Investigation of Layer Thickness Distribution During Co-Extrusion with Generalized Newtonian and Visco-Elastic Flow Models

摘要

To investigate the parameters governing layer thickness differences during co-extrusion of an a-symmetric coating, the die used in the Corus pilot line at Ijmuiden to produce this coating has been modeled using Polyflow. First the flow field in the whole die was investigated using generalized Newtonian models to map the effects of varying viscosity on layer thickness differences at the die-lips. It is, however, well known that polymer flows exhibit visco-elastic behavior, which can also influence the thickness of the various layers. Therefore and secondly, the flow field in the preland of the die will be investigated with a full visco-elastic model to show the effects of elastic forces in the liquid polymer in the preland.