| 摘要 |
PROBLEM TO BE SOLVED: To provide a viscosity index (VI) improver imparting a TE (Thickening Effect) comparable in that to high ethylene content olefin copolymr (OCP) without reduction of accompanied solubility and low temperature performance. SOLUTION: A polymer suitable for use as a viscosity index improver for lubricating oil composition, which is a hydrogenated linear, radial or star-shaped random copolymer of isoprene and butadiene, in which at least 70 wt. % of the butadiene is incorporated into the polymer as 1,4 units and the weight ratio of isoprene addition product to butadiene addition product in the copolymer is in a range of from about 90:10 to about 70:30, preferably in a range of about 85:15 to about 80:20. COPYRIGHT: (C)2005,JPO&NCIPI |
