Property Development Mechanism of Hybrid Calcium Carbonate

Hybrid calcium carbonate (HCC) was developed to simultaneously increase the bulk, stiffness, and strength of printing paper. It was prepared by the preflocculation of a mixture of ground calcium carbonate (GCC) and calcium oxide using ionic polymers in the first step. After which, carbon dioxide was injected to make semirigid agglomerates of the GCC and the precipitated calcium carbonate (PCC) that was newly formed from the calcium oxide. The final product became much larger than the original GCC and was called HCC. The HCC simultaneously improved the bulk, stiffness, and tensile strength of the paper sheets. The smoothness of a sheet containing HCC was observed to be much better than that of the large-sized GCC. It was believed that the HCC was slightly deformed by the pressure exerted during the papermaking process, which resulted in the smooth surface despite its large size. Due to its high stiffness and tensile strength without losing its smoothness, HCC has great potential for developing high-loaded printing paper that may lead to saving forest and reducing production costs.