Effect of particle size of talc filler on structural and optical properties of paper

Five different talc fillers with various particle size distributions (PSD) and platy shapes were evaluated in papermaking along with two calcium carbonate fillers, viz.: ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC). The GCC was the finest filler with a rhombohedral shape, while the PCC was coarser than GCC with a scalenohedral shape. The cationic and anionic polyacrylamide retention aids were used with talc and calcium carbonate fillers, respectively, to retain them within paper matrix. The laboratory handsheets were prepared from all fillers with the target ash in paper ranging from 14 to 24%. The effect of talc particle size and increasing ash on the optical and the structural properties of paper has been studied and has been compared with the reference calcium carbonate fillers. The optical properties of paper were improved, whereas ash retention was reduced with the finer talc filler. The retention of talc filler was the highest followed by PCC and GCC. The bulk, light scattering, opacity, porosity and roughness of paper with talc filler were the lowest, while those with PCC were the highest among all fillers.