Retention Systems for Highly Filled Paper, 1999 Papermakers Conference Proceedings

Dan S. Honig, Robert J. Turnbull & Clay Wheeler Cytec Industries Inc. A high speed pilot machine trial producing paper with 28 - 40% PCC content utilized a micropolymer system and an inorganic microparticle system (cationic polyacrylamide & swelling bentonite) as the retention systems. The micropolymer system was more robust and could more easily attain very high filler levels. Paper properties were primarily determined by filler content; at comparable retention and drainage, both systems had similar effects on formation and other paper properties. Laboratory evaluations including conventional as well as colloidal silica based retention systems showed that all could produce reasonable retention at very high filler loading. Mill examples of retention aid use in highly filled paper show runnability, speed, retention, and sheet quality benefits with the micropolymer system. Modified styrene acrylic surface sizes can address some of the concerns with very highly filled paper. Significant improvements in printability including reductions in linting, dusting, and milking have been demonstrated commercially. In some cases, significant increases in internal bond have also been achieved.