Preparation of Flexible Calcium Carbonate by In Situ Carbonation of the Chitin Fibrils and Its Use for Producing High Loaded Paper

Abstract

Flexible calcium carbonate (FCC) was developed as a functional papermaking filler for high loaded paper, which was a fiber-like shaped calcium carbonate produced from the in situ carbonation process on the cellulose micro-or nanofibril surface. Chitin is the second most abundant renewable material after cellulose. In this study, a chitin microfibril was utilized as the fibril core for making the FCC. Cellulose fibrils for the preparation of FCC were obtained by fibrillation of the TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) treated wood fibers. The chitin fibril was obtained from the β-chitin from the born of squid fibrillated in water by grinding. Both fibrils were mixed with calcium oxide and underwent a carbonation process by the addition of carbon dioxide, thus the calcium carbonate attached on the fibrils to make FCC. When used in papermaking, both the FCC from chitin and cellulose gave a much higher bulk and tensile strength simultaneously than the conventional papermaking filler of ground calcium carbonate, while maintaining the other essential properties of paper. The FCC from chitin caused an even higher bulk and higher tensile strength than those of the FCC from cellulose in paper materials. Furthermore, the simple preparation method of the chitin FCC in comparison with the cellulose FCC may enable a reduction in the use of wood fibers, process energy, and the production cost of paper materials.