Bearing bush for seat reclining device and seat reclining device

A bearing bush, for a seat reclining device, disposed in a shaft hole of an external gear of said seat reclining device, which slidingly contacts wedge-shaped pieces, said seat reclining device comprising a differential transmission mechanism for adjusting an open angle of a hinge connecting a seating surface of a seat and a backrest thereof to each other,

• said differential transmission mechanism having an internal gear;
• an external gear, having a smaller number of teeth than said internal gear, which engages said internal gear;
• a pair of said wedge-shaped pieces disposed in a circular arc-shaped gap formed between said shaft hole of said external gear and a shaft of said internal gear with tapered ends of said wedge-shaped pieces opposed to each other;
• and a compression coil spring for imparting an elastic force to said wedge-shaped pieces in a direction in which said wedge-shaped pieces depart from each other,
• wherein when said wedge-shaped pieces are moved in sliding contact with said bearing bush inside said circular arc-shaped gap with said wedge-shaped pieces being pressed by a cam provided on said shaft of said internal gear, said external gear disengages from said internal gear, whereby said open angle of said hinge is adjustable,
• characterized in that a sliding surface of said bearing bush is formed of a fluorocarbon resin composition containing fluorocarbon resin to which thermoplastic resin, carbon fibers, and molybdenum disulfide are added,
• where said thermoplastic resin has a melting point of −50° C. to +20° C. in relation to a melting point of said fluorocarbon resin.