Polymer coating composition and its use in the manufacture of layered packaging

A composition which, upon drying, provides a moisture resistant, gas and flavor tight coating for use in a packaging material, said composition consisting essentially of an aqueous solution of polyvinyl alcohol containing more than 90% (--CH.sub.2 OH) groups, a viscosity of less than 20 cp (in solution at 4% water) and an ester index between 2 and 150, and a latex of a water insensitive polymer incompatible with the polyvinyl alcohol selected from the group consisting of vinylidene chloride polymer latexes, the ratio of polyvinyl alcohol to latex polymer expressed by weight of dry material being between 0.4 and 3, said compositions being characterized by inversion to a two-phase coating upon drying in which the water insensitive latex polymer forms a continuous phase and the polyvinyl alcohol forms a discontinuous phase.