Hard surface detergency

Abstract

In a study of hard surface detergency using glyceryl trioleate, oleic acid, and octanoic acid soils with three types of anionic and three types of nonionic syndets, only potassium laurate showed maximum detergency at the CMC (critical micelle concentration), with the potassium laurateoctanoic acid system being an exception. In general glyceryl trioleate and oleic soil removal (180°F.) at the CMC was low, not over 40%; octanoic acid detergency at the CMC was substantially higher, 65 to 83%. Considerable differences in removal of the various soils by the same surfactants were found. A generalization was observed in the detergency of glyceryl trioleate soil—soil removal increased sharply on passing the CMC with increasing concentration until approximately 90% detergency was reached, at which point soil removal began to level off and approach 100% with a much smaller slope. Visual observations of the cleaning processes suggested a partial answer for the differences in soil removal. Removal or glyceryl trioleate soil by both anionic and nonionic syndets appeared to be due chiefly to a displacement action caused by preferential wetting of the basis metal. Removal of octanoic acid by the nonionic surfactants in a diffusing cloud of small particles seemed to be due to solubilization followed by emulsification and precipitation of the acid soil. Several relationships were discovered in two series of analogs (polyethenoxyethers of nonyl phenol and tridecyl alcohol). It was found that the ratio of the HLB (hydrophile-lipophile balance) values of two analogs was approximately equal to the fifth root of the ratio of their CMC values. The correlation held for analogs varying by as much as 15 moles ethylene oxide. A linear relationship was also found between HLB value and the reciprocal of the ethylene oxide mole ratio for the polyethenoxyethers of nonyl phenol.