FLEXOGRAPHIC PRINTING PROCESS WITH WET ON WET CAPABILITY

摘要

The invention refers to a flexographic printing process with wet on wet capability based on controlled polymer or polymer segment precipitation that leads to gel formation of ink compounds by controlling the solubility parameter of the ink system. The mechanism to obtain a desirable wet on wet color trapping is the formation and/or presence of a gel in the applied ink film due to a controlled physicochemical mechanism of resin precipitation. This is accomplished either by controlling a change in the Hansen Solubility Parameter of the liquid in the ink through evaporation of some or all of a non-reactive and volatile solvent, or alternatively by use of a polymer comprised of two distinct and separate segments one of which is soluble in the monomer/oligomer mix and the other of which is not. The insoluble segments form a reversible gel that is broken to a liquid by shear in the application process, allowing application of a liquid ink, and is reestablished in the applied ink film in such a manner and with such strength as to allow overprinting in the wet on wet flexographic printing process. WO2010071952A1