Effect of the amount of calcium carbonate as filler on the rheological and adhesion properties of a water-based polyurethane dispersion

In this study, the properties of water-based adhesives based on a polyurethane ionomer (PUD) and a micronised CaCO3 as filler was analysed. Different amounts of a micronised CaCO3 (5-25 wt%) were added to water-based polyurethane (PUD) adhesive formulations in order to reduce its relatively high cost. The addition of a micronised calcium carbonate filler increased the viscosity, the storage and loss moduli of the PUD adhesives, and imparted pseudoplasticity and thixotropy, more noticeably for the adhesive with the highest calcium carbonate content. The creation of acid-base interactions seemed to be responsible for the improvement in the rheological properties of the PUD adhesives containing CaCO3 as filler. On the other hand, the addition of CaCO3 filler might deteriorate the adhesion properties to PUD adhesives.