Printability Of Inks Research Articles

Atmospheric pressure DBD gun and its application in ink printability

In this paper, a plasma source discharging at atmospheric pressure and its characterization diagnosed by a Langmuir probe and a digital camera are presented. As an application the dielectric barrier discharge (DBD) gun modifying an ultraviolet cured resin surface for ink printability is reported. The results from the digital camera indicate the uniformity and homogeneity of the plasma generated from the gun in the downstream but depending on the input power, diameter of electrodes, gas flow rates and the distance between the substrates and the nozzle. The contact angle measurement proves the efficiency of gun during the surface modification. The ink printability following DBD gun processing described here was significantly improved. The performed surface analysis using Fourier transform infrared indicates that the polarity of surface grafted in plasma is responsible for the film printability.

Characterization of Surface-Treated Polyethylene for Water-Based Ink Printability

With increasingly stringent EPA guidelines for controlling emissions of volatile organic compounds on the horizon, the desirability to move to water-based printing inks is evident This paper examines the effects of corona discharge treat ments which are commonly used to improve ink adhesion to polvethylene. Electron spectroscopy for chemical analysis (ESCA) was used to determine the surface chemi cal changes induced by corona treatments in pure polyethylene extruded films and in formulated resin systems This data was correlated with surface tension and ink adhesion measurements to show the effects of treatment and additives on the final printability of the films with particular emphasis on water-based inks. In addition, the effects of stonng treated film prior to printing and of retreating these films were also examined The results of these tests have shown that formulated linear low den sity polyethylene (LLDPE) films treat and print at least as easily as high-pressure low-density polyethylene (HP-LDPE) counterparts.

Rheological Properties of Printing Inks

This paper describes the rheology of printing inks. Several kinds of pigments-linseed oil suspensions and commercial inks were used as the samples.For many years flow requirements of printing inks for various types of printing processes have been determined by skilled workers through experience rather than through experiments. However, it is very important for advances in printing or coating engineering that technical skills obtained emperically are confirmed theoretically or by scientific methods. The ink on a printing machine undergo various types of shear strain and complex deformations and flow processes. The optimum printing conditions and printability of inks are closely associated with their rheological properties. Therefore, we investigated the non-linear viscoelastic phenomena of printing ink under complicated rheological processes such as stress relaxation under large deformation, stress growth and relaxation following initiation and cessation of steady flow, non-linear creep and creep recovery.The equilibrium modulus in the long time region was observed in the stress relaxation curve. This phenomenon may be attributed to the formation of temporary network structure due to the association of suspended particles. Shear stress development after sudden initiation of steady shear flow showed an overshoot and approached an equilibrium value. The transient phenomena seem to be caused by the break down of the structure of dispersed particles. Disperse systems of pigments such as printing inks show remarkable thixotropy, rheopexy, pseudo-plastic flow, and structural viscosity attributed to a denser network structure of suspended pigments. In order to provide new concepts for these phenomena, creep compliance and creep recovery were measured under the conditions of various flow histories. The elastic properties of the network structure of suspended particles can be evaluated also from the creep experiments. The yield stress can also be determined from the relationship between recoverable strain and shear stress under steady flow. The formation of the temporary network structure of suspended particles were also investigated by an acoustical technique.