Enhancing moisture resistance of starch-coated paper by improving the film forming capability of starch film

Starch-coated paper is widely used in packaging, printing, writing, and so on. However, achieving starch-coated paper with excellent moisture resistance remains a challenge for its end uses. To overcome this challenge, we hypothesize that the film-forming ability of starch plays a pivotal role in the moisture resistance of starch-coated paper. Polyvinyl alcohol (PVA) is used to enhance the film-forming capability of starch film and the moisture resistance of PVA/CS coated paper is evaluated in terms of moisture absorption, tensile index, and stiffness. A PVA/CS film with only a coating weight of 4.0 g/m2 can fully cover the porous structure of paper that leads to a higher moisture resistance than CS-coated paper with a similar loading weight. However, as the coating weight continues to increase, the decline of the mechanical properties of PVA/CS coated paper is almost unchanged. Furthermore, the moisture resistance of PVA/CS coated paper (coating weight is larger than 4.0 g/m2) is further improved by using glyoxal as moisture proof agent (MPA). Only 4.8% and 6.3% losses in the tensile index and stiffness at a coating weight of 4.0 g/m2 are achieved before and after moisture treatment, respectively. These results may shed light on exploring new method to enhance moisture resistance of starch-coated paper.