Migration and Diffusion of Finishing Agents in Drying

Abstract

Large increases in crease-recovery angles may be obtained if the drying of methylol- melamine-impregnated cotton and rayon fabrics is interrupted at 34% and 40% regain, respectively, and the drying is completed slowly or after a delay of some hours. Resistance to abrasion is not correspondingly reduced, but the tensile strength of cotton was somewhat lower. This effect was not observed when migration during the first (constant-rate) drying period was substantially reduced, but the highest recovery angles were obtained when maximum migration to the fabric surfaces occurred. The probable explanation is that time is required for diffusion into the fibers by the methylol- melamine concentrated in the fabric surfaces. Estimates of surface resin, and of the rates of diffusion support this hypothesis.