Interaction between PCC Filler and Cellulosic Fiber in Fiber/Filler Co-refining System

keywords:cellulosic fiber  mineral filler  filler composite  paper strength  optical properties

Abstract:Mineral fillers are important for conserving raw fiber materials and reducing production costs in the paper industry. However, the increase in filler content will inevitably result in strength reduction, which limits the adding amount of filler in paper production. In this study, we designed a cellulose fiber/filler co-refining approach to improve the strength and optical properties of paper; moreover, the synergistic interaction between fibers and precipitated calcium carbonate (PCC) fillers in the co-refining process was investigated. Results of fiber separation and PCC particle size analysis showed that, compared with conventional refining, the content of fines increased, whereas the PCC particle size decreased. More importantly, composites were formed between the PCC and fines, which promoted strength improvement of paper. Physical tests show that the tensile index of paper with 15% PCC content increased by 22% compared with that of the paper filled by conventional method, whereas the brightness and opacity of paper improved by fiber/filler co-refining for a specified filler content. These findings provide a basis for the further development of co-refining filling technology.