| 摘要 |
PURPOSE:To obtain the viscosity index (VI) improver useful as a mineral oil- based lubricating oil, etc., having excellent VI improving properties, shear stability and dispersion characteristics of sludge, etc., comprising a polyester, prepared by introducing a nitrogen-containing basic group to the molecular end of a specific polymer, as an active ingredient. CONSTITUTION:This improver comprises a polyester, prepared by introducing (B) a nitrogen-containing basic group to (A) the molecular end of a polymer made by subjecting (i) a dicarboxylic acid component and (ii) a polyfunctional alcohol component to polycondensation, as an active ingredient. At least one of the component (ii) is a trihydric alcohol or at least one of the component (ii) is a dihydric or polyhydric alcohol containing a hydrocarbon chain through a hetero atom or an atomic group composed of the hetero atom and the alcohol contains at least one OH group of the tri- or polyhydric alcohol, replaced with an ester group and/or an alkoxy group. The substituted alcohol is preferably obtained by esterification reaction between a tri- or polyfunctional alcohol and a higher fatty acid. |
