Partially saponified polyvinyl acetates and their application in the homo- and copolymerization of vinyl chloride

摘要

This invention relates to novel partially saponified polyvinyl acetates with a degree of hydrolysis of 30 to 65 mole % which might be considered as vinyl alcohol-vinyl acetate block copolymers. The invention relates further to the application of said novel block copolymers as a pore-forming additive used together with at least one known protective colloid in the homo- and copolymerization of vinyl compounds, primarily of vinyl chloride in a pure aqueous medium.