Fingerprints of bleach systems

Abstract

Bleach catalysts represent cost-effective, environmentally friendly bleach systems allowing a perfect stain removal at low temperature. However, the detergent industry still hesitates to use this technology in a broader range of consumer products as it always bears an unpredictable risk of product failure. Bleach components act in the laundry process by way of chemical reactions. Whereas their main task should be the oxidation of colored food stains, side reactions with dyed fabrics and cotton fibers cannot be excluded. In this comparative study bleach performance, dye fading and fiber damage of eight different bleach systems are examined. The selection covers activators, transition metal complexes designed for peroxide and aerial bleaching, as well as oxygen transfer agents. Multi-cycle washing tests are performed under real life conditions following recently developed dye and fiber damage test protocols. The results indicate that each bleach system has its characteristic performance and damage profile. Whereas the reactivity can be controlled by the usage concentration, the selectivity seems to be an intrinsic property. Bleach catalysts are not necessarily more aggressive than common bleach systems but their performance and damage profiles might be different. A better understanding of the reaction mechanisms is needed to minimize product failures.