Haruhiko Okuyama

Studies on Removal of Fatty Soil from Cotton Fabrics

Effects of concentration of sodium dodecyl sulfate and the washing temperature on the removal of palmitic acid as a model of fatty soil from cotton fabrics were studied. In addition, the effect of the addition of lower n-fatty alcohols (C2•`C6) to the surfactant on the removal of the fatty soil was also studied. At the washing temperature below the melting point of palmitic acid, the removal of palmitic acid is only small in the vicinity of critical micelle concentration of sodium dodecyl sulfate but is very remarkable in the 10 times higher concentration than c.m.c. At the washing temperature higher than the melting point of palmitic acid, the removal was easy at the vicinity of the c.m.c. of sodium dodecyl sulfate. The removal amount of palmitic acid from cotton fabrics at the higher concentration than the c.m.c. was less than the saturated solubilized amount of the soil at the same concentration. Therefore, the complete removal by the mechanism of solubilization only would be impossible. The addition of fatty alcohols to sodium dodecyl sulfate solution was effective to increase the removal of palmitic acid. The longer the alkyl chain of the alcohol was the more effective in lesser amount of the addition.

Sorption of Fluorescent Brightening Agents (FBAs) Formulated in Domestic Detergents by Washing Clothes and Their Desorption into Artificial Sweat, Urine and Saliva Solutions

Nonfluorescenced fabrics (cotton, rayon, wool and nylon) used for baby wears were washed in heavy duty or light duty detergents, respectively formulated by Fluorescent Brightening Agents (triazinyl stilbene, distyryl biphenyl or coumarin derivative). The amount of sorption of FBAs on the washed fabrics were determined by absorption of extracted solutions and the relative fluorescence intensity of the fabrics, and its desorption from the soaked fabrics in artificial sweat, urine and saliva solutions were also determined by absorption of the humour solutions. Effects of washing temperature (20°, 40°, 60°C) on FBA sorption varied with the combinations of the fabric material and FBA. At higher washing temperature, the desorption rate of FBAs from the fabrics into the sweat, urine and saliva solutions decreased. As the amount of desorption of FBAs from the fabrics were much more in distilled water than in the artificial humours, sufficient rinsing would be the most effective means for the baby wearer to protect against the FBAs.