Effect of Applying Cellulose Nanofibers on the Properties of Multiply Paper Made from Recycled Fibers

The use of cellulose nanofibers as strength-enhancing additive in the wet end section of paper machine increases the general strengths of paper. Nevertheless, considerable increase in draining time from pulp suspension and decrease in paper porosity and opacity has been reported as substantial restriction of its application in this section of papermaking. In this study, the effect of applying cellulose nanofibers in the forming section of paper on the properties of three-ply paper made from recycled fibers has been examined. Samples of recycled fibers has been prepared from Atrak pulp and paper industries. To do, the refined and not dispersed pulp were respectively used to form top layer and other two layer. Standard sheets with 40±2 g/m2 basis weight were prepared from each of recycled pulps. Then, cellulose nanofibers spray in 1, 2, 4 and 6 levels (based on oven dry fibers) on one sheet surface and subsequently mild suction was done applying cellulose nanofibers spraying machine which designed and fabricated in Zirab research campus. Finally, three-ply paper with 120±5 g/m2 basis weight were prepared using treated sheets and its properties were evaluated. The overall results revealed that spraying cellulose nanofibers on the forming sheet has led to increase in tensile and burst indices of the paper about 33.59 and 26.29 percent respectively. This process particularly had a considerable effect on the strength improvement between layers in multi-ply paper which is most important in these kind of papers. Thereby, the value of this strength has been significantly increased from roughly 116 J/m2 to 217 J/m2. SEM micrographs prepared from paper thickness confirm larger link between layers and multi-ply condensation.