Effects of shear thinning on forward roll coating

This paper described the forward mode roll coating process of generalised non-Newtonian fluids characterised by the Ellis model. The fluid in the coating bead and the free surface formation are described by the lubrication approximation and the stability is also considered using a perturbation analysis of the downstream meniscus. Results highlight the complex behaviour of this coating process and volume flow rate and film thickness results are obtained for a range of operating conditions. The stability of the downstream meniscus is observed to improve with increasing level of shear thinning when Tin (the shear stress at which the viscosity is half that of the zero shear stress viscosity) is small, however as tau(1/2) increases the meniscus stability decreases with increasing levels of shear thinning. Crown Copyright (C) 2013 Published by Elsevier B.V. on behalf of The Institution of Chemical Engineers. All rights reserved.