Substitution of TiO₂ with PCC (Precipitated Calcium Carbonate) in waterborne paints

Paints provide protection against any possible corrosion by forming a thin film layer on the material surface. Paint is a colloidal system consisting of four main parts: binders, pigments or minerals, solvents or water, and additives. Minerals or so-called pigments with a proportion of 20 to 50% by weight play a fundamental role on paint properties. The variation of these constituents gives rise to a fluctuation in paint type and its quality. In a general architectural paint, titanium dioxide (TiO₂) is used as a main white pigment with high refractive index but is quite expensive compared to the rest. Other minerals such as calcite and calcined kaolin are also used as filler or substitute for TiO₂. Various researches on these minerals have been carried out in order to reduce TiO₂ consumption without affecting the paint quality. In present paper, the behavior of precipitated calcium carbonate (PCC) which differs from ground calcium carbonate (GCC) in terms of morphology and purity has been examined as a substitution for TiO₂ in paint mixture. The rheological properties of PCC along with the quality of paints produced by PCC was evaluated by standards based on both wet and dry paints such as viscosity, density, opacity and brightness. It was observed that PCC partly substituted for TiO₂ can improve the stability, scrub resistance, brightness and coverage of produced paints.