POLYESTER FILM OF COMPOSED STRUCTURE, FIRST OF ALL FOR PRODUCING SUBSTRATE FOR MAGNETIC DATA-BLOCKING STRUCTURES, PROCESS FOR PRODUCING THEM AND MAGNETIC DATA-BLOCKING MATERIAL COMPOSITION

摘要

Composite films comprised of an unloaded semicrystalline polyester film support with a roughness Ra no greater than 0.01 mu m having, on at least one of its faces, a coating based on a modified polymer produced by polymerising one or several acrylic monomers in the presence of a water-dispersable sulphonated copolyester. The composite films according to the invention are particularly well suited as supports for thin magnetic films.