ABSTRACT
Organic pigments are finely divided crystalline solids that are used to impart color to printing inks, paints, surface coatings generally, plastics, artificial fibers, paper coatings, and various other materials. This chapter provides some insight into how the physical character of organic pigments affects the properties of dispersions in application media. It exemplifies how this physical character can be controlled to give products that disperse readily into appropriate application media and give satisfactory performance. The crystalline nature of organic pigments is shown by their characteristic powder X-ray diffraction patterns. The primary particles of organic pigments are tiny crystals that in many cases are amenable to examination by transmission electron microscopy. Ideally, the particles of organic pigments dispersed in application media should be individual crystals. Control of flocculation of organic pigments is a topic of major importance, especially in dispersions with low viscosity, such as gravure and liquid inks and paints.
