DCCA Shrinkproofing of Wool

Abstract

Dichlorodicyanuric acid (DCCA) is one of the oldest chlorination reagents for imparting shrinkage resistance to wool. It is commonly used in the Hercosett® shrink-proof process in which certain reactive and cationic polymeric resins are applied to wool. We further investigate the use of DCCA and the importance of the subsequent antichlorination step to document the ensuing changes in fiber morphology and fabric properties. We use DCCA alone in a range of concentrations from 5 to 40% owf. Treatments with 5% applied at 30°C for 60 minutes from a citric acid buffered system, pH 4, followed by antichlorination with hydrogen peroxide or hydrogen bisulfite show small increases in alkali solubility and in bursting strength. Less than 2% chlorine is detected in 5 and 20% DCCA/antichlorinated spent baths. The 5% DCCA/hydrogen peroxide treatment improves shrinkage resistance by 54% and whiteness by 63% when compared to untreated fabrics. Structural changes in the exocuticle increase with increasing DCCA concentrations to the point of complete scale smoothing. Following the extent of oxidation with a broad range of DCCA concentrations and the effect of antichorination on 5 and 20% DCCA treatments provides useful informa tion for designing alternative systems to control shrinkage.