Viscosity improver compositions that impart improved low temperature properties to lubricating oils This application claims priority from US Provisional Application 60 / 458,666, filed March 28,2003.

摘要

A lubricant composition comprising an oil of lubricating viscosity; (A) 0.05 to 1.5 percent by weight of a copolymer comprising 70 to 79 percent by weight of units derived from ethylene ("E"), having a weight-average molecular weight of 50,000 to 100,000, polydispersity less than 3, density ("D") of 860 to 896 kg/m3, and a melting point ("Tm") of 15 °C to 60 °C, wherein E and Tm fulfill the expression 3.44E - 206 = Tm; and (B) 0.05 to 1.5 percent by weight of a block copolymer comprising a first block which comprises a vinyl aromatic comonomer and a second block which comprises a diene comonomer, the diene monomer-containing block being hydrogenated; wherein the weight ratio (A) : (B) is 20:80 to 60:40; exhibits good low temperature performance and durability.