Selection Of Vegetable Deys With Antimicrobial Activity And Their Application On Wool Fabrics

In the recent years, vegetable dyes applied on the textile dyeing have been paid more and more attentions, while little research about their functional properties is reported. The colorants of vegetable dyes are extracted from various plants, it has already been confirmed by medical research that some plants have antimicrobial action. So whether one plant both have colorants for dyeing and strong antimicrobial activity? And how do the dyeing techniques have effect on the color and antimicrobial activities of wool fabrics? These problems are approached in this thesis.Four kinds of vegetable dyes H-CY,HB,DH (yellow color) and W-CT (brown color) have been selected and evaluated in the aspects of antimicrobial behavior and dyes properties. The experimental study included two parts: Firstly, according to the measurement of minimum inhibitory concentration (MIC) of colorants which are extracted by water or ethanol in normal or ultrasonic process, some vegetable dyes with strong antimicrobial activity are selected; Further in order to make the extraction process higher efficiency and obtain the more colorants, the parameters of extraction such as temperature, bath ratio, and extraction times etc are optimized. Secondly, it is approached that the parameters of dyeing process of the selected vegetable dyes applied to wool fabrics affect the rate of dye-uptake, color and fastness of fabrics. Meanwhile, influence on antimicrobial activity of fabrics is studied through changing the dyeing parameters.The results of this study show that:(1) Dye solutions with different extraction methods for one plant have different antimicrobial activity, the solutions with water extraction have stronger antimicrobial activity than that with ethanol. Different dye solutions have different MIC values, W-CT and H-CY dye solutions using water extraction have been chosen as they have lower MIC value. The optimum extraction conditions for W-CT obtained from the statistical analysis were 90min, 100℃, 1:8 (material to water ratio) and repeat for 2 times.(2) In the process of W-CT direct and pre-mordanting dyeing, it is obvious that pH value has the most important effect on the colour character of wool knitting fabrics. And dyeing solution concentration mainly affects the rate of dye-uptake of fabrics. The soaping treatment of fabric after dyeing can improve the color fastness properties to meet the national standard. The optimum pre-mordanting dyeing conditions are mordant's (Al³⁺) concentration 2.5%, dye concentration 150%, pH 7 and temperature 98℃. In the process of H-CY dyeing, the dye-uptake of fabric for the pre-mordanting dyeing is higher than that for the direct dyeing. The optimum pre-mordanting dyeing conditions are Al³⁺ concentration 2.5%, dye concentration 200%, pH=8 and temperature 60℃. While their color fastness of fabric need to further improve.(3) Wool fabrics dyed with dye W-CT and H-CY have good antimicrobial properties, and stronger antimicrobial capacity for Staphylococcus aureus than that for Escherichia coli. The antimicrobial capacity of fabrics reduces in a certain extent after their washing for 10 times. The fabrics dyed by W-CT solution have better antimicrobial property than those dyed by H-CY solution.In a word, W-CT and H-CY two vegetable dyes with antimicrobial activity applied on the wool knitting fabrics show good performance on dyeing and inhibiting the growth of bacteria. W-CT has favorable applied value for practical production.