Investigation of Quality Parameters of Digital Printing Technologies

Abstract

In order to evaluate the stability of the characteristics of digitally printed graphic image symbols, the resistance of graphic element prints to the temperature changes and mechanical friction was studied. During investigation, prints of graphic elements printed by direct and indirect thermographic methods, digital and offset printing were used. Papers with different temperature sensitivity, surface morphology and hydrophobic properties were used for the specimens printing. It was show that thermographically produced specimens, subjected to temperature changes under mechanical wear, showed a different optical density decrease. The highest optical density decrease (from 2.05 to 0.30) was noticed in the element printed on COAT PC paper by indirect thermographic method, using Wax ink transfer ribbon. The prints on PP White paper, using Wax ink transfer ribbon, also showed significant decrease of wear resistance. In this case the print quality did not meet the standard requirements. The prints on PP White paper, using resin-based ink transfer ribbon, got wear much less (the optical density changed from 1.71 to 1.43, thus meeting the standard requirements). When offset prints were subjected to mechanical wear after a jump temperature change, the highest decrease in optical density was found in prints on Gloss paper (from 1.63 to 1.37), and the lowest – on offset paper (from 1.19 to 1.12). The resistance of digital prints to mechanical wear after a cyclic temperature change is similar to that of prints, which were not subjected to temperature changes. In this case the highest decrease of optical density is found in prints on Ensobulky paper – from 1.02 to 0.67. The optical density of prints on offset, Gloss and Silk papers decreased as follows: offset – from 1.20 to 0.96; Gloss – from 1.73 to 1.46; Silk – from 1.90 to 1.65.