RECYCLING POTENTIAL OF PRINTED THERMOMECHANICAL FIBERS FOR NEWSPRINT

In earlier investigations of repeated recycling of TMP, only some of t he individual papermaking processes, such as wet pressing, drying, and calendering, have been discussed. The results in may of these investi gations has been an increased or unchanged tensile strength. In this s tudy, a TMP has been recycled for five complete cycles, including a pr inting step and a deinking step. This implies an addition of ink mater ial into the system. Chemical changes in the TMP fiber are significant . Hydrophilicity of the fiber surface increases, Measured as charge an d oxygen-to-carbon ratio (O/C). The produced sheets show an increased surface roughness and a decreased tear and tensile index. Obviously th e printing step, the ink, or its components obstruct the interfiber bo ndings in the sheet-forming operation.