High Performance of Paper Strength and Energy Savings in OCC Pulp Papermaking via MFC Addition

Fiber screen fractionation of recycled old corrugated container(OCC)pulp and subsequent targeted processing of each fraction can lead to higher fiber quality,more uniform pulp,and increased handsheet strength and surface smoothness.This pilot-scale study evaluates the benefits of fiber fractionation using a pressure screen prior to low consistency(LC)refining.A 0.81-mm smooth holed screen cylinder is utilized,and two refiner plate patterns are adopted(wide 0.99 km/rev BEL and interim 2.01 km/rev BEL).Here,LC-refined reject fractions are mixed with the created microfibrillated cellulose(MFC),and the mixed pulp and paper qualities are compared with no-MFC OCC pulps.The results indicate that the highest tensile strength of the handsheet is obtained by the addition of MFC to the fractionated refined OCC pulp compared to the unfractionated refined OCC and primary OCC pulps at a given specific energy.Furthermore,the experimental approach adopted in this study can be used to optimize recycled OCC pulping systems.Overall,the results indicate that fractionated LC refining plus MFC addition provides higher pulp and paper qualities and the potential for saving energy to reach the desired tensile strength of the OCC pulp.