Ball bearing retainer, and ball bearing employing the same

A ball bearing retainer formed by injection molding of a resin composition containing spherical carbons and reinforcement fibers, comprising:

• a ring-shaped body entirely composed of the resin composition to be disposed between inner and outer races of a ball bearing;
• and
• a plurality of pocket surfaces provided on the body to define a plurality of pockets for retaining balls of the ball bearing, the pocket surfaces each having a concaved spherical shape similar to a shape of the ball of the ball bearing and each defining openings in an inner surface and an outer surface of the ring-shaped body,
• wherein at least one of the pocket surfaces defining the respective pockets has a projection provided in the vicinity of one of the openings defined in the inner and outer surfaces of the ring-shaped body as projecting from the pocket surface inward of the pocket,
• wherein at least the resin composition forming the projection contains the spherical carbons,
• wherein the reinforcement fibers hardly enter the resin composition forming the projection, from the resin composition composing the body, so that the projection has a lower concentration of the reinforcement fibers compared to the body, and
• wherein an amount of the spherical carbons in the resin composition is 3 wt % to 40 wt % based on the whole amount of the resin composition.