Viscosity Modifiers Comprising Blends of Ethylene-Based Copolymers

Abstract

The present invention is directed to polymer blend compositions for use as viscosity modifiers comprising at least two ethylene-based copolymer components. The viscosity modifiers described herein comprise a first ethylene-based copolymer having an ethylene content of from about 44 to about 52 wt % and/or a heat of fusion of from about 0 to about 15 J/g and a second ethylene-based copolymer having an ethylene content of from about 68 to about 75 wt % and/or a heat of fusion of from about 40 to about 65 J/g. The invention is also directed to lubricant compositions comprising a lubricating basestock and a polymer blend of the invention.

1 . A polymer blend composition comprising a first ethylene-based copolymer and a second ethylene-based copolymer, wherein:
 (a) the first copolymer has an ethylene content from about 44 to about 52 wt %;   (b) the second copolymer has an ethylene content from about 68 to about 75 wt %;   (c) the first and second copolymers have a weight-average molecular weight (Mw) less than or equal to about 130,000;   (d) the ratio of the melt index of the first copolymer to the melt index of the second copolymer is less than or equal to about 3.0; and   (e) the composition comprises from about 35 to about 65 wt % of the first copolymer, based on the total weight of the first and second copolymers.   
     
     
         2 . The polymer blend composition of  claim 1 , wherein the first copolymer has an ethylene content from about 45 to about 51 wt % and the second copolymer has an ethylene content from about 69 to about 74 wt %. 
     
     
         3 . The polymer blend composition of  claim 2 , wherein the first copolymer has an ethylene content from about 46 to about 50 wt %, and the second copolymer has an ethylene content from about 70 to about 73 wt %. 
     
     
         4 . The polymer blend composition of  claim 1 , wherein the first and second copolymers each comprise one or more comonomers selected from the group consisting of C 3 -C 20  alpha-olefins. 
     
     
         5 . The polymer blend composition of  claim 1 , wherein the ethylene content of the second copolymer is at least about 17 wt % greater than the ethylene content of the first copolymer. 
     
     
         6 . The polymer blend composition of  claim 5 , wherein the ethylene content of the second copolymer is at least about 21 wt % greater than the ethylene content of the first copolymer. 
     
     
         7 . The polymer blend composition of  claim 1 , wherein the composition comprises from about 38 to about 62 wt % of the first copolymer, based on the total weight of the first and second copolymers. 
     
     
         8 . The polymer blend composition of  claim 7 , wherein the composition comprises from about 40 to about 60 wt % of the first copolymer, based on the total weight of the first and second copolymers. 
     
     
         9 . A polymer blend composition comprising a first ethylene-based copolymer and a second ethylene-based copolymer, wherein:
 (a) the first copolymer has a heat of fusion from about 0 to about 15 J/g;   (b) the second copolymer has a heat of fusion from about 40 to about 65 J/g;   (c) the first and second copolymers have a weight-average molecular weight (Mw) less than or equal to about 130,000;   (d) the ratio of the melt index of the first copolymer to the melt index of the second copolymer is less than or equal to about 3.0; and   (e) the composition comprises from about 35 to about 65 wt % of the first copolymer, based on the total weight of the first and second copolymers.   
     
     
         10 . The polymer blend composition of  claim 9 , wherein the first copolymer has a heat of fusion from about 0 to about 10 J/g and the second copolymer has a heat of fusion from about 42 to about 62 J/g. 
     
     
         11 . The polymer blend composition of  claim 10 , wherein the first copolymer has a heat of fusion from about 0 to about 5 J/g and the second copolymer has a heat of fusion from about 45 to about 60 J/g. 
     
     
         12 . The polymer blend composition of  claim 9 , wherein the first and second copolymers each comprises one or more comonomers selected from the group consisting of C 3 -C 20  alpha-olefins. 
     
     
         13 . The polymer blend composition of  claim 9 , wherein the ethylene content of the second copolymer is at least about 17 wt % greater than the ethylene content of the first copolymer. 
     
     
         14 . The polymer blend composition of  claim 13 , wherein the ethylene content of the second copolymer is at least about 21 wt % greater than the ethylene content of the first copolymer. 
     
     
         15 . The polymer blend composition of  claim 9 , wherein the composition comprises from about 38 to about 62 wt % of the first copolymer, based on the total weight of the first and second copolymers. 
     
     
         16 . The polymer blend composition of  claim 15 , wherein the composition comprises from about 40 to about 60 wt % of the first copolymer, based on the total weight of the first and second copolymers. 
     
     
         17 . A lubricating oil composition comprising a lubricating oil basestock, a first ethylene-based copolymer, and a second ethylene-based copolymer, wherein:
 (a) the first copolymer has an ethylene content from about 44 to about 52 wt %;   (b) the second copolymer has an ethylene content from about 68 to about 75 wt %;   (c) the first and second copolymers have a weight-average molecular weight (Mw) less than or equal to about 130,000;   (d) the ratio of the melt index of the first copolymer to the melt index of the second copolymer is less than or equal to about 3.0; and   (e) the composition comprises from about 35 to about 65 wt % of the first copolymer, based on the total weight of the first and second copolymers.   
     
     
         18 . The lubricating oil composition of  claim 17 , wherein the first copolymer has an ethylene content from about 46 to about 50 wt %, and the second copolymer has an ethylene content from about 70 to about 73 wt %. 
     
     
         19 . The lubricating oil composition of  claim 17 , wherein the first and second copolymers each comprise one or more comonomers selected from the group consisting of C 3 -C 20  alpha-olefins. 
     
     
         20 . The lubricating oil composition of  claim 17 , wherein the ethylene content of the second copolymer is at least about 21 wt % greater than the ethylene content of the first copolymer. 
     
     
         21 . A lubricating oil composition comprising a lubricating oil basestock, a first ethylene-based copolymer, and a second ethylene-based copolymer, wherein:
 (a) the first copolymer has a heat of fusion from about 0 to about 15 J/g;   (b) the second copolymer has a heat of fusion from about 40 to about 65 J/g;   (c) the first and second copolymers have a weight-average molecular weight (Mw) less than or equal to about 130,000;   (d) the ratio of the melt index of the first copolymer to the melt index of the second copolymer is less than or equal to about 3.0; and   (e) the composition comprises from about 35 to about 65 wt % of the first copolymer, based on the total weight of the first and second copolymers.   
     
     
         22 . The lubricating oil composition of  claim 21 , wherein the first copolymer has a heat of fusion from about 0 to about 5 J/g and the second copolymer has a heat of fusion from about 45 to about 60 J/g. 
     
     
         23 . The lubricating oil composition of  claim 21 , wherein the first and second copolymers each comprise one or more comonomers selected from the group consisting of C 3 -C 20  alpha-olefins. 
     
     
         24 . The lubricating oil composition of  claim 21 , wherein the ethylene content of the second copolymer is at least about 21 wt % greater than the ethylene content of the first copolymer.