Cellulose nanofibrils/nanoclay hybrid composite as a paper coating: Effects of spray time, nanoclay content and corona discharge on barrier and mechanical properties of the coated papers

The objective of this paper was evaluate the effects of spray time, nanoclay content and corona discharge on oxygen transmission rate (OTR), water vapor transmission rate (WVTR), basis weight, thickness and tensile strength of the coated papers. An aqueous slurry base, a mixture of cellulose nanofibrils (CNF) and nanoclay particles, was sprayed on a kraft writing & printing paper surface as base substrate. Upon drying, the suspension on the paper surface formed a hybrid nanocomposite layer with CNF (matrix) and nanoclay (mineral filler). Paper substrate was coated by a laboratory-assembled spray coater. Corona discharge enhanced the wetting of paper surfaces, improving adherence between paper and hybrid composite. Increased spray time improved tensile strength and barrier properties i.e. OTR and WVTR. Higher nanoclay content in coated paper enhanced its barrier properties but reduced its tensile strength. Tensile strength and morphological properties demonstrated effective adhesion between base substrate and hybrid composite.