Effect of hydrolyzed ASA on sizing in calcium carbonate filled paper

Sizing literature shows that the presence of hydrolyzed ASA in paper detracts from sizing. The authors show that the calcium salt of ASA is hydrophobic. In a calcium carbonate filled paper, it does not hurt sizing and can even make some contribution. Paper sized with ASA lost sizing with application of additional hydrolyzed ASA in free acid form but more than regained the sizing when converting the hydrolyzed ASA to its calcium salt form. ToF SIMS surface analysis confirmed the changes in hydrolyzed ASA. Application : these results should reduce current concerns about the continued use of ASA in fine paper grades as the trend toward higher levels of fillers continues.