• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.6
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• pp.909-918
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• 1999

The indigo-dyed blue denim garments are favored not only by young people but also by almost everyone of life, In the early years they were casually worn on most occasions but became universal recently. Such denim garments are treated with various process to give it optimal softness and color contrast of blue and white. The processess can generate photoyellowing and thus the yellowing may damage their appearance and quality. So this study is to find the solutions to reduce the photoyellowing problem. For this prupose sample denim were treated with cellulase fluorescent brightener UV absorbent etc. The results were as follows; The yellowing would be more accelerated by fluorescent brightening. Since the yellowing was reduced by 90% In particular the application of the UV absorbent before using of the fluorescent brightener was most effective. The optimal concentration was 0.5% (o.w.f) and the benzophenone compounds were found most effective for the indigo denim. And reduction effect of yellowing by UV absorbent was lowered with repeated laundering but metal compound treatment on fabric made a removal of UV absorbent by laundering prevented.

• Textile Coloration and Finishing
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• v.6 no.2
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• pp.24-29
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• 1994

In order to investigate the crystallization in silk fibroin induced by acid treatment and its photo-yellowing reduction effect. silk fibroin were immersed in PH 3.5~4.0 sulfuric acid and 0.01N hydro-chloric acid at 2$0^{\circ}C$, and the changes of crystallinity were measured by infrared spectroscopy, X-ray diffraction. Yellowness index caused by UV irradiation were also observed. The results are as follows : 1. ${\beta}$-form transition occurs when the silk fibroin are immersed at 2$0^{\circ}C$ in pH 3.5~4.0 sulfuric acid and 0.01N hydro-chloric acid. Formation of new hydrogenbond in molecules on the amorphous region induced ${\beta}$-form structure, and increased crystallinity. 2. Crystallization owing to $\beta$-form transition reduced the initial yellowness index by ultraviolet irradiation.

• Journal of the Korean Society of Clothing and Textiles
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• v.21 no.5
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• pp.922-932
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• 1997

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%.