Tough and antifouling antireflection structures made by partial-filling ultraviolet nanoimprint lithography

Ultraviolet nanoimprint lithography (UV-NIL) is the most effective technique for the mass fabrication of antireflection structure (ARS) films. For the use of ARS films in mobile phones and tablet PCs, which are touch-screen devices, it is important to protect the films from fingerprints and dust. In addition, as the nanoscale ARS that is touched by the hand is fragile, it is very important to obtain a high abrasion resistance. To solve these problems, a UV-curable epoxy resin has been developed that exhibits antifouling properties and high hardness. However, because the developed epoxy resin has a high adhesive strength, ARS films should be fabricated by the partial-filling technique, where partial filling refers to an incomplete filling ratio of the resin. Thus, in this study, ARS films fabricated by means of partial-filling UV-NIL using a UV-curable resin with antifouling properties and high hardness are presented. The fabricated ARS films are evaluated for abrasion resistance and antifouling properties by the steel wool test and wiping test, respectively. Moreover, the reflectance of the ARS films is also evaluated. The high abrasion resistance ARS films are shown to withstand a load of 250 g/cm2 in the steel wool scratch test, and the reflectance is less than 0.4%. Hence, high abrasion resistance ARS films can be fabricated using a very high hardness resin by partial-filling UV-NIL. Furthermore, dirt is shown to be washed away from the ARS films after wiping 20 times with water containing ethanol.