The characteristics of water-based ink pigments.
Waterborne ink pigment characteristics meet the different needs of consumers for printed products. Since the aqueous ink resin is mostly alkali-soluble, it is necessary to use an alkali-resistant pigment when selecting a pigment. The distribution density of water-based ink pigments is much larger than that of solvent-based water-based inks, and the surface tension and polarity of water are greatly different from those of solvents. The dispersion of water-based ink pigments is difficult, and the stability, viscosity and pH of aqueous inks are directly.
The addition of a surfactant to the aqueous ink increases the affinity of the resin and water and the affinity of the pigment with the water-soluble binder to solve the problem of stability of the aqueous ink. The viscosity and pH of the ink are precisely controlled. When the pH value is higher than 9.5, the alkalinity is too strong, the viscosity of the aqueous ink is lowered, the drying speed is slow, and the water resistance is deteriorated; when the pH is lower than 8, the alkalinity is too weak, the viscosity of the aqueous ink is increased, and the drying speed is high. Accelerate, there will be defects such as dirty version, paste, and foaming. Water-based inks should choose high-grade pigments with bright color, low viscosity and stable system when printing pigments.
The binder, pigment, and auxiliary agent are materials that constitute the aqueous ink. The binder provides the necessary transfer properties of the aqueous ink, and the pigment imparts color to the aqueous ink. The water-based oil binder is classified into a water-diluted type and a water-dispersed type. There are many types of resins that can be used in the former. The water-dispersible binder is obtained by polymerizing emulsified monomers in water. The aqueous ink is a two-phase system in which the oil phase is dispersed in the aqueous phase in the form of particles, and although it is not soluble in water, it can be diluted with water, so it can also be considered as an oil-in-water emulsion type.