The quality of graphic and textual black film in packaging printing is determined by the use of leveling agents and rheological agents, which determine the quality of printed products. The black film of printing ink often affects the quality of the product due to issues such as orange peel, floating color, hair bubbles, shrinkage, pinholes, fluidity, water marks, and white frost. Ink additives such as leveling agents, rheological agents (also known as thickeners and anti flow agents), defoamers, wetting agents, dispersants, etc. are needed to control the performance of the product. Enhance the value of the product.
Rheological additive, also known as anti sagging additive, refers to ink sagging during printing on a vertical plane. In the area where sagging occurs, the ink film thickness becomes uneven and accumulates. We know that the forms of streamers vary greatly, some with large areas resembling curtains, while others have water patterns, water columns, ripples, vortices, and so on. The occurrence of so-called ink flow failure requires the use of rheological agents to thicken and prevent flow, which is often directly related to the rheological properties such as low solid content, low 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 to prevent sagging. However, it is not easy to flatten, and sagging and flattening are often contradictory. The anti sagging agent in the printing ink can form a network structure through secondary bonds, making the printing ink obtain structural viscosity and become a thixotropic fluid. It is an effective additive to adjust this contradiction.
The leveling agent on the ink film is the process in which the printing ink gradually shrinks to the minimum area due to surface tension after printing, even after the film is coated and has not yet dried into a solid dry film. Leveling agents often experience surface tension differences due to certain factors, which prevent the ink film from achieving a smooth and even surface state, resulting in uneven flow. This phenomenon is called ink leveling defect or unevenness fault. Furthermore, after the ink film dries, irregular surface conditions such as orange peel, scratches, ripples (water marks), shrinkage edges, pinholes, etc. appear on the surface. The effect of leveling agent on ink film leveling requires time, which 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 leveling agent is an additive added to the ink to form a flat and smooth ink film after packaging printing.
