The Effect Of Oligomers On Dyeing Properties Of PTT Fabrics Dyed With Microencapsulated Disperse Dyes

PTT(polytrimethylene terephthalate) fiber developed in the mid of 1990s is a novel textile material with good wearability. Meanwhile oligomer content of PTT fiber is the maximum among all polyester fibers. Oligomer causes a negative effect on dyeing process and dyeing behavior of PTT fiber. Although microencapsulated disperse dyes can be used to dye traditional PET in an environment-friendly way, PTT fiber dyed with microencapsulated disperse dye was just carried out exploration experiments in the laboratory. Whether or not the microencapsulated disperse dyes can solve the dyeing problem of PTT polyester fabric caused by oligomers still need further research.In this paper, three disperse dyes (C.I. disperse blue 56, C.I. disperse red 153 and C.I. disperse orange 73) with different energy levels were microencapsulated by in-situ polymerization. Then microencapsulated disperse dyes were used to dye PTT fiber in the absence of auxiliaries. Oligomers were extracted from PTT fibers by solvent extraction methods. The surface morphology of PTT fiber before and after extracting was observed by Scanning Electron Microscope. The group component of oligomers was analyzed by Infrared Spectroscopy. And the thermal properties of oligomers were obtained by thermogravimetric and DSC analysis. The dyeing behaviors of different microencapsulated disperse dyes were investigated respectively and compared with that of commercial disperse dyes. Uptake curves, build-up curves, the relevant dyeing parameters(K/S value, brightness L value, a value (red and green axis), b value (yellow and blue axis)), washing fastness, rubbing fastness, levelness, CODcr values of effluents and related thermodynamics parameters (standard free energy-Δμ0, standard staining heatΔH0, and standard staining entropyΔS0)were also studied respectively.The main results are summarized as following:(1) The oligomer content of PTT fiber is approximately 4.40 percent. Three different components were separated clearly by thin-layer chromatography. The infrared spectrogram of oligomers is similar to that of the corresponding PTT fiber, which indicates that they have the similar chemical constitution.(2) Microencapsulation can improve the build-up property of disperse dyes to some extent, especially for low temperature type C.I. disperse blue 56 and medium temperature type C.I. disperse red 153. When microencapsulated disperse dyes with the same core-wall ratio were used to dye PTT fibers without oligomers, the higher build-up power and the better color depth can be achieved compared with that of PTT fibers with oligomers.In the absence of oligomers, PTT fibers dyed with microencapsulated disperse dyes can exhibit higher K/S values and better color depth. When microencapsulated disperse dyes were used to dye PTT fibers, the leveling property was better and the color fastness, staining fastness and washing fastness were similar to those of commercial disperse dyes. However, oligomers has no obvious influence on color parameters of dyed fabrics.CODcr values of dyeing wastewater after extraction of oligomers are smaller than that of without extraction of oligomers, no matter PTT fabrics dyed with microcapsules containing disperse dyes or commercial disperse dyes. CODcr values of wastewater of microcapsules with core-wall ratio 1:2 were lager than that of microcapsules with core-wall ratio 1:4. Moreover, CODcr values of dyeing wastewater of commercial disperse dyes are far larger than that of microencapsulated disperse dyes. Therefore, the microencapsulated disperse dyes can relieve the dyeing problem of polyester fabric caused by oligomers to some extent.(3) The adsorption isotherm of C.I. Disperse Blue 56 reveals Nernst type. Compared to commercial disperse dyes, the distribution coefficient K of the corresponding microencapsulated disperse dyes is much larger. No matter PTT fabrics dyed with microcapsules containing disperse dyes or commercial disperse dyes, the existence of oligomers will impact on the adsorption isotherm to a certain extent.In the absence of oligomers, both the standard dyeing entropyΔS"and standard dyeing heat AH'decreased, which shows that the existence of oligomers can increase standard staining entropyΔS'and standard staining heatΔH" of whole system.