Stability of fatty acid-containing AKD emulsions and sizing performance on handsheets

Abstract

This paper investigated the behavior of alkyl ketene dimer (AKD) emulsions based on fatty acid addition in AKD waxes. Further, sizing performance was evaluated based on fatty acid addition in AKD waxes and the AKD emulsions dosage that was applied in the handsheet making process. Three kinds of commercial AKD emulsions, A1, A2, and A3, with different fatty acid addition present in AKD waxes (12.5, 15, and 20%, respectively) were kept in a water bath at 40, 50, and 60 °C for 15- and 30-days storage periods. After 15 and 30 days, AKD emulsions had been hydrolyzed, and the stability was evaluated in terms of particle size and viscosity. Hydrolyzed AKD was analyzed using FT-IR and 1H-NMR after a 30-days storage. According to these results, increasing fatty acid increased the viscosity and particle size, but viscosity decreased with the length of storage period. Sizing performance was also improved by increasing fatty acid addition present in AKD waxes and by using hydrolyzed AKD. Through FT-IR and 1H-NMR, bands at 1848 and 1720 cm−1 and a peak near 2.3 ppm, where ketones and carboxylic acid are typically found, clearly appeared.