Improving multilayer packaging performance with nanocellulose barrier layer

Nanocellulose, also referred to as cellulose nanofibrils (CNF) is one of the most studied innovations for the modern forest sector. Until very recently, CNF films have been produced at small-scale using slow filtration methods. In this presentation, the first steps towards continuous CNF film production are presented. VTT’s semi-industrial roll-to-roll pilot-line was successfully utilized in producing high quality CNF films with some promising technical properties (oxygen barrier, temperature resistance, tensile strength). However, as single layer CNF films have relatively weak moisture resistance, flexibility and zero sealability, the multilayer structures were also produced. Tempo-oxidized CNF was first dispersion coated onto PET film and further extrusion coated with LDPE resulting in a 3-layer structure: PET/CNF/LDPE. 3-layer structure had excellent technical properties which fulfilled the requirements of modified atmosphere food packaging. Demonstrator pouches filled with nitrogen were produced with the packaging machine and the oxygen concentration inside the packages was monitored as a function of time. As a result, CNF containing multilayer films performed better as compared to commercial 3-layer multilayer films containing EVOH barrier layer. The developed films could be used as a packaging material for dry or low moisture content food products such as dry snacks, dried fruits, nuts, spices etc.