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.     

Metal-complex Dyes for Wool and Nylon — 1930 to date

An introduction outlining the scope and limitations of this paper is followed by a brief explanation of the essential structural features of metal-complex dyes. The earliest metal-complex dyes were produced directly within the fibre material by reacting a metallisable dye with a chromium compound in situ. The first chromium complex dyes prepared in substance, were the chromium complexes containing sulpho-groups, synthesised by R Bohn of BASF, in 1912, the application of which was first made possible after the discovery by Ciba of a satisfactory dyeing process based on the use of a dyebath made strongly acid with sulphuric acid. These two classes of dye dominated the dyeing industry into the 1950s. At that time 1:2 metal-complex dyes without sulphonic acid groups but containing nonionic substituents as solubilising groups were introduced. These complexes were applicable from neutral to weakly acid dyebaths, which minimised the damage to the fibres. These dyeings were characterised by high fastness to light and wet treatments. Later, for commercial reasons, sulphonic acid groups were again introduced into the dye molecule to increase their hydrophilic properties. These dyes also have become well established as a result of the introduction of new dyeing methods and the development of dyeing auxiliaries designed to promote level dyeing. In addition to these types of metal-complex dyes, further metal-complex dyes selected from the extensive patent literature of the last 50 years because of their interesting structure are described.     

One‐pass process for the continuous dyeing of polyester/unmercerised cotton blends with disperse/reactive dyes. Part 2: Process modifications to improve the colour yield of selected reactive dyes on the cotton component of the blend†

One of the limitations of DyStar’s TTN one‐pass continuous dyeing process for dyeing polyester/unmercerised cotton blends with disperse and reactive dyes is its inability to achieve heavy depths economically and part 1 of this study indicated that the limitation could be attributed to the reactive dye [ 1 ]. In this study, the constituents of the pad liquor were varied to determine if the visual colour yield of selected reactive dyes 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 TTN process was as a result of inefficient ‘delivery’ of the dye to the reactive sites on the cotton.     

The use of ultraviolet radiation in an adsorbable organohalogen-free print preparation for wool and in wool dyeing: the Siroflash process

German legislation controlling the discharge of adsorbable organohalogens (AOX) in process effluents has focused attention on the need for environmentally acceptable alternatives to chlorination as a prepare-for-print (PFP) treatment for wool. The Siroflash process is a novel AOX-free approach which involves continuous UV irradiation of dry wool fabric, followed by conventional wet oxidation using hydrogen peroxide or permonosulphuric acid. Although permonosulphuric acid or peroxide treatments alone are ineffective as a PFP, the colour yields of prints on Siroflash-treated fabric are similar to those on chlorinated wool. The synergistic interaction between UV exposure and wet oxidation results in high levels of cystine oxidation, cuticle damage and loss of soluble protein, all of which are highly specific to irradiated surface fibres. UV irradiation of wool can significantly increase dyeing colour yields. The use of 1:1 metal-complex dyes is particularly effective, and a 3% o. w. f. dyeing on UV-treated fabric can produce a better depth of shade than a 5% dyeing on untreated fabric.     

Reactive dyeing of silk using commercial acid dyes based on a three‐component Mannich‐type reaction

Acid dyes are employed for commercially dyeing silk, which results in ionic bonds between the silk fibroin and the dye. This generally leads to low wet fastness properties for dyed silk fabrics. In this work, three commercial acid dyes with aromatic primary amine structures were selected to dye silk using a Mannich‐type reaction, resulting in improved wet fastness of dyed silk by forming covalent bonds between silk fibroin and dye. The Mannich‐type reactive dyeing was applied to silk fabrics at both 30 and 90°C in trials. Dyeing at 90°C can shorten the dyeing time compared with dyeing at 30°C, even although dye exhaustion and relative fixation at 90°C were a little lower. The dyeing process was optimised when the dyeing temperature was 90°C, dyebath pH 4, dye‐to‐formaldehyde ratio 1:30 and holding dyeing time 60 minutes. The results showed that the dye exhaustion on silk fabrics for the three aromatic primary amine‐containing acid dyes exceeded 94% and their relative fixation was over 80%. Their washing and rubbing fastness reached grade 4 or higher. Hence, the colour fastness properties of dyed silk fabrics using the Mannich‐type reactive dyeing method is superior to the conventional acid dyeing method using the same aromatic primary amine‐containing acid dyes. The Mannich‐type reactive dyeing for silk fabrics at 90°C can be developed into a novel and rapid reactive dyeing method, promising an effective dyeing process with excellent colour fastness.     

Instrumental Colour Prediction A Potential Aid to Dye and Process Selection

A relationship has been established between the dyeing properties of fibre–reactive dyes and the spectral reflectance properties of the colours produced on machine–washable wool. The information gained in routine dye calibration for instrumental colour–prediction systems may be used by the practical dyer for dye selection. The spectral reflectance properties of the resultant dyeings are explained in terms of the diffusion, fixation and level–dyeing properties of specific fibre–reactive dyes applied to wool by exhaust and pad–dyeing processes.     

Electrochemical oxidation of reactive dyes: method validation and application

Electrochemical oxidation is a very effective technique for wastewater processing and, in the textile industry, it can be employed to remove colour from residual dyeing and washing liquors. In previous studies, the main factors were established for the control of the electrochemical removal of reactive dyes from textile wastewater. Mathematical models were proposed for the decolorisation of these dyes and for the electrical consumption. In the present work, these models are analysed and a three-step methodology is established in order to determine whether a dye can be removed from wastewater by electrochemical treatment. This methodology is applied and verified on a further four reactive dyes. The mathematical models are also employed to evaluate the colour removal from textile wastewater samples containing reactive dyes.     

Dyeing and antimicrobial studies on polyamine/epichlorohydrin condensate incorporated viscose rayon fibres

Modified viscose rayon fibres were produced by incorporating different doses of polyamine/epichlorohydrin condensate in the dope. The modified fibres show excellent dyeability with heterobifunctional reactive dyes without electrolyte. The wash fastness and the light fastness of the modified fibres dyed with reactive dyes were good. The modified fibres also showed excellent dyeability on dyeing with different acid and metal-complex dyes. The amount of additive present in the fibre was assessed from its nitrogen content and percentage exhaustion was found to increase with increasing quantity of additive. Tonal changes and increase in light fastness with acid and metal-complex dyes have been attributed to the aggregation of dye in the fibre. Fibres containing more than 3% additive in the dope showed greater than 99% bacteria reduction on testing the antimicrobial activity against Escherichia coli and Staphylococcus aureus . It was observed that the antimicrobial activity deactivated on repeated washing using surfactants. The acid-dyed fibres also showed a decrease in antimicrobial activity.     

Deep‐coloured polyester/cotton blends with low concentrations of polymethylol dyes by a one‐pass continuous dyeing process

An obvious limitation of the one‐pass continuous dyeing process for polyester/cotton blends is its inability to achieve deep colour depth, which is caused by the low dye fixation yields of commercial reactive dyes. In this study, the performances of polyester/cotton blends dyed with high‐fixation polymethylol dyes and disperse dyes were compared with those of polyester/cotton blends dyed with a mixture of reactive dyes and disperse dyes. Polymethylol dyes were observed to be suitable for dyeing polyester/cotton blends when used in low concentrations; the required concentrations of polymethylol dyes were only 23–58% of the concentrations of commercial reactive dyes required to reach a given colour level on polyester/cotton blends. The wash and crocking fastness of polyester/cotton blends dyed with polymethylol dyes were similar to those of polyester/cotton blends dyed with reactive dyes.     

Pomegranate fallen leaves as a source of natural dye for mordant-free dyeing of wool

The application of metal mordants is usually necessary in dyeing of wool with natural dyes to improve the dye exhaustion and fastness properties. The majority of metal salts generally used as mordants are considered as toxic and it is important to find replacements for them. Plant sources with high content of tannins are good candidates as bio-mordant or colourant to overcome this drawback. In this study, the waste fallen leaves of pomegranate tree were used as a source of natural dye for the eco-friendly dyeing of wool fabric without the use of metal mordants. The dyeing process variables including dye concentration, dyebath pH, and temperature were optimised using response surface methodology to obtain the highest colour strength. The colour strength was increased by increasing the natural dye powder up to 100%owf while the optimum pH and dyebath temperature were 4 and 100°C, respectively. The sample dyed under the optimal condition exhibited good fastness properties against washing and light. This study approved the potential of Punica granatum fallen leaves for the dyeing of wool without any mordant, while high fastness properties were obtained.     

Synthesis,spectral and dyeing properties of phenylazopyrazolone‐containing acylamide disperse dyes designed for poly(lactic acid)

A series of phenylazopyrazolone disperse dyes containing an acylamide moiety were synthesised from carboxyl‐containing acid dyes via chlorination and amidation with different sorts of amines. The structures of these new dyes were confirmed by Fourier Transform–infrared, proton nuclear magnetic resonance, mass spectroscopy and elemental analysis. Their solvatochromic properties in different solvents were also investigated and the absorbance spectra of the acylamide dyes in solution exhibited a red shift when dissolved in dimethylformamide, compared with acetone. Their dyeing behaviour, including dye sorption, colour build‐up and colour fastness properties on poly(lactic acid) fibres, was also determined, whereupon it was found that the tertiary acylamide dyes simultaneously exhibited high dye sorption and satisfactory colour build‐up and fastness properties on the poly(lactic acid) fabric.     

Use of ultrasonic energy in reactive dyeing of cellulosic fabrics

The use of ultrasonic energy in dyeing cotton fabrics with monochlorotriazine and vinylsulphone reactive dyes has been studied spectrophotometrically. The dyeings carried out conventionally and by the use of ultrasonic techniques were compared in terms of percentage exhaustion, total amount of dye transferred to the washing bath after dyeing, fastness properties and colour values of the dyed materials. Overall results have shown that the use of ultrasound in reactive dyeing of cellulosic fabrics can result in energy savings, less water consumption, increased depth of colour and better process conditions.     

Dispersant‐free dyeing of poly(lactic acid) fabric with temporarily solubilised disperse dyes from azopyridone derivatives

Poly(lactic acid) fibre is derived from annually renewable crops and known to be 100% compostable. In order to extend its environmental friendliness into the dyeing process, dispersant‐free dyeing of poly(lactic acid) fabric with three temporarily solubilised azo disperse dyes based on hydroxypyridone moiety containing a β‐sulphatoethylsulphonyl group was investigated. The dyes were successfully applied to poly(lactic acid) fabric without the use of dispersants. The colour yields of the dyes on poly(lactic acid) fabric were observed to be dependent on dyebath pH and dyeing temperature. The optimum results were obtained at pH 4–5 and 110 °C. One of the dyes showed a colour yield as good as that of a commercial disperse dye and good build‐up on poly(lactic acid) fabric. All of the dyes could be alkali cleared owing to ionisation of the dye under mild alkaline conditions. Wash fastness was good to very good, and light fastness was good. The chemical oxygen demand levels of the poly(lactic acid) dyeing effluent from the dyes were considerably lower than those from a commercial disperse dye.     

锌金属和镀锌染色(一)

介绍了锌金属和镀锌层染色的特点,选择染料的原则及适用的染料类型(包括媒介染料、直接染料、酸性染料、活性染料和可溶性还原染料)。从染料的表面活性,染料与铬酸盐转化膜之间的作用力,染色过程及染色层的位置等方面阐述了锌金属和镀锌层染色的机理。     

Fixation of reactive dyes using radio-frequency energy

Radio-frequency (r.f.) energy has been used to increase the fixation rate of reactive dyes on cotton fabric in pad-batch dyeing. A parallel-plate r.f. applicator was used to heat batches of fabric containing reactive dye formulations. The time required for fixation of the dyes was reduced from several hours to a few minutes by heating the fabric in the radio-frequency field. Reactive dyes incorporating three different types of reactive groups, vinylsulphone, nicotinic acid, and mixed vinylsulphone/ monochlorotriazine were studied and found to be applicable using the hot pad-batch method. The colour yield and wash fastness of dyeings with the vinylsulphone/monochlorotriazine bifunctional dyes using r.f.-assisted fixation was equal or superior to those of dyeings performed by conventional cold pad-batch dyeing methods.     

One‐bath union dyeing of wool/polytrimethylene terephthalate blends†

The one‐bath dyeing of blends of polytrimethylene terephthalate (PTT) staple and wool has been investigated. The exhaustion of selected Terasil disperse dyes on PTT fibre and Lanasol reactive dyes on wool was measured as a function of temperature, together with the cross‐staining of the Terasil dyes on the wool component and the Lanasol dyes on PTT component. Most Terasil disperse dyes achieved satisfactory dye uptake on PTT at 110 °C, whereas on conventional polyester (polyethylene terephthalate) temperatures of up to 130 °C are required. An optimised union‐dyeing technique for wool/PTT blends was developed which minimised the staining of Terasil disperse dyes on wool and produced dyed goods with high levels of wet colour fastness. Carriers were not required to enhance the dyeability of PTT at low temperatures. The wool component appeared to be protected against damage at 110 °C by the reactive dyes. The results indicate the potential for blending PTT fibre and wool to produce fabrics that are easier to dye at lower temperatures than conventional wool/polyester blends.     

One‐bath dyeing of polyester/cotton blends with disperse and bis‐3‐carboxypyridinium‐s‐triazine reactive dyes. Part 2: Application of substantive reactive dyes to cotton at 130 °C and neutral pH†

An earlier paper reported that the reactive dyes (not the disperse dyes) were responsible for the inability to achieve heavy depths of shade, when dyeing polyester/cotton blends by a one‐bath process at 130 °C and neutral pH using reactive dyes containing a 3‐carboxypyridinium‐s‐triazinyl group. It was shown that the poor colour yield of the bis‐3‐carboxypyridinium‐s‐triazine reactive dyes was because of their low exhaustion level at 130 °C and pH of 7.0–7.5. We now report the synthesis and evaluation of some bis‐3‐carboxypyridinium‐s‐triazine reactive dye structures, possessing highly substantive chromophores, as a means of obtaining high colour yield, on 100% unmercerised cotton, under the specified dyeing conditions. The technical performance of these dyes under such conditions was compared with that of selected Novacron (Cibacron) LS and Procion H‐E dyes, applied under their recommended (atmospheric) dyeing conditions.     

Research in the cold pad–batch dyeing process for wool pretreated by hydrogen peroxide

The cold pad–batch dyeing process of wool pretreated by hydrogen peroxide was carried out with Lanasol reactive dyes and Realan reactive dyes. The influences of various conditions of the dyeing process, including urea dosage, sodium bisulphite dosage, pH value, batching time and the liquor pickup on colour yield, were analysed. Fixation, levelness of dyeing, dye penetration, colour fastness, breaking strength and elongation were compared between untreated and treated wool fabrics. The study showed that cold pad–batch dyeing of wool fabric is a good prospect for future use because of the resulting advantages, such as higher fixation yield, less energy usage and lower sewage discharge.     

Selecting reactive dyes for all-in dyeing of polyester/ cotton blends

As a preliminary study to an investigation of the feasibility of dyeing polyester/cotton blend by an all-in process using a pH-shift method, we have investigated the suitability of three types of conventional reactive dyes by considering the effects of pH and temperature on their hydrolysis and fixation behaviour. Monochlorotriazine, vinyl sulphone and bifunctional high exhaustion dyes were assessed but only the bifunctional reactive dye gave acceptable colour yield under the conditions likely to be employed during such a dyeing process.     

A significant approach to dye cotton in supercritical carbon dioxide with fluorotriazine reactive dyes

A series of fluorotriazine reactive dyes have been synthesized and applied to dye cotton in supercritical carbon dioxide (scCO₂) with good dyeing results. The pieces of cotton to be dyed were previously presoaked in a protic solvent and cosolvents were applied during dyeing. The colour strength of the dyeings was evaluated by K/S measurements. The K/S values achieved on cotton dyed were up to 35.8 ± 4.2. Even after the cotton was subjected to a Shoxlet extraction at 358 K for 1 h, a maximum K/S value of 20.2 ± 1.8 was measured. The percentage of dye molecules chemically fixed to the cotton was on average 85%. The excellent reactivity of fluorotriazines allowed a reduction of 3 h on the dyeing time. It is noticeable that a dye concentration of 10% on weight of the fibre (owf) can be applied to dye cotton with fluorotriazines, since no damage of the cotton fibres occurred, as observed for the chlorotriazines at this high dye concentration.Dyes with fluorotriazine as reactive group were found to be the most preferable dyes for dyeing cotton in scCO₂, as they were able to exceed the limitation of the reaction with the cotton.