Developing apparatus, developing method, image forming apparatus, and image forming method

摘要

A developing apparatus and a developing method that significantly suppress generation of fogging and form a high-quality electrophotographic images under any environments such as a high temperature and high humidity environment and a low temperature and low humidity environment are provided.;A toner wherein a covering rate X1 of the surface of a toner particle with silica fine particles, which is determined by ESCA, is 40.0 to 75.0 area %, and the diffusion index represented by (Expression 1) diffusion index=X1/X2 satisfies (Expression 2) diffusion index≧−0.0042×X1+0.62 where in the theoretical covering rate with the silica fine particles is defined as X2; and a developing apparatus including a developing carrying member which is a surface layer formed of a urethane resin having a partial structure derived from a reaction of a polyisocyanate with a compound represented by Formula 1.

主权项

1. A developing apparatus comprising:
a toner, a developing container accommodating the toner, a developing carrying member rotatably held, the developing carrying member carrying the toner fed from the developing container on the surface of the developing carrying member to form a toner layer, and conveying the toner, and a toner layer thickness controlling member controlling the thickness of the toner layer, wherein:
the toner comprises:
toner particles containing a binder resin and a colorant, andsilica fine particles, a covering rate X1 of the surface of each of the toner particles covered with the silica fine particles determined by an X-ray electron spectroscope for chemical analysis (ESCA) is 40.0 area % or more and 75.0 area % or less, a diffusion index represented by Expression 1 satisfies Expression 2,
diffusion index=X1/X2  (Expression 1)diffusion index≧−0.0042×X1+0.62,  (Expression 2) where a theoretical covering rate with the silica fine particles is defined as X2; and wherein: the developing carrying member comprises:
an electrically conductive substrate,an elastic layer, anda surface layer containing a urethane resin, and the urethane resin has a partial structure derived from a reaction of a polyisocyanate with a compound represented by Formula (1): wherein
n is an integer of 1 or more and 4 or less, andR1 is each independently any one selected from the group consisting of (a) to (c): (a) a hydroxyalkyl group having 1 or more and 8 or less carbon atoms, (b) an aminoalkyl group having 2 or more and 8 or less carbon atoms, and (c) a group represented by Formula (2): wherein m represents an integer of 2 or more and 3 or less, and R3 represents an alkylene group having 2 or more and 5 or less carbon atoms, and R2 represents an alkylene group having 2 or more and 4 or less carbon atoms.