Utilization of Cellulose Micro/Nanofibrils as Paper Additive for the Manufacturing of Security Paper

Effects of cellulose micro/nanofibrils were investigated relative to the strength and drainability of security paper made from cotton lint mixed pulp. Six types of cellulose micro/nanofibrils were made from bleached softwood kraft pulp (SwBKP) and bleached hardwood kraft pulp (HwBKP) using refining and micro-grinding processes, respectively. After their main properties were measured, handsheets were produced by adding micro/nanofibrils into a cotton pulp furnish, and the physical properties of the sheets were measured. The cotton pulp furnish drainage rate was also analyzed with respect to the dosage and the fibrillation degree of the cellulose micro/ nanofibrils. The cellulose micro/nanofibrils made from SwBKP resulted in higher viscosity, lower particle size, and higher zeta-potential than those made from HwBKP. The nanofibrils made from SwBKP were the most effective for enhancing the tensile strength, folding endurance, and sheet density of the security papers made from cotton lint mixed pulp. However, the cellulose micro/nanofibrils made from SwBKP could be limited as a paper additive in papermaking due to its high drainage resistance. Because the cellulose micro/nanofibrils made from HwBKP also reduced the drainage rate, the dosage and the fibrillation degree should be controlled by simultaneously considering the paper strength and drainage.