Siloxane additive as modifier in cationic UV curable coatings

A polysiloxane hydroxyl terminated oligomer (SIOH) was used as chain transfer additive in cationic UV curing of a dicycloaliphatic epoxy resin (CE). An increase on curing rate and final epoxy conversion was achieved together with a flexibilization of the network and a consequent toughness improvement. Also an important increase on surface hydrophobicity was induced already in the presence of very low amount of the additive.