Ink transfer and refusal mechanisms in litho-graphic offset printing and the measurement of the splitting force of fountain solution film

摘要

This paper reports a recent investigation of the ink transfer and refusal mechanisms in lithographic offset printing. These are old but poorly understood applied surface chemistry problems. An adhesion approach is taken to investigate the position of splitting of an ink-fountain solution composite layer using a near-static and a dynamic method. Results from this study show that ink transfer and refusal in lithographic offset printing cannot be predicted by thermodynamic quantities such as surface energy or interfacial energy or work of adhesion. Ink transfer and refusal must be predicted by comparing the ink or fountain solution adhesion strength to other surfaces and the film splitting forces of the ink and fountain solution. This paper also reports the development of a new method which can measure the fountain solution layer splitting force under simulated printing conditions. This method has, for the first time, provided experimental value of the fountain solution layer splitting force relative to the ink layer splitting force. These forces provide direct information which can be used to control the press operating conditions. It is possible that this method can be adapted to determine forces that cause linting and therefore will also serve as a new and useful tool for understanding and controlling linting in lithographic offset printing.