A QUANTITATIVE STUDY OF FACTORS THAT INFLUENCE THE SUBSTANTIVITY OF FRAGRANCE CHEMICALS ON LAUNDERED AND DRIED FABRICS

Model investigations of physicochemical aspects of the substantivity o f fragrance raw materials on laundered fabrics were performed. The ove rall process was divided into two consecutive steps, laundry and dryou t, which were characterized by affinity and tenacity, respectively. Th e affinities of fifteen fragrance raw materials to cotton and polyacry lonitrile were measured in standard fabric softener and detergent solu tions. Affinities correlated with the corresponding partition coeffici ent, P(o/w). To study the impact of parameters independent of the chem ical structure of the fragrance molecules, 1-[H-3]-3-ethyl-5-phenylpen tanol (phenylhexanol) was selected, and aqueous solutions of defined a nionic, nonionic and cationic surfactants were used as model detergent and fabric softener media. A sequence of experiments, based on the fr actional factorial design, was planned for quantifying the relative co ntribution on substantivity of a number of variables: the concentratio n of the fragrance chemical, the type and concentration of the surfact ants, the type and weight of the fabrics (cotton or polyacrylonitrile) and the washing temperature in the case of cotton. The affinity that characterizes the washing process depends mainly on the type of fabric and the type of surfactant and, to a lesser extent, on the surfactant concentration and the temperature. Anionic and nonionic surfactants, the main components of detergent powders, behave similarly, whereas th e combination of cationic surfactant with cotton markedly enhances the affinity. For phenylhexanol, the tenacity after dryout is largely con trolled by the type of fabric. The role of fiber swelling is discussed . The substantivity, which represents the global effect of laundering and dryout, shows the same trend as the affinity. The complexity of th e physicochemical phenomena involved is highlighted by the importance of the interactions between the main contributing factors.