High-chroma C.I. Pigment Red 254 and process for producing the same
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.
1. C. I. Pigment Red 254, wherein the ΔH* and ΔC* of a color coating film in an acrylic-melamine coating test is within a surrounded region determined by following three equations:
[Equation 1]
y =7.00 x +2.20 Equation (1)
[Equation 2]
y =1.07 x +2.20 Equation (2)
[Equation 3]
y =2.32 x +1.26 Equation (3),
on an X-Y coordinate plane to which the ΔH* is defined as the X-axis and the ΔC* is defined as the Y-axis.
2. C. I. Pigment Red 254, wherein the ΔH* and ΔC* of a color coating film in an acrylic-melamine coating test is within a surrounded region determined by following three equations:
[Equation 4]
y =9.00 x +2.20 Equation (4)
[Equation 5]
y =1.10 x +2.20 Equation (5)
[Equation 6]
y =2.92 x +1.29 Equation (6)
on an X-Y coordinate plane to which the ΔH* is defined as the X-axis and the ΔC* is defined as the Y-axis.
3. A production method for C. I. Pigment Red 254 having a mean particle diameter of 0.30-0.80 μm comprising heating 1,4-diketo-3,6-bis(4-chlorophenyl)pyrrolo[3,4-c]pyrrole having mean particle diameter of 0.10-0.20μm in a strong alkaline aprotic polar organic solvent at 100-130° C. for 2-10 hours, further comprising the step of, heating the 1,4-diketo-3,6-bis(4-chlorophenyl )pyrrolo[3,4-c]pyrrole at 100-130° C. in neutral or weaker alkaline aprotic polar organic solvent prior to heating in the strong alkaline aprotic polar organic solvent.
4. The production method for C. I. Pigment Red 254 according to claim 3 , wherein the alkali contained in the aprotic polar organic solvent prior to heating is present in a concentration of 0-0.07 parts per 100 parts of the aprotic polar organic solvent and the alkali contained in the aprotic polar organic solvent after heating is present in a concentration of 0.02-0.15 parts per 100 parts of the aprotic polar organic solvent.
5. The production method for C. I. Pigment Red 254 according to claim 3 , wherein the aprotic polar organic solvent is a hydrophilic aprotic polar organic solvent having nitrogen-containing heterocyclic ring, and the alkali is an inorganic alkali soluble in the aprotic polar organic solvent and water-soluble.
6. The production method for C. I. Pigment Red 254 according to claim 4 , wherein the aprotic polar organic solvent is a hydrophilic aprotic polar organic solvent having nitrogen-containing heterocyclic ring, and the alkali is an inorganic alkali soluble in the aprotic polar organic solvent and water-soluble.