Fabrication of Multi-Functional Optical Films by Using a Ultraviolet Curing Roll-to-Roll System

This paper presents a roll-to-roll process (R2R), combined with UV-curable molding technology, for the production of multi-functional optical films in large area without seams. Firstly, the spherical microlens array is analyzed by using optical analysis software (ASAP). Then, a seamless roller mold with a concave microlens array is utilized for pattern transfer onto a PET film coated with UV resin. Imprinting tests for the PET substrates are carried out under different web tensions (0.29-1.45 kg/cm) and rolling speeds (0.28-0.84 m/min). According to the experimental results, a multi-functional film without any defects and its replication almost duplicate the microstructures on the roller mold if the rolling speed is low and the web tension is sufficiently high. In addition, the optical performance of the multi-functional films is measured by using a luminance inspection system and haze meter. The measurement results show a luminance gain of approximately 1.19 and a haze of 79-86%. Consequently, the present study can provide a guideline for fabrication at a low-cost and for large-area multi-functional optical films by using a UV-curing R2R process. (C) 2011 The Japan Society of Applied Physics