The Enhancement of Fluorescence During Pad-Batch Whitening of Cotton Cloth 1

Abstract

The factors effecting the build-up of fluorescent whiteness of cotton cloth in a pad-batch process have been investigated. Holding of the cloth, impregnated with fluorescent whitening agent (FWA), in a wet state before drying enhances the whitening effect. Raising the temperature at which the wet cloth is held, and the presence of surfactants, both increase the rate of whiteness build-up. The presence of surfactants also has a marked enhancing effect on the optimum whiteness achicved. It is suggested that the enhancement of Huorescent intensity, which is accompanied by penetration of the FWA into the fiber, is caused by decrease in mobility of the planar FWA molecules when fixed onto the polymeric substrate. This retards internal fluorescent quenching processes. A similar mechanism may operate with fiber substrates other than cotton.