| 摘要 |
<p>PURPOSE:To obtain a carrier tough and excellent in durability against wear or peeling of a coating resin and to decrease changes in electrification property or resistance for a long time by treating the surface of the core material to have a specified shape. CONSTITUTION:The carrier consists of a core material 1 having lots of dimples 2 on the surface, and a coating layer which covers the surface of the core 1. The core 1 has 30-100mum average particle size and is preferably consists of a ferrite particle in order to make formation of dimples easy or to decrease torque during development. The dimples 2 formed on the surface of the core material 1 are preferably oval or spherical recesses satisfying the length ratio S/L=0.03-0.15, wherein S is the max. diameter (length along the major axis) and L is the diameter of the core material particle. If S/L is smaller than this range, peeling of the coating resin increases, and if it exceeds this range, resistance value of the carrier is hardly controlled. It is preferable that the ratio of the max. depth T of the dimple 2 to the max. diameter S is 0.1-0.6.</p> |
