Adhesion of Silica-Coated Toner Particles to Bisphenol-A Polycarbonate Films: Effect of Toner Charge

Abstract

Particles of electrophotographic toner (black, silica-coated, number-weighted, and volume-weighted median diameters of 6.5 and 8.0 μm, respectively), having two different charge levels (nominally 30 and 55 μC/g), were electrostatically developed on the surface of a film of bisphenol-A polycarbonate coated on nickelized polyethylene terephthalate. The thickness of the coatings varied from 0.8 to 22.0 μm. The force needed to remove the particles was determined using ultracentrifugation. We found that removal of half of the particles from the film surface required a force of approximately 200 nN for all charge levels and film thickness except for the highest charged particles on the thinnest film. These results indicate that, for toner particles of this size, which typically have a charge of approximately 20-25 μC/g, adhesion is dominated by van der Waals interactions. However, for highly charged particles, electrostatic interactions can also significantly contribute to the adhesion forces.