Indigo Dyeing Of Bio-based PA56 Fiber And Blended Yarn

Under the background of global energy stress,the development and application of biomass materials that can replace petroleum-based materials has become a popular research direction.Recently,the bio-based fiber PA56 fiber has become a research hotspot in the textile field.There have been some studies on its dyeing performance,but no relevant reports had been seen on the dyeing of PA56 with vat dyes.In this paper PA56 fiber and PA56/cotton blend yarn were used as the research object to study the basic theoretical research of the dyeing parameters of fiber,and applied the blended yarn to the yarn dyeing of denim,and obtained the process parameters.Firstly,we selected indigo,the most commonly used dye in vat dyes to study the dyeing properties of bio-based polyamide 56 fibers.Through single factor experiments,we determined the appropriate indigo concentration,sodium hydrosulfite concentration,Na OH concentration,dyeing temperature,dyeing time,and optimized the dyeing process parameters according to the K/S value of the fibers after dyeing.In this study,when the concentration of indigo is 3 g/L,the concentration of sodium hydrosulfite is10 g/L,the concentration of Na OH is 3 g/L,the temperature of dyeing is 40?,and the time of dyeing is 20 min,after dyeing,the K/S value of PA56 fiber reached the maximum 28,and it has good color fastness to washing(above 3-4)and color fastness to perspiration(above 3-4).The strength change of fiber shows that the dyeing temperature has a greater impact on the breaking strength of the bio-based PA56 fiber,and the dyeing time has less effect on the breaking strength of the bio-based PA56 fiber than the dyeing temperature.Scanning electron microscopy(SEM)showed that different dyeing conditions had little effect on the fiber surface.Infrared spectroscopy and X-ray diffraction analysis showed that dyeing had no great influence on the chemical structure and fiber crystallinity of PA56.Then,the best fitted model was screened from the perspective of dyeing kinetics and dyeing thermodynamics,and its dyeing mechanism was analyzed.It was obtained that the indigo on PA56 dyeing rate curve was most in line with the quasi-secondary model,which was chemical adsorption,and the correlation coefficient R~2 was up to0.99.And the half-dyeing time of the shortest was at 40°C,which is 6.6 min,so the dyeing balance can be reached quickly.The isotherm of indigo dyeing adsorption of PA56 was more consistent with the Langmuir model,which showed again that the ion bond may be the key to the adsorption of indigo recession to the fiber dyeing sit,which was characterized by chemical adsorption.The dyeing affinity(-??°)of indigo for PA56 increased with increasing temperature.The dyeing process was an exothermic reaction,and the dyeing heat(?H°)was-8.8498 k J/mol,so the high temperature was not conducive to dyeing.Dyeing entropy increased when dyeing,and the?S°was 49.6J·mol^-1·k^-1.Finally,PA56/cotton blend yarn was applied to the denim dyeing process.The optimal k/s worth process parameters obtained according to the single experiment were:the pretreatment concentration of the penetrant JFC was 6 g/L,the temperature was50°C,the dyeing temperature was 60°C,the dyeing time is 4 s,and the number of dyeing times is 3 times.After indigo dyeing,the strength of PA56/cotton blend yarn increased and the elongation at break was reduced.The number of dyeing had a greater impact on the twist of the yarn,the number of dyes increased,the twist of the yarn decreased,and the dyeing time and dyeing temperature have no effect on the twist of the yarn.After dyeing,the color fastness of PA56/cotton blend yarn showed that the sun-resistant fastness was 3 level,and the other fastness was above 3 to 4 level,and the staining color fastness was higher than color change.