Development of strength of mechanical and deinked pulp with low intensity levels

The use of high yield pulps has been increasing rapidly for several decades, firstly with the growth in the use of mechanical pulps such as TMP and in the last decade with the increased use of recycled fiber. These pulps generally exhibited low strength properties Paper grades such as newsprint, SC and LWC utilizing a high content of these pulps have typically used bleached chemical fibers as a reinforcing pulp to obtain the required strength properties for papermachine runnability, conversion equipment runnability and product end use requirements. A number of developments in machinery design have also contributed to make this possible. However perhaps the most significant development has been the area of low consistency refining with the introduction of refiners capable of achieving the very low intensity levels necessary to effectively treat fragile fibers. The Multi Disk refiner.