Establishing a Rapid Pad-Steam Process for Bleaching of Cotton Fabric with an Activated Peroxide System

Bleaching of cotton fabric with hydrogen peroxide (H2O2) is conventionally carried out under high temperature and strong alkaline conditions, for which the pad-steam process can be employed to present the benefits in lowering water and chemical consumptions. A notable drawback observed with the pad-steam process for bleaching of cotton fabric with H2O2 is that, although the cotton fabric is bleached to an acceptable whiteness, it is required to dwell in steam for almost an hour, causing tremendous energy consumption as well as extensive damage to the cotton fibers. It has been found that an activated peroxide system can be formed with the addition of N-[4-(triethyl­ammonio­methyl)­benzoyl]­caprolactam chloride (TBCC) to H2O2 solution to generate 4-(triethyl­ammonio­methyl)­perbenzoic acid (TPA), allowing the establishment of a rapid pad-steam process. Sodium citrate was selected as the desired alkali for use in the rapid pad-steam process to neutralize 4-(triethyl­ammonio­methyl)­benzoic acid (TBA) released from the TBCC-activated peroxide system. By shortening the steaming time to 4 min or less, the rapid pad-steam process afforded enormous advantages over the conventional pad-steam process in saving energy and increasing production efficiency, and also, the bleached cotton fabric underwent no apparent chemical damage and met the requirements for post-dyeing.