Anne Blayo

Chemical and rheological characterizations of some vegetable oils derivatives commonly used in printing inks

Abstract This study concerns the characterization of vegetable oils and some of their derivatives which are commonly used in offset printing ink formulations. Chemical and rheological characterizations were performed in order to gain a better insight into their structure/properties relationships. The aim of this study was therefore to improve the quality and performance of printing inks on the basis of sound scientific criteria rather than empirical notions.

Printing processes and their potential for RFID printing

This paper explains the basics of a number of printing processes (offset lithography, gravure, flexography, ink jet, electrophotography and screen printing). Characteristics such as the process principles, the type of inks and substrates used, the resolution, but also the limitations of these processes (in terms of regularity, for instance) are tackled. Then, their potential for RFID printing is addressed.

Cork suberin as an additive in offset lithographic printing inks

Suberin oligomers, isolated from cork (Quercus suber L.), were used as additives in ‘Waterless’ and vegetable-oil ink formulations, in the range of 2‐10% w:w. The rheological behaviour of the suberin oligomers as well as of the inks, with and without suberin, were investigated as a function of temperature. It was shown that the addition of suberin induces a decrease of viscosity of both inks. The tack of pristine inks, suberin oligomers and their mixtures were determined at different temperatures: the variation of this parameter as a function of time provided information about the drying kinetics of these formulations. The tack of the ‘Waterless’ ink was found to increase with the

Gloss optical elementary representative surface.

Roughness measurements are of main importance in characterizing the optical properties of papers and prints. However, there is a lack of knowledge concerning the surface size and the spacing of the measures to be optically representative of the surface structure. Paper is a multiscale medium, and the roughness parameters extracted from the three-dimensional (3D) surface mapping depend on both the size and the step of discretization. Ray tracing, based on optical geometry, could be a tool to model the light reflection on a paper surface. Ray-tracer software was therefore developed. A new optical device was used to measure paper surface topographies at various scales. Ray tracing simulations were then performed on the 3D mapping and compared to the scattering indicatrix obtained with a classical goniometer. Hence it was possible to identify a magnification for various types of paper grades that is optically representative of the specular gloss.