Polyisocyanates are widely used in the paints and coatings industry as multi-functional cross-linkers and adhesion promoters for many organic resins. They are derived from di-, tri- or oligomerisation reactions of the main diisocyanates used in polyurethane (PU) technology and may contain residual monomer. Their usefulness relies on the high reactivity and selectivity of the isocyanate group towards species containing an 'active' hydrogen atom. Figure 1 summarises the basic reaction. Polyisocyanates have handling difficulties and health and safety concerns, especially when they come from volatile and highly noxious precursors such as hexamethylene-1,6-diisocyanate (HDI). One ...