Effect of precipitated calcium carbonate additions on waterborne paints at different pigment volume concentrations

Titanium dioxide (TiO₂) due to its high refractive index, is widely used in paint industry as a white pigment. In order to reduce this high cost of TiO₂, a part of TiO₂ is generally substituted by some other industrial mineral fillers such as calcite and calcined kaolin; however, this substitution affects the quality of paints in terms of stability, coverage (opacity), brightness (gloss), scrub resistance (film toughness), etc. In the present paper, precipitated calcium carbonate (PCC) was substituted for TiO₂ in paint mixture at three different pigment volume concentrations (PVC). It was observed that substitution of TiO₂ by PCC depends on PVC value at which there is an optimum PCC amount. The quality of paints produced by PCC along with its rheological properties was evaluated based on standard features in both wet and dry paints such as viscosity, density, opacity and gloss values. Addition of PCC increases the opacity to a certain point. Similarly, scrub resistance and viscosity increases with the addition of PCC at all PVCs, however, viscosity is not as much critical for the paint production. On the other hand, there is no any systematic effect of PCC on gloss value of the paint. This study overall demonstrates that PCC can be successfully used to substitute TiO₂ only with a careful adjustment of PVC and other extenders used in the paint formulation.