Application of nanosericite to LWC paper.

The purpose of this study was to investigate the effects on coating color and coated paper when nano-scale sericite was substituted for a portion of the latex binder. The coating formulation was based on a lightweight coated (LWC) paper coating. Dosages of nanosericite were 0, 0.1, 0.2, 0.3, 0.5, 0.7, and 1.0 parts per hundred of the total color pigments. Respective latex dosages were 11.2, 11.1, 11.0, 10.9, 10.7, 10.5, and 10.2 parts per hundred of the total color pigments. The coating weight was controlled to 8.5g m^(-2) on one side. There were 10 experimental sets (including 2 sets of replications) in total. The results indicated that in terms of the coating color properties, adding nanosericite tended to reduce the water retention property and increased both the lowand high-shear viscosities; however, the color remained applicable. Substituting a portion of the latex with nanosericite as a co-binder did not affect the RI dry-and wet-peeling strengths of the coated paper, while paper opacity and brightness showed some improvements. Examination of CIE L*a*b* values of the coated paper suggested that the tint of the paper shifted from a greenish-yellow to a reddish-blue tone. The coated paper with modified color tended to have increased smoothness and decreased roughness; however, at both lower and the highest nanosericite dosages, the effects were reversed. The modification did not affect the unprinted gloss, but caused an increase in post-printing gloss levels.