| 摘要 |
1,205,474. Gelatine compositions; dextran sulphates. MEITO SANGYO K.K. AND KONISHIROKU PHOTO INDUSTRY CO. Ltd. 5 Feb., 1968 [6 Feb., 1967 (2)], No. 5721/68. Headings C3H and C3U. [Also in Division G2] Photographic gelatine coating compositions, including gelatine silver halide emulsions, contain dextran sulphate or a carboxyalkyl dextran sulphate or a salt thereof. The composition may be coated on a support to form an emulsion layer or an interlayer or an antiabrasion, subbing, antihalation or backing layer. The gellation temperature of the composition is raised and when the latter is an emulsion the covering power of the developed silver is increased. Salts of dextran sulphate and carboxyalkyl dextran sulphates are prepared. In Examples A to D, dextrans of various viscosities are reacted with chlorosulphonic acid in formamide and isolated as the sodium and calcium salts of dextran sulphate; E, sodium dextran sulphate is reacted with monochloracetic acid to form sodium carboxymethyl dextran sulphate; and, F, dextran is reacted with monochloracetic acid in aqueous alkali and the carboxymethyl dextran is reacted in formamide with chlorosulphonic acid and isolated as sodium carboxymethyl dextran sulphate. |
