Non-Destructive Depth Profile Analysis of UV Offset Ink Films with Confocal Raman Microscopy

Abstract

In order to maintain stable printing and avoid printing troubles during UV (Ultra-Violet) curable printing, it is important to understand the curing reaction both on the surface and within the ink films. In this study, the depth profile of offset printing ink films (with a thickness of a few micrometers) on coated paper was analyzed non-destructively from the surface side using confocal Raman microscopy (CRM). Spatial resolution of 0.2 um was obtainable using an oil lens. As a result, the structure of offset ink layers could be evaluated in detail. In addition, the UV curing reaction of overlapping multicolor offset inks could be estimated using CRM techniques. Moreover, the three-dimensional distribution of ink components in multicolor offset printing could be also visualized.