UV-curable Inkjet Research Articles

UV-inkjet Ink Penetration and Its Effect on Print Quality Formation and Drying

The increased usage of UV-inkjet for printing porous fiber based products has created a need to study the interactions between paper coating, ink and process. In this paper we have studied, how coating porosity affects print quality formation and ink curing degree of UV-curable inkjet inks. Results show, that paper requirements for UV-inkjet differ clearly from those, which are usually connected to good inkjet paper. Paper properties have quite a remarkable effect on print gloss and density formation, although the use of pinning lamps reduces this dependency. Ink curing degree depends also on the properties of the paper and interactions between ink and paper.

Dynamic Surface Tension of UV-Curable Inkjet Inks

Properties like adhesion of inkjet prints on unporous media are strongly determined by wetting characteristics of ink on media. In contrast to solvent based inks for UV-curable inkjet-systems the ink is not allowed to equilibrate on surfaces because the film is cured within a very short timeframe after jetting. Therefore the static surface tension is not able to characterise the ink-media interaction before the ink curing process is initiated. In a time-scale of milliseconds the dynamic surface tension measured with the maximum pressure bubble method can be used to describe the dynamic processes of ink on unporous media. In this paper we present a study of dynamic surface tension of mono-, di-, and trifunctional acrylates in order to evaluate the effect of molecular weight, structure and the behavior of mixtures on the resulting dynamic surface tension in UV-curable inkjet inks.

New Raw Materials for UV Inkjet Inks

UV-curable inkjet printing is a new technology that is expected to grow significantly in the next few years. The extremely low ink viscosities required for this application entail extensive modification of the conventional formulation equilibrium between oligomers, monomers, and photoinitiators. The impact in terms of curing efficiency then has to be balanced by modifying combinations of photoinitiators in this new binder environment. Pigment selection will be driven by more demanding requirements in terms of resistance to flocculation and gelling. This paper describes the influence of optimized additive and pigment selection on UV inkjet inks.