Study On Dyeing Properties Of Microencapsulated Disperse Dyes With Different Structures

The traditional dyeing using commercial disperse dye of hydrophobic fiber such as PET are those processes of heavy pollution and energy consumption due to auxiliaries solubilization.If disperse dyes are microencapsulated,the effective isolation and controlled-release behaviors of microcapsules can replace the function of auxiliaries.As the results,the values of COD,BOD,and ehromaticity of dyeing waste water can be reduced greatly.In this paper,microencapsulation technique was carried out by using melamine prepolymer as wall material.By changing wall material and core material,pure disperse dye were microencapsulated by in-situ polymerization.Scanning electron microcopy(SEM) and particle size analyzer were used to obtain information about the characters of the microcapsules on morphologies,mean particle size and size distribution.Ultraviolet-visible spectrometer was used to analysis of coating ratio and sustained-release properties.Moreover,the dyeing behaviors of microencapsulated disperse dyes with different structures were evaluated on superfine polyester fabrics without auxiliaries.Dyeing kinetics were also studied here.The main results are summarized as following:(1) The morphologies,particle size and coating ratios were varied with different microencapsulation conditions.The results show that the microcapsules with wall material Q3 exhibit larger mean particle size and more compact.Otherwise,the microcapsules with wall material Q6 are of higher coating ratio.With decrease of core-to-wall ratio,the mean particle size is increased but the coating ratio was deceased.Dyes with poor water solubility exhibit larger particle size and higher coating ratio.(2) The release process of microcapsules includes three stages.The first stage of quickly releasing is mainly affected by contained dyes.During the second stage,the release behavior of microcapsules accords with the first order reaction kinetic equation.And the third stage keeps the release quantity constant.(3) The sustained-release performance of microcapsules are more remarkable with the decrease of core-to-wall ratio,but their release rate constant is decreased.The microcapsules with wall material Q6 have higher release rate constant.It's suitable to choose Q6 wall material and 1:2 core-to-wall ratios for dyeing due to its temperate sustained-release property and release rate.(4) Dyeing of superfine polyester fabric with microcapsule disperse dyes,can be carried out as that of the corresponding commercial disperse dyes.It can not only enhance the high temperature levelness and migration,but also have such advantages as without assistants without rinsing and washing also.Because of the encapsulation and differences from dyestuff structures,there will be certain changes on dyeing properties of superfine polyester fabric.Therefore,reasonable choice must be made to obtain excellent performance.(5) Microencapsulated disperse dyes with azo,anthraquinone,and heterocycle structures were used to dye superfine polyester fabric with high temperature pressure dyeing without auxiliary.The dyeing dynamics parameters,such as diffusion coefficient(Dt),half dyeing time(t_1/2) and rate constant(k) were investigated respectively.Results show that the microencapsulated dyes with higher IOB values or IOB values near to PET fiber exhibit higher diffusion coefficient.The higher equilibrium adsorption capacity and specific rate constant are,the higher diffusion coefficient would be,but the lower half dyeing time is.(6) Microcapsules were prepared with C.I.disperse red 60,C.I.disperse yellow 211 and C.I.blue 183 individually,and the adsorption isotherm of microcapsules were investigated compared with their pure types.There are certain changes between them. The adsorption isotherm of pure C.I.disperse red 60 of anthraquinone type shows some characters of Langmuir type.C.I.disperse yellow 211 of heterocycle structure and C.I.blue 183 of azo structure reveal Nernst type as normal.But the adsorption isotherms of microcapsules display both Langmuir type and mixed type character.This research show that microencapsulation disperse dyes can be used theoretically as a substitute for the commercial dye in dyeing superfine polyester fabric.This novel dyeing process has such advantages as no need of adding dyeing assistants,and the load of pollution can be reduced greatly only after simple filtration. It is of interest on both ecological and economic grounds.