Organic pigments

The organic pigments can be principally classified into two major groups: azo pigments and polycyclic pigments.

Azo pigments are characterized by the presence of one (monoazo) or two (disazo) azo bonds –N=N–, in the molecule and cover mainly the range of yellow, orange, red violet and brown shades. Azo pigments represent about 70% of all organic pigments worldwide and depending on their properties are used over the entire range of pigment application reaching from all types of coatings to colouring of plastics and printing inks to food and cosmetic colourants.

Polycyclic pigments include a wide variety of chemical structures, but in general consists of mostly aromatic six- and/or five membered condensed carbon ring systems, and in part aromatic heterocyclic systems containing nitrogen, oxygen or sulphur. By far the most important group of polycyclic pigments are represented by the copper phthalocyanine structure. Almost all blue and green shades of organic pigments commercially used are based on this chemical entity. Other polycyclic pigment types of commercial importance are quinacridones and perylene pigments covering orange and red shades and various other structures.