The purpose of organic pigments is to color various substrates. In the coloring process, due to the different nature of the substrate, the requirements for organic pigments are different. For example, to color printing inks, organic pigments are required to have good transparency; if it is to paint. Organic pigments are required to have good hiding power, and the application of organic pigments requires the pigmentation treatment of organic pigments. Organic pigments are evenly dispersed in the application medium with fine particles during application. Although the molecular structure of the organic pigment plays an important role in its application performance, the physical properties of the solid particles have a great influence on its application performance. Disperse the organic pigment in a certain medium, the relationship between the particle size of the pigment and the light absorption coefficient is shown in the following figure: the relationship between the hiding power of the pigment and the coloring strength and particle size:
At present, the methods of ultramarine pigmentation treatment for organic pigments in industry are: acid dissolution, acid swelling, ball milling, kneading, solvent treatment and surfactant. The acid dissolution method and the acid swelling method both adjust the particle size, crystal form and surface state of the pigment in an acid medium: acid dissolution method: according to most pigments and inorganic acids (such as 98% sulfuric acid) form a salt at a lower temperature and dissolve in , And then diluted with water, with the hydrolysis of the salt to regenerate insoluble particles and precipitate. In the precipitation process, adding specific surfactants or additives, or controlling certain factors (such as temperature) can achieve the purpose of adjusting the size of the pigment particles. classification
