Study of Factors Affecting the Color Fastness of High Depth fiber Dyed in Silicon Non-aqueous Medium Dyeing System

Multiple washing and soaping are very important to remove floating color on the surface of indigo denim fabric in the traditional water bath. In indigo/silicon non-aqueous dyeing system, the once dyeing cotton usually can obtain depth color, but less washing time make the dyed fiber has poor rubbing fastness and color fastness to weathering which were ignored in traditional dyeing process. In this paper, the influence of dyeing parameters (indigo, NaOH, and Na 2 S 2 O 4 ) on the rubbing fastness and color fastness to weathering were analyzed. The results enough NaOH and Na 2 S 2 O 4 were added in dyeing system, more smooth of the fiber surface can be obtained, which shown the best rubbing fastness of the dyed fiber was obtained at 6% (o.w.f) indigo，8% (o.w.f) NaOH，25%(o.w.f) Na 2 S 2 O 4 . On the other hand, rubbing fastness will be decreased with the increase of indigo concentration. As for colorfastness of weathering, the results of High Performance Liquid Chromatography demonstrated the indigo was oxidized and decomposed into isatin during the weathering test which caused the fiber yellowing. And the yellowing resulted in an increased L value and b value. And the conclusion of SEM analysis and K/S Value indicated best color fastness to weathering can be obtained at 6% (o.w.f) indigo，8% (o.w.f) NaOH，15%(o.w.f) Na 2 S 2 O 4 , and the darker the fiber, the better the color fastness to weathering. Furthermore, this research made up for the defects that the research of factors which affect the color fastness to weathering of indigo dyed products, and has great significance to find a suitable method to improve the color fastness and promote the indigo/silicon non-aqueous dyeing technology.