Study of the influence of the surface structure of the substrates on the imprints quality

Abstract

Modern printing technologies allow the use of a diverse range of materials for printing to satisfy the requirements of the most demanding consumers. However, the quality of the imprint is not always satisfactory. Of course, there can be many reasons: non-observance of technological printing modes, problems related to setting up the operation of the main and auxiliary mechanisms of the printing machine, problems of transporting material through printing and inking units, etc. One of the problems of obtaining a high-quality imprint in all printing methods is compliance with certain technological requirements regarding the selection of the properties of the printed materials, in particular their surface. Properties of the printing base surface are one of the most important factors affecting the completeness of the image transfer and the appearance of the imprint.
Based on the methods of system analysis, hierarchical groups of imprint quality indicators in flexographic and digital printing methods, which ensure high imprint quality, are singled out. Accordingly, studies of the surface topography of imprints on paper and cardboard with and without a chalk coating, as well as on film materials (in flexographic printing technology) were conducted.
The surface topography of imprints on various materials was experimentally investigated. A change in the morphological structure of the substrate surface before and after printing was revealed. It has been studied that the presence of a chalked coating, which changes the parameters of roughness and the area of peaks and valleys on papers and cardboards, has a significant effect on the microgeometry of the surface. The method of surface treatment of film materials also affects the topography of imprints surface. It has been confirmed that with an increase in the number of surface coating layers on the substrates, the roughness parameter decreases significantly. The morphological structure of the surface of the materials before printing is preserved on imprints, but its smoothing is observed to a greater or lesser extent depending on the printing method used to obtain the printed image. Also, the indicators of the surface structure of the imprint are affected by the characteristics of inks, varnishes, the method of imprints finishing, for example, by the lamination. This is confirmed by the results of electron microscopy.
Based on the results of experimental studies and taking into account the ISO model, a conceptual model and algorithm for the functioning of imprints quality assurance system were proposed, which take into account the problems associated with the dependence of the parameters of the surface structure of printed materials.