Magnetic coated carrier, two-component type developer and developing method

摘要

A magnetic coated carrier suitable for constituting a two-component type developer for use in electrophotography is composed of magnetic coated carrier particles comprising magnetic carrier core particles and a resinous surface coated layer coating the magnetic carrier core particles. The carrier is suitably constituted so as to satisfy the condition of: (a) the magnetic carrier core particles has a resistivity of at least 1x10<10> ohm.cm, and the magnetic coated carrier has a resistivity of at least 1x10<12> ohm.cm, (b) the magnetic coated carrier has a number-average particle size of 1- 100 mu m and has such a particle size distribution that particles having particle sizes of at most a half of the number-average particle size occupy an accumulative percentage of at most 20 % by number, (c) the magnetic coated carrier has a shape factor SF-1 of 100 - 130, (d) the magnetic coated carrier has a magnetization at 1 kilo-oersted of 40 - 250 emu/cm<3>, and (e) the resinous surface coating layer comprises a coating resin composition which in turn comprises a straight silicone resin and a coupling agent. The straight silicone resin includes trifunctional silicon and difunctional silicon in an atomic ratio of 100:0 - 40:60. <IMAGE>