Charge control agents and triboelectrically-adjusted pigments in electrophotographic toner

Abstract

In electrophotographic printing systems the print quality is strongly influenced by charge control agents (CCAs) and organic pigments used in the toner (electronic ink). Quaternary ammonium salts as CCAs exhibit a large potential both for positive and negative applications. Their triboelectric efficiency could be adjusted by varying chemical constitution and controlling solid-state parameters. Organic pigments provide the color of the toner. Additionally, they exhibit a certain triboelectric influence depending on their chemical constitution and solid-state properties. Low electrostatic influence together with appropriate “coloristic properties” (tinctorial strength, shade, transparency) are necessary. A specially-designed yellow benzimidazolone pigment meets these requirements. Both toner key ingredients - CCAs and pigments - have to be optimally dispersed into the polymer matrix (so-called binder or resin) in order to develop their desired electrostatic and coloristic properties. Finally, they work together perfectly if the optimum coloristic and electrostatic properties are fulfilled and if the appropriate process conditions (dispersion) are employed.