Numerical simulation of the water-based ink transfer process in roll-to-roll gravure printing based on fluid–solid interactions

The roll-to-roll gravure printing ink transfer process plays an important role in enhancing printing quality and saving on costs. The static analysis and fluid–solid interaction method are used for the first time to conduct a systematic study on the coupling between the fluid flow state and the solid deformation in the whole process of roll-to-roll gravure printing. The static compression stage, the initial moment of ink transfer, and the process of ink passing through the gap between two rollers and the separation of the ink layer with the rotation of two rollers are considered. The effect of ink layer thickness on the ink transfer process is studied. At a printing pressure of 0.2 MPa and a printing velocity of 200 rpm, the ink thickness has a great influence on the ink flow state, which leads to backflow; the phenomenon causes irregularities in the effective ink transfer ratio. The critical ink layer thickness is 70 µm under the above gravure printing conditions. This should not be exceeded to ensure the stability of ink transfer. Under the above printing conditions, when the ink layer thickness is in the range of 30–50 µm, there is no ink backflow phenomenon and the width of the ink flow channel is relatively large, and the effective ink ratio is almost stable at 50%. This study is helpful for controlling the ink quantity in the gravure printing, providing strong theoretical support for the improvement of the gravure printing process, and promoting the application of the water-based ink.