미세 그라비아 옵셋 인쇄공정 내 잉크 전이에 관한 수치해석

Abstract

A numerical study of the ink transfer processes that occur during micro-gravure- offset printing is carried out. Specifically, liquid transfer between two parallel separating plates and between a trapezoidal cavity and an upward moving plate are simulated, as models of the printing of ink from the offset pad onto the substrate and the picking up of ink from the gravure plate by the offset pad, respectively. During the liquid transfer between two parallel plates, the stretching, breaking and recoil of the liquid are illustrated, and the generation of a satellite droplet is observed. The influences of the separation velocity, liquid viscosity, surface tension, gravity force, and contact angles on the liquid transfer are estimated. For the transfer of liquid from the cavity to the upward moving plate, the findings indicate that the process can be divided into three stages: 1) a whole stretching stage; 2) a central stretching, breakup and recoil stage; and 3) an equilibrium stage.