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.     

Print-Batch(Cold)—A New Process for Wool

A cold printing process has been developed from the IWS pad-batch(cold) method for the dyeing of wool cloth. The chemical aspects of the technique are discussed with particular reference to the role of sodium bisulphite in promoting dye fixation and increasing the colour yield. The system used for the selection of reactive dyes for application to wool in the cold is described. Typical printing procedures are outlined.     

Prediction of recipes for cotton cationisation and reactive dyeing to shade match conventionally dyed cotton

Cationisation allows cotton to be dyed with anionic dyestuffs (including anionic pigment dispersions) without the need for salt, and with decreased usage of dye, water, and energy. Appropriate cationisation levels play a part in dyeing properties such as fabric levelness, in fastness properties such as lightfastness, and in the overall cost of the cationisation treatment. The objective of this work is to assess whether it is possible simultaneously to predict a dye recipe and cationisation treatment level for cotton to yield a colourless or nearly colourless dyebath at the completion of the dyeing to match the shade of conventional fibre reactive dyeing of cotton. It has been shown that it is possible to model a cold pad batch cationisation process, relate the colour yield data and cationisation level for individual dyes, and finally predict a dyeing recipe and the required corresponding cationisation treatment to match the shade of conventional fibre reactive dyeing of cotton. The predicted dye recipe and cationisation amount yield colourless or nearly colourless dyebaths at the conclusion of the dyeing process.     

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.     

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.     

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.     

Pad-Batch Dyeing of Wool with Reactive Dyes

A process for the production of fast, bright dyeings on wool cloth is described. Reactive dyes applied by a pad-batch (cold) method yield level dyeings with very high colour yields. Virtually 100% fixation has been obtained with Procion M (ICI) dyes applied to wool from mildly acidic solutions, after batching for up to 24 h at room temperature. Yellowing of wool does not occur under these conditions, which facilitate the production of dyeings of a brightness and fastness that cannot be achieved under conventional dyeing conditions for wool.     

Effect of atmospheric pressure helium plasma on felting and low temperature dyeing of wool

Wool fabrics were treated with atmospheric pressure helium glow discharge plasma in an attempt to improve felting and dyeing behavior with cold brand reactive dyes using cold pad‐batch method at neutral pH. On glow plasma treatment, the hydrophilicity of wool surface and its resistance toward felting was greatly improved without any significant damage to the cuticle layer. The color strength of the plasma treated dyed wool on the surface (in terms of K/S) was found to be nearly double of the color strength of dyed untreated wool fabric. However, the corresponding total dye uptake of the treated wool increased by a much lower value of 40%–50%. The reason behind this altered dyeing behavior was investigated by studying the dye kinetics using infinite bath and surface characteristics using SEM and SIMS. It was found that the glow plasma treatment greatly transformed the chemical surface of the wool fibers. It resulted in uniform removal of hydrophobic cuticular layer, which resulted in better diffusion of the dye molecules into the fiber, and formation of hydrophilic ? NH₂ groups near the surface, which helped in anchoring the dye molecules close to the surface giving higher color strength than expected. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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.     

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.     

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.     

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.     

The accelerating effect of a small cationic quaternary ammonium compound and the adsorption kinetics in the dyeing of silk with reactive dyes

In order to develop an eco‐friendly method for silk reactive dyeing that uses a lower accelerant dosage to achieve a higher dye fixation, hexyl dimethyl octyl ammonium chloride was synthesised as an accelerant for the dyeing of silk with reactive dyes. The accelerating effect, corresponding adsorption kinetics, and interaction mechanisms among hexyl dimethyl octyl ammonium chloride, reactive dyes, and silk were investigated. At hexyl dimethyl octyl ammonium chloride concentrations of 10.8–14.4 mm , the dye fixations for three reactive dyes were much higher than those achieved with sodium sulfate, even though the required dosages of hexyl dimethyl octyl ammonium chloride were 30–40 times lower than those of sodium sulfate. The wash fastness, rub fastness, light fastness, K/S, and colour difference values after dyeing with hexyl dimethyl octyl ammonium chloride were similar to those obtained using sodium sulfate, and silk can be dyed uniformly. The adsorption kinetics followed a second‐order kinetic model. The activation energies of surface adsorption for the three reactive dyes were lower than those of sodium sulfate. The high fixation of reactive dyestuffs and the low required dosage of hexyl dimethyl octyl ammonium chloride demonstrate that the use of this new accelerant provides a novel, highly efficient method for silk dyeing. A possible acceleration mechanism of hexyl dimethyl octyl ammonium chloride for reactive dyes adsorbed on the surface of silk was proposed, based on a series of activation parameters of the adsorption process.     

羊毛活性/分散染料染色染料相互作用研究

在一定工艺条件下，用活性染料染羊毛，再用分散染料套染，其K／S值大于单独使用活性和分散染料染色的K／S值之和，活性染料对羊毛起到了改性作用，使分散染料染色湿牢度有显著提高。随着活性染料浓度的增加，分散染料的上染率也增加。用分散染料套染活性染料，其匀染性相对于单独使用活性染料有提高。     

Studies on Some New Reactive Disperse Dyes

The preparation of some new reactive disperse dyes which can be used for dyeing 100% synthetic and fibre blends is described. The preparation of some disperse dyes containing a chlorohydrin group is also described. This radical is the precursor of the epoxide reactive group in the active form of these dyes. Dyeings produced on various fibre blends by a two–stage high–temperature and by a carrier–dyeing technique are assessed. It was found that dyeings produced by the high–temperature technique were brighter, more level and possessed much better technical properties than those obtained using the carrier–dyeing method. The fastness properties of dyed samples were determined and found to be comparable with those of conventional disperse and reactive dyes. The colour yield was also determined in order to examine the possibility of obtaining deep dyeings on blended fibres, and to evaluate the potential commercial use of these dyes for dyeing blends as well as 100% synthetic–polymer fibres.     

Some Observations on the Dyeing of Wool,Polyester and Acrylic Fibre Tops by Continuous Pad–Steam Methods

Meeting of the West Riding Region, held at the University of Bradford on 8 October 1970, Mr J. Furniss in the chair The continuous dyeing of wool, polyester and acrylic tops by pad–steam methods is discussed. For wool, evidence is given to indicate the specific action of pad-liquor additives and to show that successful results can be obtained by both one-phase and two-phase methods. In the pad–steam dyeing of polyester top, the problems encountered in the selection of compatible dyes can be solved by a study of the effect of time and temperature on exhaustion. The problems associated with the production of heavy depths on acrylic fibre tow are considered in detail. Under practical conditions, the saturation obtained in pad–steam dyeing is lower than that in conventional dyeing methods.     

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.     

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.     

The Monitoring of Dyebath Composition by Transmission Measurements

A preliminary investigation has been made of the concept of using transmission of solutions of diluted dyebaths as a means of monitoring the baths prior to use in bulk–dyeing processes. So far this has been done only by calculation, using the methods of computer match prediction, to establish a correlation between the colour of the diluted pad–Liquor in the application of Dispersol T and Procion T dyes to a polyester–cotton blend fabric by a pad–bake process, and the expected colour of a dyeing made from it. The correlation obtained suggests that the method justifies further development work, in circumstances specific to its intended use, as a means of checking that a prepared dyebath is suitable to produce a dyeing which is within specified tolerance limits.     

Synthesis and Application of Some New Reactive Chlorohydrin Dyes

Azo and phthalocyanine dyes carrying the chlorohydrin group, as the precursor of the reactive epoxy group, were prepared using new catalyzed reactions. The reactive group is attached to the coupling component in some cases and to the diazonium component in other cases. A phthalocyanine dye carrying two reactive groups was also synthesized. The dyeing of cotton, wool and multifibre fabrics was studied, under different dyeing conditions. Various techniques of dyeing and printing were used. Exhaustion and padding methods were investigated for dyeing, and direct, reserve and discharge methods for printing. One–stage and two–stage procedures were employed for both printing and dyeing. It was found that the chlorohydrin reactive dyes prepared in the present work could be applied by nearly all known methods of dyeing and printing on cotton, wool, viscose rayon, nylon and acrylic fibres. The dyeings obtained had satisfactory fastness properties and showed fairly good dye fixation on the substrate.