STARCH-POLYVINYLALCOHOL-ACETAL - A WATERSOLUBLE FILM

To ensure more comfort, dosage units of active ingredients may be pack ed in water soluble film prior to application. In the mean time plasti cised polyvinylalcohol (PVAL), with limited metabolitic degradability in common water epuration units, is used for present purpose. In this work we found that the reducing chain ends of degraded starch molecule s form semi acetals with the hydroxyl moieties of (PVAL). Reaction con ditions could be selected for processing in a twin screw extruder. Due to replacement of around 50% of the polyvinylalcohol by starch the pr oduction costs are significantly lower than that of pure PVAL-films. T he acetal films show better mechanical properties, seal easier, dissol ve faster in water and mineralise at lower temperatures if compared wi th pure PVAL.