Analysis on the ink transfer mechanism in R2R application

Ink transfer process from the printing roll to the web was investigated using a Computational Fluid Dynamics (CFD) technique for the roll-to-roll (R2R) printing application. A parametric study was conducted to identify the effects of fluid parameters such as viscosity, surface tension and contact angle. To make the present analysis more relevant to the real printing system, a three-dimensional computational configuration for the commercial software was set up using the information obtained from the typical R2R system. Simplified one-dimensional semi-analytic model based on Reynolds equation was compared with the CFD results to assess the validity of the results. Pressure distribution states that 1-D analysis is reasonably good in capturing the flow physics. The 3-D simulation with VOF (Volume of Fluid) shows that viscosity is the most important parameter. Moreover, the larger surface tension resulted in smaller amount of ink transfer.