| 摘要 |
PURPOSE:To obtain the substantial max. image density (Dmax) even if the amt. of a specific low. mol. wt. coupler is decreased, to make possible the reduction in thickness in an emulsion layer (more particularly the improvement in sharpness) even if the image density is made high and to reduce the time for a development process by incorporating the above-mentioned coupler into a silver halide layer. CONSTITUTION:The low mol. wt. coupler has the mol. wt. as low as 250-450 and therefore the amt. of the coupler is decreased while the substantial Dmax. is maintained. The amt. of a hydrophilic colloid such as gelatin (further the amt. of a high boiling solvent) is thereby decreased, by which the improvement in the sharpness as a result of the reduced film thickness of the emulsion layer and further the prevention of perspiration are realized. The low mol. wt. coupler has the higher reaction rate of coupling than a polymer coupler latex, thus contributing to the satisfactory coloration efficiency and reduced time for the developing process. Even if the mol. wt. (MW) of the coupler is <=450, the cou pler and the dye obtd. by development are both made non-diffusive. The coupler is made easier to diffuse in the protective colloid layer when the MW is 250. The low mol. wt. coupler expressed by the formula is more preferable. |
