Waterborne barrier coatings on cellulose nanofiber layers
Layers of cellulose nanofibers have great potential to be used in food packaging applications because of their oxygen and grease barrier properties. But they have to be protected against moisture.
Layers of cellulose nanofibers (CNF) are sensitive to moisture. Therefore, it makes sense to use them in a layered structure with water vapor barrier layers. Waterborne barrier coatings (WBBC) have the potential to provide this water vapor barrier, but as the researchers of a recent study point out, their performance on paper with a CNF layer has not been described in the literature so far.
Improved water vapor barrier
In their study, paper that had a CNF layer was coated with three different WBBC with various levels of two different barrier pigments to improve the water vapor barrier properties of these systems. test resluts showed that the presence of the CNF layer on paper improved the performance of the water vapor barrier layer, in some cases, by a factor of six. Adding barrier pigment to the WBBC improves barrier properties at low concentration by 15%, but as the concentration of pigment increases, the barrier properties decrease. This result likely is linked to fine bubbles in the coatings that are hard to remove or other defects that are generated during coating or drying. All samples had good grease barrier properties.
The study has been published in Journal of Coatings Technology and Research, Volume 19, 2022.
