GREASE COMPOSITION, GREASE-PACKED BEARING, UNIVERSAL JOINT FOR PROPELLER SHAFT, LUBRICATING OIL COMPOSITION, AND OIL-IMPREGNATED SINTERED BEARING

摘要

A grease composition or lubricating oil composition which can effectively prevent the rolling surfaces of a rolling bearing or the like from suffering hydrogen embrittlement and resultant flaking, has excellent high-temperature high-speed durability, and can be used for long. Provided is a grease-packed bearing (1) which is equipped with an inner ring (2), an outer ring (3), and a plurality of rolling elements (4) and in which sealing members (6) for enclosing a grease composition (7) around the rolling elements have been disposed in both shaft-direction edge openings (8a, 8b) between the inner ring (2) and the outer ring (3). The grease composition (7) comprises a base grease comprising a base oil and a thixotropic agent and an additive incorporated in the base grease, the additive comprising at least one compound selected from plant-derived polyphenol compounds and products of decomposition thereof, the compounds being tannin, gallic acid, ellagic acid, chlorogenic acid, caffeic acid, curcumin, quercetin, quinic acid, etc.