Study on the composition of inks for UV-curable printing

UV-curing is a widely adopted and rapidly developing technology used in printing to instantly dry inks, resulting in high-quality prints with excellent durability. This technology offers important advantages, including minimal space requirements and lower capital investment in curing equipment. Notably, UV ink is much more environmentally friendly than most other inks and can be created using a variety of ink formulations. All these benefits have led to increasing popularity of this technology in recent years, paving its way for new applications. An interesting challenge is the development of methods to enhance document protection using the described UV printing technology, which may be achieved through the addition of luminescent powders. In this work, we present results of study on the optimization of composition and properties of UV-curable inks for document tagging based on acrylate oligomers. The ceramic powder CaYAl₃O₇ doped with Eu³⁺ is showed as the exemplary of luminescent taggant that can be incorporated into fabricated inks. The investigation included study of morphology and photoluminescence of synthesized powders, rheological and wetting properties of obtained inks and their printability on selected substrates – security paper and polycarbonate foil which are used for tax stamps and ID cards. The conducted works involved optimizing combinations of the constituents including acrylate monomers and oligomers, photoinitiators, and additives to obtain the inks with properties meeting the requirements of specific printing techniques. The ultimate goal of this work was to develop unique anticounterfeiting photoluminescent inks for the following methods: flexographic, screen- and offset-printing, by incorporating luminescent taggants into the prepared inks. Nevertheless, the future potential of these components in identifying forged documents demands further research.