Research And Application Of New Dyeing Technology Of Polyamide Fiber For Deep Water-saving And Pollution-reduction

Because of low percentage of exhaustion and percentage of dye-fixing of dye, polyamide fiber needs repeated washing in later period of dyeing. The washing has brought about great water consumption and high pollution emission. This paper develops a new dyeing technique of polyamide fiber. The technology uses common dyeing equipment and conventional process to dye polyamide fiber with Erionyl A and Lanaset dyes.Additives added after dyeing can decolor and degrade the dyes in dye bath and remove the loose color on the surface of fibers. When oxidizing stage is completed dye liquor is directly discharged and fibers are dewatered and dried without being washed.The organic pollution in dye liquor is converted into inorganic in situ without emission,so the technology also is called dyeing technology of mineralization in situ(DTMIS). This paper does research on the optimum process of DTMIS, the relationship between the amount of dye and the amount of mineralization additives, the contrast of conventional dyeing process(CDP) and dyeing process of mineralization in situ(DPMIS), the principle of DTMIS and damage degree of polyamide fibers processed by different dyeing process.On the basis of the contrast with conventional process, the optimum process of DTMIS is determined with the principle of single variable. In optimum process, the p H value is 4 to 5, the temperature is 80℃, the duration is 60 min, the quality ratio of XBJ to hydrogen peroxide stands at 1:10. The relationship between the amount of dye and the amount of mineralization additives is determined by the same method. When the amount of Erionyl A dye is x%(owf), the amount of XBJ is 0.4x%(owf) and the amount of hydrogen peroxide is 4x%(owf); When the amount of Lanaset dye is x%(owf), the amount of XBJ is 0.32x%(owf) and the amount of hydrogen peroxide is 3.2x%(owf).Polyamide fiber is dyed by CDP and DPMIS and the indicators of dyed fabrics and dye liquor processed by CDP and DPMIS are compared. The dyed fabrics processed by DPMIS can reach the level of color fastness of the fabrics processed by CDP except the fabrics dyed by Lanaset Yellow 4GN. The K/S values of fabrics processed CDP and DPMIS are close.CDP needs four or five vat of water and DPMIS only needs one. The total COD of liquor of CDP is about 3900~22300 mg/L, so the pollution of the residual liquor isextremely serious. Compared to the CDP, the water consumption of DPMIS is reduced by75%~80%, the COD of residual liquor of DPMIS is reduced by 44%~76%. Compared to the CDP, the effect on water-saving and pollution-reduction of DPMIS is remarkable, but the damage degree of polyamide fiber processed by DPMIS is larger than that of polyamide fiber processed by CDP.