Indicator Ink Checkable for Security Printing and Packaging Application

Abstract

　The checkable indicator ink (C_ii) was developed on the basis of semiconductor (SC) photocatalyst reaction and the redox dye (D) which could be printed as security ink and checked by exposing to UVA-light for counterfeit products. The C_ii comprised of SC (titanium dioxide, TiO₂), D (anthraquinone-2-sulfonate, AQS) and electron donor (glycerol), was dispersed in a polymer medium. Upon UVA exposure, the C_ii label abruptly changed from colorless to yellow. At this state, the yellow-green luminescence of this Cii label was distinctly revealed when it was witnessed under dark condition. However, the C_ii could be recovered to its original color when it was placed under room atmosphere for ~1.5-6.5 hrs.