In the last few years, interest and demand of high bright paper have forced paper manufacturers to think new ways to improve brightness and whiteness of coated paper. Pigment coating is widely used to enhance the optical properties such as brightness, whiteness, and gloss of paper and paperboard. These optical properties are the most important for end user and also determine the final cost of coated paper. Calcium sulfate has inherent better optical properties compared to other conventional pigments for example ground calcium carbonate, precipitated calcium carbonate and kaolin clay. The present study was carried out with an aim to synthesize calcium sulfate using waste procured from phosphoric acid industry and to study its impact on the rheology of coating color as well as optical properties of coated paper. Addition of calcium sulfate improved the water retention property of coating color which can be helpful for improving the machine runnability. The results also revealed that calcium sulfate can be used as a pigment to produce coated paper of high brightness and whiteness. The brightness and whiteness of the coated paper were improved 4 and 15 points, respectively by using 50 parts of calcium sulfate as a pigment replacing clay from the coating formulation. The surface strength in terms of IGT pick value of coated sheets was found signiifcantly comparable using calcium sulfate as pigment. The print gloss results were observed analogous with matt grade coated paper.%在过去的几年间，人们对于高亮度纸的关注和需求已经驱使造纸厂家探寻新的方法来提高涂布纸的亮度和白度。用以提高纸和纸板光学性能（如亮度、白度和光泽度）的颜料涂布得到广泛应用。这些光学性质对于最终使用者非常重要，同时也决定了涂布纸的最终成本。相比于其它的常规颜料，如重质碳酸钙、沉淀碳酸钙和高岭土，硫酸钙具有固有的更好的光学性能。本研究的目的是利用从磷酸厂购得的废弃物合成硫酸钙，并研究它对涂料的流变性以及对涂布纸光学性能的影响。加入硫酸钙可以提高涂层的保水性，这对于改善运行性能是很有帮助的。结果还表明，将硫酸钙用作颜料，可以生产出高亮度和高白度的涂布纸。在涂料配方里，用50份的硫酸钙代替高岭土，涂布纸的亮度和白度可以分别提高4%和15%。研究表明，使用硫酸钙作为颜料，涂布纸板I GT印刷粘着性能的表面强度很高，印刷光泽度与无光泽涂布纸相似。
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