Natural colors have attracted the attention of the entire world, because of their non-hazardous nature. In the present study, nylon fabric was dyed with three natural dyes derived from Onion (Allium cepa), Lac (Laccifer Lacca) and Turmeric (Curcuma longa) using various mordants by two different techniques (viz. open bath and HTHP dyeing methods). HTHP dyeing has been found to give better results as compared to the open bath dyeing. Good washfastness (4) was obtained with all three natural dyes. Comparative higher ratings (4-5) for lightfastness were achieved in the case of Onion and Lac, as compared to that of Turmeric (3-4). Table I: Effect of mordants on CIELAB values and fastness properties for dyeing c h. T T T p -
In order to investigate mercerized cotton fiber swelling, raw and bleached cotton fibers have been treated with various concentrations of sodium hydroxide solutions, with and without a wetting agent. Water retention method (WRV) and Propanol-2-retention method (PRV) has been used to determine the fiber swelling, while the barium activity number method (BAN) has been implemented to determine the rise of absorptivity, as well as the moisture regain. The cotton fiber treated with alkali and wetting agent for 120 s swelled more than the fiber treated in pure alkali for 1 hr. The correlation degree of swelling, BAN and moisture regain of the mercerized and unmercerized fiber have been determined through a statistical analysis. A good correlation is obtained between swelling, expressed as PRV and BAN in the case of raw mercerized fibers and there is no correlation between BAN and WRV. For bleached fibers equal correlation is obtained between swelling, expressed as WRV and PRV, BAN and moisture regain. Thus, PRV can be recommended as better for practical work.
Several new bifunctional reactive dyes of the Sumifix Supra range that carry monochlorotriazine and sulphato ethyl sulphone reactive systems were developed and their dyeing performance studied. Suitable characteristic properties and fastness properties were examined over the knitted cotton fabrics. The dyes were characterized by spectral data and elemental analysis. The dyes structures were established by preparing the coupling component using H-acid, cyanuric chloride and 2methoxy-5-methyl (sulphato ethyl) SUIphonyl aniline which was readily coupled with various diazotized 2-amino benzo-thiazole (Figure 1). The results indicated good solubility, a high degree of exhaustion and fixation, excellent fastness degree and higher substantivity over the knitted cotton fabrics. While cotton fabric is an essential element in today's world, reactive dyes are needed to complete ready to wear clothing requirements. With the introduction of the three Procion dyes by ICI for cellulosic fabric in 1956, the covalent bonding of cellulosic fiber to the reactive systems proved to be noteworthy. Further research on cotton goods resulted in the eventual introduction of a newly variable reactive system in reactive dyes.' The term heterobifunctional dyes became widespread after the 1980's through the involvement of four dyes containing monochloro-triazine masked vinyl sulphone (VS/MCT) by Sumitomo,2 which was later called Sumifix Supra dyes. In 1959, I.C.I 3 and, in
This article studies the complete reuse of reactive dyebaths. Because of the hydrolysis of residual reactive dyes due to the fixation conditions and because of relatively large amounts of dyes and salts left in the effluent, reusing hydrolyzed reactive dyes is a challenge to dyers. Seven reactive By Yiqi Yang, Lan Xu', Institute of Textile Technology, Charlottesville, Virginia dyes, C.I. Reactive Red 120, Black 5, Blue 5. Violet 5, Orange 13 and 16, and Yellow 2, and two fabrics, nylon 6,6, a n d wool, were examined. It is shown that when using suitable dyeing conditions, hydrolyzed reactive dyebaths could be reused for nylon and wool dyeing with very good wash and crocking colorfastness. Introduction A major environmental problem of textile effluent is from the dyeing waste water.',' Colorants, heavy metals, and high concentrations of salts are all water pollutants. To decrease the concentration of these chemicals in the effluent discharged, the major effort is on the removal of toxic materials from the effluent. Another approach, dyebath reuse, has received more and more attention only decreases the amount of toxicity of dyeing effluent remarkably, but it also saves the expense of dyes, chemicals, dyebath is a complex system with many variables not easily controlled exactly the same for reuse, excellent batch-tobatch shade uniformity could be achieved. It was reported that the multishade reuse was also feasible in addition to single shade reuse, but the buildup of finishes and other extractable impurities from the fiber may limit the reusing cycles due to the possible interference of these chemicals with dyes Reactive dyes are one of the most commonly used dyes because of their excellent wash-fastness and convenience in application. The affinity of reactive dyes to cellulose is not very high. Therefore, lots of salt (e.g. 50-1 00 g/l) is, used to improve dye sorption. However, the fixation of reactive dyes is not high, with a yield of 50-90%. In other words, up to 50% of the dyes are left in the bath after dyeing. Both high concentrations of salt and dyes left in the bath cause pollution. As a matter of fact, it was reported that “reactive dyes pose the main problem in color cleanup”.0 It is not an exaggeration to state that without solving the problems of reactive dyebath reuse, dyebath reuse technology is incomplete. Reactive dyes need alkaline conditions for fixation. However, during the dye-fiber reaction (fixation), dye-water reaction (hydrolysis) is unavoidable. Alkaline fixation hydrolyzes a major part of the reactive dyes left in the dyebath. The hydrolyzed dyes could not react further with fiber to be fixed. Therefore, reactive dyebath reuse leads to poor wet colorfastness. Furthermore, reactive dye sorption increases during fixation for the covalent bonding between the dye and fiber changes the sorption equilibrium. For hydrolyzed dyes this second sorption does not exist. Because of this difference, the shade of goods dyed from a reused bath is not easy to control even if the initial dye concentrations are exactly the same. Although the direct reuse of a reactive dyebath after alkaline fixation for cellulosics was tes ted , 31 the feasibility was questionable. In addition to the direct reuse of reactive dyebaths for cellulosics after
The dyeing properties of three natural dyes from vegetable sources were evaluated. Colorfastness to light, colorfastness to washing, exhaustion, and color strength were compared for Ukon ( Curcuma longa L.), Ouren ( Coptics japonica Makino), and Kariyasu ( Miscanthus tincrius Hack) dyes. The lightfastness of Kariyasu was very high compared with the other dyes.
