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Antireflection (AR) films are useful in preventing the reflection of light from the displays of mobile phones and tablet computers. In particular, films with an AR structure known as the moth-eye structure show excellent performance in preventing light reflection. In a previous study, the authors reported the fabrication of an AR structure by oxygen ion-beam irradiation of glassy carbon (GC). The fabricated pattern consisted of a series of self-assembled conical structures and it had a low-reflection surface. In this study, the authors transferred this AR structure onto a polymer film by roll-to-roll ultraviolet nanoimprint lithography using a replica mold produced from a GC master mold with the AR structure. As a result, the authors were able to produce high-performance AR film at a feed rate of 1.8 m/min. The reflectivity of the film was about 0.1% and its transmittance was about 95% at visible wavelengths.

Ultraviolet nanoimprint lithography (UV-NIL) requires high durability of the mold for the mass production of nanostructures. To evaluate the durability of a line-patterned replica mold made of high-hardness UV curable resin, repetitive transfer and contact angle measurements of the replica mold were carried out. In the line patterns, as the contact angle decreases due to repeated transfer, capillary action occurs, and water flows along them. Therefore, it can be said that a mold with a line pattern exhibits an anisotropic contact angle because these values vary depending on the direction of the contact angle measurement. Subsequently, these anisotropic characteristics were investigated. It was determined that it was possible to predict the lifetime of line-and-space molds over repeated transfers. As the transcription was repeated, the contact angle along the line patterns decreased significantly before becoming constant. Moreover, the contact angle across the line pattern decreased slowly while maintaining a high contact angle with respect to the contact angle along the line pattern. The contact angle then decreased linearly from approximately 90°. The mold was found to be macroscopically defect when the values of the contact angle along the line pattern and the contact angle across the line pattern were close. Predicting the mold’s lifetime could potentially lead to a shortened durability evaluation time and the avoidance of pattern defects.

Ultraviolet nanoimprint lithography (UV-NIL) is the most effective technique for mass fabrication of antireflection structure (ARS) films. For ARS films applied on touch-panel devices such as mobile phones and tablet computers, however, it is necessary to protect them from fingerprints and dust. Therefore, a UV-curable epoxy resin has been developed with antifouling properties for use with UV-NIL. However, because the developed epoxy resin possesses a high adhesive strength that ultimately reduces the lifetime of nanopatterned molds such as those for ARS, the ARS films herein were fabricated by a partial filling technique. The technique of partial filling uses an incomplete filling ratio of resin, and the work herein specifies the lower and higher filling pressures used for the repetitive transfer test. As a result, up to 200 ARS film imprints were successfully fabricated that exhibited excellent performance using lower pressure filling UV-NIL; while the reflectance obtained was less than 0.5%. In addition, the fabricated ARS films were evaluated for their antifouling properties and their transfer durability performance using the wipe test and the repeated transfer test, respectively.