Coating flows of power-law non-newtonian fluids in slot coating

Abstract

One-dimensional flow equations were derived for non-Newtonian fluids in slot coating and a simple numerical method was proposed to solve the equations. We investigated non-Newtonian effects on coating performance and coating quality in slot coating. In some cases, computational results and experimental data were compared and both agreed well. A series of numerical computations showed that the one-dimensional approach can describe non-Newtonian flow under lips in a few minutes and that a pressure field equation proposed by Higgins can determine the location of an upstream meniscus. Moreover, it was found that the non-Newtonian characteristics of coating liquids affect both coating performance and coating quality. Because each non-Newtonian effect is quite different, we should optimize the conditions of slot coating and die geometries according to the target problem. © 2010 The Society of Rheology, Japan.