Abstract
In a previous study, sodium N-methyltaurine was shown to apparently function as fatty acid counter-ion and free lauric acid may become more separated from solution of fatty acid soap whose counter-ion is sodium N-methyltaurine at high temperature or lower concentration. Surface tension of sodium N-methyltaurate laurate solution and interfacial tension with silicone oil were low compared with those of sodium laurate solution. C.m.c. of sodium N-methyltaurate laurate exceeded that of sodium laurate. The properties of sodium N-methyltaurate laurate thus differ from those of sodium laurate. Sodium N-methyltaurate laurate as detergent was compared with other laurate soaps. Compared with sodium laurate and potassium laurate, both foam and detergency performance of sodium N-methyltaurate laurate solution are high because its surface tension and interfacial tension with oil are low. Its detergency was similar to that of triethanolammonium laurate. Less calcium laurate was noted to form with calcium ions in hard water and adsorb to skin when washing with sodium N-methyltaurate laurate solution compared to other lauric acid soap solutions. This suggests that sodium N-methyltaurate laurate should less likely lead to skin stiffness in that less calcium laurate adsorbs to skin.
