Details:
Summary:
In general, the inks printed on rough-surfaced papers by offset printing methods are physically dried spontaneously. These inks are oil-based, and a certain absorbency of the papers is required for the inks to dry. On the other hand, the liquid-absorbing capacity of the papers is determined by the rate and nature of paper ingredients (e.g, cellulose, paper additives, and filling materials). No lustering process (e.g., coating or calendering) was performed on the surface of these papers. Therefore, these kinds of papers have a porous media with micro-capillary tubes in their structures.
In the present study, white and dark book paper and newspaper were chosen as best examples of rough-surfaced papers. These papers were prepared in a conditioning room in a relative humidity of 65% at 23degC. Then, the following tests were performed on the papers: Cobb 60 liquid absorbing, ash, surface roughness, air permeance, thickness, and grammage. Background prints produced using IGT printing test equipment, which gives a force value of 300 dyn/cm2, were taken on the surfaces of the papers with oil-based black ink. Density measurements and their evaluations were performed at certain intervals until complete drying was obtained. Photographs of the paper-ink interface were taken, and the depth of absorbance of the ink was determined. Finally, suggestions were reported for the optimum printability of the ink on rough-surfaced papers.