Application Of Indigo And Maddar Plant Dyes In Polyester Fiber Dyeing

In recent years,with the enhancement of people’s awareness in green environmental protection and healthy ecology,natural dyes have returned to people’s vision with their excellent ecological advantages.For a long time,natural dyes are mainly used in the dyeing of natural fibers,but there are not many studies on their application in polyester and other synthetic fibers,especially the research on the dyeing mechanism of plant dyes on synthetic fibers.In this paper,Indigo,Maddar plant dyes and polyester fibers were used as objects to study the dyeing mechanism and optimize the dyeing process of dyeing polyester fibers on Indigo and Madder.Firstly,in view of the structural characteristics of Indigo plant dyes and polyester fibers,using the method of dyeing plant Indigo to dye polyester fibers to analyze the dyeing mechanism of Indigo plant dyes and polyester fibers.The kinetic and thermodynamic experiments of dyeing polyester fiber with Indigoleuco-acid showed that the rate curve of Indigoleuco-acid moved upto polyester fiber was conformed to the pseudo-first-order model,and the adsorption isotherm is most consistent with Freundlich’s model.In the range of 110℃¹20℃,the amount ofequilibrium adsorption,time ofhalf dyeing and dyeing affinity of dyes all increased with the increase of dyeing temperature.The dyeing heat was 2.7946 kJ·mol^-1,indicating that the dyeing process of Indigoleuco-acid on polyester fiber was endothermic reaction,and the dyeing entropy was 0.0523 kJ·mol^-1· k^-1.Secondly,the optimal dyeing process of Indigo leuco-acid for polyester fabric was obtainedthrough single factor and orthogonal experiment as follows: the dosage of indigo dye was 0.8%owf,the dosage of sodium bisulfite was 2g/L,the pH value of dye was 6,the dyeing temperature was 135℃,the dyeing time was 20 min,and the dosage of potassium citrate was 9g/L.According to the analysis of the properties of the dyed fabrics,polyester fiber dyed by Indigoleuco-acid had a good rubbing fastness,with dry rubbing fastness being up to level 4,wet rubbing fastness was up to level 3-4,soaping fastness and sun fastness was up to level 4,and a certain UV resistance,UPF value was up to 87.32.In addition,to study the dyeing properties of Madder plants dye,this article studied the Madder dye solid thermal stability and thermal stability,pH stability of dye solution and the stability of metal ions firstly,and the analysis found that: powder of Madder plant dyes and dyeing liquid in 60-135℃ could save 3 hstably.It had better thermal stabilitytouse in the dyeing process within 135℃;The pH value and metal ion stability of madder dye solution were not good,and its color and solution state would change with the pH value and metal ion type of dye solution.Finally,on the basis of the research,the applicability of three dyeing methods of pre-mordant,meta-mordant and post-mordant in high temperature and high pressure dyeing of polyester fiber was discussed by using alum,ferrous sulfate and iron sulfate as mordant respectively.Designing single factor and orthogonal experiment to study the Madder plants dye with mordant dyeing of polyester fabric,the dosage of mordant,the dyeing temperature,dyeing time and dye solution pH value on the influence of rule to polyester fabric dyeing effect,the results showed that the dosage of alum,ferrous sulfate and ferric sulfate was 0.5%,2.5% and 0.5%owf respectively,the dyeing temperature was 135℃,dyeing time was 50 min,pH value of dye solutionwas 3 could make the best dyeing effect.After dyeing with three mordant and madder plant dyes,the polyester fabric had excellent color fastness,and the sun fastness was higher than grade 5,and the UPF value exceeded 93.98.Using Madder plant dye to dye polyester fiber can obtain different colors of fabric by adjusting the pH value of the dye solution or using different mordant.It has rich colors,good color fastness and UV resistance,but the evenness of the dyed fabric needs to be improved.