Numerical and experimental study of the filling stage of roll-to-roll UV embossing process with micro features

Roll-to-roll (R2R) UV embossing is a promising low cost and high throughput process that leverages on rapid photo-curing to achieve high embossing speeds for manufacturing large area functional films. There are many potential commercial applications of this process such as flexible displays and functional optical films. However, productivity improvement was hindered by the low web speed at which the system can run without losing the feature fidelity. The current work aims to study the filling-stage of the R2R UV embossing process for s via numerical simulation and experimental validation, in order to better understand the process and identify the limiting factor for productivity improvement. Coupled Eulerian–Lagrangian algorithm was employed in the simulation to consider both deformation of the solid backing film and flow of the liquid UV resin. Their interaction is deemed to influence the mold filling distance. Model predicts that for the web speed of 3 and 30 m/min, the mold filling distance increases fractionally from 2.4 to 2.8 mm, indicating that the filling stage plays a minor role in the feature fidelity control if air entrapment is not considered. Experiments with the micro feature embosser further validate the simulation in a way that to point out it is the air entrapment which causes the incomplete filling. Some basic design rules of the micro features are also provided.