Photostability and influence of phthalocyanine pigments on the photodegradation of acrylic paints under accelerated solar radiation

Raman spectra acquired on both, unaged and aged specimens did not show any difference concerning the pigment bands, whereas Py-GC/MS in double shot mode, revealed a decrease in the thermal stability of the pigments as well as of the acrylic binders identified (nBA/MMA, EA/MMA, nBA/Sty/2-EHA, and 2-EHA/MMA). Typical photooxidation products of acrylic binders, such as increased monomers and oligomers, related to side-chain scission as well as main-chain scission reactions, were characterized by means of Py-GC/MS and FTIR-ATR. Commercial paints revealed also whitening and chalking phenomena, mainly due to the presence of white fillers and additives in the paints formulations. These phenomena could be registered also by UV-Vis spectroscopy.