Liquid Transfer between Two Separating Plates

In recent years, gravure offset printing has received great attention for its high throughput rate and fine quality for printed electronics. However, as the dimensions of printed features decrease, the ink left over in the patterned gravures usually dries quickly and leads to defects, such as undesired dots or broken lines. These defects not only deteriorate the printing quality but also shorten the life time of gravures. One way to solve this problem is to increase the transfer ratio, which is the volumetric ratio of the liquid transferred from the gravure to target media.
To study the fundamental physics of liquid transfer phenomena in the printing process, a liquid bridge is used in this study for its simple geometry. The stretching process of a liquid bridge between two separating large plates is recorded by a CCD camera. Image analyses are performed to obtain the transient interfacial profiles of liquid bridges. From the experiment results, we observe that the contact angle first decrease to a minimum value even below the receding angle, and then increase until the liquid bridge breaks up. The minimum contact angle has an exponential relationship with the top plate’s velocity. Furthermore, the boundaries on both sides stop receding when the contact angle increases to the receding angle. Also, when the top plate’s velocity increases, the boundaries stop at larger values. This phenomenon makes the transfer ratio vary differently in different substrates combination.