The effect of reactive dyes on damage in wool dyeing

This paper demonstrates that reactive dyes exert a significant fibre–protective effect when dyeing wool fabric; this effect may be measured, in a reproducible manner, using the wet–burst strength test. The effect of dyebath pH, dye concentration, dyebath temperature and dyeing time on wool can thus be evaluated. The magnitude of the above protective effect has been compared with that achieved using commercially available fibre–protective agents. It is concluded that reactive dyes are significantly more effective than the latter agents when employed in medium to full depths. It is proposed that the unusual protective effect afforded by reactive dyes is related to the following factors. Reactive dyes readily react with sulphur nucleophiles, thus inhibiting thiol–disulphide interchange reactions and thereby significantly interfering with the level of set produced in a boiling dyebath. Reactive dyes react preferentially with non–keratinous proteins in the intercellular cement and the endocuticle thus reducing their tendency to hydrolyse and to partially dissolve in the hot aqueous dyebath.     

Desorption of hydrolysed reactive dyes from wool

The desorption of the hydrolysed forms of nine reactive dyes from wool has been examined in soap solution (ISO 2 test) and in urea-surfactant solution. It was found that the desorption of the hydrolysed dyes was slower in soap solution than in the urea-surfactant solution. After the standard 45 min of the ISO 2 washing test equilibrium was not reached, while after 60 min in the urea-surfactant solution equilibrium desorption was reached with most of the hydrolysed dyes. These findings clearly explain the discrepencies which sometimes occur between the two methods when used to assess wash fastness in relation to fixation ratios. If the time of the ISO 2 test is extended until equilibrium desorption is achieved then the two methods give essentially the same results. It was also found that the desorption rate constants appear to be inversely related to the molecular weights of the hydrolysed dyes.     

Reactive dyeing systems for wool fibres based on hetero-bifunctional reactive dyes. Part 1: Application of commercial reactive dyes

The wool dyeing properties, such as exhaustion and fixation parameters, of selected hetero-bifunctional Sumifix Supra dyes and some other commercial reactive dyes were quantified under various dyebath pH conditions. Studies of the dyeing of wool serge fabric indicated that Sumifix Supra dyes could produce reasonably high fixation values. However, remarkably improved fixation values were obtained when these dyes were pre-activated to the vinylsulphone form and dyed in this form, especially at low pH values (pH 4 or lower).     

Surface modification of wool fabric for printing with acid and reactive dyes

The present study investigates environmentally safe pretreatments for wool fabric to improve its printing with acid and reactive dyes. Wool fabric was pretreated either with activated hydrogen peroxide using tetraacetylethylenediamine or with lipase enzyme under specified conditions. Some acid and reactive dyes were applied for wool printing using normal techniques. These treatments were found to improve the colour intensity of the printed fabrics to a level comparable with those of prechlorinated wool fabrics.     

Application of chitosan/nonionic surfactant mixture in reactive dyes for dyeing wool fabrics

The feasibility of wool fabrics pretreated with a chitosan/nonionic surfactant mixture and dyed with reactive dyes was studied. The results showed that the presence of the chitosan/surfactant improved the application to wool, which greatly enhanced the color strength when dyed at 50°C but little change was observed when dyed at 80°C. The higher the concentration of chitosan/surfactant added, the greater was the color strength of the dyed wool fabrics. The amounts found to be optimum for dyeing were 0.5% chitosan and 1.0% surfactant. The washing fastness of the dyed wool fabrics was in the range of grades 4–5, the dry rubbing fastness was in the range of grades 4–5, and the wet rubbing fastness was in the range of grades 3–4. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2859–2864, 2001     

Investigation into the dyeing of wool with Lanasol and Remazol reactive dyes in seawater

Freshwater is an increasingly scarce resource that is extensively used in textile wet‐processing. In seeking to identify alternative low freshwater‐usage coloration technology, this study examined the potential use of seawater (SEAW) as the dyeing medium for wool coloration using a range of reactive dyes. Initially, the dyeing behaviour of the wool fabric in simulated seawater (SSW) was compared with conventional dyeing from distilled water (DW) using α‐bromoacrylamide‐based Lanasol dyes and sulphatoethyl sulphone‐based Remazol dyes. These preliminary studies demonstrated that comparable coloration could be achieved in the SSW medium based on an assessment of the dye exhaustion, dye fixation, colour yield and levelness. Subsequent dyeing studies of wool using Mauritian seawater with both the Lanasol and Remazol reactive dyes confirmed that, based on the dye exhaustion, dye fixation, colour yield and levelness, comparable coloration could be achieved, highlighting the possibility of substituting freshwater with seawater as the dyeing medium.     

国内外活性染料的进展

两个三聚氯氰取代基分别在染料母体两端,藏青色染料结构如下[42]:     

One-bath dyeing of wool/acrylic blends with reactive cationic dyes based on monofluorotriazine

A series of reactive cationic dyes containing the monofluorotriazine structure has been synthesised and their dyeing behaviour on wool, acrylic and a 50:50 wool/acrylic blend studied using a one-bath method. The results indicate that reactive cationic dyes having this structure give a high level of exhaustion and fixation on these fibres. Fastness properties on the wool/acrylic blend were also in general very good.     

The release of reactive dyes from wool fibres by alkaline hydrolysis and their analysis by thin layer chromatography

A method is described for releasing reactive dye adducts from wool fibres. The resulting solutions are amenable to analysis by thin layer chromatography.     

Crosslinking nucleophilic dyes on wool

Nucleophilic amino-alkyl dyes have been synthesised by the simple expedient of reacting existing reactive dyes with ethylene diamine. These dyes when applied to wool behave as acid dyes, although there is a small amount of covalent bonding to the fibre, presumably through Michael addition at dehydroalanine residues formed from cystine degradation.

If substantive crosslinking agents could be applied then it might be expected that excellent dye-fibre covalent bonding could be achieved to produce dyeings with very high wet fastness properties. The crosslinking agent might be added either before, during or after the amino-alkyl dye application; the latter procedure should, in principle, give the most level dyeings. Crosslinking agents evaluated include hexamine, triacroylamino-hexahydro-s-triazine, methylene-bisacrylamide and 2-chloro-4.6-di(aminobenzene-4′-sul-phatoethylsulphone)-s-triazine. Hexamine and methylene-bisacrylamide are available commercially but the other agents were synthesised. Results obtained are very promising and offer potential wool dyeing methods which have better levelness than existing reactive dye systems.     

The use of reactive dyes in protein separation processes

The salient points of the chemistry of triazine based reactive dyes judged to be of interest to biochemists are summarised and the various alternative reactive systems and chromophores used in reactive dyes outlined. The development of the use of reactive dyes in dye affinity chromatography is discussed, parallels being drawn between textile dyeing and immobilisation techniques to provide suggestions for improvements in technique. The properties of the matrix are considered and structural features in the dye responsible for protein attraction analysed. The recent tailoring of dye structures to enhance utility in dye affinity chromatography and progress in the scaling up of high performance liquid affinity chromatography is reviewed.     

Laser Raman studies of α–bromoacrylamide reactive dyes and wool

The use of laser Raman spectroscopy in the investigation of interactions in α–bromoacrylamide reactive dye–wool fibre systems has been established. The spectra obtained (in particular using C. I. Reactive Red 84) provide some evidence to support the proposal that the dye reacts via addition at the double bond of the reactive group, followed by ring closure through nucleophilic substitution. Furthermore, preliminary studies of the effect of the commercial levelling assistant Albegal B on the aqueous dye environment have been made using C. I. Reactive Yellow 39. The results show that, whilst the primary interaction between the dye and auxiliary may be via the water–solubilising sulphonate groups of the dye, hydrophobic interactions are also important.     

One‐bath union dyeing of a modified wool/acrylic blend with acid and reactive dyes

Pretreated wool/acrylic fibre was obtained by a facile amidoximation process. Fibre characterisation (nitrogen content, tensile strength, shrinkage, infrared spectra and X‐ray diffraction) proved the success of the pretreatment. Union dyeing of wool/acrylic fabrics with acid and reactive dyes, namely CI Acid Red 40, CI Acid Blue 25, CI Reactive Red 194 and CI Reactive Blue 25, was obtained using a one‐bath dyeing process. Different factors that may affect the dyeability of the blend fibre, such as dyebath pH, liquor ratio, temperature, time and dye concentration, were evaluated with respect to the dye exhaustion, fixation, colour strength, levelling and fastness properties. Excellent to good fastness was obtained for all samples, irrespective of the dye used. The result of the investigation offers a new viable method for union dyeing of wool/acrylic fibres in a one‐dyebath process.     

The dyeing of cotton with phosphonic reactive dyes in alcohols

The poor fixation achieved with phosphonated reactive dyes on cotton in practice, particularly in printing, has prompted a study of the effect of reaction conditions and the use of different diimides to achieve fixation. It has been possible to achieve as much as 95% fixation with a typical dye under suitable application conditions, where decomposition of the diimide can be minimised.     

Dyeing of wool with temporarily solubilised disperse dyes

Temporarily solubilised disperse dyes derived from aminophenyl-4-(β-sulphatoethylsulphone) have been applied to wool fabric without the use of a levelling agent. By virtue of their characteristic dye structure, excellent levelling properties were observed on wool fabric. Good exhaustion, fixation and fastness test values were also obtained.     

Some novel azo reactive dyes

The synthesis of some novel azo dyes is described. They have an aldehyde auxochromic group in the dye molecule, and show promise as effective reactive dyes for wool.     

Jet printing with reactive dyes

The history of ink jet printing on textile substrates is reviewed and the major projects currently under examination are examined. The development of Procion reactive dye formulations and associated application technology for the ink jet printing of cellulose fabrics is discussed in detail.     

The efficiency of reaction between reactive fluorescent whitening agents and wool

Potential fluorescent whitening agents (FWAs) containing halogen atoms which intramolecularly quench fluorescence have been synthesised and applied to wool in a number of ways. Application by cold pad-batch methods revealed that the complete displacement of all halogen atoms by nucleophilic groups in wool did not take place. Treatment of these materials with morpholine, sodium carbonate or water was necessary to develop the full potential fluorescence yield of the FWA on the fabric. The fluorescence of FWAs can be quenched by the heavy atom effect, as shown by the fact that no fluorescence was observed when commercial FWAs were applied to brominated wool. If the FWA-treated brominated fabrics were subjected to a reduction treatment then the bromine atoms were removed and the fluorescence of the FWA was restored. Application of the potential FWAs by exhaustion, with thioureadioxide present in the liquor, at high temperatures always led to strongly fluorescent fabrics, implying that the halogen atoms were completely displaced using this application method, but the question remains as to how much of the displacement leads to covalent bonds between the fabric and the FWA.