Crystallization of precipitated calcium carbonate with anionic polyacrylamide and its application to papermaking

摘要

Precipitated calcium carbonate (PCC) is widely utilized as a papermaking filler. Herein, the morphology of PCC is controlled by addition of anionic PAM during the carbonation process. The particles of PCC crystallized with anionic PAM were larger than those of scalenohedral PCC. Notably, PCC synthesized with high-molecular-weight and low-charge anionic PAM exhibited good stability against shear stress. Furthermore, the particle size of PCC crystallized with high-molecular-weight anionic PAM increased to 10-20 mu m owing to the salt effect, which resulted in a contraction of the coils due to electrostatic screening and counterion condensation effects. PCC had positive effects on the paper properties and papermaking process. The retention of PCC crystallized with anionic PAM was superior to that achieved with scalenohedral PCC. Addition of PCC enhanced the paper bulk and paper formation index. The mechanical properties of paper, such as the tensile strength and bending stiffness, were enhanced with the use of PCC crystallized with anionic PAM given that the larger PCC particles resulted in the use of fewer particles with consequently less disturbance of the fiber-fiber interactions in paper. In addition, the opacity and light scattering properties of paper were enhanced by the addition of PCC crystallized with anionic PAM because the probability of light scattering increases with increasing paper bulk.