Study On Dyeing Behavior Of Natural Vegetable Dyes On Protein Fibre Fabrics

Nowadays people pay more and more attention to environmental protection and the eco-textile is becoming one of the most important parts in textile industry.The R&D of natural dyes is of great interest because natural dyes are reproducible,biodegradable,with a wide range of raw material.They also show no toxic and allergic effect on people's health.The dyeing behavior of two kinds of vegetable dyes,one of which was extracted from peony and another was extracted from madder,on protein fiber fabrics was discussed in this paper.The main components of the yellow dye extracted from peony are flavonoids,and the possible chemical structure is 3,4',5,7-tetrahydroxyflavone or 3,3',4',5,7-pentahydroxyflavone characterized by some diagnostic reagents such as sodium methoxide,sodium ethoxide and aluminium chloride etc.The total content of flavonoids is 67.46%determined by UV-spectrophotometry using rutin as comparison sample.This can provide quality standard for its application.The main chemical structure of the red dye extracted from peony is anthocyanin.It is hard to be used in the dyeing of protein fiber fabrics because it is positive charged in acid condition.So another kind of vegetable dyes----alizarin,extracted from madder,was used in our research.In order to obtain bright red dyeing fabrics,several kinds of pretreatments of madder were carried before alizarin was extracted.The application of these two kinds of vegetable dyes on the dyeing of protein fiber fabrics was discussed in this paper.The effects of mordants and mordanting methods were investigated and the best dyeing conditions were optimized by single factor and orthogonal experiments. Furthermore,the mathematic method(Matlab) was used in the dyeing process-controlling.The relationship between K/S value of fabrics and dyeing conditions including ratio,concentration of mordant,time of mordanting and dyeing was obtained.Its practicability can be proved through the verification test.The improvement of color fastness(washing fastness and light fastness) was also discussed in this paper.Adding waterborne polyurethane in the dyeing bath can improve washing fastness to 3,without any obvious change in light fastness.Whenβ-cyclodextrin was added in the dyeing bath,both of washing fastness and light fastness can be improved to 3(yellow dye extracted from peony).The application of different mordants mixture was also tried with the improvement of washing fastness(alizarin).