Viscocapillary Model of Slide Coating: Effect of Operating Parameters and Range of Validity

Slide coating is one of the premetered high-precision coating methods. The layer thickness is set by the flow I-ate and web speed. The uniformity of the layer, however, can be affected by other operating conditions. Modeling the flow in the coating bead is necessary in developing the range of operability conditions where the layer is adequately uniform. Lubrication and viscocapillary models have beet? used to describe the flow and some of the operability limits of different coating processes. However, the available models of slide coating were developed with adhoc hypotheses that compromise their accuracy. We present a critical review of the available viscocapillary models and proposed changes to improve its range of applicability. The accuracy of the model is tested by comparing its predictions to the solution of the full two-dimensional Navier-Stokes equation. The model is valid at low capillary and Reynolds number regime and at low gap-to-wet thickness ratio. (C) 2009 American Institute of Chemical Engineers AIChE J, 55: 2491-2505, 2009