Innovation and application of dyes with high fixation

Reactive dyes are the main species for cotton dyeing due to their wide range of hue, satisfactory color fastness and facile application method. Aiming at increasing fixation on cotton fibers, benzimidazolone yellow reactive dyes, sulfonamide red reactive dyes and anthraquinone azo blue reactive dyes are designed. The preparation, characterization and application properties of these dyes with high fixation are introduced in detail. In order to achieve dye fixation to near 100%, macromolecular cro...     

深色活性染料的近期进展

讨论了深色活性染料的发展现状,指出今后进一步发展的焦点在于提高活性深黑的固色率和改进活性深红的湿处理牢度,对目前存在的问题提出了改进措施。     

Application of a reactive cationic dye to wool

This is a study on the application of a new type of reactive cationic dye. Stripping agents and the influence of aftertreatment are discussed. The result shows this kind of dye is more suitable than conventional reactive dyes for wool and the urea-surfactant method is the best stripping method.     

Developments in the chemistry of reactive dyes and their application processes

This review describes the immense impact of reactive dyes on the textile industry. Their use on cellulosic fibres is especially important, but their growing popularity on polyamide substrates is notable. Detailed information is given about developments both in the chemistry of reactive systems and in the chemical technology involved in their application to a variety of fibre types. It is also pointed out that further research is necessary to improve dye–fibre fixation efficiency, especially when dyeing full shades on cellulosic fibres. This work is necessary to address the current environmental problem of colour in dyehouse effluent. The potential solutions reviewed include multifunctional reactive dyes, cationic reactive dyes, and cellulose fibre modification.     

Design, synthesis and application of easy wash-off reactive dyes

New dyes that not only give good fixation levels but also relatively low substantivity in the hydrolysed form were the targets of this research. Our approach involved lowering the substantivity of the hydrolysed dye by reducing the planarity that is required for dyes to have high substantivity on cotton. In this regard, bifunctional bis-dichlorotriazine (bis-DCT) and tetrafunctional bis-monochlorotriazine/bis-sulphatoethyl sulphone [bis-(MCT/SES)] reactive dyes were made, using selected diaminobiphenyls. Bis-DCT bifunctional reactive dyes were applied to cotton by a pad–batch method, while bis-(MCT/SES) tetrafunctional reactive dyes were applied to cotton by a pad–dry–cure. Following dye application, it was found that the resultant hydrolysed dyes easily washed off the fibre surface and that the dyed cotton fabrics had colour fastness to rubbing and laundering properties that were comparable with the commercial prototypes used in this study. However, it is also apparent that the combination of relatively low water solubility and large molecular size has an adverse effect on fibre penetration.     

Synthesis and properties of poly(styrene-co-maleic acid) macromolecular reactive dyes

To obtain a new type of macromolecular reactive dye with high fixation and good light fastness, poly(styrene-co-maleic acid) was synthesised by co-polymerisation of styrene and maleic anhydride, then, through nitration, reduction, diazotisation and coupling reaction, novel macromolecular reactive dyes were prepared with a solubility greater than 60 g/L. The dyes were used to dye cotton fabrics; the results showed their fixation was more than 92%, and both the rub and wash fastness of the dyes were good. The light fastness of the red and blue dyes with the ethoxy group on melamine was grade 4, and for the yellow dye reached grade 5. The poly(styrene-co-maleic acid) macromolecular reactive dyes exhibit very good application prospects in practice.     

3D-QSPR method of computational technique applied on red reactive dyes by using CoMFA strategy

Cellulose fiber is a tremendous natural resource that has broad application in various productions including the textile industry. The dyes, which are commonly used for cellulose printing, are "reactive dyes" because of their high wet fastness and brilliant colors. The interaction of various dyes with the cellulose fiber depends upon the physiochemical properties that are governed by specific features of the dye molecule. The binding pattern of the reactive dye with cellulose fiber is called the ligand-receptor concept. In the current study, the three dimensional quantitative structure property relationship (3D-QSPR) technique was applied to understand the red reactive dyes interactions with the cellulose by the Comparative Molecular Field Analysis (CoMFA) method. This method was successfully utilized to predict a reliable model. The predicted model gives satisfactory statistical results and in the light of these, it was further analyzed. Additionally, the graphical outcomes (contour maps) help us to understand the modification pattern and to correlate the structural changes with respect to the absorptivity. Furthermore, the final selected model has potential to assist in understanding the characteristics of the external test set. The study could be helpful to design new reactive dyes with better affinity and selectivity for the cellulose fiber.     

Pad-Batch Dyeing of Wool Fabric—Development of an Industrial Process*

This paper describes an industrial procedure developed for the application of dyes of good fastness properties, especially reactive dyes, to wool fabric by a pad-batch technique, following the initial observations (7) that by dyeing from concentrated solutions of urea the rates of diffusion and of reaction of reactive dyes with wool are greatly increased. The chemical and mechanical developments necessary to apply this initial observation under practical dyeing conditions are described.     

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.     

Sequential decolourization of reactive textile dyes by laccase mediator system

BACKGROUND: The use of enzymes has attracted much interest for the decolourization of dyes from wastewater as an alternative to conventional treatments, which have limitations. Laccase can be used to decolourize dyes and its substrate range can be extended by inclusion of mediators. RESULTS: Sequential decolourization of reactive dyes was carried out by a laccase mediator system using as mediators violuric acid and 1‐hydroxybenzotriazole. Violuric acid resulted in a high level of decolourization on the first and second cycles for reactive blue 114 (≥95%), reactive yellow 15 and reactive red 239 (≥80%), while for reactive black 5 a slightly lower value was observed (70%) on the second cycle. The degree of reactive blue decolourization remained at 90% after the third cycle, and at about 60% after seven cycles. With the other dyes decolourization decreased to 50–70% on the third cycle and further up to the final cycle (lower than 20%). When using 1‐hydroxybenzotriazole as mediator a slight decrease in decolourization efficiency was obtained. Correlation between dye oxidation peak potential and dye degradation after 10 min reaction was obtained for both mediators. CONCLUSIONS: These results show that sequencing batch decolourization by laccase mediator system is a useful methodology for treating textile dying wastewaters with a high potential for application at industrial level. Copyright © 2008 Society of Chemical Industry     

Haloacetyl reactive dyes-synthesis and application to silk

A series of haloacetyl reactive dyes have been synthesised. The reactivity of haloacetyl groups and the dyeing properties of the dyes on silk fabric were studied. The results show that the bromoacetyl group is more reactive than the chloroacetyl group and molecules containing a bromoacetyl group would dye silk under relatively mild dyeing conditions. Both the exhaustion and fixation on silk fabric are increased if a second reactive group is present in the molecule     

Fading of reactive dyes on cellulose under light and perspiration

The fading of nine reactive dyes on cotton fabrics under light and perspiration was investigated using the ATTS standard and many factors affecting the stability of these dyes were discussed, viz. exposure environment, chromophores of dyes, the pH value and components of the artificial perspiration. The experimental results show that reactive dyes exhibit lowest stability under simultaneous exposure to light, perspiration and oxygen in a wet state. Among all selected dyes, Cu-complex azo reactive dyes appear to be the most sensitive, whereas anthraquinone reactive dyes show the best stability. The pH value of perspiration may also greatly influence the fading of dyes by affecting the hydrolytic stability of dye–fibre bonding. Furthermore, the study on the contribution of artificial perspiration components discloses that some acidic components play major roles in the fading of the dyes and inorganic salts usually decelerate the fading extent.     

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 cotton with reactive dyes under neutral conditions

This paper describes a new method to dye cotton with selected reactive dyes by long-liquor – or so-called 'exhaustion'– processes under neutral conditions. Particularly promising results were obtained with reactive dyes containing free vinyl sulphone residues. Although there are dyes on the market that contain free vinyl sulphone groups, for example, the Novacron C (Huntsman) range of dyes, many of this class contain 'blocked' vinyl sulphone residues; examples include sulphatoethylsulphone or chloroethylsulphone precursor groups, and these may be preactivated to the highly reactive vinyl sulphone form simply by a mild alkali treatment. After this activation, neutral, long-liquor dyeings can be carried out at the boil in the presence of electrolyte. This new dyeing method gave very good results in terms of overall fixation efficiency values, without the need for alkali additions.     

Application of heterobifunctional reactive dyes on silk

The behaviour of heterobifunctional reactive dyes, containing a monochlorotriazine and a vinyl sulphone group, on silk has been investigated. Maximum exhaustion and fixation were obtained in a neutral medium at 90d? C. The addition of sodium sulphate was found to promote the exhaustion of reactive dyes at _pH values above the isoelectric point of silk. A reduction in the solubility of dyed silk indicated that crosslinks were formed with bifunctional reactive dyes.     

Neutral-fixing reactive dyes for cotton.

Research into a new type of reactive dye based on the monochlorotriazine group is described. Reactive dyes of the 3-carboxypyridino-1,3,5-triazine type have been investigated, with a nicotinic acid leaving group, having high stability and fixation efficiency. Dyes of this type react with cellulose in a neutral bath, so widening the scope of reactive dyeing. A classification scheme for reactive dyes is outlined.     

Synthesis and application to cotton of a polymeric black colorant prepared by grafting of reactive dyes to polyvinylamine

A novel polymeric black dye was synthesised by grafting yellow, orange, red, and blue reactive dyes onto polyvinylamine. Such a polymeric black dye takes the onus away from dyers to worry about the compatibility of individual dyes. The polymeric black dye was characterised by Fourier transform infrared, ultraviolet‐visible, and nuclear magnetic resonance spectroscopy. The absorption of the polymeric black dye in aqueous solution was nearly constant across the wavelength range 400–700 nm. Compared with a black mixture of reactive dyes with low fixation on cotton, which was prepared by mixing yellow, orange, red, and blue reactive dyes, the polymeric black dye reached 99% fixation on cotton through the use of a crosslinking agent. The colorimetric properties of cotton dyed with the polymeric black dye and with the black mixture of reactive dyes showed that better blackness can be obtained by using the polymeric black dye. Analysis of the thermal stability and penetration ability of the polymeric black dye showed that the polymeric dye has high stability in the application and a uniform distributution in the cotton fabric.     

Achieving expected depth of shade in reactive dye application using artificial neural network technique

Achieving the expected depth of shade in the production of dyed goods is a very important aspect. It requires the termination of the process at the right time in other words, correct duration of dyeing should be used. Prediction of this duration for the application of reactive HE dyes on cotton fabric using artificial neural network (ANN) is reported. The results obtained from the network gives an average training error of around 1% in the prediction of the time duration for achieving the correct depth of shade. The trained network gives the same average error % when tested with other reactive HE dyes even when the input parameters selected are beyond the range of inputs, which were used for training the network.     

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.     

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.