Cold Pad-batch Pretreatment And Dyeing Process Of Cotton Knitted Fabrics

Traditional rope batch pretreatment and dyeing process of cotton knits is of the characteristics of high energy consumption, water consumption, and serious sewage. Cold pad-batch technology completely accords with the production requirements of green environmental protection, energy conservation and emissions reduction with short technological process, high production efficiency, low energy consumption, simple equipment, low cost. At present, many enterprises have done research for the application of cold pad-batch process, and achieve good performance on the cotton woven fabric, while it is not ideal on cotton knitted fabrics. The development of knitted fabric from cylinder processing to open width processing makes it possible. In these studies, the cold pad-batch pretreatment and dyeing process of cotton knits were improved and further promoted in large-scale industrial application.In the first part of this paper, a novel low temperature bleaching compound additive Texbleach DZ-1 was applied to cold pad-batch pretreatment process of cotton knits. Influences of the dosage of sodium hydroxide, scouring agent and activator, batching time on fabric whiteness were studied through single factor experiment. The optimal bleaching process was listed as follow:Texbleach DZ-1 4.0 g/L, Na OH 4.0 g/L, 30% H2O2 30 g/L, stabilizer 3.0 g/L, scouring agent 10g/L, the reaction temperature 40 ℃, batching time 6h.Under the optimum process conditions, the whiteness and wettability of fabric treated by cold pad-batch pretreatment with Texbleach DZ-1 is similar to those by traditional high temperature and conventional cold pad-batch pretreatment process, while the dosage of alkaline, the batching time and the strength loss were all remarkablyreduced, which meant cold pad-batch pretreatment process had obvious advantages of energy saving and emission reduction.In the second part of this paper, cold pad-batch dyeing process was conducted on cotton knits with C.I Reactive Blue 250, C.I Reactive Red 198, C.I Reactive Red 239 three kinds of known structure reactive dyes. It was found that the three dyes all had good building up properties.Compared with caustic soda/ sodium silicate, when caustic soda/ sodium carbonate were used as mixed alkali, the dyed fabrics had a higher color yield and became softer. The fabrics treated by Texbleach DZ-1 cold pad-batch pretreatment, conventional cold pad-batch pretreatment and traditional high temperature pretreatment process of cotton were dyed by two different methods,exhaust dyeing and cold pad-batch dyeing. Results showed that when the dyeing method was the same, the dyeing effect was basically the same. In other words, different ways of pretreatment had little effect on the subsequent dyeing. When using different dyeing methods on the fabrics treated by the above three different kinds of pretreatment processes. dyeing effect was obviously different.For reactive dye with low substantivity and whose active group were monochloro triazine and vinyl sulfone type, there showed higher color depth and fixation dyed by cold pad-batch dyeing method compared with exhausted dyeing method, which meant that this kind of reactive dye is more suitable for cold pad-batch dyeing process.According to the conclusion of the second part, three different types of commercialized reactive dyes Argazol-CBM series, Anozol-L series, Anozol-M series reactive dyes were selected and applied to cold pad-batch dyeing process on the cotton. in the third part. Effects of sodium hydroxide, sodium carbonate, batching up temperature and time on color depth and fixation were studied by single factor experiment to optimize process conditions. The results showed that the optimized dyeing process of reactive dyes with different structure and properties were different.