An Influence of Residual Metals on Yellowing of Indigo Dyed Bluejean after Stonewashing

스톤워싱후 잔류된 금속성분이 인디고로 선염된 블루진의 황변에 미치는 영향

Blue jeans are finished with stonewashing process to give it optimal softness and color contrast of blue and white. So, Yellowing may well be generated during storage or use and thereby, their appearance may be damaged much. So, this study was aimed at finding the solutions to reduce the yellowing problem caused by residual metals after stonewshing. To this end, sample blue jeans were made to be finished with various methods of wet-treatment and then, be subject to daylight to check their photoyellowing. The results of this test can be summarized as follows; Since the stonewashing process was found to affect the yellowing, the residual metals of stone- washed blue jeans was analyzed. And it was found that it contained such residual metal as Al, Ca, Cu, Ti, Si, K and Zn. In particular, it was conceived that Al was a prime cause affecting the yellowing. Meanwhile, when the blue jeans were treated by the metal ionchelating agent of EDTA-2Na, the residual levels of Al and Ti were reduced by about 50%, while the photoyellolving was lowered by 75%, which is suggesed that EDTA is very effective in preventing the yellowing. On the other hand, when the blue jeans were bleached by the hypochlorite, chlorine remained in blue jean accelerated the yellowing. However, when this blue jean was treated again by the sodium thiosulfate for its dechloridization, the residual of chlorine was reduced, and the yellowing was lowered by about 43%.