| abstract |
An α-diketopyrrolopyrrole pigment characterized by giving an X-ray diffraction spectrum in which the ratio of the peak density (I020) for the plane index (020) to the peak intensity (I-141) for the plane index (-141), I020/I-141, is 0.40 or lower and the ratio of the peak density (I-141) for the plane index (-141) to the peak intensity (I111) for the plane index (111), I-141/I111, is 1.28 or lower. Also provided are: a coloring composition containing this pigment; and a red film formed with this coloring composition. In a color filter formed with the α-diketopyrrolopyrrole pigment, which has that property, the red filter segments have a high contrast ratio and a small absolute value of birefringence. Consequently, a color liquid-crystal display or the like having a small viewing-angle dependence and showing excellent display characteristics can be produced. |