The Role of Organic Pigment Surface Treatment
Pigment red 3 manufacturer says that surface treatment of organic pigments is the generation or deposition of suitable particles on the surface of the pigment and the covering of the surface of the organic pigment particles with a monomolecular or multimolecular layer structure. Depending on the different structures and properties of the surface treatment agents used, the properties of the surface of the primary color particles can be changed, i.e., the pigment particles are surface modified according to the requirements of the application object.
Compared with hydrophilic substances, organic pigments have very low hydrophilicity, and most of them are lipophilic. In the production process of organic pigments, organic pigments are precipitated by fine particles, so its surface has a very large surface energy. Under the influence of pigment concentration, Brownian motion between particles, gravitational settling, stirring, filtration and drying process of capillaries, the aggregation of particles reduces the specific surface area, which affects the final transparency, color strength and vividness of the product and other application properties.
The main function of organic pigment surface treatment is to inhibit the growth of crystal particles in the pigment, and to improve the surface characteristics of the pigment as well as its dispersion, wettability and compatibility with the medium. With the rapid development of pigment chemical industry, the demand for pigment is expanding, and the development prospect of China’s pigment industry is very broad. The dispersed state and surface polarity of pigments have an important influence on the viscosity and inkiness of paints and printing inks, as well as the color and vividness of plastic and resin coloring products.
The role of surface treatment of organic pigments mainly includes the following five aspects:
● The pigment particle size distribution uniformity, particle and wettability enhancement, directly affecting the physical and chemical properties of printing ink products, improve the rheology, can greatly improve the printing speed.
● Surface treatment with specific additives, so that the particles are more likely to be wetted by the colorant, not only to accelerate the wetting of the new interface generated in the crushing process, but also to prevent the particles from re-aggregation, but also to the light oxidation effect of the shielding effect to improve the organic pigments of light resistance, weather fastness.
● According to the different performance of the surface coating, the pigment particles are more lipophilic or more hydrophilic, so as to improve the compatibility of the pigment in oily medium, non-aqueous polar medium or aqueous medium.
● After surface treatment, even if the product has a certain degree of aggregation or flocculation, due to the low bonding force between the particles, it can still be easily re-dispersed with the help of small shear force, so as to prepare pigment dispersion with uniform particle size distribution.
● Surface treatment of pigment by natural resin, synthetic resin and surfactant and other additives can inhibit the growth of crystal particles, reduce the aggregation between particles, reduce the number of aggregates, improve the dispersion of the product, and obtain pigment with soft structure.