Comparison of Toner Adhesion Theories

Recent measurements of toner adhesion have been reported [Dejesus et al., J. Imag. Sci. Technol. 52, 010503 (2008)] in which the ground plane was separated from the charged toner particles by a thin dielectric coating of varying thickness (0.8, 4.5, 9, and 22 mu m thick), which is less than and approximately equal to the diameter of the toner particles used in the experiment, 7.1 mu m. It is claimed that such data can be understood only in terms of an adhesion theory based on van der Waals adhesion. It is demonstrated in this article that the data are, in fact, consistent with the Proximity Theory of toner adhesion, which is an electrostatic theory of toner adhesion that assumes that there is electrostatic adhesion at every contact point due to the discreteness of charge. Combining this result with a comparison of theories of toner adhesion with data showing the effects on toner adhesion of changing the toner charge-to-mass ratio and the extraparticulate concentration leads to the conclusion that the Proximity Force dominates toner adhesion. (C) 2009 Society for Imaging Science and Technology.