Mechanical Strength and Optical Properties of LWC Wood-Containing Paper

This study investigated optical and strength properties of light-weight coated (LWC) printing paper. Two different pigments, namely nanoclay and precipitated calcium carbonate (PCC) with rhombohedral particle shape, were used with acrylic styrene latex to coat base paper using a blade method. Strength properties such as: tensile, burst, and tear indices, stiffness and optical properties including brightness, yellowness, and opacity were measured. Surface topography was studied using atomic force microscopy (AFM). Comparison between the coated paper and the control sample demonstrated that surface of the paper coated with nanoclay was more uniform than the paper coated with PCC. Although there were no significant differences in terms of the strength of these paper samples, burst and tear strength were enhanced by up to 10 and 16% in some or all treatments, respectively. There was a slight increase in paper opacity with PCC because it has a narrower particle size distribution in comparison with that of nanoclay. Yellowness of the papers treated with nanoclay was degraded about 20% as compared to the control sample, while some small differences were also noticed in brightness and opacity of the papers.