Vinylcarbonates as low-toxic monomers for digital ink-jet inks: Promising alternatives to acrylate based systems

The last decade has seen a significant increase in research on UV curable digital inks for industrial printing applications with the focus to expand this technique into new markets. However, most of the commercially available inks are based on acrylic monomers, which provide a significant toxicological behavior limiting their applicability in promising fields, e.g. printing on food packaging materials. In this study, a variety of biocompatible monomers based on vinylcarbonate building blocks were evaluated regarding their application in UV curable digital inks. Although, the viscosity and surface tension of these monomers is appropriate for ink-jet printing, the curing speed is far too low for high speed printing processes. In order to circumvent this limitation, thiol-vinylcarbonate formulations were prepared that offer reactivities and double bond conversions (DBC) similar to those of acrylates. For that purpose, a multifunctional thiol was synthesized providing both, low odor and an appropriate low viscosity facilitating the formulation of basic ink-jet inks, which offer excellent jetting behavior, together with good film forming properties and adhesion on PET. Although there are some challenges regarding stability, in particular for pigmented formulations, this system represents a promising alternative to commercially available acrylate based inks.