Enhanced thermal and surface properties of waterborne UV-curable polycarbonate-based polyurethane (meth)acrylate dispersion by incorporation of polydimethylsiloxane

摘要

The increasing sophistication in design of waterborne PUs has enabled trie performance gap with their solventborne counterparts to be narrowed. The present article represents one of the approaches that may be adopted combining siloxane modification of the PU with UV curing capability. Initially a polycarbonate diol was reacted with isophorone diisocyanate to produce a NCO-terminated intermediate. Hydroxyl-terminated polydimethylsiloxane was then incorporated by reaction with the NCO groups, followed by incorporation of dimethylol propionic acid to produce ionisable groups. Finally the prepolymer was end-capped with either HEMA or pentaerythritol triacrylate (PETA), neutralised with an amine, dispersed in water with a photoinitiator being added. The UV-curing behaviour of coatings was monitored by FTIR and photo-DSC (DSC equipped with a photocalorimetric accessory).