Non-Newtonian ink transfer in gravure–offset printing

清泥

a b s t r a c t
The inks used in gravure–offset printing are non-Newtonian fluids with higher viscosities and lower surface
tensions than Newtonian fluids. This paper examines the transfer of a non-Newtonian ink between a
flat plate and a groove when the plate is moved upward with a constant velocity while the groove is held
fixed. Numerical simulations were carried out with the Carreau model to explore the behavior of this
non-Newtonian ink in gravure–offset printing. The volume of fluid (VOF) method was implemented to
capture the interface during the ink transfer process. The effects of varying the contact angle of the ink
on the flat plate and groove walls and geometrical parameters such as the groove angle and the groove
depth on the breakup time of the liquid filament that forms between the plate and the groove and the ink
transfer ratio were determined. Our results indicate that increasing the groove contact angle and decreasing
the flat plate contact angle enhance the ink transfer ratio and the breakup time. However, increasing
the groove depth and the groove angle decreases the transfer ratio and the breakup time. By optimizing
these parameters, it is possible to achieve an ink transfer from the groove to the flat plate of approximately
92%. Moreover, the initial width and the vertical velocity of the neck of the ink filament have significant
influences on the ink transfer ratio and the breakup time.

2010 Elsevier Inc.