The novel method to distinguish poor-recyclable prints from recovered papers by using ATR-IR

摘要

In recent years, the quality of recovered paper has been deteriorated due to an increase of materials to be avoided, such as prints with ultra violet (UV) curable ink (here after called UV prints). The aim of this paper is to develop a method which can easily and promptly distinguish those poor-recyclable prints from recovered paper, and to put the method into practical use in deinked pulp (DIP) mills. In order to achieve this purpose, first, the recyclability of several kinds of prints was evaluated. Second, the spectrum data of those prints were obtained by using the attenuated total reflection infrared spectroscopy (ATR-IR) method, and a database was made by correlating the spectrum data and their recyclability. Finally, the ATR-IR method had been applied to entrance quality control in those mills for half a year. From the results of lab-experiments, the numbers of dirt speckles in DIPs from UV, UV varnish over coated, and polystyrene over coated prints, respectively, were much higher than those of conventional prints (oil-based ink). It was also revealed that high sensitive UV prints, which were getting popular in a field of commercial printing, brought fewer dirt counts than the conventional UV prints. In case of using the ATR-IR method, those prints were distinguished more promptly and precisely compared with a solvent detection method used in DIP mill. As for the incoming inspection of recovered paper in the mill by using a portable ATR-IR device with the database, prints with poor recyclability, such as UV prints, were sorted out more efficiently, which reduced the incidence rate of dirt troubles in DIP production. Therefore, it was considered that the method using ATR-IR was effective in sorting out poor-recyclable prints from recovered paper, and improving the quality of DIP and the runnability of DIP production.