Printing is an ancient and extremely vital industry, and an indispensable part of social economy and life. From the perspective of the latest printing technology classification, offset printing, gravure printing, flexographic printing and screen printing are still the most There are four main printing processes, and the importance and market share of gravure printing have been increasing year by year. According to incomplete statistics, the output value of gravure printing accounts for about 24% of the total output value of printing, second only to offset printing. Now, in order to meet the increasingly stringent environmental protection requirements, water-based environmental protection is an inevitable trend. Therefore, the promotion of water-based gravure inks with low VOCs emission is inevitable. In order to better grasp the construction process conditions of water-based inks, especially the special performance requirements of water-based inks can be printed with a silver-white dazzling metal than the beautiful oil-based gravure process. Effect. To this end, we need to start by selecting high-quality water-based resins and water-based aluminum pastes for gravure, and then formulate a water-based varnish by designing and optimizing the formula. Finally, add the special water-based aluminum paste for gravure and other water-based pigments, mix and stir, then add a certain amount of water-based diluent, and adjust the appropriate viscosity to prepare the water-based ink. Among the more important technical features are:

1. In the preparation process of water-based ink, the most difficult thing is to select a suitable water-based aluminum paste, because the high-speed printing process of water-based gravure has very strict requirements on the performance of metallic pigments, and it needs to have excellent metallic feeling and excellent brightness at the same time. , Mainly fine powder above 1000 mesh, uniform particle size distribution, no sieve residue (350 mesh), high hiding power, good transferability is very important, smooth and regular discharge, easy to level and disperse, compatible with resin It has good performance, and must also meet the corrosion resistance and weak alkali resistance water-based system, which can be stored stably for a long time.

2. Water-based inks do not add harmful chemical solvents to achieve clean printing. At the same time, the use of water and ethanol as diluents greatly reduces production costs compared to lipid chemical solvents. Among them, water is used as a slow-drying agent and ethanol is used as a quick-drying agent. The drying and curing speed is adjusted by adjusting the ratio of water to alcohol to adapt to the temperature of different seasons and production environments.

3. Water-based ink has a certain degree of insolubility. The printing plate and the ink circulation system need to be cleaned in time when the machine is shut down to avoid blockage or pollution of the new plate. The washing liquid can be mixed with alcohol and water. If ethanol is not used, pure water can be used. Add a small amount of non-ionic surfactant, the cleaning effect is very good.

4. Appropriate shallow printing. On the one hand, the water-based system causes the ink to have the rheological characteristics of a Newtonian fluid, and the ink transfer volume is 15% larger than that of the solvent-based ink. On the other hand, the water-based ink has a high solid content and the same area. The dry ink thickness can be smaller. Therefore, the ink holes of the same surface area can be engraved lighter, the general plate depth is 45~50um, compared with the solvent-based ink with a plate depth of 60um, the ink consumption can be reduced by up to 25%, saving costs.

5. Use defoamer, water-based ink is weakly alkaline, the printing process is easier to produce bubbles than solvent-based inks, white spots, blisters and other quality problems on the printed matter, so you can add about 0.1% of the defoamer.

6. Drying temperature control is very important. Water-based inks are mainly volatile and dried with a certain degree of reaction drying. The resolubility of the dried ink film is worse than that of solvent-based inks. Therefore, the hot air temperature control is very important. If it is too low, the surface of the ink will dry, but the interior will not be dry, and anti-stickiness will appear during color register; if it is too high, the ink will dry quickly, and the dry ink layer will no longer be dissolved in water, making it difficult to clean.

7. Water-based inks with different binder formulations cannot be mixed, let alone mixed with other solvent-based inks, otherwise it will cause serious quality problems.

8. PH value should be controlled and stable. As alcohols and amines are volatile, the PH value of ink is prone to change. Pay attention to frequent detection and addition of corresponding additives during the printing process.

9. The difference between water-based ink and solvent-based ink is that the solvent used in water-based ink is not an organic solvent but water. The volatilization loss in the ink fountain is small, and there is no solvent erosion problem on the printing plate. The biggest feature of this type of water-based ink is that it significantly reduces the emission of organic volatiles, prevents air pollution, improves the printing environment, and benefits the health of employees. It completely eliminates the harm of certain toxic and harmful substances in solvent-based inks to the human body and the pollution of packaged goods. It is especially suitable for packaging and printing products with strict sanitary conditions such as food, beverages, medicines, etc., but the pH value of such inks is stable and dry The performance needs to be improved, especially for the colorful printing on non-absorbent printing materials, there are still technical problems, which require special attention.