Multifunctional antistatic and scratch resistant UV-cured acrylic coatings

Organic–inorganic antistatic hybrid acrylic coatings were prepared. Trialkoxy-silyl ammonium salt was added to the photocurable formulations in order to introduce an antistatic additive which could be covalently linked to the hybrid network through a co-condensation reaction involving the alkoxy groups. The influence of the antistatic additive on the radical photopolymerization reaction of the acrylic resin was evaluated by real time FTIR, keeping the inorganic precursor content constant at 20 phr and increasing the trialkoxy-silyl ammonium salt in the range between 5 and 15 phr. When the samples were cured under nitrogen atmosphere, a complete conversion of acrylic double bonds was achieved after 90 s of irradiation both for the acrylic resin and the formulations containing the ammonium salt. The scratch behavior of coatings was investigated by carrying out of progressive load scratch test. The penetration depth (Pd) and the residual depth patterns were investigated for all the hybrid films. A consistent improvement of penetration resistance by increasing alkoxy-ammonium salt content was noted in terms of Pd. Inorganic component and antistatic additives increase ε′ and σAC values of the hybrid coatings and decrease the resistivity ones, showing their efficiency for increasing antistatic properties of coatings, improved with respect to the pure acrylic resin.