Study On One-time Dyeing Technology For Deep Shade Cotton Fibers Using Indigo /D5 System

The method of indigo dyeing bath exists disadvantages including complicated dyeing process, low production proficiency, hardness of achieving deep shade in one-time dyeing process, etc. Aiming at these problems, Decamethylcyclopentasiloxane(D5), which is environmentally friendly, were used as dyeing medium instead of water and developed an innovative indigo/D5 system to achieve deep shade in one-time dyeing process. This technology, which simplifies the dyeing process, and saves dying time and cost, and reduces waste water significantly, has wide range of potential applications. This paper focuses on three aspects:1. Study on the impacts of dyeing property in scouring process by using D5 as the mediumDesigning and establishing the process of using D5 as the medium to scour, using the color depth as the evaluative indicator, and optimizing the process of D5 scouring to match the indigo/D5 system. The results presented that the optimal process of indigo /D5 system as follows: Cotton fibers with liquid(alkali liquor) ratio 200%, sodium hydroxide 50 g/L, scouring at 80? for 40 min; compared with the effects of water bath scouring, using D5 as the medium performs better, which could be the matching technology of indigo/D5 system dyeing technology; During the process of scouring, cotton fiber only charges minute quantity of sodium hydroxide so that saving plenty of water and greatly decreases the waste water consumption.2. Preparation of indigo dye leuco with high concentrationsIn order to reach the requirements for the past dyeing, optimal process of indigo dye leuco with high concentrations have been studied. In addition analyse the influencing factors of indigo dye reduction process, and each factor's function to the dyeing property. The results presented the optimal dyeing process as follows: Indigo dye 30 g/L, sodium hydroxide 40 g/L, sodium hydrosulfite 140g/L, reduction at 60 ? for 20 min; high concentration indigo dye leuco production could fulfill the past indigo dye leuco/D5 dyeing system.3. Study and mechanism analysis of indigo dye leuco/D5 system dyeing technologyDesigning and establishing the process of indigo dye leuco/D5 dyeing system, using the color depth and level coloring as the evaluative indicators to optimize the process, and studying the mechanism of dyeing process. The results presented that the optimal process as follows: Cotton fiber with liquid(de-ionized water) ratio 140%, m cotton(dry weight): m leuco solution = 1: 2, m cotton(dry weight): m D5= 1: 30, dyeing at 60 ? for 60 min. Compared to the water as dyeing medium, color yield of indigo dye/D5 system increased by more than three times and dye uptake increased by 30~40%, the deep shade could be achieved in one dyeing process as well. In the indigo dye leuco/D5 system, only minor amount of leuco solution were needed and this system saved amount of water and significantly reduced the waste water.