Abstract
Two kinds of novel single-component black pigments have been presented. The first product is benzimidazo perylene compounds. The black color is achieved by superposition of two absorption bands in the visible region, one of which is due to individual molecules and the other arises from intermolecular interactions between transition dipoles. The present pigment is characterized by deep black-shade, as well as light-and heat-fastness. In addition, it exhibits high electrical resistivity and possesses no IR-absorption. On the other hand, the second black pigment has accidentally been obtained in the course of our investigation on the crystal growth of diketopyrrolepyrroles from solution. This pigment is basically prepared by only 2-methyl-2, 4-pentanediol and nitric acid in an autoclave at about 160°C. The product possesses all necessary pigmentary properties and also exhibits high electrical resistivity. However, details on the molecular structure remain still unclarified.
