Use of Computational Fluid Dynamics to simulate Polyester Coextrusion

Polyester based multilayered films are a core part of DuPont Teijin Films' product portfolio. A multilayered film is a film consisting of several different polymer layers. The main application areas for multilayered films include digital displays, food packaging, reflector film and security cards. Such multilayered films are formed via coextrusion when separately extruded polymer melt streams come together for the first time in either an injector block linked to a die or a multi-manifold die. The formed melt curtain is then quenched into film using a cooled casting drum. As multilayered film structures increase in complexity it becomes more difficult to control the individual layer thicknesses. To improve the layer thickness control, STAR-CCM+ computational fluid dynamics software was used to model both coextrusion geometries and polymer melt flows (assuming Newtonian, inelastic behaviour) typical of DuPont Teijin Films' operations.