Ink splitting in gravure printing: localization of the transition from dots to fingers

Abstract

For the gravure printing process, ink transfer from the printing cylinder to the substrate is studied in the parameter regime at the very border between point and lamella splitting. In this parameter regime, ink drop deposition from adjacent gravure cells is such that, by capillary and wetting forces in the nip, the drops are at the onset of mutual coalescence. This process offers the possibility to deposit an ultimately thin and closed ink film. We discuss the particular type of pattern and defect formation in the printed layer and show that these apparently stochastic patterns have reproducible features. We claim that, besides the two known regimes of point and lamella splitting, at least one additional ink transfer regime is possible, with well-controllable wetting and ink flow dynamics. A classification scheme is proposed, based on raster-scale pattern phenomenology, by which the printer can recognize and distinguish this third regime by optical inspection of the printed product. Gaining control over this regime offers novel opportunities for gravure printing in thin-film related applications such as printed electronics and package printing.