Study Of Azo Disperse Dye Struture And Its Dyeing Properties For Polylactic Acid Fabrics

Due to low melting point,high dyeing temperature lead to a strong loss of strength and relatively low dyeing temperature result in lower dyeing strength?K/S value?for polylactic acid?PLA?fabric using disperse dye by high temperature and high pressure dyeing method.Therefore,design and synthesize suitable disperse dyes for PLA fabric dyeing is of great significance for the dyeing of PLA fabrics.Based on this,this paper studied the dyeing properties of five different structures of disperse dyes dyed PLA fabrics under high temperature and high pressure dyeing and carrier dyeing conditions of 80-120?.Three azo disperse dyes with different chemical structures were designed and synthesized.The dyeing kinetics and thermodynamics of three azo disperse dyes on PLA fabrics under the dyeing conditions were analyzed.The dyeing properties of disperse dyes and their properties on PLA fabrics were investigated.The specific research content was as follows:In this paper,five disperse dyes with different structures were selected and the dyeing properties of PLA fabrics dyed under high temperature and high pressure dyeing at 80-120? and carrier dyeing conditions were studied.The results show that in the high temperature and high pressure dyeing method of 80-120?,the apparent color depth of the PLA fabric increases with temperature,however,when the dyeing temperature is 110-120?,the bursting strength drop rate of PLA fabric exceeds 20%;Under the same dyeing process conditions,C.I.Disperse Red 343 has the highest K/S dyeing of PLA fabric and the best saturation.The results of carrier dyeing showed that the esteramine compound?90BHC?could significantly improve the K/S value of PLA fabric dyeing,and the carrier was 90BHC.Under the preferred dyeing conditions of 0.25%?relative dyeing solution?,dyeing temperature of 90? and holding time of 30 min,the dyed PLA fabric was less damaged,and the leveling property and the fastness were better.Based on this,2-chloro-4-nitroaniline is used as the diazo component,N,N-dihydroxyethylaniline,N-ethyl-N-hydroxyethylaniline and N,N-diethylaniline were designed as coupling components to synthesize three different azo disperse dyes?D1,D2 and D3?and to synthesize dyes.The structural characterization was carried out,and the spectral properties of the solvents in different polar sizes were studied.The azo dye molecules were calculated based on the quantum functional chemistry method of 6-31G?d?based on density functional theory?DFT?.Structural parameters.The results show that the?_max of the same dye in DMF is greater than acetone,?_max in ethanol and ethyl acetate;compared with dye D1,the conjugated structure of the dye molecule is slightly changed after the introduction of the-CH₂CH₃ substituent in the dye D2 and D3 coupling components,and the HOMO orbital electron cloud shifts to the right N atom.The excitation energy??E?of the dyes D1-D3 is calculated by theoretical calculation to be?E_D1>?E_D2>?E_D3,and the maximum absorption wavelengths of the corresponding dyes are 524 nm,524.8 nm and 525.6 nm,respectivelyThe dyeing kinetics and thermodynamics of three azo disperse dyes on PLA fabrics under carrier dyeing conditions were also investigated.The dyeing properties of disperse dyes and their properties on PLA fabrics were analyzed.The results show that the adsorption isotherms of D1 and D2 at different dyeing temperatures are consistent with Langmuir adsorption model?R² is more than 0.99?,and dye D3 is consistent with Langmuir adsorption model?R²>0.99?at higher temperature?373.15K,363.15K?.At a lower temperature?353.15K?,the Nernst adsorption model is met?R²>0.99?;The dyes D1,D2 and D3 have an affinity?-??°?greater than10 kJ/mol at dyeing temperatures of 353.15 K,363.15 K and 373.15 K and a dye content of 2%?omf?.The dyeing entropy??S°?is linearly fitted to the relative molecular weight,molecular volume and molecular dipole moment???of the dye.The results show that the linear relationship between dyeing entropy and dipole moment is the strongest?R² is 0.9993?.The compensation effect of??S°?and dyed Enthalpy??H°?gives a quantitative relationship between dye affinity and dipole moment,the affinity of the disperse dye-dyed PLA fabric by dipole moment is established.based on the experimental affinity and model calculation,the linear fitness of the affinity is 0.99487.It is verified that the established affinity prediction model is established.This provides theoretical support for the design and synthesis of new dyes suitable for polylactic acid dyeing.