Importance of Monomer Interfacial Tension for UV Curable Litho Inks Performances

Since many years, the goal of ink-makers is to improve the runnability and lithographic behaviour, dot gain, cure speed and odour for UV offset inks. But unfortunately, the formulation of UV curable printing inks depends on many variables both in ink making and in lithography process. One of the key properties of a good lithographic ink is its ability to emulsify the fountain solution and its water pick-up. The ink-water interaction is determined by the hydrophilic properties of the various raw materials used in the formulation, such as UV binders, pigments, photo-initiators and UV monomers in our particular case. The aim of this paper is to describe the lithographic behaviour from different grades of GPTA (glycerol propoxylated triacrylate) at 19 % in a magenta UV offset ink. The two GPTAs were tested with various interfacial tension properties which are for one more hydrophilic and for the other one more hydrophobic.