Effects of carrier types and mixing methods of developer on polymerized toner charging

Abstract

The triboelectric property of a two-component developer is an important factor in an electrophotographic system. There are many factors that affect the charging properties. This research investigated the toner concentration of the four types of polymerized toner (black, cyan, magenta and yellow toners), carrier type and charging mechanism consisting the vertical mixing and horizontal mixing methods. The print quality was focused on the solid density, tone reproduction, the sharpness of the alphabets and lines, color gamut and gamut volume. All toners were evaluated for their print qualities by a commercial printer (Canon), with the polymerized toner and compared with the prints from a model printer (Fuji), with the pulverized toner. The charge-to-mass ratio (q/m) value decreased when the toner concentration was increased. At the high toner concentration, the coverage of the toner particles on the carrier surface was higher and occupied more than one layer. The outer layer had some free toner particles that could not be charged by rubbing with the carrier particles. The carrier particles containing only Fe (TSV-200 and Z-250) have the higher work function than the carrier particles containing Fe, Cu and Zn (F-150). So, the q/m values of both TSV-200 and Z-250 were higher than F-150. Difference in toner and carrier shapes is responsible for the varied q/m values. Various charging mechanisms gave different q/m values. The q/m values of vertical mixing method with 800 rpm were higher than the q/m values of horizontal mixing method with 120 rpm but became lower at the lower concentration because the effect of the higher mixing force, the greater the toner rubbing and collision. Both print-outs produced equally the same tone reproduction. The polymerized toner has the spherical shape while the pulverized toner has the irregular shape. The spherical shaped toner is more efficiently, uniformly and triboelectrically charged than the irregular shaped toner. So, the sharpness of the alphabets and lines printed from the polymerized toners were sharper and smoother than those printed by the pulverized toners. The color gamut and gamut volume of the polymerized toner print-outs were wider than those printed by the pulverized toners. However, the solid density of the polymerized toner print-outs was lower than those printed by the pulverized toners because the polymerized toners have the lower gloss than the pulverized toners.