Photocatalytic self-cleaning coatings for painted surface without interlayer
Researchers have demonstrated that double layer coatings composed of a TiO2 clear top coat and a latex film are crucial for the fabrication of robust fotocatalytic self-cleaning coatings without the need for an interlayer.
The fotocatalytic coatings were prepared based on an aqueous TiO2 dispersion in a hybrid binder synthesised from tetraethyl orthosilicate and methyl trimethoxy silane via a sol-gel process.
Transparent to visible light
Coatings with various levels of nano TiO2 were prepared and found to be transparent to visible light; i.e., the clear coat could be directly cast on architectural latex coatings without changing its original appearance. The fotocatalytic coating system was composed of a TiO2-based clear top coat and an opaque latex film underneath. The coatings were evaluated through outdoor exposure studies and accelerated weathering tests.
No photocatalytical degradation
Results showed that the fotocatalytic coatings with a TiO2 content range of 33–45% exhibited excellent self-cleaning performance, while displaying none of the expected degradation. In fact, this nano TiO2-based clear coat actually protected the latex film from UV-induced damage. The increased stability of the organic film may have resulted from reduced UV transmission through the foto-catalyst containing clear coat as well as reduced water permeability.
The study is published in: Progress in Organic Coatings, Volume 113, December 2017.
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