The quality of packaging printing ink film determines the quality of printed products, so the surface state of the ink film is one of the main performance indicators of the ink. The ink film of printing ink often results in poor packaging quality due to issues such as orange peel, floating color, hair bubbles, shrinkage, pinholes, sagging, water marks, and white frost. To prevent surface failure of the ink film, it is necessary to use leveling agents, anti floating agents, defoamers, anti sagging agents, and white frost control agents for control.
Ink flow hanging, also known as flow hanging, refers to the phenomenon of ink sagging when printing on a vertical surface. In the area where flow hanging occurs, the thickness of the ink film becomes uneven, resulting in accumulation. We know that streamers come in various forms, some with large areas resembling curtains, while others are in the form of water ripples, water columns, ripples, vortices, and so on.
The occurrence of ink flow failure is often directly related to the rheological properties such as solid content, viscosity, printing ink film thickness, and ink yield value in the printing ink system. Packaging printing ink has low viscosity and thick ink film, which helps with leveling and is also prone to sagging; The ink system has a high solid content and viscosity, and the printed ink film is thin, which helps prevent sagging, but it is not easy to flatten. Flow hanging and leveling are often contradictory, and the preventive agent for preventing flow hanging is an effective additive that can form a network structure through secondary valence bonds in printing ink, allowing the printing ink to obtain structural viscosity and become a thixotropic fluid, thus adjusting this contradiction.
The leveling of ink film is the process in which printing ink gradually shrinks to the minimum area due to surface tension after printing, even after laminating, before it has dried into a solid ink film. Ink is affected by certain factors. When there is a difference in surface tension, the ink film cannot achieve a smooth and flat surface state, resulting in uneven flow. This phenomenon is called ink leveling defect or unevenness fault. After the ink film dries, irregular surface conditions such as orange peel, scratches, ripples (water marks), shrinkage, pinholes, etc. may appear on the surface. The time required for ink film leveling increases with the increase of ink viscosity, scratches, and wavelength, and decreases with the increase of surface tension and ink film thickness. To prevent the above-mentioned malfunctions of printing ink film, it is necessary to add leveling agents to solve them. This additive is a type of additive added to ink to form a smooth and even ink film after printing. The additive only seeks the result and does not consider the leveling process.
The factors that affect the flow and leveling of ink film, such as ink viscosity, ink film thickness, width and depth of imprints, and interfacial tension between ink and substrate, directly affect the flow and leveling of graphic ink film.
