Modulation of water based commercial varnish by adding ZnO and SO2 nanoparticles to enhance protective function on printed packaging

The packaging sector of graphic industry is continuosly growing and developing in terms of packaging function used materials and production technology. The aim of this paper was to evaluate modification of commercial water-based varnish by determining its protective properties regarding colour degradation as well as barrier properties. For that purpose a set of composite coatings of different composition was prepared and applied onto cardboard prints. The prepared samples were characterized by measuring CIE L *a*b*􀀁 colour density and water vapour transfer rate before and after accelerated ageing. Results showed that applying prepared nanocomposite coatings do not cause significant colour change (max. dE2000 = 2.84} but do increase the tone value at 80% nominal value for almost 5%. Furthermore􀀁 barrier to the water vapour is increased by adding nanoparticles. Adding ZnO into the composite decreases yellow fading because of accelerated ageing. This research proved the positive influence of added nanoparticles into the commercial varnish by increasing its protective role in prinf s ageing and barrier properties while just slightly changing the primary colour apearence.