Lubricating oil compositions

Abstract

Lubricating oil compositions and viscosity index (VI) improver concentrates containing combinations of first polymers that are amorphous ethylene α-olefin copolymers; and second polymers that are star polymers, the arms of which are derived from diene, and optionally vinyl aromatic hydrocarbon monomer, wherein the star polymers have a Shear Stability Index (SSI) of from about 1% to about 35% (30 cycle).

1 . A lubricating oil composition comprising a major amount of oil of lubricating viscosity, and a viscosity index (VI) improver composition comprising a first polymer comprising an amorphous ethylene-α olefin copolymer or ethylene-α olefin-diene terpolymer having a crystallinity of not greater than about 1.0%; and a second polymer comprising a star polymer, the arms of which are derived from diene, and optionally vinyl aromatic hydrocarbon monomer, wherein the star polymer has a Shear Stability Index (SSI) of from about 1% to about 35% (30 cycle). 
     
     
         2 . A lubricating oil composition as claimed in  claim 1 , wherein the first polymer and the second polymer are present in a mass % ratio of from about 80:20 to about 20:80. 
     
     
         3 . A lubricating oil composition, as claimed in  claim 2 , wherein said first polymer is an ethylene-propylene copolymer having less than 2% of units derived from diene. 
     
     
         4 . A lubricating oil composition, as claimed in  claim 3 , wherein said ethylene-propylene copolymer is an amorphous copolymer having a shear stability index (SSI) of from about 20% to about 50%. 
     
     
         5 . A lubricating oil composition, as claimed in  claim 4 , wherein said ethylene-propylene copolymer is polymerized via Ziegler-Natta catalysis and contains from about 40 mass % to about 55 mass % ethylene. 
     
     
         6 . A lubricating oil composition, as claimed in  claim 4 , wherein said ethylene-propylene copolymer is polymerized via single site (metallocene) catalysis and contain from about 35 mass % to about 50 mass % ethylene. 
     
     
         7 . A lubricating oil composition, as claimed in  claim 2 , wherein said second polymer is a hydrogenated polymer derived from a polyolefinic linking agent coupled to arms comprising diene units and optionally vinyl aromatic units. 
     
     
         8 . A lubricating oil composition, as claimed in  claim 7 , wherein said diene units comprise butadiene, isoprene, or a mixture thereof. 
     
     
         9 . A lubricating oil composition, as claimed in  claim 8 , wherein said second polymer comprises from about 75 to about 90 mass % of units derived from isoprene, and from about 10 to about 25 mass % of units derived from butadiene, wherein greater than about 80 mass % of the butadiene derived units are incorporated as 1,4 addition product. 
     
     
         10 . A lubricating oil composition, as claimed in  claim 8 , wherein said second polymer comprises butadiene wherein from about 30 to about 80 mass % of the butadiene units are incorporated as 1,2-addition product and from about 20 to about 70 mass % of the butadiene units are incorporated as 1,4-addition product. 
     
     
         11 . A lubricating oil composition, as claimed in  claim 8 , wherein said second polymer further comprises from about 0 to about 35 mass % of units derived from styrene. 
     
     
         12 . A lubricating oil composition, as claimed in  claim 2 , wherein said first polymer is an ethylene-propylene amorphous copolymer having an SSI of from about 20% to about 50%; and said second polymer comprises from about 75 to about 90 mass % of units derived from isoprene, and from about 10 to about 25 mass % of units derived from butadiene; greater than about 80 mass % of the butadiene derived units are incorporated as 1,4 addition product; and said second polymer has an SSI of from about 1% to about 15%. 
     
     
         13 . A lubricating oil composition as claimed in  claim 1 , further comprising a nitrogenous dispersant derived from a polyalkene having a number average molecular weight (M n ) of greater than about 1500. 
     
     
         14 . A viscosity index (VI) improver concentrate comprising diluent oil; a first polymer that is an amorphous ethylene α-olefin copolymer having a crystallinity of not greater than about 1.0%; and a second polymer comprising a star polymer, the arms of which are derived from diene, and optionally vinyl aromatic hydrocarbon monomer, wherein the star polymer has a Shear Stability Index (SSI) of from about 1% to about 35% (30 cycle), wherein the total amount of polymer in the concentrate, including at least said first polymer and said second polymer is at least 5 mass %, based on the total mass of the concentrate. 
     
     
         15 . A VI improver concentrate, as claimed in  claim 14 , wherein the first polymer and the second polymer are present in a mass % ratio of from about 80:20 to about 20:80. 
     
     
         16 . A VI improver concentrate, as claimed in  claim 15 , wherein said first polymer is an ethylene-propylene copolymer having less than 2% of units derived from diene. 
     
     
         17 . A VI improver concentrate, as claimed in  claim 16 , wherein said ethylene-propylene copolymer is an amorphous copolymer having a shear stability index (SSI) of from about 20% to about 50%. 
     
     
         18 . A VI improver concentrate, as claimed in  claim 17 , wherein said ethylene-propylene copolymer is polymerized via Ziegler-Natta catalysis and contains from about 40 mass % to about 55 mass % ethylene. 
     
     
         19 . A VI improver concentrate, as claimed in  claim 17 , wherein said ethylene-propylene copolymer is polymerized via single site (metallocene) catalysis and contain from about 35 mass % to about 55 mass % ethylene. 
     
     
         20 . A VI improver concentrate, as claimed in  claim 15 , wherein said second polymer is a hydrogenated polymer derived from a polyolefinic linking agent coupled to arms comprising diene units and optionally vinyl aromatic units. 
     
     
         21 . A VI improver concentrate, as claimed in  claim 20 , wherein said diene units comprise butadiene, isoprene, or a mixture thereof. 
     
     
         22 . A VI improver concentrate, as claimed in  claim 20 , wherein said second polymer comprises from about 75 to about 90 mass % of units derived from isoprene, and from about 10 to about 25 mass % of units derived from butadiene, wherein greater than about 80 mass % of the butadiene derived units are incorporated as 1,4-addition product. 
     
     
         23 . A VI improver concentrate, as claimed in  claim 22 , wherein said second polymer comprises butadiene units wherein from about 30 to about 80 mass % of the butadiene units are incorporated as 1,2-addition product and from about 20 to about 70 mass % of the butadiene units are incorporated as 1,4-addition product. 
     
     
         24 . A VI improver concentrate, as claimed in  claim 21 , wherein said second polymer further comprises from about 5 to about 35 mass % of units derived from styrene. 
     
     
         25 . A VI improver concentrate, as claimed in  claim 15 , wherein said first polymer is an ethylene-propylene amorphous copolymer having an SSI of from about 35% to about 50%; and said second polymer comprises from about 75 to about 90 mass % of units derived from isoprene, and from about 10 to about 25 mass % of units derived from butadiene; greater than about 80 mass % of the butadiene derived units are incorporated as 1,4 addition product; and said second polymer has an SSI of from about 1% to about 15%.