| abstract |
A grease composition comprising a base oil containing not less than 10% by weight of an ester oil based on the total base oil and having a kinematic viscosity of 50 to 200 mm2/sec at 40 DEG C. and 15 to 35% by weight, based on the total grease composition, of a diurea compound represented by formula (I): <IMAGE> (I) wherein R2 represents an aromatic hydrocarbon group having 6 to 15 carbon atoms; and R1 and R3, which may be the same or different, each represent an aromatic hydrocarbon group having 6 to 12 carbon atoms or an aliphatic hydrocarbon group having 8 to 20 carbon atoms, the proportion of the aromatic hydrocarbon groups in the total of R1 and R3 being 50 to 100 mol %. When applied to outer race rotating bearings, the grease composition is excellent in flaking resistance, leak resistance, and low noise properties and prevents premature seizing under high temperature and high speed conditions. |