Dispersion blend strategy to optimize 1-k and 2-k PVDF hybrid dispersion formulations

 
Recent advances in poly(vinylidene fluoride) hybrid technology have led to OH-functional waterborne dispersions, which can be crosslinked with polyisocyanates in 2-component (2-k) formulations to make ultra-durable PVDF/urethane coatings with exceptional hardness. In this paper, we present studies in which the performance of these OH-functional PVDF dispersions is modified through the incorporation of new commercial catalysts or blocked isocyanate crosslinkers in the formulation. In 2-k formulations, several catalyst dispersions with different chemistries can be effective in increasing the property development rate. Using dispersions of blocked polyisocyanates, good performance can be achieved in a 1-component system at a relatively low (120-130 °C) bake temperature, although the performance improvement in this case appears to be attributable as much to the effect of baking on the base resin as to the effects of crosslinking.