Ink is too thick to cause defects such as heaping ink and stencil, and the coloring power and hue of the ink will also be deteriorated. If the ink is too thin, the liquidity will be large and will flow after printing. This flow will cause the dot to expand, affecting Print quality. In addition, the thickness of the ink also affects its dispersibility. When the dispersibility of the ink is not satisfactory, its printing performance is not satisfactory, and the print surface is not smooth, smooth, and soft, and it may produce a "block"-like feeling, thereby greatly reducing the printing effect.
In the actual printing, inks with different thicknesses can be selected according to specific requirements. In the case of prints with relatively fine mesh and high precision, the fineness of the ink must be relatively high. When the print is not very precise or the actual print, the thickness of the ink may be appropriately reduced. This is also for the sake of Reduce costs and increase economic efficiency.
4. Dryness
Dryness of ink is a very important technical indicator. In addition to the performance of the ink itself, the drying speed of the ink is related to the printing speed, the drying capacity of the drying equipment, and the performance of the substrate. This article only considers the ink's own factors.
The principle for selecting the ink drying property is usually: the ink should be able to be fully dried before the next printing and before rewinding or stacking under the existing conditions of the printing machine, but cannot be dried on the printing plate.
Ink uses water as the solvent, and uses alkali-soluble acidic resin as the linking material. It is mostly used for the printing of corrugated cartons and paper bags. Therefore, the drying mode is mainly osmotic drying and a small amount of volatile drying. Since water is used as a solvent, its volatilization rate is slower than other solvents, so the ink drying is slower than the solvent ink. Therefore, a small amount of alcohol is usually added to the solvent to increase the drying speed of the ink. In addition, the selection of different types of resins under solvent-specific conditions also has an effect on the drying properties of the ink. Because different resins have different curing speeds on the substrate and different solvent release characteristics, the ink drying performance is also different.
In practical applications, the drying property of ink is also related to its viscosity and PH value. The ink is dry but may be too viscous, and can be solved by further dilution; the ink dries quickly, may be PH value below 8.5, and stabilizers may be added for adjustment. In addition, a quick-drying agent or a slow-drying agent may be added to the ink according to the actual printing speed, and the drying speed of the ink may be appropriately changed to obtain a stable printing effect. The amount of quick-drying agent or slow-drying agent is generally 1% to 2% of the total amount of ink.
5. Conclusion
There are still many quality indicators that need to be controlled in the application of ink and ink. In addition to the main indicators mentioned in this article, they also include: color, gloss, adhesion, and stability. In actual printing, in order to comprehensively improve printing quality, comprehensive consideration should be given to index.