Nitrocellulose nanoparticle dispersions as binder for waterborne coating formulations

Abstract Nitrocellulose (NC) is a well-known binder for economic coating formulation. However, it is only available in solventborne systems. In this work, a waterborne alternative based on NC nanoparticles will be investigated. Starting from a precipitation process using water, nanoparticles are prepared from a solution of NC in ethanol and acetone. The resulting aqueous dispersions contain highly uniform, self-stabilized nanoparticles and show the typical characteristics of NC. Various coalescing agents are investigated to understand the specific mechanism of film formation. Apparently, the nature of the coalescing agent is crucial for the formation of smooth surfaces after drying of the dispersion. The mechanism of coalescence is investigated on the microscopic scale. It is assumed to be different from a classic coalescence process, and appears as a hybrid version between a water- and a solvent-based coating. In the end, water-dilutable formulations are achieved, revealing a reduced VOC-content by 75%, compared to common solventborne NC-systems.