USING ULTRAVIOLET-RADIATION TO REDUCE PILLING OF KNITTED WOOL AND COTTON

The Siroflash anti-pilling treatment for knitted fabrics is a process involving exposure of the fabric or garment surface to short wavelengt h ultraviolet radiation (UVC), followed by a mild wet oxidation treatm ent using, for example, hydrogen peroxide or salts of permonosulphuric acid. UVC exposure is confined to the surface fibers and presensitize s them to the wet oxidation process, which selectively weakens them re lative to the bulk fibers responsible for fabric strength. Because the surface fibers are much weaker after treatment, no anchor fibers are available to secure pills to the fabric surface. The treatment is a hi ghly effective, chlorine-free method of preventing pilling in wool kni twear, which has now been demonstrated in wear trials. In addition, UV treatment of knitted garments prior to aqueous oxidation can effectiv ely limit facing up in wool knitwear during garment dyeing. A variatio n of the Siroflash process can also be used on cotton and cotton/wool blend fabrics by first padding hydrogen peroxide onto the fabric befor e UV exposure, then treating with continuous UV irradiation with a med ium-pressure are system similar to those used commercially for uv curi ng of polymer films. However, the continuous process is ineffective on pure wool knitted fabrics. The irradiation times necessary for effect ive treatment on wool using low power germicidal UV tubes vary dependi ng on fabric or garment construction. Using these sources, however, ir radiation times are too long for commercial use, and continuous exposu re with a focused medium-pressure mercury are is only partially effect ive. More powerful UV sources providing a high level of we radiation, for example noncoherent excimers or high-intensity low pressure arcs, or hybrid methods for weakening surface fibers (such as UV/H2O2 with a protease enzyme) may provide a rapid, effective, anti pilling treatme nt for wool.