VISCOSITY IMPROVER COMPOSITIONS PROVIDING IMPROVED LOW TEMPERATURE CHARACTERISTICS TO LUBRICATING OIL

摘要

PROBLEM TO BE SOLVED: To provide good shear stability and low temperature performance to lubricant formulations.SOLUTION: A lubricant composition comprises: 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/m, and a melting point ("Tm") of 15°C to 60°C, where E and Tm satisfy the equation in the figure; 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; where the weight ratio (A):(B) is from 20:80 to 60:40. The lubricant composition exhibits good low temperature performance and durability.