| 摘要 |
949,440. Photographic rehalogenation baths. CIBA Ltd. Aug. 23, 1962 [Sept. 8, 1961], No. 32462/62. Heading G2C. A photographic silver bleach bath comprises a water-soluble aliphatic carboxylic acid, a cupric salt and a free hydrohalic acid. The hydrohalic acid must be present in excess of the amount that would result from double decomposition between the carboxylic acid and any halide which may be present in the bath though it may be introduced by double decomposition e.g. by incorporating potassium bromide and sulphuric acid in the bath. Carboxylic acid specified are acetic, lactic, cyanacetic, acrylic, succinic, tartaric, citric and maleic. The copper salt may be the sulphate, nitrate or acetate. Optional ingredients mentioned are surfactants, e.g. polyglycol ethers of fatty alcohols and fluoro-aliphatic carboxylic acids, and biguanide base antioxidants for the dye. Specific examples illustrate the use of such baths as the silver bleach bath following the dye bleach bath in conventional silver dye bleach procedures. |
