| 摘要 |
<p>A developing roller is provided which has a mandrel, a conductive elastic layer covering the mandrel and containing silicone rubber and carbon black as a conducting agent, and a surface layer, and can keep ghost images from occurring. The developing roller has a conductive shaft member, a conductive elastic layer formed around the shaft member in a thickness of from 0.5 mm to 6.0 mm, and a surface layer. The elastic layer contains carbon black and silicone rubber serving as a binder for the carbon black, the carbon black is in a content of from 7% by mass to 17% by mass based on the mass of the elastic layer, the carbon black in the elastic layer has at least two peaks in its particle size number distribution, the minimum diameter peak center in the particle size number distribution is within the range of from 10 nm to 40 nm, the elastic layer has density within the range of from 1.01 g/cm 3 to 1.07 g/cm 3 , and, where the ratio of carbon atoms to silicon atoms (C/Si) in the vicinity of the surface of the elastic layer is represented by X, the ratio of carbon atoms to silicon atoms at a depth of 100 µm from the surface of the elastic layer by Y, and the ratio of carbon atoms to silicon atoms at a depth of 200 µm from the surface of the elastic layer by Z, the X, the Y and the Z satisfy a specific relationship.</p> |
