Vinyl alcohol copolymers for use in aqueous dispersions and melt extruded articles

摘要

A sulfonic acid-functionalized vinyl alcohol copolymer is provided which is characterized by a substantial absence of compositional drift. The copolymer is produced by polymerization in two continuously-fed reaction zones such that the ratio of sulfonic acid-containing comonomer fed to the first reaction zone to the sulfonic acid-containing comonomer fed to the second reaction zone is within the range of about 55:45 to about 80:20. The resin is characterized by a resistance to irreversible dehydration upon exposure to harsh chemicals and by retention of hydroxide functionality upon aging. A resin composition comprising a copolymer lacking compositional drift is also provided for preparation of an oil and grease barrier coating, an oxidation resistant water soluble package, or a battery separator.