Whether the mold system of the digital printing equipment can work normally and stably on the machine directly determines the product quality. If the continuity is not good, it will cause insufficient ink supply, resulting in ink cut during the printing process, which affects printing to a large extent the quality of. So what are the factors that affect the fluency of printing ink?

1. Ink particle size

The particle size of printing ink has a great influence on the stability of the ink system. Because the average diameter of the nozzle is only about 50um, it is easy to block the nozzle when the particle size is too large; the average particle size of the ink should be negligible compared with the pipe and nozzle hole, so as to ensure good flow properties. Therefore, when the ink is configured, it must be filtered at 1um and 0.5um (the pore size of the filter membrane is specifically adjusted according to the type of ink) to control the size of the particle size.

2. Moisturizing properties of ink

The moisture retention and stability of water make it difficult for its viscosity and surface tension to change with temperature, which promotes the formation of a thin and brittle film at the nozzle, which is easy to dissolve without clogging when inkjet printing again. The ink is mainly based on water-based systems, and most of the solvents used are water-soluble organic mixtures. Commonly used water-soluble solvents are alcohols, polyols, etc. These organic mixtures can improve the stability of the ink.

3. Ink wettability

The wettability of the ink is related to the surface tension. The surface tension and dynamic surface tension of the ink will affect the wetting of the pipeline and the nozzle, and the final wetting and spreading on the printing medium. If the surface tension is too high, it may cause insufficient wetting and insufficient ink supply; if the surface tension is too low, that is, if the wetting is too strong, it may cause the ink droplets to gather on the print head, causing the ink dot to break. Appropriate surface tension is the key factor. Generally, the surface tension is controlled at about 30-50mN/m.

4. Digital printing equipment and printing environment

The pipeline of the ink supply system is not airtight. During the printing and placement of the ink, some water and low boiling point solvents will evaporate, which will cause changes in the viscosity and surface tension of the ink and other physical and chemical parameters. Printing stability. Therefore, the digital printing equipment needs to be maintained regularly.
The environmental temperature is too high or too low, and the humidity is too high or too low to a certain extent, which will also cause changes in the physical and chemical parameters of the ink, requiring suitable temperature and humidity. In northern China, humidifiers and heating equipment are required in autumn and winter; in southern China, air conditioning and other cooling equipment are required in summer and autumn.

From this point of view, the factor that affects fluency is not a single individual, but a combination of various factors. High-quality ink and the perfection of external systems can fully reflect the fluency of printing ink.