FORMATION OF 3D STRUCTURES IN OFFSET PRINTING TECHNIQUES BY UV INDUCED FOAMING OF INKS

The present work addresses the formation of 3D structures via UV assisted foaming of commercially available acrylic offset inks. The microcellular foaming relies on the excitation of selected photoacid generators with UV light to release Brønsted acids. Once formed, the acids react with calcium carbonate particles under the release of carbon dioxide that is employed as blowing agent. To obtain a higher exploitation of the emission light and thus a higher level of acid formation, photosensitizers are added to the ink formulation. With optimized process parameters, the relative thickness of the expanded ink layer exceeds 90% with a corresponding cell diameter in the range of 10 to 15 μm. The results give evidence that the UV induced foaming represents a promising approach towards the one step production of three dimensional patterns in offset printing techniques.