PROCESS FOR THE MANUFACTURE OF FILMS AND COATINGS CONTAINING POLYVINYL ALCOHOL AND HAVING A REDUCED SOLUBILITY IN WATER

摘要

Polyvinyl alcohol containing films and coatings having a reduced water solubility are prepared from polyvinyl alcohol having an ester number of at most 200 mg of KOH/g. This polyvinyl alcohol being readily soluble in water is submitted in aqueous phase to an after saponification with alkali metal or alkaline earth metal hydroxide rendering it insoluble at elevated temperature. The alkali or alkaline earth metal ions then are precipitated in the form of compounds difficultly soluble in water by additions of substances containing corresponding anions. The precipitate remains as inert filler in the suspension of polyvinyl alcohol thus prepared. The suspension is applied in form of films or coatings and dried.