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Title: One-bath dyeing of polyester/cotton blends with disperse and bis-3carboxypyridinium-s-triazine reactive dyes at 130°C and neutral pH
Author: Le, Tuong Thuy
ISNI:       0000 0001 3606 432X
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2008
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Over the last 20 years, selected disperse dyes and bis-3-carboxypyridinium-striazine reactive dyes have been widely promoted for the exhaust dyeing of polyester/cotton blends in a one-bath-one-stage ('All-in') process under neutral conditions. However, despite the time and energy savings afforded by this elegant dyeing process, there is a belief in the dyeing industry that economical production is limited to pale and medium depths of shade. The two dye classes (disperse dyes on polyester and bis-3-carboxypyridinium-striazine reactive dyes on cotton) were investigated to understand why heavy depths of shade could not readily be obtained, economically, using this process. The bis-3carboxypyridinium- s-triazine reactive dyes were responsible for the inability to achieve heavy depths of shade, economically, when dyeing at 130°C and neutral pH. The poor colour yield of the dyes was due to their low exhaustion level and low fixation efficiency at 130°C and pH 7.0-7.5, particularly when compared with the parent bis-monochlorotriazine dyes, fixed under alkaline conditions at 80°C. The synthesis and evaluation of some bis-3-carboxypyridinium-s-triazine reactive dye structures, possessing highly substantive chromophores, were investigated as a mecm of obtaining high colour yield, on 100% unmercersised cotton, at 130°C and pH 7.0-7.5. When a highly substantive bis-3-carboxypyridinium-s-triazine dye chromophore was incorporated into the reactive dye structures, heavy depths of shade could be readiiy obtained when dyeing at 130°C and neutral pH, using conventional salt concentrations. However, the wet fastness properties of the dye were poor, due to the slow removal of the hydrolysed dye and its propensity for back-staining adjacent white areas. If the high substantivity of a dye could be assigned to the reactive group, which is removed during the fixation of the dye, it may be possible to offer both acceptably high levels of build-up (and costeffectiveness) and wet fastness. The synthesis and evaluation of novel reactive dye structures, possessing substantivity-conveying reactive groups, when applied to cotton at 130°C and pH 7.0 - 7.5, were investigated. When a substantivity-conveying reactive group was incorporated into a reactive dye structure, as a replacement for a chlorine atom, the dye exhibited a higher substantivity than the parent monochlorotriazine dye. The use of amide derivatives of nicotinic acid as the reactive group in a s-triazinyl reactive dye resulted in an increase in the substantivity, compared with the parent 3carboxypyridinium- s-triazinyl dye. When two substantivity-conveying reactive groups were incorporated into a dye molecule, without changing the reactivity of the dye, the above effect is enhanced, resulting in higher colour yield than from the corresponding Kayacelon React dye. Since the substantivity-conveying reactive group is removed during the fixation of the dye, the high substantivity of the parent dye should not be an impediment to achieving good wet-fastness properties, without the need to use excessively long wash-off sequences.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available