Paper sizing by liquid-type ketene dimers. Part 1. Comparison with alkylketene dimer and oleic anhydride

Liquid-type ketene dimers were synthesized from oleic acid chloride and iso stearic acid chloride, and their sizing efficiencies were compared with tha t of alkylketene dimer (AKD) or oleic anhydride. Cationic emulsions of thes e size compounds (AKD, alkenyl-KD, branched-AKD and oleic anhydride) were p repared, and used as internal sizes in sheet-making. Pyrolysis-gas chromato graphy was applicable to the alkenyl-KD-sized laboratory sheets for determi ning their size contents, but inapplicable to branched-AKD-sized sheets. In the case of heated sheets, sizing degrees of alkenyl-KD- and branched-AKD- sized laboratory sheets were a little lower than those of AKD-sized sheets at the same addition levels. Oleic anhydride had clearly lower sizing effic iency than AKD. However, retention ratios of alkenyl-KD on laboratory sheet s were a little lower than those of the AKD size. Thus, when sizing levels were compared at the same size contents in the laboratory sheets, alkenyl-K D (and probably branched-AKD) had sizing efficiencies similar to AKD.