This work documents the chemical processing, colorimetric properties and fastness characteristics of sulphur dyed cellulosic textiles. It is well-known that cotton is the most commonly used cellulosic fibre and the sulphur dye class is reported to have the highest consumption among all other colorants applied to cotton. The most attractive feature of sulphur dyes is their low cost which makes their application attractive for dark shades including black, navy, brown and olive. They possess moderate to good fastness which allows them to broadly satisfy the needs of industry, but with the increasing performance demands of garment suppliers and customers, the use of these dyes is gradually declining as they are getting replaced by other dye classes. A major reason for their continuing unpopularity is the environmental impact that is created by the use of the conventional reducing agent sodium sulphide, which is highly toxic for marine life and sewerage systems. Secondly, cellulosic goods dyed with sulphur dyes are particularly susceptible to perborate bleach-containing washing powders thus exhibiting impaired washfastness against oxidative bleaching.The aim of this research is to explore possible solutions for the aforementioned problems. In order to address the environmental concerns related to dye application, a comparative analysis for the conventional and alternative glucose-based biodegradable reducing systems was made. The fastness properties and cross staining performance of sulphur dyed fabric is usually characterised with the standard ISO 1O5 CO6 benchmark. In recent times, a distinctive combination of standard detergent, a low temperature tetraacetylethylenediamine (TAED) bleach activator has been developed which mimics modern detergent formulation and laundering practices. This is the ISO 1O5 CO9 washing protocol, the effect of which has not been reported for sulphur dyes. The purpose of this research is to determine the resistance of the sulphur dyes against such formulations and crucially to identify aftertreatments to reduce the wash down of dyes during repeated laundering cycles over the life time of a cellulosic textile material.In order to produce dyed fabric with improved wash fastness against the aggressive ISO 1O5 CO9 washing regime, a protective system was developed involving the sequential application of a cationic fixative and tannin-based product. The process parameters were optimised to formulate a standard workable recipe. The optimised parameters were evaluated for five different sulphur dyes for the colour strength (K/S), wash fastness, light fastness and dry/wet crocking fastness of the treated fabric. The effects on surface morphology of the untreated and treated fabrics were examined through Scanning Electron Microscopy (SEM). In order to identify the presence of possible functional groups produced as a result of the aftertreatments, FTIR and X-Ray Photoelectron Spectroscopy (XPS) techniques were utilised.
|Date of Award||31 Dec 2015|
- The University of Manchester
|Supervisor||Franz Wortmann (Supervisor)|
- sulphur dyes, wash fastness