| 摘要 |
PURPOSE:To improve sensitivity and property of a film, by first placing an acid in a reaction vessel in preparing a photographic emulsion by an ammonia method. CONSTITUTION:An aq. ammoniacal silver nitrate solution is added to the reaction vessel where an aq. acid or aq. acid and ammonia solution has been already present, in preparing a silver halide emulsion from an ammoniacal silver nitrate and an aq. alkali halide solution. In the back mixing method using a single jet, the aq. ammmonical silver nitrate solution is placed in the reactor in advance, but in the other mixing methods, large drop of pH is avoided by use of a strong acid. Lowering of pH to >=1 permits photographic performance to be improved without changing grain size distribution and crystal forms, etc., and the emulsion to be prepared at high temperatures, and therefore, reaction time to be shortened. |
