Abstract
The use of filler in printing and writing papers has become a prerequisite for competing in a global market. Calcium carbonate is the filler most widely used in the paper industry, at levels that average 18% and may reach 30%. Increasing the filler content in paper in order to reduce the cost of materials is an ongoing effort by papermakers. The proper selection of calcium carbonate additive during the production process for each type of paper is the key to achieving this goal. Quality requirements of each type of paper vary widely according to its use; understanding the effect that different types of calcium carbonate have on paper properties allows producers to choose the best filler in each case. Given that the market for uncoated digital printing paper is one that continues to introduce exciting growth projections; this study is focused on selecting the optimal calcium carbonate for the production of uncoated digital printing paper, using eucalyptus pulp. In this study, handsheets were produced with a wide variety of types of calcium carbonate available in the market. The effect on the main structural, optical and strength properties was analyzed in detail. This study found that the optimal calcium carbonate for uncoated digital printing paper production based on eucalyptus pulp is Scalenohedral PCC, with a particle size of 1.9 um, due to its very positive effect on the thickness, stiffness, brightness, and opacity.