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purpose and performance requirements of wetting liquid Use purpose and performance requirements of wetting liquid in carton printing plant
- May 16, 2018 -

In the lithographic printing process of the carton printing plant, the gift box is not only to give ink to the printing plate, but also to give water to the printing plate. The water mentioned here is the wetting liquid. The performance of the wetting fluid has a great influence on the quality control of the lithography, especially the control of the ink balance. Therefore, correct selection of wetting fluid, adjustment of wetting fluid properties, and adaptation to the needs of lithographic processes are prerequisites for the transfer of lithographic printing inks.

      First, the purpose and performance requirements of the wetting liquid of carton printing factory

      The purpose of using wetting fluid in lithographic printing is mainly the following three aspects:

      First, a uniform water film is formed on the blank portion of the printing plate to resist the infiltration of the ink in the graphic portion to the blank portion, thereby preventing the dirty plate.

      Second, the friction between the blanket cylinder, the water roller, the ink roller and the printing plate, and the friction between the paper powder and the paper fluff on the paper and the friction of the printing plate will cause the printing plate to wear. With the increase in the number of printing, The hydrophilic layer on the layout was destroyed. This requires the use of an electrolyte in the wetting fluid to chemically react with the plated aluminum metal or zinc metal exposed by wear to form a new hydrophilic layer and maintain the hydrophilicity of the blank portion of the printing plate.

      Third, controlling the temperature of the layout ink, the viscosity of the ink in general, is very sensitive to changes in temperature. Experiments have shown that if the temperature rises from 25°C to 35°C, the viscosity of the ink will drop by 25 Pa.s from 50 Pa.s, which will inevitably cause serious spreading of the ink. The high-speed operation and friction of the printing press will cause the surface temperature of the printing plate to rise. Someone once used a printing press at 25°C and did not supply printing plate wetting fluid. The lithographic printing machine was continuously operated for 30 minutes, and the temperature of the ink roller was measured. It is 40 °C. Therefore, each printing should provide less than 25°C wetting fluid to the plate to prevent the surface temperature of the plate from rising.

      In order to achieve the purpose of using the wetting liquid, the wetting fluid should have the following properties, good wetting, can fully wet the blank part of the wet plate; do not make the ink seriously emulsified; does not reduce the transfer performance of the ink; with cleaning layout The ability of blank parts to be oily and not fat-sensitive; does not allow the ink to spread on the surface of the wetting fluid; does not corrode the metal components of printing plates and printing presses; and always maintains a stable pH during the printing process.

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