The reason why the reactive chemical structure of alkenyl succinic anhydride is necessary for efficient paper sizing

Abstract

ASA-sized handsheets were prepared, and extractability of the size components from the handsheets was studied by either Soxhlet extraction in sheet form with chloroform or 1% Tween 80 extraction in fibrous form. Although a part of size components could not be removed by the Soxhlet extraction, most size components were removed by the 1% Tween 80 extraction at 70°C for 4 h. This result indicates that most size components are present in ASA-sized paper without forming ester bonds with hydroxyl groups of cellulose. Scanning electron microscopic observation showed that, when an old ASA emulsion was used in handsheet-making, large flocs of size emulsion particles were formed owing to hydrophobic interactions between the particles, thus resulting that no sizing features appeared on the handsheets. Thus, the reactive chemical structure of ASA molecules in each ASA emulsion particle is necessary for avoiding flocculation of the size emulsion particles in papermaking process.