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.     

Pretreatment of cotton fabrics with polyamino carboxylic acids for salt‐free dyeing of cotton with reactive dyes

In this study, polyamino carboxylic acids have been used to improve the dyeability of cotton in a salt‐free reactive dyeing process. These polyamino carboxylic acids were prepared by partial carboxylation of polyvinylamine. Cotton fabric was pretreated with polyamino carboxylic acids and dyed with reactive dyes. The colour strengths of the dyed fabrics were evaluated by measuring the K/S values. The fastness properties (washing, rubbing and light fastness) of the dyed cotton fabrics were also measured. The pretreatment of cotton with polyamino carboxylic acids creates positive charges on the fabric surface. In this way, salt‐free reactive dyeing of cotton or dyeing with only a small amount of electrolyte is possible.     

Synthesis of a new,yellow crosslinking polyvinylamine dye and its crosslinking/dyeing process through a crosslinker

A new, yellow crosslinking polyvinylamine dye was synthesized by the reaction of 2,4‐dinitrochlorobenzene with polyvinylamine prepared from Hofmann degradation of polyacrylamide. It was crosslinked and dyed to cotton and silk by a crosslinker synthesized from 1,3,5‐trichloro‐s‐triazine and sodium 2‐(p‐aminophenylsulfonyl)ethyl sulfate. The crosslinking/dyeing conditions of the yellow polyvinylamine dye, such as pH, cure temperature, and concentration of the crosslinker were investigated. The fixations of the polymeric dye by the crosslinker on cotton and silk were greater than 99%. The crosslinking covalent dye–fiber bond was proved indirectly by the comparison of IR spectra of the undyed fiber, the dyed fiber, and the crosslinked one, and also by the fact that no dye was stripped off from the crosslinked and dyed sample by extraction with DMF/water (1 : 1). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1568–1573, 2006     

A novel resist technique based on secondary amines for the printing of cotton with reactive dyes

In an earlier paper we have described sulphite‐based resist printing using ink‐jet procedures. This paper describes an alternative approach to sulphite inactivation of vinylsulphone dyes by using secondary amines to inactivate fluoro‐s‐triazine dyes while maintaining the reactivity of the vinylsulphone dyes. Monofluoro‐s‐triazine reactive dyes are padded onto cotton fabrics and then deactivated by ink‐jet printing with a suitable secondary amine formulation to produce a white image on a solid ground colour after appropriate fixation and soap‐off procedures have been undertaken. A coloured image can be achieved by overprinting the resist‐printed areas with a coloured ink formulation containing a β‐sulphatoethylsulphone‐type reactive dye; such dyes form a β‐bis‐alkylaminoethylsulphone dye via reaction with the secondary amine. This latter dye ‘unblocks’ during a mildly acidic steaming process to form the reactive vinylsulphone dye, and so, unlike the monofluoro‐s‐triazine dye, is not deactivated towards subsequent covalent reaction with the cotton substrate.     

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.     

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.     

Design,synthesis, and application of amphoteric macromolecular dyes with controllable solubility

A series of amphoteric macromolecular dyes were designed and synthesized from poly(acrylamide‐co‐vinylamine) oligomer and reactive dyes. The structure of the synthesized dyes was characterized by fourier transform infrared spectra, mass spectra, and ultraviolet–visible spectroscopy analysis. The solubility of the dyes was also investigated. The results showed that the solubility of the dyes can be controlled by tuning the ratio of amino to sulfonate groups in amphoteric macromolecular dyes. Based on the results of controllable solubility conducted by visible light transmittance measurements, amphoteric macromolecular dyes were used to dye cotton fiber; the fixation of the dye on cotton was more than 95% when crosslinking agent was added. The dyed samples exhibited good fastness to washing and rubbing. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41120.     

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.     

Electrostatic self‐assembly dyeing of cotton fabrics

A new approach to the dyeing of cotton fabrics using an electrostatic self‐assembly method was evaluated. Cotton fabrics were pretreated with 2,3‐epoxypropyltrimethylammonuium chloride and cationic charges were produced on the fabric surfaces. For the dyeing of cotton fabric, reactive and acid dyes were used. Oppositely charged anionic reactive/acid dyes and cationic poly(diallyldimethylammonium chloride) were alternately deposited on the surface of cationised cotton fabrics. Ten multilayer films of dye/poly(diallyldimethylammonium chloride) were deposited on the cotton fabric surfaces using a padder. The build‐up of the multilayer films and the level of colour strength (K/S) achieved are discussed. Samples of cotton fabrics were also dyed with the same dyes, but using the exhaust method, and both types of dyed samples were compared. The washing, rubbing and light fastness properties were evaluated for the dyed fabrics.     

Influence of Eri silk fibre on the physical characteristics and dyeing properties of Eri silk/cotton blended yarn

Different blending ratios of Eri silk and cotton fibres were prepared. The optimum bleaching condition chosen for the blends containing 0–25% silk content was the oxidative bleaching method, whereas the blends at 50–100% should be bleached using the two‐stage bleaching method (oxidative bleaching followed by reductive bleaching). These conditions did affect the force–displacement characteristics of the fibres with no yield point. X‐Ray diffraction results showed that the percentage of crystallinity of the cotton yarn tended to increase after bleaching, whereas the percentage of crystallinity of the Eri yarn decreased marginally. Dyeing properties of the blended yarns were investigated using warm‐dyeing reactive dyes. Percentage exhaustion and the colour yield of the blends tended to decrease with the increasing silk content. Shade variation was observed on the yarns at different blend ratios. This was expected to be caused by the different physical nature of Eri silk and cotton fibres. Consequently, the dye uptake and visual shade of each dye on the two fibres were different.     

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.     

Synthesis and application of KM‐type reactive dyes containing 2‐ethoxy‐4‐chloro‐s‐triazine

A new kind of hetero‐bifunctional reactive dye containing 2‐ethoxy‐4‐chloro‐s‐triazine, with better activity matching with β‐hydroxyethyl sulphone sulphate at a low fixation temperature, was successfully synthesised and characterised. An ethoxy group was designed to be introduced into triazine to increase the substantivity and the reactivity of the dyes. Thereby, the fixation of mono‐s‐chlorotriazine/hydroxyethyl sulphone sulphate (KM‐type) bifunctional reactive dyes on cotton was improved, and dyeing under mild conditions with high fixation was realised. Nineteen dyes with orange, red and blue colours were synthesised and characterised by UV‐Vis and infrared spectroscopy and mass spectrometry. Synthesised dyes were dyed at 60, 75 and 90°C, respectively. Exhaustion and reactivity for all of the ethoxy‐containing KM‐type dyes was over 90% at the optimal temperature, and fixation was over 87%, which was higher than the ethoxy‐free comparative dyes. The optimal fixation temperature of ethoxy‐containing dyes was initially reduced to 75°C, and then to 60°C. Compared with comparative dyes, the wash fastness and light fastness were basically unchanged, and the wet rub fastness of the H‐acid series was reduced by one grade.     

Synthesis and application to cellulose of reactive dye precursor of anti‐bacterial N‐halamine

To achieve textile dyeing and functional finishing in one process, a bleach‐resistant reactive dye precursor to anti‐bacterial N‐halamine was synthesised by reacting a type of dichlorotriazine reactive dye with 4‐amino‐2,2,6,6‐tetramethylpiperidine. The synthesised compound, which can be transformed to an N‐halamine molecule by exposure to dilute bleach solution, was used to dye cotton fabrics. After exposure to a dilute sodium hypochlorite solution, dyed cotton fabrics showed excellent anti‐bacterial properties against Staphylococcus aureus and Escherichia coli O157:H7, facilitating a ca. 6‐log reduction in bacteria within a short period of contact. Compared with the dichlorotriazine reactive dye, the reactive dye precursor demonstrated comparable dyeing properties including exhaustion and fixation values. No differences in rub fastness, wash fastness or bleach fastness were detected between fabrics dyed with, respectively, dichlorotriazine reactive dye and the reactive dye precursor to N‐halamine.     

Adsorption and fixation behaviour of CI Reactive Red 195 on cotton woven fabric in a nonionic surfactant Triton X‐100 reverse micelle

To achieve the goals of saving water and being salt‐free in the coloration of cotton fabric with reactive dye, nonionic reverse micelles were prepared and optimised with a surfactant, Triton X‐100, n‐octanol and isooctane by injecting a small amount of CI Reactive Red 195 aqueous solution. The adsorption, diffusion and fixation of this dye on cotton fabric in Triton X‐100 reverse micelle and bulk water were then investigated. The equilibrium and kinetic data of the dye adsorption process were evaluated. The colour strength and fixation rate of cotton fabrics dyed in the micelle and in bulk water were also examined and compared. The results indicated that the amount of dye adsorbed increased with the increasing temperature and the initial dye concentration. The dye adsorption process could be described using the Langmuir isotherm and pseudo‐second‐order kinetic equations. It was found that CI Reactive Red 195 showed a stronger adsorption property on cotton fabric in Triton X‐100 reverse micelle than in bulk water without the addition of sodium chloride. Using Triton X‐100 reverse micelle as the dyeing medium offered the reactive dye better diffusion performance within the cotton fibre as compared with bulk water. Moreover, higher fixation of the dyes absorbed on the cotton fibre was achieved when the optimum concentration of sodium carbonate was used as the alkali agent in Triton X‐100 reverse micelle.     

Mordant dye application on cotton: optimisation and combination with natural dyes

It is well known that cotton fibres can be dyed through the formation of coordinate bonds involving cellulose chains, mordants such as alum, and natural dyes such as alizarin. Similarly, synthetic dyes known as mordant acid dyes can be used to dye wool fibres. Unlike mordant dyes on wool, the fastnesses of natural dyes on cotton are often low. Although concerns surrounding textile sustainability have sparked renewed interest in the use of natural dyes, extensive replacement of synthetic dyes with natural dyes is neither practical nor fundamentally possible. However, similarities in dyeing methods using mordant and natural dyes raise the possibility of using mordant dyes as alternatives to natural dyes in the dyeing of cotton. Further, the potential for combining suitable dyes from these two classes to expand the colour gamut currently available from natural dyes on cotton seem worthy of exploration. The results of this study indicate that shades comparable with those produced by natural dyes can be obtained on cotton using select mordant dyes following Fe²⁺ and Al³⁺ pretreatments. The best results were obtained using a two‐step/two‐bath process and dyes such as CI Mordant Blue 13 and CI Mordant Orange 6. In evaluations of mordant and natural dye combinations using the two mordant dyes logwood and Osage orange as prototypes, interesting fabric shades were obtained. However, the fastness properties of these dyes must be improved in order to produce commercially viable dyeings.     

Cellulase digestion of cotton dyed with reactive dyes and analysis of the products by thin layer chromatography

Enzymatic digestion of cotton fibres dyed with reactive dyes produces coloured solutions. These are not true dye extracts but they are nonetheless amenable to separation and analysis by thin layer chromatography.     

Dye Fixation Using Radio—frequency Heating

Radio-frequency (r.f.) heating has been used to achieve the fixation of acid dyes on nylon fibres. This permitted rapid heating to the fixation temperature, and some enhancement in the degree of dye penetration was observed. Success was also obtained in fixing disperse dyes on polyester and reactive dyes on cotton using r. f. techniques. The experiments clearly demonstrate that r.f. heating offers a versatile method for enhancing dye fixation.     

Study of the desorption of hydrolysed reactive dyes from cotton fabrics in an ethanol–water solvent system

The factors influencing the desorption of hydrolysed dyes resulting from reactive cotton dyeings in an ethanol–water solvent system, including the volume ratio of ethanol to water, pH, and temperature, were investigated. The maximum desorption was achieved when the volume ratio of ethanol to water was optimised to 4:6. Desorption increased with an increase in pH and temperature. The kinetic curves of dye desorption at three different temperatures fit a two‐step kinetic model. The dye desorbability at 60 °C in an ethanol–water system was similar to that observed using conventional water washing in the presence of detergent at 95 °C. Findings suggest that wash‐off in an ethanol–water system can be considered as an alternative, more effective process for removing hydrolysed dyes from reactive cotton dyeings.     

Application of polycarboxylic acid sodium salt in the dyeing of cotton fabric with reactive dyes

In this study, the effects of polycarboxylic acid sodium salt on the dyeing of cotton with reactive dyes were evaluated by measuring and comparing the K/S values and dyeing fastnesses of the dyed cotton fabric samples. Results showed that the K/S value and dyeing fastness of cotton fabrics dyed with polycarboxylic acid sodium salt, substituting inorganic salts as exhausting agent were close to that of with sodium chloride when dip‐dyeing process was used. While, in pad‐dry dyeing, the K/S value of cotton fabric samples dyed with polyacid salts as exhausting agent was higher than that of with sodium sulfate, and the dyeing fastnesses of these samples were nearly the same. The dyeing mechanism of cotton fabric with reactive dye, using polycarboxylic acid sodium salt as exhausting agent was analyzed. The dyeing exhausting mechanism of reactive dye seems different when the inorganic salt and polycarboxylic acid sodium salt were used as exhausting agent in the dyeing of cotton fabric with reactive dye. The polycarboxylic acid sodium salt, as weak electrolyte, increased the dye‐uptake of reactive dye on cotton fabric not only by screening negative charges on cotton surface, but also by the effect of salting‐out or hydrophobic combination. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Dyeing of natural fibres from perfluoro-polyether reverse micelles in supercritical carbon dioxide

The dyeing of natural fibres from a reverse-micellar system in supercritical carbon dioxide has been investigated using ammonium carboxylate perfluoropolyether as surfactant. Protein fibres such as silk and wool were satisfactorily dyed in deep shades with conventional acid dyes without special pretreatment. Exhaustion was excellent. It was however found that on these fibres the performance of acid dyes was strongly influenced by temperature and carbon dioxide density. Conventional reactive dyes in this system were adsorbed on cotton, even in the absence of dyeing auxiliaries, but the fixation of the dye was not satisfactory. Compared with supercritical dyeing methods reported previously, it was found in this study that the temperature and pressure required were significantly lower.