Procédé de fabrication de films ou de feuilles à partir d'une solution filmogène

A casting layer for the manufacture of films; sheets is produced by coating a metal support with a solution of cellulose acetate, evaporating the solvent, hydrolysing the surface of the cellulose acetate, applying a solution in an organic solvent or in a mixture of water and water-miscible organic solvent of a Werner chromium complex salt in which a trivalent chromium atom is co-ordinated with a carboxylic acido group to form a coating of thickness 0.01 micron to 5 micron, and heating the coating to 50 DEG C. The support may be a rotating metal drum or an endless metal belt forming part of a film casting machine. Films and foils can be prepared by casting a film-forming solution, for example a solution of cellulose triacetate or other film-forming polymer. Carboxylic acido groups mentioned are acrylic, methacrylic, stearic, palmitic, lauric acid, p-amino-benzoic, cyanoacetic, mercapto acetic acid, maleic acid, fluorinated aliphatic carboxylic acids. The chromium complex salt composition may be applied by roll, dip, knife coating. The chromium complex salt coating composition may be applied as a small strip to either side of the cellulose acetate surface when it is only intended to avoid the tearing of the film edges and when emhancing of the repellancy of the casting layer as a whole is not so important. The casting layer may be used to form films of cellulose triacetate, polycarbonates, polyphenylene oxide, copolyesters of isophthalic acid, terephthalic acid and 2, 2-bis (4-hydroxyphenyl)-propane.