Disazo (Bishydrazone) condensation pigments

Disazo condensation pigments were developed in the mid-twentieth century as a range of high-performance azo pigments to meet the stringent demands placed on the technical properties required for applications in growing markets such as automotive paints, plastics, and fibers. The commercial products vary in shade from yellow through red to brown. Structurally, the pigments are related to the classical yellow azoacetoacetanilides or red azonaphthols by synthetically connecting two monoazo derivatives by a condensation reaction involving an aromatic diamine. The resulting pigment molecules are of extremely large molecular size with the presence of several amide groups, factors that determine their excellent set of fastness properties. The procedures used in their manufacture involve complex and demanding multistage processes, and this explains the higher cost of these pigments. The application performance attributes provided by the individual commercial products are discussed in detail in the final section.