| 摘要 |
PURPOSE:To obtain a low-fogging silver halide photographic emulsion for direct positives having high sensitivity by incorporating at least one kind of specific org. desensitizers into the emulsion. CONSTITUTION:The pyridium salts expressed by formula I or II are used as the novel org. desensitizers. In formula, R<1>-R<8> may be the same or different, and respectively denote hydrogen, alkyl group; R<1> and R<2> or R<2> and R<3> or R<3> and R<4> or R<5> and R<6> or R<7> and R<8> may form a benzene ring. R denotes an alkyl group which may be substd. (for example, sulfo group) and X<-> is anion, and denotes halide anion, sulfonic acid anion, perchlorate, tetrafluoroborate, etc. The low-fogging silver halide photographic emulsion for direct positives having the high sensitivity is thereby obtd. |
