GB746291A - Improved film casting compositions and film made therefrom - Google Patents

Abstract

A film-casting composition comprises a cellulose acetate propionate of 29-31 per cent acetyl content and 13-15 per cent propiony content or a cellulose acetate butyrate of 30-32 per cent acetyl content and 12-14 per cent butyryl content, in solution in a solvent mixture consisting of methylene chloride, methyl alcohol, and n-butyl alcohol. The composition may be formed into base films for motionpicture films. The solvent mixture may contain 80-90 per cent of methylene chloride, 3-10 per cent of methyl alcohol, and 5-15 per cent of n-butyl alcohol. In an example, 100 parts by weight of cellulose acetate propionate of 14 per cent propionyl and 30 per cent acetyl are dissolved in a mixture of 434 parts of methyllene chloride, 25 parts of methyl alcohol, and 51 parts of n-butyl alcohol, to which are added, after the ester is in complete solution, 8 parts of triphenyl phosphate. The solution is cast on a polished cylinder at 80 DEG F. and, after partial drying, the film so formed is stripped from the cylinder and passed to further drying and treating apparatus. Instead of triphenyl phosphate, there may be used as plasticizer, tricresyl phosphate, diethyl phthalate, dibutyl phthalate, or tripropionin. Dyes, colouring agents, or fluorescent materials may be incorporated in the film-casting composition, or they may be applied to the formed films. Among those specified are Eastone Red R, Nigrosine, coumarin dyes, anthracene, rhodamine, chrysene, methyl umbelliphorone, anthranilic acid, and 2-phenyl-5-amino-benzoxazole.