Charging member, electrophotographic process cartridge, and electrophotographic image forming apparatus
The charging member includes: an electroconductive support; and an electroconductive elastic layer serving as a surface layer, wherein the elastic layer contains a binder, and holds electrically insulating hollow particles in such a state that at least a part of each of the hollow particles is exposed at a surface of the elastic layer, wherein the charging member has protrusions derived from the hollow particles in an outer surface of the charging member, and the outer surface of the charging member includes an outer surface of the elastic layer and an outer surface of an exposed portion of each of the hollow particles, and wherein the protrusions each have a depression in an outer surface of each of the protrusions, and an edge of the depression constitutes an apex in each of the protrusions.
1. A charging member, comprising:
an electroconductive support; and
an electroconductive elastic layer serving as a surface layer,
wherein the elastic layer contains a binder, and holds electrically insulating hollow particles in such a state that at least a part of each of the hollow particles is exposed at a surface of the elastic layer,
wherein the charging member has protrusions derived from the hollow particles in an outer surface of the charging member, and the outer surface of the charging member includes an outer surface of the elastic layer and an outer surface of an exposed portion of each of the hollow particles,
wherein the hollow particles have an average diameter of hollow portions of each of the hollow particles of 7 μm or more and 100 μm or less,
wherein the hollow particles have an average shell thickness of 0.05 μm or more and 3.00 μm or less,
wherein the protrusions each have a depression in an outer surface of each of the protrusions, and an edge of the depression constitutes an apex in each of the protrusions, and
wherein the depressions have an average depth of 1.0 μm or more and 6.0 μm or less.
2. A charging member according to claim 1 , wherein a Martens hardness at an indentation depth of 0.1 μm measured at each of the protrusions is 8.0 N/mm 2 or more, and a Martens hardness at an indentation depth of 1.0 μm measured at each of the protrusions is 1.2 N/mm 2 or less.
3. A charging member according to claim 1 , wherein:
the elastic layer is the only elastic layer of the charging member; and
the elastic layer has a thickness of 0.8 mm or more and 4.0 mm or less.
4. A charging member according to claim 1 , wherein a Martens hardness at an indentation depth of 1.0 μm measured at the surface of the elastic layer included in the surface of the charging member is 2.0 N/mm 2 or more.
5. An electrophotographic process cartridge, comprising at least a charging member, the electrophotographic process cartridge being removably mounted onto a main body of an electrophotographic image forming apparatus,
wherein the charging member comprises a charging member including an electroconductive support, and an electroconductive elastic layer serving as a surface layer,
wherein the elastic layer contains a binder, and holds electrically insulating hollow particles in such a state that at least a part of each of the hollow particles is exposed at a surface of the elastic layer,
wherein the charging member has protrusions derived from the hollow particles in an outer surface of the charging member, and the outer surface of the charging member includes an outer surface of the elastic layer and an outer surface of an exposed portion of each of the hollow particles,
wherein the hollow particles have an average diameter of hollow portions of each of the hollow particles of 7 μm or more and 100 μm or less,
wherein the hollow particles have an average shell thickness of 0.05 μm or more and 3.00 μm or less,
wherein the protrusions each have a depression in an outer surface of each of the protrusions, and an edge of the depression constitutes an apex in each of the protrusions, and
wherein the depressions have an average depth of 1.0 μm or more and 6.0 μm or less.
6. An electrophotographic image forming apparatus, comprising at least a charging member, an exposing apparatus, and a developing apparatus,
wherein the charging member comprises a charging member including an electroconductive support, and an electroconductive elastic layer serving as a surface layer,
wherein the elastic layer contains a binder, and holds electrically insulating hollow particles in such a state that at least a part of each of the hollow particles is exposed at a surface of the elastic layer,
wherein the charging member has protrusions derived from the hollow particles in an outer surface of the charging member, and the outer surface of the charging member includes an outer surface of the elastic layer and an outer surface of an exposed portion of each of the hollow particles,
wherein the hollow particles have an average diameter of hollow portions of each of the hollow particles of 7 μm or more and 100 μm or less,
wherein the hollow particles have an average shell thickness of 0.05 μm or more and 3.00 μm or less,
wherein the protrusions each have a depression in an outer surface of each of the protrusions, and an edge of the depression constitutes an apex in each of the protrusions, and
wherein the depressions have an average depth of 1.0 μm or more and 6.0 μm or less.