Effect of Hydrophile-Lipophile Balance Values of Surfactant Mixtures on the Detergency of Oil-Soiled Single Fibers

Abstract

The detergency of Lyocell and polyester fibers soiled with octadecane or oleic acid is investigated with anionic-nonionic surfactant mixture solutions of various hydrophile-lipophile balance (HLB) values. The HLB values for anionic-nonionic surfactant mixtures, sodium dodecyl benzene sulfate (LAS)-nonyl phenol ethoxylate (NPE), 1-hexadecanesul-fonic acid sodium salt (HOS)-NPE, and sodium dodecylsulfate (SDS)-NPE are calculated at various mixing ratios. Detergency is evaluated by the work of detergency calculated from interfacial tensions of an oily soil/surfactant solution and contact angles of a soiled fiber/surfactant solution, which is in turn compared with the percentage of soil removal determined by the liquid scintillation counting method. This study shows that the general trend of soil removal increases as the work of detergency decreases. In terms of effective oily soil removal, anionic and nonionic surfactants tend to perform best on polar and nonpolar soils, respectively. In addition, it is easier to clean fibers soiled with polar oil than fibers soiled with nonpolar oil. We have confirmed that different surfactant structures with similar HLB values are important in determining the efficiency of detergency. Furthermore, although HLB values of 12 to 15 are known to be suitable for achieving optimal detergency, the SDS-NPE systems well beyond the 12-15 range show better detergency than the HOS-NPE systems in the 10.4-16.5 range of HLB values.