| CPC G03G 15/0818 (2013.01) [G03G 15/095 (2013.01)] | 11 Claims |
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1. A developing device comprising:
a developing roller;
a toner; and
a toner supply roller that supplies the toner to the developing roller,
the developing roller comprising:
an electro-conductive substrate; and
a surface layer on the electro-conductive substrate, the surface layer being composed of a single layer, wherein
the surface layer has a matrix comprising a crosslinked urethane resin as a binder,
wherein when an elastic modulus of the matrix in a first region in a cross section in a thickness direction of the surface layer is defined as E1, the first region being from an outer surface of the surface layer to a position at a depth of 0.1 μm from the outer surface, and
an elastic modulus of the matrix in a second region in the cross section is defined as E2, the second region being from a position at a depth of 1.0 μm from the outer surface to a position at a depth of 1.1 μm from the outer surface,
E1 and E2 satisfy following relational expressions (1) and (2):
E1≥200 MPa (1)
10 MPa≤E2≤100 MPa (2), and
wherein:
fine particles are attached to the outer surface of the surface layer, and the fine particles form protrusions on the outer surface of the surface layer;
each of the fine particles comprises an organosilicon compound, and
in a cross-sectional view of each of the fine particles and the outer surface of the surface layer, each of the fine particles has a substantially flat surface that is in surface contact with the outer surface of the surface layer and a curved surface that constitutes at least a part of each of the protrusions;
a number-average value of the longest diameter w of the substantially flat surface of the fine particles is 10 nm to 400 nm;
the toner comprises a toner particle and silica particles as an external additive;
the toner particle comprises a binder resin; and
an adhesion rate of the silica particles to the toner particle measured by a water washing method is 50% or more.
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