Effect of Corona Discharge on the Surface of Wool and Its Application to Printing

Abstract

Corona discharge has been widely used to modify polymer surfaces because it can be operated at an atmospheric pressure in air. In this study, wool fiber and fabric were corona discharged, and afterwards wettability, laundry shrinkage, and frictional coef ficients were determined. An ESCA analysis was done to elucidate the changes of chemical composition on the fiber surface. The corona discharge incorporates oxygen atoms into the fiber and increases wettability and laundry shrink resistance of wool fabrics, but the effects are smaller than those from low temperature O₂ plasma. After the pretreatment with corona discharge, the fabric was printed with color pastes of two acid dyes, and then treated with superheated or high pressure steam. The corona discharge pretreatment, in particular the single pretreatment, improved color depth considerably, which increased in the following order: untreated ≃O₂ plasma treatment < three-fold corona discharge < single corona discharge. From these results it is likely that a small change in hydrophilic properties on the fiber surface plays an important role in improving the color depth of wool fabric in printing.