Screens of offset prints and ink content in recycling process

Abstract

The influence of the screen of the offset colour prints on the recycling effectiveness has been investigated in this work. The printing form contained four parts. Two parts were realized by the amplitude modulated screening with the screen ruling L 60 lines cm–1 screen and 80 lines cm–1 screen, while the other two were realized by frequency modulated screening (diameter of the individual dot 20 :m and 40 :m). Gloss and mat fine art paper and paper made from the recycled raw materials were used for the preparation of samples. On the basis of the obtained results it can be concluded that the dirt spot number and the area are greater when the print made with AM screening was used for recycling in relation to the print made with FM screenings. Number of the particles formed in the disintegration process of prints has been explained from the aspect of the printing surface coverage. It was proved that in that combination the coating of the printing substrate is an essential factor for the effectiveness of the deinking flotation. The number and the area of the dirt spots as a function of their classes are depleted according to the exponential function used as a fit in one model.