Thermal Stability of Organic Pigment (II)

Mechanism of Thermal Degradation and Thermal Stability of Azo Lake Pigments

Abstract

Thermal stability of azo lake pigments (Orange II, Alizarin Yellow GG) was studied by thermal glavimetric analysis.
The pigments were decomposed through two or three stages from room temperature to 600°C on heating. In the first stage the azo group of Orange II was decomposed, then the aromatic rings were decomposed in the residue of thermal degradation and the color changed completely. The influence of the metal salts on thermal stability was better in order Ba, Sr and Ca.
The enolform of Alizarin Yellow GG was preferentially decomposed in the first stage and the ketoform was decomposed in the second stage and the color changed through both stages. These tendency was indistinct in order Ca, Sr and Ba salt.