Abstract
Alkenyl succinic anhydride (ASA) is one of the reactive sizes used as cationic emulsions at wet-end of papermaking process. In order to make clear the mechanism of ASA sizing, structures of ASA components retained in handsheets were studied using model compounds and analytical techniques. The results of model experiments using low-molecular-weight cellulose and cationic starch showed that ASA was predominantly hydrolyzed to alkenyl succinic acid (ASAcid) in the presence of water without forming ester linkages with hydroxyl groups of carbohydrates. Sheet-form and fibrous-form extractions with organic solvents under various conditions indicated that most of ASA components were present as the structure of ASAcid in ASA-sized handsheets. The results of curing treatments of ASA-sized handsheets and impregnation treatments of ASA-related compounds into filter papers also were negative to the formation of ester linkages between ASA and cellulose-OH. Cellulase-treatments of ASA-sized handsheets followed by IR analysis of the obtained residues showed that ASA components were mostly present as the structure of ASAcid in papersheet. ASAcid aluminum salts may be present to some extent in papersheet prepared by ASA-alum systems. All these results imply that appearance of sizing features for ASA-sized papersheet is brought about by ASAcid molecules in papersheet. However, since non-reactive ASAcid has no sizing effect when added to pulp suspension, the reactive structure of ASA must be necessary for paper sizing because of some mechanisms other than the formation of ester linkages with hydroxyl groups of pulp fibers.
