Study On The Method Of Cold Pad-batch Dyeing With Reactive Dyes

Compared with traditional exhausting dyeing technique, the Cold Pad Batch (CPB) dyeing process with reactive dyes is low energy consumption and high fixation, which has been used widely in the world. However, there are still some problems, such as shade stripe at seams of fabrics and the low rate of color conformity, which limit the application of CPB technology in our country. A method of sample dyeing with high veracity and applicability is a key of applying CPB technology successfully.The goal of this topic was to solve the problem of color conformity. In the research, the K/S value, the color difference (includingΔE_Cmc,ΔL,Δa*,Δb*,ΔC*) and the dyeing time were all analyzed. A method of sample dyeing was obtained, by which the colors of lab samples were closest to the factory products, through simulating the cold pad batch and exploring the method of rapid fixation.Firstly, in this paper, the major factors (including the manner of laminated fabric, temperature, time and pressure) influenced the color were studied with Drimaren Red HF-3B. According to changing of the fixation of reactive dyes, the lab samples and the factory products were compared. The results showed that the color difference could be decreased low to 4-5 in AATCC grey grade, between the factory products and the samples which were enveloped and batched in thermostatic bath with a special pressure for 8 hours. The research results provided a basic way for factory to obtain a product with accurate color.Secondly, to satisfy the experiment demands of sample dyeing in a factory, the methods of rapid fixation using microwave ovens under different conditions, thermostatic bath with different temperatures and various combined methods were also studied with dark tricolor of Drimaren HF/CL. By comparing the results of different methods and analyzing the absorption, penetrating and fixation of dyes, the optimal method of "pre-batched at room temperature and then heat-batched fixation in thermostatic bath" was confirmed.The experiment of combined fixation methods suggested that the color difference (ΔE_Cmc) could be decreased to under 0.5, between the cold-batch sample and the sample which was pre-batched at room temperature for 30 min and then batched at 60°C for another 30min in thermostatic bath; while the color difference (ΔE_cmc) was about 1.0, sometimes could reach to 0.5, between the sample of cold-batched and which was pre-batched in room temperature for 30 min and then heated by microwave oven. With this method for ten of Drimaren CL/HF reactive dyes, the results were all satisfying, whichΔE_cmc<0.53 except blue CL-R, also the color difference of dyeing sample was only 0.44 with tricolor dyes for matching compound shade. As a result, this rapid fixation method had a high used value for factory and it would play a good role in practice.At last, the dyeing sample of unreported method of "pre-batched at room temperature and then heat-batched fixation in temperature-constant water bath" was also compared with factory poplin productions using the same recipe and fabrics. The result showed that the value ofΔE_Cmc of beige dyeing sample was 0.59 which can fit the demands of production in the factory; while that of the light grey sample was larger (ΔE_Cmc=1.43), but it was smaller than dyeing sample (ΔE_Cmc=2.72) using microwave oven in the factory. There might be other factors affect the experiment, so further research still need to be done.