Angular Plane Curtain Coating by Drawdown of Extruded Polymer

By Fan Ding , A. Jeffrey Giacomin

An approximate analytic solution for an angular plane curtain coating of a highly viscous Newtonian fluid is developed. We obtain expressions for the melt curtain shape, coating thickness, contact length, contact pressure, drawing force, apparent contact angle, and contact convexity. Specially constructed examples enable practitioners to apply the results without advanced training in fluid mechanics.

We identify a process indeterminacy that arises in curtain coating employing a parallel slit. We show that, with a rapidly converging extrusion slit, this indeterminacy vanishes. Thus, a unique solution for the contact length is always obtained. The extension to a viscoelastic fluid is also briefly considered.