Dispersion Stability And Application Perfor Mance Of Self-Dispersible Dyes

As the main colorants for synthetic fibers,disperse dyes have a wide range of uses and are in great demand in the dyeing and printing industry.They exhibit low water solubility and suspend in the dye liquor with the existence of dispersants,and the dye particles in the suspension are very easy to aggregate,flocculate and even sometimes produce precipitate at the dyeing temperature. Because of the poor effectiveness of conventional dispersants,the weight ratio of dye to dispersant can often reach a level of 1:2 or even more,which results in relatively high COD(chemical oxygen demand) and BOD(biochemical oxygen demand) values of the dyeing effluents and other environmental problems due to the large quantity of dispersants remaining in the effluent..Based on the outstanding performance of hyper-dispersant and the application conditions of disperse dyes,a new super-dispersant(dye-polyether derivative) prepared from the modification of di-block poly(etbylene oxide-co-propylene oxide) ethers by disperse dye molecule.Then the dye dispersion was prepared by milling dye-polyether derivative with the parent dyes.This paper explores the application performance of this dye dispersion system and the feasibility of the dye-polyether derivative as a new dispersing agent in polyester ecological dyeing,with a view to reduce the environment pollution.A series of polyether derivative of C.I.Disperse Yellow 64 was prepared by the substitution reaction between four kinds of Amino-terminated polyether and the dye.The structure of such dye-polyether derivative was confirmed by ~1H NMR,SEC and amine titration analysis.The adsorption amount of dye-polyether derivative on the particle surface of parent dye was measured by spectrophotometry method and the adsorption mechanism was inferred.And the dispersibilities of these derivatives as dispersants for C.I.Disperse Yellow 64 in aqueous medium are also studied to investigate the influence of the architectures of the derivatives.The results showed that:the protective layer which allows a steric stabilization around the particles comprises two important parts:the adsorption layer and the hydration layer.Adsorption layer thickness and the hydration layer thickness determined by the length of polyoxypropylene chain and the length of polyoxyethylene chain respectively.Thus the length of the polyoxypropylene and polyoxyethylene chain should be adequate to prevent particles aggregation and ensure an efficient stabilization of the dispersions.The study also finds that YL207 is more efficient for DY64 than the other polyether derivatives in aqueous medium and the addition of YL207 even at the weight ratio of 10:1(dye/dye-polyether derivative) still have good stability in room temperature.Through comparing with dispersion property of dye-polyether derivative YL207 and that of six kinds of common nonionic dispersants,further study the application performance of dye-polyether derivative YL207.The particle size distribution after grinding and stored at room temperature(25-35℃) after 15 days as well as dye particle size changes before and after high temperature treatment was determined.The results showed that the dye dispersion has excellent dispersibilities when dye-polyether derivative YL207 and parent dye mixed in certain ratio.The storage stability and high temperature stability of the dispersion exceeds the conventional nonionic dispersing agents.The storage stability reaches the level of commercial dyes,but the high temperature stability still less than the commercial dyes.Furthermore,the author explored the effect and capacities of various traditional anionic dispersants in the enhancement of high-temperature stability of the dye dispersions through the determination of the turbidity and the particle size changes before and after high temperature treatment.Polyester dyeing was carried out with prepared dye dispersions to investigate the effluence of anionic dispersant on its dyeing performance.The results indicate that the high temperature stability of all the dye dispersions were increased after added with anionic dispersants, especially Sodium Lignosulfonate A,MF and CNF,and the self-disperse dyes exhibit better leveling property.Through added with the formulation of anionic dispersants,the dye uptakes and related fastness of the dyed fabrics could be more excellent than that of conventional commercial dyes,and COD values of dyeing effluents could be far less than those of commercial dye.