Synthesis and properties of some polycyclic barbiturate pigments

The synthesis, characterisation and properties of some polycyclic barbiturate pigments are described. The pigments have been tested as colourants for plastic and paint and the results of lightfastness, heatfastness and contact bleed tests are reported. Results suggest that only the barbiturate pigments with large aromatic moieties such as the pyren-1-yl and fluoren-2-yl substituents have good lightfastness properties at reduced shades in plastic and only the pyren-1-yl pigment has good lightfastness properties at reduced and full shades in paint. However, all the pigments suffer from poor heatfastness properties in plastic. The absorption coefficient (epsilon) of some of the pigments is low confirming their weakness in colour strength when tested in high density polyethylene. (C) 2003 Elsevier Ltd. All rights reserved.