One-bath Two-step Dyeing Technique For Cotton-polyester Blended Fabric

Compared with the traditional two-bath dyeing process in the factory,the one-bath two-step dyeing process of cotton/polyester blended fabrics has the advantages of time saving,water saving,power saving,steam saving and so on.what's more,it needs less water,which meets the trends of times and energy saving,emission reduction and environmental friendship.Before choosing the one-bath two-step dyeing process of cotton/polyester blended fabrics,it is necessary to screen the application properties of the reactive dyes,disperse dyes and auxiliaries used,to optimize the recipes and process parameters;moreover,color-matching works are required to achieve performance requirements such as dyeing depth,shade,and fastness.The one-bath two-step dyeing process of cotton/polyester blended fabrics in this paper is as follows: firstly,adding reactive dyes and disperse dyes into the dyeing bath,adjusting the pH value of the dyeing bath to 5-5.5,then raise the temperature to 130? to dye polyester part with disperse dye by high temperature and high pressure method.Thirdly,cooling the dyeing bath to 80?,and adding sodium sulfate and soda ash to dye cotton part with reactive dyes.The last step is to soap and wash the fabric,drying to get the final shade.In this paper,17 reactive dyes were tested according to the one-bath two-step dyeing process,and the dyeing parameters such as color,strength,depth(K/S value),color difference(DE value),washing fastness and rubbing fastness are compared in order to select reactive dyes that have good thermal stability under the dyeing conditions of polyester(130?)and are suitable for one-bath two-step dyeing process.The reactive dyes suitable for one-bath two-step method are Reactive Red RHS,Reactive Navy RHS,Reactive Dark Red CD,Reactive Orange CD,Reactive Navy CD,Reactive Blue 2GF,Reactive Black CD-G,Reactive Black CDM,which are mainly used vinyl sulfone reactive groups.Then the dyeing performance of four conventional disperse dyestuff are perform on this dyeing process to test the washing fastness and rubbing fastness after soaping process.The results showed that the conventional disperse dyes are also suitable for one-bath two-step dyeing processes.The following dyes were selected in this experiment: Disperse Red S-BR,Disperse Yellow Brown S-2RFL,Disperse Navy S-2GRL,Disperse Black AP-B.Subsequently,the auxiliaries used in the one-bath two-step dyeing process and their dosage are also selected.The two important factors in the one-bath two-step process are the buffer system and soaping agent.The buffer system is HAc/NaAc system,the optimized pH range is between 5 to 5.5,and the dosage buffer solution is 1g/L.Screening from fumaric acid/acrylic copolymer soaping agent MJ-01,maleic acid/acrylic acid copolymer soaping agent AP-SN,polyester soaping agent WWRC and weakly reducing soaping agent ECO.The best soaping agent is WWRC with dosage 8g/L.This paper also conducts a single factor test on the one-bath two-step dyeing method,optimizing the process recipe and process conditions.It is determined that in the reactive dyeing process,the dosage of sodium sulfate is 60g/L,soda ash is 5g/L,the dyeing temperature is 80?,and the dyeing time is 40 minutes.The conditions of soaping process is 95?,20 minutes.Finally,the color matching dyeing process on Polyester/Cotton fabrics are done with one bath two-step dyeing process.It was found that the dyed fabric can achieve the same depth,shade and fastness as two bath dyeing process with good dyeing reproducibility.By comparing the dyeing cost of the two dyeing processes,it was shown that the one bath two-step dyeing process can save 42% water and increase the production efficiency by 1.75 times.