Effects of sheet moisture and calender pressure on PCC and GCC coated papers

摘要

Previous work demonstrated that narrow distribution coating PCC allows high moisture calendering with no loss of optical properties of coated papers.Broad particle size distribution pigments exhibit a significant loss of optical properties,when moisture increases and supercalendering pressure is adjusted to achieve a gloss larget.In this study,we rationalize these results by considering macro- and micro-smoothness and demonstrating that narrow distribution coaling PCC produces high micro-smoothness even in the absence of supercalendering.Calendering is necessary only to supply macro-smoothness through base paper deformation.Therefore,at high moisture,pressure can be reduced so that no additional base paper deformation occurs and optical and physical properties of the final coaled paper are equivalent to those achieved with lower moisture and higher pressure.