Roles of short amine in preparation and sizing performance of partly hydrolyzed ASA emulsion stabilized by Laponite particles

Alkenyl succinic anhydride (ASA) is an internal sizing agent used to hydrophobize paper and paperboard in paper making process. Partly hydrolyzed ASA (hereinafter referred to as PH-ASA) emulsions can be stabilized by Laponite and short amines such as ethylamine, n-propylamine and n-butylamine. It is found that the short amines may improve the affinity of Laponite particles to PH-ASA, favoring PH-ASA emulsification, forming emulsion of high stability and small droplets. It is further observed that the sizing development of the PH-ASA on bleached chemi-mechanical pulp (BCTMP) is promoted when aluminum sulfate is added. Amine with longer carbon chain is more efficient both in promoting PH-ASA emulsification and in its sizing process. The amine molecules adsorbed on Laponite are more effective in stabilizing PH-ASA emulsions while the free amine in the dispersion work more efficiently in promoting sizing performance through a mechanism of accelerating the reaction between hydrolyzed ASA and aluminum sulfate. However, the PH-ASA emulsions lose most of their sizing effect by hydrolysis within 60 min.