로진 변성 페놀 수지의 분자량에 따른 평판 잉크의 유변학적 특성

Abstract

The rheological properties of printing ink must be maintained adequately at various shear rates or shear stress. So it is necessary to understand its rheological properties in order to regulate the printability of printing ink on the performance. In this paper, the physical properties of lithographic ink are investigated according to the molecular weights of rosin-modified phenolic resin. Various vehicles and inks are prepared with different molecular weights of rosin-modified phenolic resin, and are tested to obtain the following results. 1. As the molecular weight of the resin increases, viscosity, zero shear viscosity, zero thinning index, relaxation time and delay time are raised and its gel points are shifted to low frequency region with elevated frequency. 2. At high molecular weight, shear thinning occurs, compliance value lowers and stress relaxation increases. In addition, thixotropy index, yield value, tack, Laray viscosity, shortness factor and activation energy are increased, while the Newtonian value drops. 3. With increased emulsion ratio ink viscosity decreases, free ink shortness factor rises and fixation lowers. 4. At high molecular weight the maximum transition and ink fixation decrease, but free ink shortness factor elevates. 5. The transition ratio and ink fixation diminish and free ink shortness factor rises when molecular weight increases.