| 摘要 |
1,184,126. Photographic material containing an optical brightening agent. AGFA-GEVAERT A.G. July 19, 1968 [July 22, 1967], No.34491/68. Heading G2C. A photographic material comprises at least one silver halide emulsion layer on a paper support which is provided with a baryta layer, in which material 0À05 to 50 parts by weight per 1 part by weight of gelatine, of particles of an anionic polyurethane are heterogeneously distributed in at least one of the layers thereof, which particles contain dissolved therein an optical brightening agent which is insoluble in water. The optical brightening agent is preferably present in the anionic polyurethane in a concentration of 0À05 to 5%, based on the dry weight of the mixture of anionic polyurethane and brightening agent. The anionic polyurethane may be a sulphonated or carboxylated polyurethane obtained by reacting a linear compound that has at least two active hydrogen atoms, at least one of which is present in a hydroxyl group and which linear compound has a molecular weight of from 300 to 20, 000, with polyisocyanates and if desired, chain lengthening agents with active hydrogen atoms.
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