Redispersable nanopowders for wet chemical coating processes. Application to transparent conducting coatings*

In2O3:Sn (ITO) sols made of crystalline nanoparticles fully redispersable in an ethanol solution con-taining hydrolyzed organosilanes have been developed to get thick conducting transparent and antiglare coatings on substrates which do not withstand high temperature such as plastics (PMMA, polycarbonate) and already processed glasses. The coatings were deposited by spin, dip and spray coating processes and cured by UV irradiation and/or by a low temperature heat treatment (T = 130 °C) in air and reducing atmosphere. Their electrical, optical, textural and mechanical properties are reported. Stable sheet resis-tance as low as 2 kW ¨ was obtained with a single 500 nm thick transparent layer. Antiglare-antistatic coatings exhibiting similar sheet resistance, a gloss of 60–70 GU, a clarity of 75–90 % and an optical resolution> 8 lines/mm were obtained by a room temperature spraying process. The abrasion resistance of the transparent coatings is in agreement with DIN 58196 G10 – class 1, the adhesion with DIN 58196-K2 (tape test) and the pencil hardness (ASTM D 3363-92a) is 1H