Influence of water quality softening of fountain solution on printing process

The quality of the fountain solution is important for the wetting system. Excessive water quality can affect the normal operation of the wetting system, and has an impact on the printing process and print quality. The company installed a Crown reverse osmosis RO membrane water purifier in July 2003, reducing the hardness of the wetting system water from 18 degrees to 2 degrees, and the change in water quality hardness has the following impact on the actual printing process: .

1. The ratio of various ingredients in the tank changes and the nature of the water changes

Improve the ratio of various ingredients in the tank and the nature of the water. After using soft water, the hardness and chemical impurities decreased, and the electrical conductivity dropped sharply. In addition, the use of fountain solution suitable for soft water (which is cheaper than hard water) and reduced alcohol concentration reduce the consumption of raw materials while improving the quality of the wetting system.

2. Help solve the crystallization problem on the roller surface

The hardness of water mainly depends on the content of calcium and magnesium ions in water. When the hardness of the water is too high, that is, when there are many free calcium ions and magnesium ions in the water, they will react chemically with the pigments (especially the magenta ink) so that the pigments are separated and adhered to the ink string roller and the rubber roller. The vitreous crystallized surface is formed so as to influence the transferability of the ink to the roller. This problem rarely occurs in soft water due to the relatively low content of calcium and magnesium ions. Since the company installed a water purifier, there have been no printing failures such as insufficient ink transmission or ink transmission due to crystallization of the rollers, which often occur before installation.

3 is conducive to the balance of ink control

Soft water mainly affects the balance of water and ink from three aspects: (1) The reduction in hardness improves spreadability of the fountain solution on the PS plate, thereby reducing the amount of fountain solution. (2) After the soft water is used, the crystallization phenomenon of the rollers rarely occurs, and the ink is very smooth during the transfer process. (3) The content of calcium ion and magnesium ion in soft water is small, and it basically does not affect the printability of the ink. Therefore, it is easier to achieve the ideal ink-water balance with soft water.

4. Improve the printing quality

Before using soft water, the company basically uses Tianjin Tianshi brand ink. When using other brands of ink, the magenta ink is very easy to paste at a fine level formed by some outlets, which affects the printing quality and efficiency. After the soft water is used, the phenomenon of stencil disappears, and the soft water wetting system can satisfactorily satisfy the printing conditions of the ink.

In China, especially in the north, the hardness of water is generally high, generally above 14 degrees, and the hardness of water for printing is below 8 degrees. Therefore, from the perspective of process improvement, water quality softening is very necessary for many printing companies. .

Source: Coinprint