Bleach baths for processing silver halide photographic materials - contg. ferric iron complex with biodegradable nitrilo mono:acetic acid di:carboxylic acid complex former

摘要

Bleach- or bleach-fixing baths for processing Ag halide colour photographic materials, contg. an Fe(III) complex in which the complex former is made up of at least 20 mol.%, esp. at least 80 mol.% of a cpd. HOOC-CH2-N(CH2-X-COOH)2 (I), in which X = CH2, CH2-CH2 or CHOH. Pref. complex former (I) is nitrilomonoaceticdipropionic acid HOOC-CH2-N-(CH2-CH2-COOH)2 (Ia) (Claimed). Pref. bleach baths contain 0.05-1.0 mol./l of the Fe(III) complex and 0.1-2.5 mol./l of a halide such as NaCl, NaBr, KCl, KBr, NH4Cl and NH4Br to rehalogenate the Ag. Bleach/fix baths pref. contain 0.04-0.4 mol./l of the Fe(III) complex, 0.2-2 mol./l thiosulphate and 0.02-0.3 mol./l sulphite. Both baths pref. contain up to 1.3 mol./l of the free complex former. USE/ADVANTAGE - The baths have a good bleaching action and improved biodegradability in comparison to prior art bleach baths of this type.