Synthesis And Application Of An Alkali-clearable Carboxylic Ester Disperse Dye

With the rapid development of synthetic fibers,disperse dyes in the dye industry,a larger proportion.Disperse dyes are characterized by a small molecular weight,the structure does not contain water-soluble groups;In the dyeing process showed a dispersed state for dyeing a class of non-ionic dyes.In the dyeing process,part of the dye will be adsorbed on the fiber surface to form a floating color,affecting the dyed fabric vividness and color fastness.Therefore,after the dyeing of polyester fabric,it is usually necessary to remove the fiber surface by reduction cleaning(reduction cleaning process: 2 g/L sodium hydrosulfite,1 g/L NaOH,bath ratio 1:50,70?,15 min).But in this process,azo-type disperse dyes azo bond breakage,the formation of two kinds of toxic aromatic amine compounds,causing water pollution;anthraquinone-type disperse dyes were reduced to leucosome,and leucosome long time in the water will increase the amount of BOD,COD.In order to solve the above-mentioned environmental problems,select low-toxicity alcohols and disperse dye precursors have been synthesized by diazotization,coupling reaction and esterification reaction to synthesize carboxylate disperse dyes.The dyes in the reduction cleaning treatment,can be exempt from sodium hydrosulfite,in the presence of low concentrations of alkali can occur carboxylate hydrolysis,re-generated water-soluble disperse dye precursors(carboxylate dyes)and low-toxicity alcohol compounds,so as to remove the polyester fabric surface color,to color fastness requirements.This kind of dyes can not only avoid the use of sodium hydrosulfite,but also reduce the appearance of harmful substances in the production and use of dyes.It has a good application prospect and environmental benefits.Firstly,1-naphthylamine was used as diazo component and 2-hydroxy-3-naphthoic acid as coupling component.Azo-type acid dye AD-1 was obtained by diazotization and coupling reaction in two steps.Followed by esterification reaction to obtain a carboxylic acid ethyl ester-type disperse dyestuff Dye-1;Which was prepared by the reaction of bromine acid and p-aminobenzoic acid,and copper sulfate and stannous chloride as the catalyst to obtain the sulfonic acid group-containing anthraquinone acid dye AD-2,glucose in the alkaline conditions and AD-2 reaction to remove the sulfonic acid groups,and then with the esterification of ethanol to carboxylate-type disperse dyestuff Dye-2;another choice of p-aminobenzoic acid as the diazo components,1-phenyl-3-methyl-5-pyrazolone as the coupling component,by diazotization,coupling reaction get pyrazolone type acid dye AD-3;The Dye-3,Dye-4 and Dye-5 were obtained by esterification of isopropanol,sec-butanol and n-amyl alcohol respectively.Themolecular structure was characterized by MS,FTIR,1H NMR,13 C NMR.Finally,the hydrolysis kinetics and application properties of the five alkali-clearable carboxylic ester disperse dyes.Based on the hydrolysis kinetics,the alkaline hydrolysis of the five alkali-clearable carboxylic ester disperse dyes conformed to the quasi-first order kinetics and was independent of the dye structure.Besides,according to the results of hydrolysis kinetics,we obtained the optimum alkali wash condition process of dyed fabric: Dye-1 was pH 11,80?,30 min;Dye-2 was pH 11,80?,20 min;Dye-3,Dye-4 and Dye-5 were pH 11,70?,20 min.Finally,the dyeing properties of alkali-washable carboxylate disperse dyestuffs on polyester fabrics were studied.It was found that the dyeing rate of the five alkali-clearable carboxylic ester disperse dyes was above 85% when dyeing polyester fabrics,Which can meet the requirements of dyeing depth of polyester fabrics.In the fastness to dyeing,the washing fastness,rubbing fastness and sublimation fastness of the polyester fabrics can reach 4 and above after alkali washing.By comparing the alkali washing process and the color fastness values after the reduction cleaning process are described.It is shown that the alkali washing process of the alkaline washable carboxylic acid ester type disperse dye can achieve the same or even better effect as the reduction cleaning.