Cold Pad-Batch Dyeing Of Cotton Knitted Fabric With Reactive Dyes

The continuous wet-process of open-width knitted fabrics is the new green production technology with saving60%water,50%energy consumptions and reducing production costs by more than20%, which energy saving and emission reduction are remarkably superior to that of traditional rope intermittent dyeing. In order to verify the feasibility of cold pad-batch dyeing(CPB) process on the open-width knitted fabrics, a series of experiments were carried out in the paper.The results showed that the color depth of the dyed woven fabric was higher than the knitted fabric under the same conditions. The knitted fabric therefore was mercerized before dyed by CPB process. Then the result showed that when the dye concentration was low (less than30g/L), color depth of the woven fabric was equal to the mercerized knitted fabric, but when it was mid-high (higher than30g/L), color depth of the mercerized knitted fabric was higher than the woven fabric. Furthermore, the CPB process dyeing parameters of un-mercerized knitted fabric were relatively optimized by adjusting the concentration of NaOH, batching temperature and time, whereas the Integ value in dyed woven fabric cannot be attained. It showed that mercerizing process changed the cotton fiber structure with significant effect on CPB dyeing.The color depth of fabrics dyed by CPB process and exhausted dyeing method varied widely depended on different dyes. The color depth of dyed knitted fabric by exhausted dyeing method was higher dyed with ANOZOL(?) red L-S, but then the result was higher dyed with Argazol(?) red CBM, because the structures of two reactive dyes were different, such as double vinyl sulphonein ANOZOL(?) red L-S while chlorine-triazine and vinyl sulfone active groups in Argazol(?) red. Dyeing process, therefore, closely related to the substantivity and activity of the dyes.Based on the results of single factor experiments, central composite design (CCD) within response surface method was adopted to optimize the CPB process including four factors:dosage of alkali agents, pre-batching time, batching temperature and time on cold pad-batch dyeing processing of cotton fabricusing3primary colors of ANOZOL(?) reactive dyes. The optimum processing parameters of cold pad-batch dyeing of knitted fabric was obtained:NaOH2g/L, pre-batching time50min, batching temperature50oC, time2h. The dyed fabric had good dry rubbing fastness, wet rubbing fastness and soaping fastness level with5.4,4-5、respectively.Considering the improvement of dyeing sample by CPB in laboratory, pre-batching and oven rapid fixing method were used simultaneously, which had good reproducibility. The dye fixing mechanism of this method was the same with whole CPB production with less dyeing time.