| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing roll excellent in durability and capable of obtaining an excellent image without toner scattering nor image thinning. SOLUTION: This developing roll is constituted by forming a base rubber layer along the outer peripheral surface of a shaft body, forming an electrode layer on the outer peripheral surface of the base rubber layer and further forming a surface layer on the outer peripheral surface of the electrode layer. It satisfies an inequality (x) and has characteristics (y) and (z). The inequality (x) is (ta.Ea+tb.Eb+tc.Ec)/(ta+tb+tc)<=6.2. In the inequality (x), ta: the thickness of the base rubber layer (cm), tb: the thickness of the electrode layer (cm), tc: the thickness of the surface layer (cm), Ea: the elastic modules of the base rubber layer (kgf/cm<2> ), Eb: the elastic modules of the electrode layer (kgf/cm<2> ), and Ec: and elastic modulus of the surface layer (kgf/cm<2> ). (y): The developing roll is rotated at revolving speed 64 rpm under environment 23 deg.C×53%RH, and the residual charge on the surface of the developing roll in the case of electrifying the surface of the developing roll by impressing a corona current 100μA is <=50 V. (z): The toner scattered surface of the developing roll where toner is scattered is placed on an elastic heat-resistance plastic film for adhesion test and the adhesive force of the toner in the case of leaving the toner for 170 deg.C×20 minutes in a state where the load of 0.7 kg is applied to one end of the developing roll and peeling the elastic heat-resistance plastic film for adhesion test is <=30 gf/2.54 cm. |
