Viscosity of water-based inks The water-based inks referred to in flexographic printing are low-viscosity, and their viscosity is measured by a standard measuring cup. Water-based ink is a combination of four different chemical raw materials. They are: pigments, which give the ink a certain hue, so that we can see the color; resin, after drying, wrap the molecules of the color material to form a smooth layer. Membrane; Additives, it is to improve the physical and chemical properties of ink additives, not much, but the role can not be underestimated; solvent, it is to reduce the viscosity of water-based ink, so that the ink can be easily transferred to the substrate, and then volatile drying. The typical composition of printing ink is: solvent 70%, pigment 10%, additive 5%, resin 15%. The viscosity of water-based inks is very important. Whether it is transferred from one batch of printing to another, or from one printing press to another, or in other situations, different ink viscosities may be required. It depends on several aspects, different printing presses, doctor blades, anilox rollers and mesh thickness. The viscosity of the water-based ink is easily measured in the cup, but the measuring cup must pay attention to the temperature change and the cleaning and protection of the measuring cup during use.
Water-based ink colorants In today's printing, the main function of the ink is to express the color and tone of the print, so the most important part of the ink is the color material. Pigments are divided into dyes and pigments. Dyes are general color agents. Dyes are found in foods and ball point inks. Although the printing effect of dye ink is not good and it is easy to fade, there are still some paper printing and cardboard printing still being used due to low price. Dryness of water-based inks In terms of drying, evaporation of water is a very important factor, especially in non-absorbent materials, where energy can be used to evaporate the solvent. Drying of water-based inks absorbs both substrates and non-absorbing substrates. It is clear that non-absorbing substrates such as plastic films do not absorb water. Even absorbing the substrate can only absorb a considerable amount of water. However, if the water and the resin are not completely absorbed and separated when they are dry, that is, the water capacity of the substrate is saturated, it will not be dry. At this time, if there is any grinding, it will be colored. Transfer.
The pH value of water-based ink in aqueous ink, PH value is a very important factor, lack of control or incorrect PH value will cause many problems. The pH value is a method for measuring the acidity and the basicity of the solvent. The pH value ranges from 0 to 14, and the pH value affects the viscosity of the aqueous ink. In the typical water-based ink from the graph shows that the general PH value range should be between 8-9. Several simple steps to control the ink: before use, fully stir, detect the ink viscosity when printing on the machine, adjust the viscosity and reconfirm the viscosity and PH value.
Source: 21st Century Fine Chemicals Network
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