EFFECT OF CLAY:GCC RATIO IN COATING ON SURFACE, OPTICAL AND PRINTING PROPERTIES

Abstract

We have coated sheets of 121-g/m2 base paper in the laboratory, using different proportions of ultrafine ground calcium carbonate and no.1 Brazilian clay pigments along with additives and binders in coating formulation. The sheets were calendered on a laboratory Supercalender. The coated sheets have been evaluated for optical, surface and printing properties. The addition of GCC to the clay pigment reduces viscosity of the coating mixture as well as increases the brightness, whiteness, and surface strength of the coated sheet. On the other hand coating formulation having higher proportion of clay give reduced oil penetration and increased gloss of unprinted and printed sheets. The details of experimental procedure and the results obtained have been discussed in the dissertation.