THE EFFECT OF ELECTROSTATIC FORCES ON THE COHESION OF ELECTROPHOTOGRAPHIC TONER POWDERS

摘要

The influence of electrostatic forces on the cohesion of electrophotographic toner was studied theoretically and experimentally. A theoretical model was created to estimate the electrostatic force between spherical insulative particles that possess discrete surface point charges. The model results suggest that the electrostatic force between two contacting, electrically net neutral particles can be significant when charged regions are located near the point of contact. Experimentally, the relative cohesivity or flow of two morphologically identical, net neutral electrophotographic toner samples that possessed different surface charge states were compared. A processed toner sample, while remaining electrically neutral and assumed to contain a larger number of positive and negative surface charges exhibited significantly higher levels of cohesive forces compared to an unprocessed toner sample. The relative difference in measured cohesion between the two toner samples is attributed to the difference in electrostatic cohesive forces arising from the surface charge state differences of the two samples. This work demonstrates that electrostatic forces should be considered when experimentally or theoretically analyzing the cohesion/flow of electrophotographic toner.