EPOXIDIZED POLYBUTADIENE - A NOVEL PREPOLYMER FOR CATIONICALLY UV-CURABLE COATINGS

Epoxidized polybutadiene was evaluated as a reactive prepolymer for ca tionically curable photosensitive compositions. Various epoxy or vinyl ether functional reactive diluents were used as viscosity reducers. C ompositions with an average content of 5 mmol.g(-1) of polymerizable f unctions were submitted to viscosity measurements, and their reactivit y under UV-irradiation was examined by UV and/or IR spectroscopy. The initiator photolysis can be monitored easily and adequate exposure tim es were determined by simple kinetic treatment. The polymerization of epoxy monomers was driven to high conversion (over 95%) provided that the film was submitted to a soft thermal post treatment. Coatings of h igh flexibility and showing good adhesion to aluminum, steel, and glas s were obtained by adequate adjustment of the formulations composition . The content in reactive diluent was kept to a low level without loss of curing ability.