Application of Defoamers in Lithographic Inks
Lithographic ink is a general term for various inks suitable for lithographic printing. The various parts of the lithographic printing plate are basically on the same plane, the pattern is oleophilic, and the non-pattern is hydrophilic. Printing is carried out based on the principle of oil-water repulsion, so lithographic ink must have water resistance. When lithographic ink is used or produced, foam often occurs, which affects the quality of lithographic ink. Lithographic ink defoamer is compounded by special process containing special modified polyether, which is very easy to dissolve in water. It is particularly suitable for defoaming of oil phase foaming system, with good product stability; good compatibility with organic hydrocarbon substances, adding oil system does not affect product transparency; has certain leveling performance. It can be widely used in various harsh systems for foam elimination and suppression in a wide temperature range.
Before using lithographic ink defoamer, it is recommended to take a small sample to simulate the actual use conditions, conduct defoaming test, and then determine the amount of defoamer to be added. The general amount of defoamer is 0.05-0.3% of the total amount of laminating glue.
The following are factors that influence lithographic ink foaming:
Ink suppliers can change ink formulations to make inks less prone to foaming.
If bubbles form in the ink or air is trapped in the ink, the system that controls the ink can exacerbate foaming.
Operators take incorrect actions that cause foaming to become more severe.
When the ink foams, each factor has its own responsibility to create a stable condition that minimizes the risk of severe foaming.
Foaming occurs because of air contained in the ink. When foaming occurs, the density of the ink drops significantly. If measured with a viscosity cup, the viscosity increases. When the operator adds water to reduce the viscosity, the foaming increases. If the viscosity of the ink is measured when the ink foams, it will lead to incorrect corrective actions.
