Application of chitosan emulsion as a coating on Kraft paper

Kraft paper was coated with chitosan emulsion film. The novelty of this paper is the formation of a packaging bilayer system in only one drying step, which combines a biodegradable polymer emulsion (chitosan and palmitic acid) with Kraft paper. This system is described in detail and characterized for barrier properties (water vapor permeability rate (WVPR), air permeability and water absorption capacity (Cobb test)), mechanical properties (tensile properties, Taber stiffness and tear strength) and structural properties. The application of chitosan coating (3.5 gm(-2), wet basis) on Kraft paper sheets provides a significantly lower WVPR (by ca 43%) and water absorption capacity (by ca 35%) as compared to uncoated Kraft paper. The incorporation of palmitic acid into the chitosan film solutions at 1.8 gm(-2) improves the properties of Kraft paper even more by further reducing the WVPR and water absorption capacity by 51 and 41%, respectively. The air resistance of the coated Kraft systems is lower by 8- and 11-fold compared to uncoated Kraft paper, which could be associated with the chitosan film acting as a gas barrier and as a coating agent that fills the pores between cellulose fibers. (C) 2011 Society of Chemical Industry