ELECTROPHOTOGRAPHIC TONER

摘要

PROBLEM TO BE SOLVED: To optimize the electrical characteristics of a toner, to stabilize image density at a high level even in use over a long period of time and to suppress scattering by regulating the dielectric tangent of the toner to a proper range. SOLUTION: The dielectric loss tangent of an electrophotographic toner contg. at least a resin binder and carbon black is regulated to 1×10<-3> -10×10<-3> . The particle diameter of the carbon black is <=30nm and the carbon black is contained by 3-10 pts.wt. based on 100 pts.wt. of the resin binder. The weight of the toner per unit area of a solid black part is regulated to <=1mg/cm<2> when the image density of the solid black part fixed on recording paper is 1.35. The specific surface area of the toner is regulated to 1.0-2.5m<2> /g. Since the quantity of electric charges per one toner particle can be varied without varying the quantity of electric charges per unit area by varying the specific surface area, image density can be stabilized at a high level even in use over a long period of time by optimizing the specific surface area.