Study On Improving Of The Shade Stripe In Cold Pad-batch Dyeing With Reactive Dyes

Reactive dyes is one of the important dyestuffs using in cotton fabric dyeing process due to the excellent performance. Compared with traditional pad-cure technique, the Cold Pad Batch (CPB) dyeing process with reactive dyes is simple and energy-saving, which has broad development prospects. However, there are still some problems, such as shade stripe at seams of fabrics, which limit the application and extension of CPB technology in our country.In this paper, the problem of shade stripe at seams of fabrics was studied with the dyestuffs of Drimarene HF and Argazol N/Blue CB-2G which were fit for Cold Pad Batch dyeing process. The method and dyeing process of analog experiment about creating the shade tripes in CPB was confirmed by analysing the color depth, the fixation yield and theΔE value of the stripe. All the factors influenced the shade stripes at fabric sewing seams in CPB dyeing were researched, which included stitches material, color, dyes concentration and fabrics texture type. The difference of stripes of two reactive dyes was studied by paper-chromatographic analysis with alkaline developing solution. This method would be used to select reactive dyes for reducing sewing seam stripes. The airing treatment was applied to decrease the stripes shade after batching.The results showed that the shade depth of the shade stripe was changed with the stitches. The cotton stitch had light shade stripe, while the terylene stitch had deep shade stripe and many fabric layers were affected. This was unreported before.By comparing the shade strips on khaki (twill cloth) and poplin (plain cloth), different shade stripes were obtained. The shade strip on khaki was more obvious than that on poplin under the same dyeing process.For different dyestuffs, the shade stripes formed with the dark tricolor dyestuffs group were distinct, while the stripes formed with the light tricolor dyestuffs group were relatively indistinct. The concentration of dyestuff had a remarkable effect on the color depth of shade stripe and the reason was analyzed by chromatism in this paper.The migration of dyestuffs was analyzed by paper-chromatographic analysis. The results suggested that the degree of migration which influences the stripe was different with the alkaline agent.By changing temperature, humidity and time, and airing the fabric after batching under different condition, the migration of dyestuffs between the sewing seams and the adjacent fabric layer was decreased. The results suggested that the fabric including twill and poplin were aired under 30℃, 90% RH for 4-5 min or twill was aired under 20-30℃, 75% RH for 3-5 min, theΔE value of the stripe could be decreased low to 0.3-0.4, the color depth and fixation rate were not influenced.The research results provide a feasible way for the improvement of the Cold Pad Batch (CPB) dyeing process with reactive dyes. The paper-chromatographic analysis with alkaline developing solution which was used to investigate the migration of dyestuffs explores a new analysis method for selecting the dyestuffs.