Crystal Structures of Isoindoline Pigments

185 can also be produced in a one-step process in a water/solvent mixture starting with the formation of 10 in an organic solvent, followed by the addition of N-methylcyanoacetamide, and carrying out the final condensation with barbituric acid. The very specific crystal size required for ink application of the pigment can be formed directly by appropriate choice of temperature and dispersant without isolation of the crude pigment 

In contrast to the synthesis of P.Y. 139 and 185, the synthesis of P.0.69 and P.R. 260 pigments is not possible in aqueous media. The monocondensation products of p-chlorocyanoacetanilide and cyanomethylquinazolone are synthesized instead in organic solvents because of the insolubility of the starting materials. The final step has also to be carried out in an organic solvent for the same reason. 

The properties of isoindoline pigments depend strongly on their chemical strac-ture as well as on particle size and shape. The influence of the physical properties of the pigments on the color behavior is more pronounced for isoindoline pigments than for other pigment groups, e.g. copper phthalocyanines. 

Depending on particle size, brilliant opaque grades with lower color strength and transparent types with higher color strength can be produced. 

Light fastness varies from that required for ink applications and indoor coating levels (D/L 1155 and D 1819) to the level of other polycydic high-performance pigments for outdoor and other long-term applications like industrial and automotive paints (L 2140 HD, P.O. 66, P.Br. 38). 

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