Clean Disperse Dyeing Of Alizarin And Application In Digital Printing

With the gradual enhancement of people’s awareness of environmental protection and the strong demand for clean printing and dyeing in the textile industry,clean printing and dyeing raw materials and printing and dyeing processes have attracted more and more attention and research.As a typical representative of clean printing and dyeing raw materials,natural dyes have the characteristics such as environmental protection,non-toxic and harmless.Alizarin is a representative plant dye among the natural dyestuffs of red tint.The application of plant dye alizarin in textile dyeing and printing has broad application prospects.The plant dye alizarin has very low solubility in water at room temperature.In the traditional dyeing process,it is usually necessary to use metal ions as a mordant to dye under high temperature conditions,or to use a reducing agent to dye fabrics under alkaline conditions.The methods of metal ion mordant dyeing and alkaline reduction dyeing not only increase the cost of alizarin dyeing textiles,but also produce a large number of metal ion wastewater and alkaline solution.The traditional screen-printing method is generally used for textile printing with plant dyes.This traditional printing method not only leads to lengthy process preparation in preliminary process preparation,but also causes a large amount of printing wastewater in the later production process.These dyeing and printing processes of alizarin destroy the environmental protection and cleanliness of alizarin as a natural plant dye.In response to the above problems,this thesis used the disperse dye characteristics of the plant dye alizarin,and selected a suitable dispersant to prepare an alizarin dispersion dye solution to dye cotton fabrics at room temperature and neutral p H conditions.Alizarin printing ink was prepared by adding alcohol additives to realize the digital printing of alizarin on cotton fabric.Through the performance test of alizarin disperse dye solution,alizarin printing ink,dyed cotton fabrics and printed cotton fabrics,it shows that it is feasible to prepare alizarin disperse dye solution and alizarin printing ink through dispersant to realize the clean printing and dyeing process of plant dye alizarin.The specific research contents and results about this thesis are as follows:（1）Alizarin dispersion was prepared at room temperature and neutral p H with linear sulfonic anionic surfactant（LAS）as dispersant.The study on the properties of alizarin dispersion dye solution showed that the use of LAS can effectively increase the dispersion solubility of alizarin in water at room temperature,so that alizarin can be dispersed in water to form a stable dispersion dye solution.Through single factor dyeing experiment and orthogonal design dyeing experiment,the process parameters of alizarin dispersion dyeing cotton fabric were optimized,and the property index such as dyeing fastness of the dyed cotton fabric was tested.The dyeing fastness of dyed cotton fabrics such as washing dyeing fastness and rubbing dyeing fastness both reached above grade 3 ～ 4,and the K/S value was 3.301.（2）Based on the preparation of alizarin dispersion,alizarin printing ink was further prepared according to the performance requirements of digital printing ink.The ink performance was optimized by controlling the ink viscosity,moisture retention and surface tension.When 20%mixed alcohol of ethylene glycol and diethylene glycol was added to alizarin disperse dye solution as alcohol additives to prepare printing ink,the alizarin printing ink had good performance.The obtained ink was subjected to a digital printing test on the pretreated fabric,which showed that the obtained alizarin printing ink meets the performance requirements of digital printing ink.The property index test such as color fastness test of printed cotton fabric showed that the printed fabric printed with alizarin printing ink had a certain K/S value and color fastness.