Methods for controlling the ink quantity of printed paper used for deinking experiments

Printing inks should have good deinkability to meet requirements of the recycling process. Thus, deinkability should be evaluated when the new kinds of printing inks were developed and applied in printing process. To assess the deinkability of a given ink or contrast deinking properties of different kinds of inks, ink quantity on the paper should be measured and controlled because of its great influence on deinking results. Optical solid density of presswork, which incorporated an image analysis technique, was believed to be a suitable method to measure and control ink.quantity on printed paper. In this study, optical solid density method was used to measure the thickness of ink layers and image analysis technique was used to measure the ink overlay proportion on the paper. Special software was designed to analyze images of printed papers. Printing and deinking experiments were done to verify this method. The results indicated that this method could control ink quantity on printed matters accurately and conveniently. A new way to control the ink quantity of printing papers used in deinking experiments was developed, which could be used for contrasting the deinkability of different kinds of inks.