Patent ID: 8609598

Claim:
A nitrate free grease composition for avoiding an abnormal peeling of a rolling surface of a bearing, said nitrate free grease composition comprising: a base oil, a thickener, and an additive, wherein the base oil consists of symthesized hydrocarbon oil and 20% by weight or more of alkyldiphenyl ether oil or consists of alkyldiphenyl ether oil, and has a kinetic viscosity of 20 to 150 mm 2 /s at 40 degree° C., and wherein the thickener is an aromatic diurea compound represented by the following formula (2) where R2 and R4 are the same or different, and represent each an aromatic hydrocarbon group having 6 to 15 carbon atoms, and R3 represents an aromatic hydrocarbon group having 6 to 15 carbon atoms, and is contained in an amount of 5 to 30% by weight based on the total amount of the base oil and the thickener, and wherein the additive contains as an essential component 1 to 3 parts by weight of a sodium sebacate based on 100 parts by weight of the base oil and the thickener, wherein the additive contains a rust preventative which is a partially esterified multivalent alcohol or an organic sulfonic acid salt of an alkali metal or an alkali earth metal.