In China, since flexographic printing has only emerged in recent years, when controlling ink and wash, printing workers either use inertial thinking or do not know where to start. The result is often a waste of manpower, material and financial resources, and heavy losses. . Therefore, it is particularly important to understand the technical control indicators of ink and wash correctly. This article will discuss the main technical indicators of viscosity, pH, thickness, and dryness of flexo ink.

Viscosity is a property that prevents the flow of fluids. It is a measure of the ability of fluids to interfere with the relative movement of molecules, that is, the resistance to fluid flow.

Viscosity is the most important control index in ink application, because it directly affects the transfer and transfer performance of ink and the quality of flexographic printing. In addition to the viscosity of the resin in the binder and its density, it is also related to the type and particle size of the pigment. In printing, low-viscosity ink transfers quickly, which will cause light color, large dot expansion, high-gloss dot deformation, and uneven ink transfer. High viscosity and slow ink transfer will affect the transfer performance of the anilox roller and produce ink color. Uneven, sometimes the color is not deep, and the disadvantages of dirty and pasted plates.

Low viscosity can be adjusted by mixing with new ink; while high viscosity, it can be diluted with water or water and ethanol (50% each), or it can be adjusted with ink stabilizer. In addition, during the printing process, the temperature also has a greater impact on the viscosity of the ink. Generally, the viscosity decreases when the temperature increases, and vice versa. Therefore, in the printing process, in order to keep the density of the printed products consistent, the temperature in the printing shop should be kept constant.