| 摘要 |
PURPOSE:To form stably a sharp image having high density without fogging for a long period of time by consisting a carrier of particle groups of prescribed grain sizes made by dispersing the pulverous powder of a magnetic material into a binder resin, using ferrite particle groups having reverse spinel structure and prescribed grain size for the pulverous powder of the magnetic material and using a two-component developer contg. such small-size carrier having excellent conveyability. CONSTITUTION:The carrier of the developer is formed by dispersing and incorporating the pulverous powder of the magnetic material into the binder resin and incorporating a charge control agent and other additive components according to need thereto. The average grain size thereof is made 10-50mum. The pulverous powder of the magnetic material is the magnetic material consisting of ferrite Mo.Fe2O3 (M consists usually of at least one kind of Pb, Ba, Sr and Co) having the revese spinel structure. The average grain size of the magnetic material particles is 0.01-10mum. The ferrite having the reverse spinal structure is BaO.Fe2O3, SrO.Fe2 O3, etc. and the ratio at which the pulverous powder of the magnetic material is incorporated into the carrier is 40-90wt% by the weight of the carrier. The surface of the pulverous particle of the magnetic material is preliminarily coated with a styrene resin or higher fatty acid such as oleic acid in order to prevent the adverse influence of the frictional electrostatic chargeability of the surface of the carrier particles with the frictional chargeability. |
