An Evaluation of Ultra-Fine Ground Calcium Carbonates and a Precipitated Calcium Carbonate for Properties in Coated Paper

This thesis is a study of four ultra-fine ground calcium carbonates and one precipitated calcium carbonate. These five carbonates were evaluated at five levels of carbonate in a coating formulation based on the weight of pigment. The evaluation of the performance of the five carbonates is concluded from brightness, opacity, Brookfield viscosity, K & N Index, gloss, and gloss development. As the level of carbonate increased, so did the brightness of the coated sheet for all of the carbonates. All carbonates at all five levels of addition show the same relevant opacity. Differences in viscosity for the carbonates are essentially due to different particle size, shape, and distribution. Three of the carbonates showed a relative linear increase in the K & N Index value. One of the carbonates was an outstanding exception when comparing gloss, but showed increased gloss with increased levels of carbonate addition. Further studies into the areas of viscosity, ink absorption, and gloss for coated papers containing calcium carbonate are indicative for understanding the effects of these calcium carbonates