Use of Confocal Microscopy as a Nondestructive Method in the Study of Ink Jet Dot Formation

Abstract

The formation of the printing ink dot on the substrate is the final and the most critical phase in the printing process. The ink distribution on the printing surface and the drying mechanism depend on ink characteristics as well as on many other factors, for example, surface energy, roughness, sizing, and porosity. Suitable dot gain and high circularity (near unity) of printed dots predict the final print quality. High deviation from ideal circularity could cause undesired phenomena like wicking and bleeding. The aim of the present study is to determine ink dot formation by three different microscopic methods, optical microscopy (OM), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). The main goal of the authors research was to evaluate the applicability of CLSM as a nondestructive method for three-dimensional visualization in the analysis of ink dot formation on UV ink jet prints. To validate the feasibility of such means in a three-dimensional context, the images obtained are compared to those obtained by traditional two-dimensional imaging systems such as OM and SEM. The authors show that the CLSM produces a replica of the cross-sectioned dot profile as seen in SEM. This means that the CLSM technique can be used to rapidly assess the dot profile without physical sectioning.