RESIN COATED CARRIER FOR TWO-COMPONENT TYPE DEVELOPER, TWO-COMPONENT TYPE DEVELOPER AND DEVELOPMENT METHOD

摘要

PROBLEM TO BE SOLVED: To provide a resin coated carrier for a two-component type developer capable of maintaining a stable electrostatic charge quantity and obtaining copies of stable image quality free from the degradation in image density and thinning. SOLUTION: This resin coated carrier for the two-component type developer has a carrier core material and carrier particles having of coating layers for coating the surfaces of this carrier core material. The resin coated carrier contains 0.1 to 20 number % carrier particles smaller than 22 μm having a 50% grain size C(D50) of 25 to 70 μm and contains 2 to 35 number % carrier particles of =62 μm. The BET specific surface area SW1 of the carrier core material subjected to the removal of the coating layers and the BET specific surface area SW2 of the resin coated carrier satisfy the equations I: 80=SW1- SW2=650(cm2/g). The resin coated carrier specific the shape coefficient SF-1 of the equation II: 110=SF-1=160 and the shape coefficient SF-2 of the equation III: 105=SF-2=150.