Neutral dyeing of wool and wool/polyester blend fabrics using sulphatoethylsulphone reactive‐disperse dyes

Two models of temporarily anionic sulphatoethylsulphone reactive disperse dyes were applied to wool, polyester and wool/polyester blend fabrics at different dyeing pH. Maximum exhaustion values and colour yield were observed at pH 7. The results showed that reactive disperse dyes containing bis‐sulphatoethylsulphone reactive groups were more convenient for neutral dyeing of wool and wool/polyester blend fabrics if compared with a dye containing a mono‐sulphatoethylsulphone group. Excellent to very good wet fastness properties on all dyed fabrics were achieved.     

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.     

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.     

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.     

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.     

Improving the dyeability of wool by treatment with chitosan

A study of pretreatment of wool fabrics with chitosan by a pad-dry method has been carried out. The pretreatment effectively eliminates differences in dyeing behaviour between damaged and undamaged wool fibres, with an increase in the rate of dye uptake and the exhaustion of acid and reactive dyes. Penetration of the fibre by dyes has been followed using fluorescence microscopy and the role of the chitosan coating in the dyeing process clarified. Similar colour fastness properties were obtained on both untreated and chitosan-treated wool fabrics. The chitosan coating on wool fabrics has been examined by scanning electron microscopy. Evidence for the presence of chitosan was sought using a colorimetric method. It is believed that an approximately uniform and adherent chitosan sheath is formed on individual wool fibres.     

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.     

聚乳酸纤维的常压染色研究

在常压下,用七种分散染料及其复配染料对聚乳酸纤维进行染色,并对染色纤维进行了牢度性能测试。除了黄棕色外,其余染料的上染率都随着色度的增加而下降。同一只染料在同一的色度下,延长染色时间对增加染料的上染率作用不明显。随着染色温度的升高,黄素色和蓝色染料的上染率得到明显的提高,而对深红色和黄棕色染料而言这种作用并不明显。同时,通过测量染色纤维的色彩强度定量的描述了染料上染率对温度的敏感性。     

The effect of polyhydroxyurethane on dyeing of cellulosic fabrics with direct and reactive dyes

Dye yields and fastness properties are reported for direct and reactive dyes using a modified dyeing solution with polyhydroxyurethane. Excellent dye yields and colour fastness properties were obtained without the use of electrolytes, multiple rinsing or fixation agents, which are normally employed in cotton dyeing. From the results, it was found that polyhydroxyurethane media exhibit better dyeability and fastness than the normal aqueous media. Dye adsorption in polyhydroxyurethane media was much higher than in other aqueous systems. The dyed samples showed good hot pressing and washing colour fastness properties within the color change range. The excellent solubility of these dyes in the polyhydroxyurethane aqueous solution makes them ideal for use in exhaustion dyeing.     

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.     

Dyeing and finishing of lyocell union fabrics: an industrial study

Lyocell union fabrics, namely lyocell/silk and lyocell/polyester fabrics, were woven in different fabric constructions and dyed with reactive dyes, acid dyes and a disperse dye. The resulting dyed fabrics were given a resin finishing treatment and their wash fastness was measured. With appropriate dye selection and control of dyeing conditions, some bright solid shades and effective cross‐dyed shades were obtained. The dyed and finished fabrics had a smooth, lustrous handle, ideal for lightweight garments.     

红色复合多活性基活性染料的结构与性能关系研究--染色特性参数

应用直接性S、反应性R、竭染率E、表观固色率F、实际固色率Fr、移染指数MI、易洗涤性因子WF、匀染因子LDF等八个参数，描述了10只红色复合双活性染料的上染、匀染、清洗等染色特性。M型染料的上染曲线形状介于碱控型和盐控型之间，直接性相对较小的染料，上染曲线更接近于碱控型；直接性相对较大的染料，更相似于盐控型。在本文研究的染料中，用苯系重氮组分的染料直接性较小，易洗涤性好，移染指数和匀染性好，但竭染率和固色率相对较低。用蔡系重氮组分的染料具有良好的直接性，因而导致较好的竭染率和固色率和中等的匀染性。尤其是以2-萘胺-1，5-双磺酸为重氮组分的R4，适中的直接性、缓和的上染速度和易洗涤性，加上良好的移染性与匀染性，使其被选为M-型染料三原色之红色组分。但其固色率尚属中等水平。重氮组分上也具有硫酸酯乙基砜基的活性染料R5、R6，具有中等直接性，其反应性、竭染率、固色率均较高，和优异的易洗涤性和很好的湿处理牢度，但移染性和匀染性稍低．乙烯砜染料的直接性比相应的乙基砜硫酸酯染料大，在苯系重氮组分中差别比萘系明显。但E，F相差不大，乙烯砜的易洗涤性略差于相应的硫酸酯乙基砜染料。通过不同芳环、磺酸基和硫酸酯乙基砜基引入重氮组分，可以调节本文涉及的复合双活性基染料的亲和力、反应性，从而对染料的竭染率、固色率、易洗涤性、匀染性和湿处理牢度作出大致的预测，并可作为染料结构和复配增效配方设计的参考依据。     

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).     

Determining the dependence of colour values on yarn structure

The colour values of knitted cotton fabrics made from single and plied ring and compact yarns were investigated before and after dyeing. The fabric samples were knitted under the same constructional properties and then dyed with direct and reactive dyes. It was found that fabrics with ring yarns had high lightness and low chroma and colour strength values compared with fabrics with compact yarns. Also colour strength and colour difference values of dyed fabrics were assessed after increasing abrasion cycles (2500, 5000, 7500 and 10 000). The main changes in colour strength values were observed at 2500 abrasion cycles. The effect of abrasion on colour difference values of fabrics having ring yarns was more obvious than fabrics having compact yarns.     

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.     

Dyeing of nylon with reactive dyes. Part 2. The effect of changes in level of dye sulphonation on the dyeing of nylon with reactive dyes

Four mono-functional reactive monochlorotriazinyl (MCT) dyes, each derived from the same chromophore and possessing a single monochlorotriazinyl reactive group, but differing only in degree of sulphonation, were synthesised and evaluated on nylon. The colour yield, degree of exhaustion, fixation, and the fastness properties of each dye were assessed. Initial exhaustion, at pH 4, was high for all dyes but percentage fixation, via covalent bond formation, increased with increasing levels of sulphonation. In all cases fixation efficiency reduced markedly with increasing concentrations of dye applied.     

The use of trisodium nitrilo triacetate in the pad–steam dyeing of cotton with reactive dyes

This paper presents results on the use of trisodium nitrilo triacetate, a biodegradable alkaline organic salt, for pad–steam dyeing of cotton with reactive dyes as a replacement for conventionally used inorganic electrolyte and alkali. Two widely used dyes, CI Reactive Red 147 and CI Reactive Blue 250, were used in the study. The colour yield, dye fixation and ultimate colour fastness achieved by using trisodium nitrilo triacetate were closely comparable with those obtained by using inorganic electrolyte and alkali. The tensile breaking force and wrinkle recovery angle of the dyed fabrics were also measured and were slightly improved when using organic salt. Additionally, the dyeing effluent showed reductions in total dissolved solids content with trisodium nitrilo triacetate.     

Effect of Sandospace R on the dyeability of gamma-irradiated wool,wool/polyester and polyester fabrics with some disperse dyes containing amino groups

The effect of Sandospace R on the dyeability of gamma-irradiated wool, wool/polyester and polyester fabrics towards disperse dyes has been investigated. The effects of the different factors that may affect the colour yield of the dyed samples (such as radiation dose, Sandospace R concentration, pH strength of the dye bath, dye concentration, dyeing temperature and time were studied. In general, and regardless of the studied factor, the irradiated fabric showed a significant dye affinity for the disperse dyes employed compared/to the unirradiated fabrics. However, the different fabrics irradiated to a dose of 2Mrad showed the highest colour strength with a high level of dyeing. Also, it was observed that a concentration of Sandospace R as low as 0·5% effectively enhances the dye affinity for the disperse dyes used here. Moreover, it was found that the pH of the dyeing bath at which the highest colour strength obtained was 3. Increasing the dye concentration up to 4% based on fabric weight, caused a significant enhancement in the colour strength, whilst raising/the dyeing bath temperature from 60°C to 100°C appreciably accelerated the rate of dye uptake. Complete exhaustion absorption of the disperse dye occurred over a period of 2h. © 1998 Society of Chemical Industry     

The Development of Dyes and Methods for Dyeing Polyester

Early work on the dyeing of polyester fibre showed that only dyes of very low aqueous solubility had substantivity for the fibre, and that for dyeing at the boil without a carrier only the smallest molecular weight disperse dyes, and selected azoic combinations, had sufficiently high dyeing rate to give adequate colour yield in a practicable time of dyeing. The development of carriers for dyeing at the boil, and of machinery for batchwise dyeing under pressure at temperatues up to 140°C, extended the range of suitable dyes to those of lower dyeing rate but higher heat–fastness properties. As an alternative to exhaust dyeing, polyester may be dyed with disperse dyes by padding followed by dry heat fixation at temperatures up to 220°C, and this method has found its main commercial application in the continuous dyeing of polyester–cellulosic blend fabrics. The development of new disperse dyes has followed these trends in application methods, and the proportion of available dyes having higher heat–fastness properties has steadily increased from about 1950 onwards. Improvements have also taken place over the same period in the physical properties of the dyes, to meet the increasingly severe demands on dispersion properties imposed by the newer dyeing methods.     

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.