The dryness of the ink is an important technical indicator. In addition to the drying speed of the ink, it is also related to the printing speed, the drying capacity of the drying equipment and the performance of the printing material. This article only considers the factors of the ink itself.

The principle of selecting the ink drying property is generally: the ink should be able to fully dry before the next printing and rewinding or stacking under the existing conditions of the printing machine, but it cannot be dried on the printing plate.

Ink and wash use water as the solvent, and alkali-soluble acid resin as the binder, which is mostly used for printing of corrugated boxes and paper bags. Therefore, the drying form is mainly penetrating drying and a small amount of volatile drying. Because water is used as a solvent, its volatilization speed is not as fast as other solvents, so the drying of ink is slower than that of solvent-based inks. Therefore, a small amount of alcohol is usually added to the solvent to increase the drying speed of ink. In addition, under the conditions determined by the solvent, the selection of different types of resins will also affect the drying properties of the ink. Because different resins have different curing speeds on substrates, and their release characteristics to solvents are different, the drying properties of inks are also different.

In practical applications, the dryness of the ink is also related to its viscosity and pH. The ink is dry but may have too high viscosity, which can be solved by further dilution; the ink dries quickly, and the pH value may be lower than 8.5, which can be adjusted by adding a stabilizer. In addition, a fast-drying agent or a slow-drying agent can be added to the ink according to the actual printing speed, and the drying speed of the ink can be appropriately changed to obtain a stable printing effect. The amount of fast-drying agent or slow-drying agent is generally 1% to 2% of the total ink volume.

There are many quality indicators that need to be controlled in ink application. In addition to the main indicators mentioned in this article, they also include: color, gloss, adhesion, stability. In actual printing, in order to comprehensively improve the printing quality, various factors should be comprehensively considered. index.