Photostabilization of cationic UV-cured coatings in the presence of nanoTiO2

The effect of TiO2 nanoparticles for sun-weathering protection of UV-cured coatings is investigated. TiO2 is either introduced in the form of nanoparticles in the photocurable formulations or generated in situ via sol-gel process. Cured films containing comparable amounts of TiO2 were weathered for 800 h under UV irradiation and compared with free-TiO2 coating. The TiO2 presence induces a clear lower mass loss decrease during weathering as well as a lower gel content decrease. The TiO2 screen effect is also confirmed by a lower alkyl-band reduction monitored by FT-IR during weathering. The TiO2 generated in situ via sol-gel gives rise to transparent coatings without interfering with photopolymerization process and therefore without compromising UV-cured film properties. (C) 2007 Elsevier B.V. All rights reserved.