Preparation, characterisation and properties of UV-curable waterborne polyurethane acrylate/silica coating

摘要

Waterborne UV-curable polymer/mineral nanocomposite materials have evolved as an important class of product capable of matching the performance of solventborne coatings in industrial applications. A wide range of publications on this subject is available with many of the research studies employing the sol-gel process to create the inorganic nanoparticles. In the present article the preparation, characterisation and evaluation of UV curable PU oligomers and in situ-generated silica nanoparticles is reported. PU prepolymers (oligomers) were prepared by the standard mixing process with the terminal -NCO groups being capped with HEMA. Control UV curable PU dispersions were prepared by the conventional process of neutralisation and dispersion of the prepolymer in water. PU/mineral composites were prepared by mixing the PU prepolymer with an epoxysilane (coupling agent) and blending with an aqueous dispersion of hydrolysed tetraethoxysilane. By this means a series of composite oligomers were prepared with silica contents varying from 0.1-0.5 wt%. A solution of BA, tripropylene glycol diacrylate and photoinitiator was added to the respective aqueous dispersions prior to coating application and UV cure.