Introduction of Computer Print-Outs in the Recycling Process of Printed Folding Box-Board

摘要

Packaging paper grades are nowadays rarely considered as furnish for chemical deinking flotation processes. However, there are trends towards lower basis weights and the need to lower the chemical contaminants of food packaging papers, while maintaining the specified quality of fibers and the finished paper. In this study the offset printed folding box-board samples were subjected to the double-stage laboratory deinking flotation process. The flotation had positive effect on recycled handsheets properties. Results of the study show improvements in brightness value of the recycled papers up to 2%, reduction of inorganic matter (ash content) from 13.2 % to 7.4 % and improvements in mechanical properties of 17%. As a case study, the mixture of office laser print-outs and offset printed folding box-board samples were subjected to double-stage laboratory deinking flotation process as well. The office laser print-outs were introduced to the offset printed box-board furnish in order to improve the mechanical and optical characteristics of recycled handsheets. The role of primary paper grades, with its longer and more flexible fibers, was to help the weaker brown grade fibers to knit the stronger paper. Primary paper fibers have contributed to improved mechanical sheet characteristics up to 40% on average and have improved handsheet optical properties as well (lightness increased up tq 9%).