Reactive dyeing systems for wool fibres based on hetero-bifunctional reactive dyes. Part 2: Investigation of dyeing properties during the dyeing cycle

The dyeing behaviour during the dyeing cycle of a Sumifix Supra dye and some other commercial reactive dyes under various dyebath pH conditions was investigated. Studies of the dyeing of wool serge fabric indicated that the diffusion properties of hetero-bifunctional Sumifix Supra dyes generally lie between those of b-sulphatoethylsulphone (Remazol dyes) and monochlorotriazine (Procion H dyes).     

The effect of various anti-setting systems in wool dyeing. Part 1: Hydrogen peroxide based systems

Extensive setting of wool fabrics occurs during piece dyeing at the boil and gives rise to adverse changes in dimensional stability such as variable hygral expansion, loss in tensile strength and the appearance of unsightly marks such as 'crow's-feet' on the fabric surface. Anti-setting agents such as stabilised hydrogen peroxide systems have thus been marketed to control this problem. Much has been published regarding the anti-setting and hygral expansion properties achievable but little information regarding the chemical effect of boiling wool with acidic solutions of hydrogen peroxide is available. Fourier transform infrared reflectance spectroscopy has thus been extensively used to quantify the chemical changes occurring on boiling wool in such aqueous solutions of hydrogen peroxide.     

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.     

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     

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 effect of various anti-setting systems in wool dyeing. Part 2: Sodium maleate based systems

Wool is subject to permanent setting reactions during dyeing at the boil. Sodium maleate additions to the dyebath exert an anti-setting effect, and in the case of wool piece-goods dyeing, the magnitude of anti-setting was evaluated using the crease angle method. To achieve anti-setting, the key reactions are the nucleophilic addition of the activated double bond in sodium maleate with wool thiolate anion groups and with free hydrosulphide anions generated by cysteine thiol decomposition. Optimum antisetting effects were achieved when wool fabric was treated with sodium maleate at pH 3. Fourier transform infrared reflectance spectroscopy was used to monitor chemical changes to the wool fibre. Compared to untreated wool, two new frequencies at 1354 and 865 cm⁻¹ were apparent; the highest intensity values for these bands were obtained for wool treated at pH 3, which indicates that wool, being positively charged in this acidic solution, adsorbed more sodium maleate, thus enhancing the chances for nucleophilic addition reactions.     

Dyeing of nylon with reactive dyes. Part 1. The effect of changes in dye structure on the dyeing of nylon with reactive dyes

The dyeing behaviour of seven red commercial cellulosic reactive dyes, all based on the same chromophore and possessing one or more reactive group, and one to three chromophore units, were evaluated on nylon. Fixation levels appeared to be independent of the number of either reactive groups or chromophore units. Also, the degree of sulphonation, per se, appeared to have little effect on fixation, whereas the type of reactive group was important. The major determinant of dye fixation appeared to be associated with the shape of the molecule and the type, not the number, of reactive groups.     

Controlled coloration: a success strategy for the dyeing of cellulosic fibres with reactive dyes

The impact of improving the rate of right-first-time production on productivity and profitability for a batchwise dyehouse processing cellulosic fibres is reviewed. The measurement and level of performance required from reactive dyes to support right-first-time production is defined in the form of a reactive dye compatibility matrix (RCM). The application of the RCM as a diagnostic tool in dye selection and process design is outlined.     

The effect of various anti-setting systems in wool dyeing. Part 4; Sodium tetrathionate based systems

The tetrathionate anion has the potential to oxidise thiols specifically to disulphides; this property has been investigated in this paper from the point of view of using tetrathionate as an anti-setting agent in wool dyebaths. It was found that at pH 3 the addition of tetrathionate actually made the degree of permanent set greater than in its absence; however at pH 5 and pH 7 significant anti-setting benefits were achieved. The reason for the apparently contradictory result at pH 3 was found to be the substantivity and subsequent reactivity of thiosulphate anion for wool – this anion is a product of the reduction of tetrathionate by wool cysteinyl thiol residues.     

The effect of various anti-setting systems in wool dyeing. Part 3; Sodium thiocyanate based systems

Wool fabrics undergo setting during dyeing. The degree of set can be controlled by careful selection of dyebath conditions and also by the addition to the dyebath of chemicals termed anti-setting agents. The anti-setting effect of sodium thiocyanate has been evaluated according to its concentration in the dyebath and the dyebath pH. The fabric crease-angle method was adopted to estimate the degree of anti-setting. In the case of wool fabric boiled in the presence of sodium thiocyanate, good anti-setting effects resulted from the pH 3 and pH 5 treatment baths. Chemical changes in the wool were detected using FTIR analysis.     

Synthesis of reactive dyes based on the bis-(N-carboxymethylamino)monoquaternary-triazine-bis-ethylsulphone reactive group. Part 1: Application to cotton cellulose

Reactive dyes containing the bis-( N -carboxymethylamino)monoquaternary-triazine-bis-ethylsulphone [bis-( N -CMA)-MQT-bis-ES] group and related derivatives have been synthesised. When boiled under mildly acidic conditions, such dyes are able to form two small vinylsulphone dye molecules through a process of 1,2-trans elimination. The bis-( N -CMA)-MQT-bis-ES dye was applied using different dyeing procedures (novel dyeing methods 1 and 2). The dyeing and soaping-off results of bis-( N -CMA)-MQT-bis-ES dye were compared with a model sulphatoethylsulphone dye applied using the conventional alkaline fixation method used for applying this type of reactive dye to cotton. The bis-( N -CMA)-MQT-bis-ES dye showed higher exhaustion and fixation values applied using novel dyeing method 2 compared with the sulphatoethylsulphone dye applied using the alkaline fixation method. The soaping-off efficiency for the large bis-( N -CMA)-MQT-bis-ES dye applied using novel dyeing method 2 was the same as that obtained for the sulphatoethylsulphone dye applied using the alkaline fixation method.     

Accessibility of man-made cellulosic fibres. Part 1: Exhaust application of reactive dyes to never-dried lyocell, viscose and modal fibres

Exhaust application of a given reactive dye to never-dried lyocell, viscose and modal fibres gave virtually identical levels of exhaustion on each fibre, whether in the presence of salt alone or in salt plus alkali, as well as similar levels of fixation. This suggests that the accessibility and reactivity of the three never-dried fibres for selected reactive dyes, during a typical exhaust dyeing process, are the same.     

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.     

Solvent assisted dyeing of acrylic fibres. Part 2-dyeing with disperse and cationic dyes

The plasticising solvents ethylene carbonate, propylene carbonate, nitromethane and iso-amyl alcohol have been added to aqueous dyebaths containing disperse and cationic dyes. The dye uptake in all the cases was found to increase linearly with decrease in the glass transition temperature of the acrylic fibres.     

Protection of lyocell fibres against fibrillation; influence of dyeing with bis-monochloro-s-triazinyl reactive dyes

Four bis-monochlorotriazinyl (bis-MCT) reactive dyes, including Procion Orange H-ER, together with Remazol Black B, were applied, in turn, to lyocell fibres and their wet abrasion resistance (Nass-Scheuer-Festigkeit) measured. The bis-MCT dyes performed poorly, showing that little cross-linking had occurred and all were inferior to Remazol Black B. The cross-linking propensity of Procion Orange H-ER was not superior to the other bis-MCT dyes evaluated. A possible explanation for the apparent superiority of Procion Orange H-ER in a recent paper published in this journal may lie with fabric construction but not with the suppression of fibrillation once it has occurred.     

Textile applications of photochromic dyes. Part 5: application of commercial photochromic dyes to polyester fabric by a solvent‐based dyeing method

A series of commercial photochromic dyes was applied to polyester by a solvent dyeing process followed by thermal fixation using dichloromethane as the solvent. The process was optimised in terms of solvent/fabric ratio, dye concentration and the conditions of thermal fixation. The dyed fabrics showed reversible photochromism, developing colour on ultraviolet exposure and fading after removal of the ultraviolet source. The degree of photocoloration, background colours, fading characteristics, fatigue resistance and storage stability of the dyes were evaluated and comparisons made with the outcomes of a traditional aqueous disperse dyeing method. A study of the visible spectra of concentrated solutions of the dyes in a range of solvents provided evidence for the origin of the permanent background colours on the fabric when applied from solvents. Relationships were established between the magnitudes of the visible absorption in solution and the background colours developed, in relation to the nature of the solvents. The results suggest that toluene and ethyl acetate may offer certain advantages as solvents for the application of these dyes.     

Reactive dyeing of cellulosic fibers: Use of cationic surfactants and their interaction with reactive dyes

Cotton fabrics were dyed with three reactive dyes, C.I Reactive Blue 263, C.I Reactive Red 269, and C.I Reactive Yellow 208, after pretreatment of the fabrics with three alkyl trimethyl‐ammonium bromides (tmabs) having 12, 14, and 16 carbon atoms in the alkyl chain. The pretreated samples were dyed with standard dyeing methods using conventional, reduced amounts of electrolyte, and no electrolyte. Pretreatment with the three cationics (tmabs) resulted in an increase in dye exhaustion with all dyes used, whereas total dye fixation was lower for both red and blue dye and equal for the yellow, when compared to the reference untreated samples dyed according to the same standard dyeing method. The interaction between dodecyl trimethyl‐ammonium bromide and the three dyes was studied and the stoichiometry of the various dye/dodecyl trimethyl‐ammonium bromide (12‐tmab) complexes formed has been deduced. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Neutral-fixing reactive dyes for cotton. Part 1 —synthesis and application of quaternised S-triazinyl reactive dyes

A number of different tertiary amines have been employed to prepare the corresponding quaternised triazines from a selected monochloro-s-triazine reactive dye. Preparation conditions have been established along with suitable analytical methods. The reactivity of the quaternised dyes with cellulose has been determined, special attention being paid to neutral fixation at high temperatures (100°C). Good neutral fixation was achieved with all the tertiary amine derivatives studied. In the case of the nicotinamide derivative an anomalous hydrolysis reaction involving ring opening was noted; this reaction led to the formation of aminotriazine rather than the expected hydroxytriazine.