STUDY OF THE DEHYDRATION AND REHYDRATION CAPACITY OF MICROFIBRILLATED CELLULOSE (MFC)

GONZÁLEZ, G.; FELISSIA, F.E.; COLMENAREZ LOZADA, O.; AREA, M.C.; EHMAN, N.; VALLEJOS, M.E.

Lisboa

Congreso; XXIV TECNICELPA 2021 | XI CIADICYP 2021; 2021

TECNICELPA

The fibrillation process to produce microfibrillated cellulose (MFC) involves large quantities of water, and the final product has low consistency (1-2%), which leads to problems associated to transport costs. This study analyzes the effect of reducing MFC water content using coagulation/flocculation commercial reagents and evaluates the eventual changes in MFC performance as a dry strength additive of paper and paperboard. MFC was obtained from unbleached softwood kraft pulp using a disk refiner at 1% consistency during 60 min. Combinations of commercial retention reagents conventionally used in the paper industry were mass-applied using different aggregation mechanisms (coagulation/flocculation). Then, the samples were filtered using a filter cloth. Transmittance, turbidity, and consistency after centrifugation were measured to compare the behavior of the suspension before and after the thickening. Optical, scanning, and transmission electron microscopy were also applied. MFC was added at 3wt.% to an old corrugated container OCC pulp to produce handsheets. Physical-mechanical properties such as permeability, tensile index (TI), elongation, tensile energy absorption (TEA), burst index (BI), and tear index were measured. Besides, the typical mechanical test of paperboard as ring crush test (RCT), short-span compressive test (SCT), cóncora corrugating medium test (CMT), and Taber stiffness, were performed. The obtained transmittance (at 800 nm) and turbidity of MFC were 33.3% and 427 NTU, respectively. A dual flocculation system combining patch and bridge models produced the highest water removal (from 0.89% to 4.82% consistency, reaching up to 15.88% when filtered in fabric). Higher doses of reagents did not result in consistency increases. The application of both initial and thickened MFC improves paper and paperboard properties. Nevertheless, results are better in the first case (except permeability and stiffness), demonstrating the value of water-MFC links on its performance as paper and paperboard reinforcement.