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Viscocapillary model of slide coating: Effect of operating parameters and range of validity

Authors

  • K. Tjiptowidjojo,

    1. Coating Process Fundamentals Program, Dept. of Chemical Engineering and Material Science, University of Minnesota, Minneapolis, MN 55455
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  • M. S. Carvalho

    Corresponding author
    1. Dept. of Mechanical Engineering, Pontificia Universidade Católica do Rio de Janeiro, Rio de Janeiro, RJ 22453-900, Brazil
    • Dept. of Mechanical Engineering, Pontificia Universidade Católica do Rio de Janeiro, Rio de Janeiro, RJ 22453-900, Brazil
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  • This article is dedicated to the late Prof. L. E. “Skip” Scriven.

Abstract

Slide coating is one of the premetered high-precision coating methods. The layer thickness is set by the flow rate 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 been 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. © 2009 American Institute of Chemical Engineers AIChE J, 2009

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