Grease composition, pivot assembly bearing, and bearing apparatus including the bearing

Abstract

Object Objective is to provide a grease composition for a pivot assembly and a pivot assembly bearing filled with the grease composition, and to provide a bearing apparatus as well as a drive apparatus including the bearing apparatus, which is capable of suppressing adhesion of a volatilized component to a magnetic disk or the like even when the grease composition is volatilized by application of the grease composition and the bearing, thereby suppressing occurrence of read/write errors of an HDD. Solution Provided are: a grease composition for a pivot assembly bearing including an aromatic ester-based base oil and a thickener, the aromatic ester-based base oil containing an aromatic ester compound having an ester group *—(CO)O— as a substituent on a ring, where * is a bonding site to an aromatic ring, and having an alkyl group with a total of 8 or more carbon atoms bonded to an oxygen atom of the ester group; a pivot assembly bearing filled with the grease composition for pivot assembly bearing; a bearing apparatus including the pivot assembly bearing; and a disk drive apparatus equipped with the bearing apparatus.