Dielectric characterization of magnetite-loaded toners

Abstract

In most xerographic copy processes, the latent electrostatic image on a photoconductor is developed (toned) in the development nip by bringing the photoconductor into contact with a continuous supply of flowing developer material. The dry ink (toner) is either already charged or becomes charged by the electrostatic field of the image itself and is then attracted to the image. The dielectric behavior of the developer layer in the nip is very important, because such parameters as dielectric constant and effective relaxation time determine the development field, process time constants, etc. Characterization of single-component xerographic developers is complicated by several factors. The materials are granular, typically composed of a polymer resin with dispersed pigment, and sometimes magnetite or flow agents. A further complication is that the toner in the nip is flowing and sometimes strongly coupled by magnetic or electrical forces. The effects of flow and agitation on charge transport in xerographic developers is largely unknown.