| 摘要 |
PURPOSE:To obtain the silver halide emulsion composed of the silver iodobromide particle having the high aspect ratio and a narrow distribution of particle sizes and an improved reproducibility by controlling a concn. of iodide ion to a prescribed range in a reactor before introducing at least a silver salt and a bromide salt, and then by maintaining the concn. of the bromide ion to the more than prescribed value after introducing them. CONSTITUTION:The photosensitive silver iodobromide having the high aspect ratio, in which emulsion particles with >=50% of the total projecting area of emulsion particles are occupies with dispersion medium and silver iodobromide particles having >=0.5mum particle size, <=0.3mum thickness, and >=5 the means aspect ratio, is produced by introducing the silver salt and the bromide salt or a bromide and a diode salt in the reactor accommodated at least a part of the dispersion medium. Thus, the concn. of the iodide ion (PI) in the reactor is controlled as shown by the formula before introducing at least the silver salt and the bromide salt to the reactor. The pBr value is maintained to >=0.8 (preferably 0.8-3.5) after introducing them to the reactor.
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