Light-sensitive mixture and light-sensitive copying material prepared therefrom wherein image produced therein is visible under yellow safety light

摘要

Disclosed is a light-sensitive mixture comprising (a) a 1,2- quinonediazide or a mixture of (a.sup.1) a compound forming an acid on exposure and (a.sup.2) a compound having at least one C--O--C bond cleavable by acid; (b) a water-insoluble binder soluble in aqueous- alkaline solutions; (c) a photolytically cleavable organic halogen compound of one of the formulae ##STR1## in which R.sup.1 denotes an aromatic radical bonded directly or via a conjugated chain, and X denotes a halogen atom; and (d) an azo dyestuff containing at least one nitro group in the molecule. Also disclosed are light-sensitive copying materials produced from these mixtures.