INFLUENCE OF PRINTING SPEED AND RADIATION DOSE ON THE CURING OF UV INKS AND VARNISHES

This work is focused on curing of UV curable printing inks and varnishes and evaluation of the conversion degree after printing with various printing speeds (between 4 and 10 thousands of sheets per hour) and settings of curing units. Five sets of process offset printing inks (SunCure® FLM – Sun Chemical, Suncure® Starluxe – Sun Chemical, UltraCURA® Sens – Flint Group, NewV Pack MGA® Premium – Huber Group, Sicura Litho Nutriplast – Siegwerk) and one UV curable varnish (ExCure All Round EXC90006 – Toyo Ink) were tested. Printing inks and varnish were printed on KBA Rapida 142 6+L and curing of inks/varnish was examined by Fourier transform infrared spectroscopy. The results show the importance of optimization of both the printing speed and the settings of curing units to achieve appropriate curing connected with good adhesion, no surface tackiness and maximum elimination of migrating components from cured inks that is important mainly in food packaging.