On the composition characteristics and application

Talking about the composition characteristics and application of water-based inks

like the composition of general printing inks, water-based inks usually also have colorants, binders, auxiliary agents and other components. Colorants are the color rendering substances of water-based inks, which give inks a specific color. In flexographic printing, pigments with good chemical stability and high coloring power are generally used as colorants to make the imprinted colors bright; The binder is composed of water, resin, amine compounds and other organic solvents

I. composition and characteristics of water-based inks

like the composition of general printing inks, water-based inks usually also contain colorants, binders, auxiliary agents and other components. Colorants are the color rendering substances of water-based inks, which give inks a specific color. In flexographic printing, pigments with good chemical stability and high coloring power are generally used as colorants to make the imprinted colors bright; The binder is composed of water, resin, amine compounds and other organic solvents. Resin is the most important component of water-based ink, and water-soluble acrylic resin is usually used. The composition of binder directly affects the adhesion function of ink, drying speed, anti fouling requirements: temperature 10 ℃ ~ 40 ℃, humidity 20% RH ~ 70% RH performance, etc. at the same time, it also affects the gloss and inkability of ink. Amine compounds mainly maintain the alkaline pH value of water-based ink, so that acrylic resin can provide better printing effect, Water or other organic solvents are mainly used to dissolve the resin and adjust the viscosity and drying speed of the ink; Auxiliary agents mainly include defoamer, blocker, stabilizer, diluent, etc. As the water-based ink is a soap composition, it is easy to produce bubbles in use. Therefore, silicone oil should be added as an defoamer to suppress and eliminate bubbles and improve the transmission performance of the ink. The blocking agent is used to inhibit the drying speed of water-based ink, prevent the ink from drying on the roller and reduce the paste. The stabilizer can adjust the pH value of the ink, and can also be used as a diluent to reduce the viscosity of the ink. Diluent is used to reduce the color of water-based ink, and can also be used as a brightener to improve the brightness of water-based ink. In addition, water-based inks also need to add some wax to increase their wear resistance

second, the pH value of water-based ink Li Ning also told reporters about graphene technology innovation

the pH value of water-based ink is directly related to the viscosity, dryness and other printability of water-based ink. Experiments show that the viscosity of water-based ink increases linearly with the decrease of pH value, and its dryness decreases linearly with the gradual increase of pH value. The pH value of water-based ink is mainly maintained by amine compounds. The volatilization of amine substances in the printing process reduces the pH value, resulting in the increase of ink viscosity. The transfer includes two linear differences in production, accelerated drying, blocking of wrinkle rollers, and the occurrence of paste failure. Therefore, to keep the pH value of water-based ink stable, on the one hand, we should try to avoid the leakage of amines, such as covering the upper cover of the ink tank. On the other hand, stabilizer should be added regularly and quantitatively. Generally, the pH value of water-based ink should be kept at 8 5, too high or too low pH value will affect the printing quality, and too low pH value will affect the printing performance of acrylic resin; When the pH value is too high, the ink dries slowly, which is prone to the problems of dirty back and poor water resistance

III. problems in the use of water-based inks. Water based inks can be mixed with water before drying. Once the ink dries, it will no longer dissolve in water and ink. Therefore, the water-based ink must be fully stirred before use to keep the ink composition uniform. When adding ink, if the remaining ink in the ink tank contains impurities, it should be filtered out first, and then used with new ink. When printing, do not let the ink dry on the roller to avoid blocking the ink hole. Hinder the quantitative transmission of ink, resulting in printing instability. During the printing process, the flexo should always be wetted by the ink to avoid blocking the text pattern on the printing plate after the ink dries. In addition, it is found that when the viscosity of water-based ink is slightly large, it is not suitable to add water casually, so as not to affect the stability of the ink. An appropriate amount of stabilizer can be added to adjust it

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