Synthesis and application of calcium sulphate pigment for paper coating: Potential and prospects

In the present study, calcium sulphate pigment has been synthesized experimentally from commercial grade calcium chloride. The effect of various factors on the particle size of calcium sulphate formed in a wet process and its potential application as pigment in coating recipe has been investigated. The operating factors investigated include concentration of calcium chloride solution, temperature, addition of different rheology modifiers and their optimization. The particle shape and size distribution of synthesized calcium sulphate pigment have been studied through image analyzer, scanning electron microscope (SEM) and particle size analyzer. Significant improvement was observed in various coated paper properties like brightness, whiteness, gloss, stiffness, surface strength and water retention properties of coating color with respect to conventional ground calcium carbonate (GCC) coating pigment.