Synthesis of reactive diluents for cationic cycloaliphatic epoxide UV coatings

Reactive diluents for cationic cycloaliphatic epoxide UV coatings were synt hesized using caprolactone polyols and tetraethyl orthosilicate (TEOS). The structures of the TEOS functionalized polyols were characterized using IR, H-1-NMR, Si-29-NMR, and ESI-FTMS spectroscopy. The resulting siloxane func tionalized polyols were used to formulate cationic UV coatings with 3, 4-ep oxycyclohexylmethyl-3, 4-epoxycyclohexane carboxylate (a cycloaliphatic die poxide). The crosslinking reactions were monitored using IR and Si-29-NMR s pectroscopy. The cured films were evaluated in terms of tensile properties and glass transition temperature. The resultant coatings showed greater ten sile modulus, lower elongation, and higher glass transition temperature. In addition, the siloxane functionalized polyols also effectively reduced the viscosity of the coatings formulations. Based on the curing behaviors and spectroscopic data, possible crosslinking reaction(s) were postulated. (C) 1999 Elsevier Science Ltd. All rights reserved.