High-chroma c.i. pigment red 254 and process for producing the same

Abstract

The present invention relates to C. I. Pigment Red 254 for coloring, which can color an object to be colored so as to have a higher chroma than that with conventional technology and a production method for easily producing it. For the purpose, the inventors provide the production method for the pigment, wherein the intersection of mass tone ΔH* and ΔC* of a color coating film in an acrylic-melamine coating test is, on X-Y coordinate plane to which the ΔH* is defined as the X-axis and the ΔC* is defined as the Y-axis, within the surrounded region determined by specific three equations; and a production method for the pigment provides the production method of the pigment, including a process of heating crude pigment at 100-130 ° C. for 2-10 hours in an aprotic polar organic solvent which is strongly alkaline, which comprises the step of, prior to the heating process, beforehand, heating at 100-130 ° C. in neutral or weaker alkaline aprotic polar organic solvent, the mean particle diameter is finally larger than the mean particle diameter before heating.

Dependencies are inferred from the claim text.