Effect of hydrophile-lipophile balance values of surfactant mixtures on the detergency of oil-soiled single fibers

The detergency of Lyocell and polyester fibers soiled with octadecane or ol eic acid is investigated with anionic-nonionic surfactant mixture solutions of various hydrophile-lipophile balance (HLB) values. The HLB values for a nionic-nonionic surfactant mixtures, sodium dodecyl benzene sulfate (LAS)-n onyl phenol ethoxylate (NPE), 1-hexadecanesulfonic acid sodium salt (HOS)-N PE, and sodium dodecylsulfate (SDS)-NPE are calculated at various mixing ra tios. Detergency is evaluated by the work of detergency calculated from int erfacial tensions of an oily soil/surfactant solution and contact angles of a soiled fiber/surfactant solution, which is in turn compared with the per centage of soil removal determined by the liquid scintillation counting met hod. This study shows that the general trend of soil removal increases as t he work of detergency decreases. In terms of effective oily soil removal, a nionic 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 diff erent surfactant structures with similar HLB values are important in determ ining the efficiency of detergency. Furthermore, although HLB values of 12 to 15 are known to be suitable for achieving optimal detergency, the SDS-NP E systems well beyond the 12-15 range show better detergency than the HOS-N PE systems in the 10.4-16.5 range of HLB values.