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Title: One-pass process for the continuous dyeing of polyester/unmercerised cotton blends with disperse/reactive dyes
Author: Mehmood, Arshad
Awarding Body: The University of Manchester
Current Institution: University of Manchester
Date of Award: 2008
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Abstract:
In the continuous dyeing of polyester/cellulose blends, the trend over the last 20 years, towards shorter production runs and greater numbers of fashion shades, has led to the development of more productive processes, in particular, the use of a onepass Pad-Dry-Thermofix-Wash-off process for the application of disperse and reactive dyes. However, there are limitations to such a one-pass process, of which the most important is the colour depth that can be achieved on polyester/unmercerisedc otton blends, economically. The current study, which has focused on the performance of the dyes (disperse/reactive) used in DyStar's one-pass (TTN) continuous dyeing process, showed that it was the reactive dyes, which were responsible for the difficulty in achieving heavy shades, economically. It also suggested that the level of reactivity of the medium - low reactive dyes, most commonly recommended for use in this process, was not the prime reason for the poor performance in the one-pass process. The constituents of the pad liquor were varied to determine if the visual colour yield of selected reactive dye could be improved. In so doing, it was possible to speculate whether the low colour yield from some of the reactive dyes used in the one-pass process was due to inefficient `delivery' of the dye to the reactive sites on the cotton. It was also observed that, in a modification of the one-pass (TTN) continuous dyeing process, fixation efficiency of the reactive dyes but not the visual colour yield can be improved up to the level of that on mercerised cotton, if humidity (approx 25%) is injected during the drying stage @ 110°C. Furthermore, in the case of the yellow reactive dyes currently recommended for use in the process, the level of hydrophilicity (number and distribution of sulphonate groups) was a more important factor than the level of reactivity, in improving the fixation efficiency of these dyes on unmercerised cotton.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.505866  DOI: Not available
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