ALPHA-DIKETOPYRROLOPYRROLE PIGMENT, COLORING COMPOSITION CONTAINING THE SAME, AND RED FILM

摘要

An ±-diketopyrrolopyrrole pigment characterized by giving an X-ray diffraction spectrum in which the ratio of the peak density (I 020 ) for plane index (020) to the peak intensity (I -141 ) for plane index (-141), I 020 /I -141 is 0.40 or lower and the ratio of the peak intensity (I -141 ) for plane index (-141) to the peak intensity (I 111 ) for plane index (111), I -141 /I 111 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 ±-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 small viewing-angle dependence and showing excellent display characteristics can be produced.