| Silk is a protein fiber and known as "Queen of fiber", which is deeply loved by the people. However, the quality and wearing performance of silk fabric is affected by its poor washing fastness. This kind of problem has not been well resolved yet and seriously hampers the development of silk industry.Silk protein contains a high content of tyrosine residues. Studies on chemical modification of protein showed that the Phenol methylene in tyrosine residues could be coupled with diazonium salts of aromatic amines to form a colored chromophores group with azo. In the paper, a series of coloration at side groups of silk protein as a coupling component were directly synthesized on silk fibers.The conditions of the coupling reaction of the coloration process of silk fabrics were studied in terms of the color value (K/S) and levelness as evaluation criteria. The optimum process conditions were selected as following:the sodium hydroxide concentration was6g/L,the concentration of diazonium was0.024mol/L, pH was5-6, liquor ratio was1:100, coupling time was10min.With the selection of aromatic amines, different diazonium solutions were prepared. Changing the molecular structure of diazo compounds was to obtain kinds of different colors. there were two ways to change the molecular structure of the diazonium:one method is to introduce different type, different quantity or different substituted position group to the aromatic amine, where some structures can make colored fabrics occur dark or concentrated color effect. Another method is to use two chromophoresto form a blending color effect.In order to realize the blending color effect, the anthraquinone dye A containing m-phenylenediamine group and dye B containing p-phenylenediamine group, were respectively generated by Ullmann condensation with bromine acid, m-phenylenediamine and p-phenylenediamine. Both dye A and dye B have reactive amino group, which could be diazotized and color silk fabric. The products were characterized with FT-IR,1H-NMR,MS The results showed that they were the designed target products.The products were dissolved in N,N-Dimethylformamide (DMF) and the UV-vis maximum absorption peak of the solution showed that the colors of dye A and dye B were blue and green blue.Color fastness tests of the colored silk fibers which were obtained by the novel coloration were carried out. After a series of color fastness tests, such as washing fastness, rubbing fastness and solvent extraction fastness. The results showed that the washing color fastness was rate>4. The dry rubbing fastness of the dyed silk fabrics was in the range of grades4-5, and the wet rubbing fastness was in the range of grades≥4. The colored silk fibers stained of the coupling of side groups on silk protein can not easily be extracted down by DMF.The light resistance of silk fabric colored by aromatic amine diazonium was better than those colored by dye A and dye B,but the latter was superior to the ordinary anthraquinone acid dyes. In summary,the results showed that the coupling of side groups on silk protein is a novel coloration with high color fastness for silk.In addition, the breaking strength was tested after rolling alkali treatment and coupling reaction,and the results showed that the silk fabric breaking strength loss were less than10%,and no significant adverse effect existed in the mechanical properties of the colored silk fabrics. |
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