Patent ID: 6641967
Filing Date: 2003-11-04
Classification: G03G

Abstract:
An image forming method comprising:rotationally transporting a two component developer having a toner and a carrier, onto a developer carrying member; and developing in a developing zone an electrostatic latent image held on an electrostatic latent image bearing member with the toner of the two component developer carried on the developer carrying member, wherein said two component developer comprises (i) a negatively chargeable toner having toner particles and external additive and (ii) a carrier comprising magnetic carrier core particles and a resin coat layer comprising a silicone resin coating the magnetic carrier core particles, said carrier having a weight average particle diameter from 10 to 45 &mgr;m and a saturation magnetization from 20 Am2/kg to 70 Am2/kg, wherein: said toner particles comprise a colorant and a binder resin having a polyester resin, said polyester resin being prepared by co-condensing an etherified bisphenol with a mixture comprising a dibasic carboxylic acid and a tribasic or higher carboxylic acid, said tribasic or higher carboxylic acid present in amounts from 0.1 to 10 mole % based on the total moles of the components for preparing the polyester resin, said negatively chargeable toner has an acid value from 1 KOH mg/g to 20 KOH mg/g, a glass transition temperature (Tg) from 45Â° C. to 70Â° C. and a weight average particle diameter from 1 to 9 &mgr;m, said external additive comprises inorganic fine particles having been subjected to hydrophobic treatment and having a number average particle diameter from 0.005 &mgr;m to 0.2 &mgr;m; and said magnetic carrier core particles are formed of a magnetic ferrite component represented by the following Formula (I): (Fe2O3)x(MnO)Y(A)Zâ€ƒâ€ƒFormula (I) wherein A represents a member selected from the group consisting of Na2O, K2O, CaO, SrO and mixtures thereof; and x, y and z each represent a molar fraction and satisfy the condition of:0.3<x<0.8, 0.010.5, 0.06&lE;z&lE;0.16, x+y+z&lE;1.