Electrification analysis of a web or sheet moving between pinch rollers

A model is developed which provides a phenomenological understanding of the static electrification of a web or sheet by a pinch roller system through which it passes, in terms of the electrostatic characteristics of the separate regions of the system. The total pinch roller interaction is characterized by a matrix and vector derived from the characteristics of the component parts of the interaction. It is therefore possible to examine the effect on the electrostatic performance of the whole system caused by a change in one or more components. The mode of accumulation of electrostatic charge on a web subjected to many repeated passes through the pinch roller system is derived and reveals that a unique equilibrium charge density on each surface is approached regardless of the initial charge density configuration. However, the sequence of discrete charge density changes on each surface by which the equilibrium charge configuration is approached is a unique function of the initial charge density on each surface. The model should be useful in designing or improving pinch roller devices, i.e., in choosing roller materials and their physical configuration