Ink-jet printing has developed as an important technology for the controlled deposition of functional fluids in applications as diverse as graphics, textiles, biological printing and digital fabrication. In such applications polymers may be used to impart functionality to an ink – as a dispersant, for example, or a viscosity control agent. Alternatively they may form a functional element of the finished product, in which case it may be advantageous to print with a high-molecular-weight polymer and/or at high polymer concentrations to enable single-pass printing and/or to produce a robust film without applying post-curing technologies. In all these situations, the effect of the printing process on the properties of the polymer can be crucial in defining its effectiveness; polymer breakdown can severely impair the resulting finish, compromising product value.
In this article we examine the processes used for ink-jet printing and the stresses to which they subject a polymer. Experimental studies of the impact of continuous ink-jet (CIJ) printing on polymer molecular weight (MW) provide clear evidence of polymer degradation and insight into breakdown mechanisms. The results demonstrate the value of gel permeation chromatography (GPC) in supporting the optimal application of polymers in printing processes and in printer design.