The invention relates to a method for preparing lignin derivative-based lubricating greases thickened by a polyurea thickener, lubricating greases thus prepared, and the use of such lubricant greases, inter alia, in transmissions, constant-velocity driveshafts and sealed roller bearings.

An object of the invention is to provide a grease composition that does not deteriorate resin, particularly, acetal resin, in contact therewith even under a high temperature condition. The object can be attained by a grease composition for resin, including (A) a lubricating base oil, (B) a thickener, and (C) at least one selected from the group consisting of an organic molybdenum compound and a sulfur-based extreme pressure agent, wherein when the grease composition includes the sulfur-based extreme pressure agent, a content of the sulfur-based extreme pressure agent is from 0.05 mass % to 2.5 mass % based on a total amount of the composition, and the grease composition is substantially free of zinc dialkyldithiophosphate.

It is an object of the present invention to provide a grease composition, for an outer ring rotation type rolling bearing, which is capable of satisfying all of high-temperature durability, low-temperature property, peeling resistance, and rust-preventive property. A grease composition (7) to be enclosed in the outer rig rotation type rolling bearing for use in automotive electric auxiliary machines contains base oil, a thickener, a peeling-resistant additive, a wear-resistant additive, and a rust-preventive agent. The base oil is mixed oil of trimellitic acid ester oil and synthetic hydrocarbon oil mixed therewith in a mass ratio of (70:30) to (90:10). The thickener consists of a diurea compound shown by a formula (1).
R.sup.1NHCONHR.sup.2NHCONHR.sup.1(1)
wherein a reference symbol R.sup.2 denotes a divalent aromatic hydrocarbon group having a carbon number of 6 to 15, and a reference symbol R.sup.1 denotes a cyclohexyl group.

Provided is a grease composition containing a base oil, a thickener, and an additive. The base oil contains a poly--olefin and has a kinematic viscosity of 20-60 mm.sup.2/s at 40 C. The thickener contains a urea compound produced by reacting a diisocyanate compound with a mixed amine containing an alicyclic amine and an aromatic amine. The additive contains a phosphorous acid ester, an ether compound, and an oxidized paraffin.

The invention relates to a method for preparing lignin derivative-based lubricating greases thickened by a polyurea thickener, lubricating greases thus prepared, and the use of such lubricant greases, inter alia, in transmissions, constant-velocity driveshafts and sealed roller bearings.

A grease composition including: a base oil, a thickener, and 0.2 wt % or more of a dispersing agent. The dispersing agent includes at least one of a metal salt of a carboxylic acid, a metal salt of a polycarboxylic acid, and a copolymer of a carboxylic acid metal salt and a hydrocarbon compound, and the dispersing agent has an average particle diameter of 0.5 m or more and 5 m or less. The metal salt of the carboxylic acid, the metal salt of the polycarboxylic acid, and the carboxylic acid metal salt forming the copolymer of the carboxylic acid metal salt and the hydrocarbon compound may be an alkali metal salt including at least one of a sodium salt, a lithium salt and a potassium salt, or an alkali earth metal salt including at least one of a magnesium salt and a calcium salt.

It is an object of the present invention to provide a grease composition, for an outer ring rotation type rolling bearing, which is capable of satisfying all of high-temperature durability, low-temperature property, peeling resistance, and rust-preventive property. A grease composition (7) to be enclosed in the outer rig rotation type rolling bearing for use in automotive electric auxiliary machines contains base oil, a thickener, a peeling-resistant additive, a wear-resistant additive, and a rust-preventive agent. The base oil is mixed oil of trimellitic acid ester oil and synthetic hydrocarbon oil mixed therewith in a mass ratio of (70:30) to (90:10). The thickener consists of a diurea compound shown by a formula (1).

R.sup.1NHCONHR.sup.2NHCONHR.sup.1(1)

wherein a reference symbol R.sup.2 denotes a divalent aromatic hydrocarbon group having a carbon number of 6 to 15, and a reference symbol R.sup.1 denotes a cyclohexyl group.