comprises copolymers of ethylene copolymerized with at least one additional alphaolefin monomer having from 3 to 30 carbon atoms. 
   
   
       6 . The lubricant composition according to  claim 1 wherein the semi-crystalline viscosity modifier comprises an ethylene alphaolefin copolymer containing a small amount of one or more non-conjugated dienes. 
   
   
       7 . The lubricant composition according to  claim 1  wherein the LOFI comprises a poly(alkyl methacrylate) polymer. 
   
   
       8 . The lubricant composition according to  claim 1  wherein the LOFI comprises a poly(alkyl acrylate) polymer. 
   
   
       9 . The lubricant composition according to  claim 1  wherein the LOFI comprises a poly(styrene-dialkyl maleate). 
   
   
       10 . The lubricant composition according to  claim 1  wherein the LOFI has a specific viscosity ranging from 0.3 to 1.0. 
   
   
       11 . The lubricant composition according to  claim 1  wherein the LOFI is present in an amount ranging from 0.005 weight percent to 1.0 weight percent, based on the total weight of the lubricant composition. 
   
   
       12 . The lubricant composition according to  claim 1  further comprising one or more of the following components: corrosion inhibitors, oxidation inhibitors, friction modifiers, dispersants