Application of Chitosan as a Barrier Coating on Coated Ivory Board

Chitosan solution was applied to coated ivory board as a barrier material.The surface microstructure, oxygen resistance and water vapor permeability of chitosan-coated paper with different coating weight were studied. According to the images of scanning electron microscope (SEM) and atomic force microscope (MM), the coated ivory board surface has a smooth contour, without pores and cracks after being coated with chitosan. With increasing coating hold-out of chitosan, the smoothness and the oxygen barrier properties of coated paper were improved considerably, but no improvement was obtained on the water vapor resistance. An Oxygen transmission rate (OTR) of 119.0 cm(3)/m(2).2411-0.1MPa was obtained when the coating weight of chitosan was 3.96 g/m(2). Single-layer and double-layer techniques were used to coat coated ivory paper with chitosan; it was found that the OTR of the paper that was obtained by double-layer coating technique, was lower than that of the single-layer paper with similar coating weight. In order to reduce the water vapor transmission rate (WVTR) of chitosan-coated paper, Poly(vinyldene chloride)(PVDC) was applied on the chitosan-coated paper. Water vapor and oxygen barrier properties were enhanced as the coating weight of PVDC increased from 1.05 g/m(2) to 7.40 g/m(2). While the chitosan and PVDC was coated on coated ivory paper through bi-layer technique for 1.96 g/m(2) and 7.40g/m(2), respectively, the WVTR and OTR of paper decreased by 66.3% and 98.0% separately, compared to that of the chitosan-coated paper for 1.96g/m(2).