OIL-SOLUBLE POLYESTER, ADDITIVE FOR LUBRICANT AND LUBRICANT COMPOSITION

摘要

PURPOSE: To obtain an oil-soluble polyester improved in viscosity index and shear stability and exhibiting good oxidation stability and low viscosity at low temperature by adding a polyester of specific composition CONSTITUTION: This oil-soluble polyester having a weight - average mol.wt. of 10,000-1,000,000 is obtained by polycondensing (A) a dibasic higher carboxylic acid component, (B) a dihydric alcohol component containing a glycol of formula: HO-CH2 -CR<1> R<2> -CH2 -OH (R<1> , R<2> are alkyl groups wherein the total carbon atoms in the alkyl groups are >=3), and (C) at least a compound selected from tribasic or more-basic carboxylic acids and trihydric or more-hydric alcohols in an amount of 0.1-15mol.% based on the total amount of both the components (A), (B) with each other. An additive for lubricants contains the polyester as a main component. This invention also relates to lubricant compositions containing the polyester and containing the polyester and a polymethacrylate.