A HYDROPHILIC POLYMER WITH INCREASED RESISTANCE TO HYDROPHILIC SOLVENTS

摘要

An aliphatic polyester with low water absorption is selected as a coating material for hydrophilic polymers like starch. The polyester can be degraded by bacteria or fungi. This polyester may, for example, be a polyhydroxycarbonic acid. It is dissolved and applied to the components, of starch, for instance, by one of the customary physical or chemical coating processes. Once the solvent has evaporated, a coating film is left on the surface. If the coating thickness is adequate, the starch thus treated can no longer dissolve or swell. Such combinations of coatings adhere poorly to one another. Improved adhesion may be achieved by various methods, e.g. by prior corona treatment of the surface for the starch and/or the addition of a solvent or swelling agent for the starch to the coating solution.