Application of hydrophilic starch-based coatings on polyethylene surfaces

Coatings were applied to polyethylene (PE) film surfaces by spraying formulations prepared from a jet cooked dispersion of waxy cornstarch, a water-born epoxy resin, a wax emulsion, and a fluorinated surfactant. The air-dried coatings were comprised of discontinuous areas of polymer that adhered tightly to the PE surface. Although the starch component separated rapidly from the coating when the film was placed in water at room temperature, heating the coated film for 24 h at 80 degrees C increased the adhesion of starch and produced a surface coating that remained uniformly wet when the film was placed in water. Most of the starch, however, could be still be removed by gently rubbing the wet surface. If melamineformaldehyde resin was added to the formulation as a crosslinking agent for starch, and the coated film was then heated for 24 h at 80 degrees C, most of the starch remained bonded to the wet coating, even after the surface was gently rubbed. Identification of successful spray application techniques and formulations will allow the development of commercial production methods for starch-coated PE films and similar products. (C) 2008 Wiley Periodicals, Inc.