MAGNETIC COATED CARRIER, TWO-COMPONENT DEVELOPER AND DEVELOPING METHOD

摘要

PROBLEM TO BE SOLVED: To obtain a magnetic coated carrier which shows excellent electrification property and does not cause deposition of the carrier when the carrier is used in combination with a small particle size toner, by controlling the distribution of particle size to a specified range and decreasing the amt. of such particles having a specified or smaller average particle size. SOLUTION: The magnetic coated carrier consists of magnetic carrier core particles and a coating layer which covers each core particle. The core particle contains at least binder resin and magnetic metal oxide particles. The magnetic metal oxide particles are subjected to such treatment to make the surface oleophilic. The core particle has >=1×10<10>Ω.cm specific resistance while the carrier has >=1×10<12>Ω.cm specific resistance. The number average particle size Dn of the carrier is 5 to 100μm and satisfies Dn/σ>=3.5 in the distribution of particle numbers, whereinσis the standard deviation in the number distribution of the carrier. The proportion of carrier particles having <=2/3 Dn particle size is <25%.