| 摘要 |
1,255,550. Photographic silver halide emulsions and materials. EASTMAN KODAK CO. May 1, 1969 [May 1, 1968], No.22247/69. Heading G2C. A photographic material comprises a support and a layer of a photo-sensitive silver halide photographic emulsion which contains incorporated in the emulsion layer or a layer adjacent thereto a substantially water-insoluble (i.e. having a solubility of less than 5 grams per litre of water at 20‹ C . ) silver halide developing agent dissolved in a solvent which comprises a di (tetrahydrofurfuryl) ester of a dibasic carboxylic acid which solvent is a liquid of 25‹ C. Many examples of suitable developing agents are listed including nordihydroguaiaretic acid, 4-phenylcatechol being used in the examples. The esters, defined above, of phthalic, succinic, adipic and glutanic acid are preferred. The di (tetrahydrofurfuryl) ester may be mixed with another ester which is substantially water-insoluble (as hereindefined), has a boiling point above 150‹ C . and a molecular weight between 100 and 1000, for example tricresylphosphate and dibutyl phthalate. The ratio of developing agent to total solvent is preferably in the range 1:1 to 1:15 by weight. The silver halide emulsion layer may be a direct-positive layer and the photographic material defined above may be used to provide a lithographic printing plate. The support may be paper bearing a sublayer of TiO 2 pigmented polyethylene and backing layer of clear polyethylene.
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