THE EFFECTS OF BIOLATEX BINDERS ON THE DYNAMIC WATER RETENTION PROPERTIES OF PAPER COATING FORMULATIONS

The following paper is a continuation of findings presented by the authors at PaperCon 2012 demonstrating the interesting rheological properties of biolatex binder dispersions and their coating colors relative to conventional coating starches and SB latex binders. The previous work indicated that the rheological performance of biolatex binder is significantly different from that of conventional cooked coating starches and all-synthetic latex containing formulations. This study investigates the dynamic water retention and wall slip properties of the same materials in order improve the understanding on coater runnability performance. Ensuring the correct rheology and water retention of coating colors is important as coater speeds increase and in order to achieve good runnability, productivity and final product quality it is critical to have a comprehensive understanding. It is common that quality and runnability problems originate from the interaction between base paper and the water phase of the coating color. Failure to control this interaction can lead to excessive migration of coating color to the base paper. This results in poor machine runnability, unstable systems and a non-uniform coating layer. In these evaluations an ultra-high shear ACA Viscometer (ACAV) was used to provide further insight into the wall slip properties of coating colors at shear rates that are relevant to industrial-scale paper coating processes. Results from these studies in combination with the results from previously presented rheological studies help explain some of the fundamental differences of these binder systems.