Improvement of Dye Properties of the Azo Pigment Yellow 12 Using a Micromixer-Based Process

The properties of coloured pigments are primarily affected by the particle size as well as the size distribution. As both are influenced by the production process, the pigment synthesis of Yellow 12 was investigated using a micromixer apparatus. The micromixer ensures fast mixing by multilamination of thin lamellae and thereby a faster complete mixing of the reactants compared to batch processes. It was found that the micromixer-based process leads to a smaller pigment size distribution. This results in an improvement of the pigment properties. Compared to a commercially available Yellow 12 standard the glossiness was increased by 73% and the transparency by 66% with unchanged tinctorial power.