Preparation Of The Microencapsulated Disperse Dyes And Dyeing PET Fabric In Absence Of Auxiliaries Without Afterwashing

In this paper,the disperse dye microcapsules are prepared and used in the HT dyeing of weave and knit PET fabrics,cotton/PET blended fabrics,microfibre fabrics,and package yarns.There is neither formaldehyde nor other pollutions when the microcapsules are used.What more important is that, microencapsulated disperse dyes dye PET in the absence of auxiliaries such as the dispersing agents,penetrating agents,leveling agents or other auxiliaries.The dyeing process is simplified and the dyed fabrics would not need any afterwashing,i.e.thorough rinsing including reduction clearing and soaping,which totally saving water,energy and chemicals used in these processes.Microencapsulated disperse dyes can lighten the environmental pollution.The exhausted microcapsules in the dyebath can be separated by precipitation or filtration.The dyebath recovered by filtration is virtually colorless and values for COD and BOD of dyebaths from dyeing with dye in microcapsule form are much lower than those values form the traditional one. The used bath is shown to be suitable for reuse in the pretreatment,a "non-effluent",non-pollution dyeing is thus realized making the dyeing process environmental friendly and then obtain both economical and environmental benefits.We used two methods to prepare microencapsulated disperse dyes in this paper.The principle of polymerization of polyurea microcapsules(PM)was that multi-isocyanate reacted with water and forms amine,and then the amine reacted quickly with unreacted isocyanate and formed polyurea by means of interfacial polymerization method.And melamine resin microcapsules(MRM) were prepared by means of interfacial-in-situ polymerization method and the melamine resin prepolymer further crosslinked each other in the surface of disperse dyes and form the thermosetting shell.The core materials used in this experiment included C.I.disperse blue 56,C.I. disperse blue 60,C.I.disperse red 60,C.I.disperse red 167,C.I.disperse orange 29,C.I.disperse orange 30 and C.I.disperse yellow 24.The wall forming materials were liquid biphenyl methane-4,4'-diisocyanate(MDI),as well as trihydroxymethyl melamine(TMM)and hexahydroxymethyl melamine (HMM)prepolymer.GPE-2040 and polymer disperse agent PDA were used as emulsifier.Microcapsules have been characterized in terms of their thermal properties, particle size and size distribution,morphological structure,composition and dyeing behavior.The quality of the polyester fabric dyed in this manner-without reduction clearing-was determined and compared with that dyed traditionally after washing and reduction clearing.The dyebath could be reused.Dyeing properties of the poly(ethylene terephthalate)(PET)film with polyurea microencapsulated disperse dyes were investigated in terms of their kinetic factor,such as diffusion coefficient(D)and activation energy of the diffusion (ED).It is economic and convenient to prepared microcapsules in this formulation by these method.Dyeing using microencapsulated disperse dyes is more simple and convenient.The results indicated:1.The polyurea microencapsulated dye by interfacial polymerization method was found to have an anomalous shape and rough surface comprising large numbers of micropores.The mean size of all the resulting particles was about several decadal micrometers and the size distribution was narrow.Moreover,the microcapsules behaved as heat-resistant containers with good thermal properties.2.The melamine resin microencapsulated dye was prepared by interfacial-in-situ polymerization.The microencapsulated dye was found to have original shape of dye crystal and smooth surface without obvious pores,and they also have narrow size distribution and thermosetting wall.The mean size of all the resulting particles was about several decadal micrometers.It could be assumed from their morphology that two kinds of microcapsules are well suited to the protection and sustained release of core material.3.When PET was dyed using microcapsules at high temperature in the absence of auxiliaries levelness was improved and fastnesses to washing, rubbing,perspiration,sublimation and light and weather on PET fabric were at least as good as by dyeing traditionally.4.At the end of dyeing,the supplements of dyes are ceased and the dyeing process is conducted for further 10-20 min named non-afterwashing process.Most of the dissolved dyes and adsorbed dye molecules can get into fiber further.There is only extremely small quantity of the dye molecules,the so-called unfixed color left on the fiber surface giving good enough fastnesses.It's totally saved water,energy and chemicals used in the afterwashing process i.e.thorough rinsing including reduction clearing and soaping.These savings,including a reduction on the effluent load,are a key objective in implementing the "rapid dyeing" approach for polyester.5.The wastewater after dyeing with microcapsules was recovered by filtration and was almost colorless,whereas that from the traditional dyeing process was dark.It was also striking that using dye in the form of a microcapsule dramatically reduced the COD and BOD pollutants in the effluent.The used bath is shown to be suitable for reuse in other washing processes,and if used for the pretreatment,a "non-effluent",non-pollution dyeing is thus realized6.Dyeing properties of the poly(ethylene terephthalate)(PET)film with polyurea microencapsulated disperse dyes were investigated in terms of their kinetic factor,such as diffusion coefficient(D)and activation energy of the diffusion(ED).The results were compared with corresponding properties of the conventional disperse dyes with or without auxiliaries.For all three studied disperse dye types,as the temperature increased the D increased.The conventional disperse dyes with auxiliaries had the highest D at every temperatures and disperse dyes absence of auxiliaries showed the similar values of the D.The Ed of disperse dyes was decreased by surfactant.7.The melamine resin microencapsulated disperse dyes were produced in medium-yield at chemical plant.The polymerization process was stable and the product of microencapsulated disperse dyes were consistent and had narrow size distribution.The dyeing performance was excellent for all kinds of PET fabrics i.e.weave and knit PET fabrics,cotton/PET blended fabrics,microfibre fabrics,and package yarns at dyeing and printing plant. The recovered wastewater by filtration was colorless and value for COD was low.8.In the case of dyeing black PET with tricolor microencapsulated disperse dyes in the absence of auxiliaries,dye consumption was low and temperature control was undemanding,which leveling dyeing was achieved depending on the releasing effect of microcapsules.After dyeing, there were not afterwashing processes anymore.So dyeing process was simplified and dyeing time was shortened.Fastness satisfied requirements of consumer.Differing from the traditional disperse dyes, microencapsulated ones can greatly lighten the environmental pollution.