The dyeing of cellulosic fabrics by simultaneous application of azoic components and vinylsulphone or monochlorotriazine reactive dyes

The paper reports preliminary work on the dyeing of cellulosic fabrics by applying vinylsulphone or monochlorotriazine reactive dyes simultaneously with an azoic coupling component.     

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.     

Foam properties and application in dyeing cotton fabrics with reactive dyes

The foam dyeing of cotton fabric with CI Reactive Red 120 has been studied as a low‐add‐on technology. The foamability of different types of foaming agent and the stability of foam stabilisers were compared. Factors influencing foam dyeing, including wet pick‐up, fixation agent, foam stabiliser, and blow ratio, were evaluated by colour strength and dye fixation rate. Wet pick‐up, fixation agent, and foam stabiliser were found to be the main factors in the foam dyeing process. The comparative build‐up properties, dyeing properties, and total consumption between foam dyeing and conventional dyeing were assessed. The results indicate that, in foam dyeing, the dyestuff has a better build‐up property, the dyed fabric has excellent wash and rub fastness, and large amounts of water and energy are saved. Moreover, foam dyeing requires smaller dosages of chemical agents and reduces the difficulty of effluent treatment.     

The effect of reactive dyes on damage in wool dyeing

This paper demonstrates that reactive dyes exert a significant fibre–protective effect when dyeing wool fabric; this effect may be measured, in a reproducible manner, using the wet–burst strength test. The effect of dyebath pH, dye concentration, dyebath temperature and dyeing time on wool can thus be evaluated. The magnitude of the above protective effect has been compared with that achieved using commercially available fibre–protective agents. It is concluded that reactive dyes are significantly more effective than the latter agents when employed in medium to full depths. It is proposed that the unusual protective effect afforded by reactive dyes is related to the following factors. Reactive dyes readily react with sulphur nucleophiles, thus inhibiting thiol–disulphide interchange reactions and thereby significantly interfering with the level of set produced in a boiling dyebath. Reactive dyes react preferentially with non–keratinous proteins in the intercellular cement and the endocuticle thus reducing their tendency to hydrolyse and to partially dissolve in the hot aqueous dyebath.     

交联改性壳聚糖在棉织物活性染料染色中的应用

采用交联改性降解壳聚糖对棉织物进行接枝改性,考察壳聚糖接枝改性对棉织物雷马素活性染料染色性能的影响.结果表明:棉织物经壳聚糖改性后,增加了织物表面对染料阴离子的亲和力和固着力,上染率和K/S值都有所提升,其固色率也有很大提高,均达80%以上;经雷马素红RR和雷马素黄RR染色后,改性棉织物的干、湿摩擦牢度和耐皂洗褪色同未改性棉织物一样,分别为4、3~4和4级,耐皂洗沾色降低半级,为3~4级.用雷马素蓝RR染色后,改性棉织物干摩擦牢度提高半级,达4级,湿摩擦牢度和耐皂洗等级同未改性棉织物一样,分别为3~4和4级.     

Reactive dyeing of cellulosic fibers: Use of cationic surfactants and their interaction with reactive dyes

Cotton fabrics were dyed with three reactive dyes, C.I Reactive Blue 263, C.I Reactive Red 269, and C.I Reactive Yellow 208, after pretreatment of the fabrics with three alkyl trimethyl‐ammonium bromides (tmabs) having 12, 14, and 16 carbon atoms in the alkyl chain. The pretreated samples were dyed with standard dyeing methods using conventional, reduced amounts of electrolyte, and no electrolyte. Pretreatment with the three cationics (tmabs) resulted in an increase in dye exhaustion with all dyes used, whereas total dye fixation was lower for both red and blue dye and equal for the yellow, when compared to the reference untreated samples dyed according to the same standard dyeing method. The interaction between dodecyl trimethyl‐ammonium bromide and the three dyes was studied and the stoichiometry of the various dye/dodecyl trimethyl‐ammonium bromide (12‐tmab) complexes formed has been deduced. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Controlled coloration: a success strategy for the dyeing of cellulosic fibres with reactive dyes

The impact of improving the rate of right-first-time production on productivity and profitability for a batchwise dyehouse processing cellulosic fibres is reviewed. The measurement and level of performance required from reactive dyes to support right-first-time production is defined in the form of a reactive dye compatibility matrix (RCM). The application of the RCM as a diagnostic tool in dye selection and process design is outlined.     

Interaction of vinylsulphone reactive dyes with cellulosic fabrics. Part 2-dye associations and dyesurfactant interactions

The ability of reactive dye molecules (CI Reactive Red 180 and CI Reactive Yellow 23) to undergo self-association and to associate with different surfactants has been examined spectrophotometrically. The stability constants K_DS of the dye-surfactant complexes were calculated at dye:surfactant ratios varying from 1:0 to 1:10 and for different surfactant types (anionic, zwitterionic, nonionic and cationic). Dye uptake on viscose fibre observed for a dye:surfactant molar ratio of 1:0.5 was found to be related to K_DS values.     

Triazinylamino-alkylphosphonate reactive dyes for cellulosic fibres

A bifunctional reactive bis-phosphonoalkylaminotriazine dye was synthesised by condensing 2 mol of aminoethylphosphonic acid with the commercially available bis-monochloro- s -triazinyl dye, CI Reactive Red 120. A similar but much lower molecular weight dye was prepared by condensing the commercially available dichloro- s -triazine dye, Procion Red MX 8B, with aminomethylphosphonate. A model aryl-phosphonate dye was also prepared by diazotising m -aminobenzene-phosphonic acid and coupling the diazonium salt to R-salt. These dyes were isolated as their free acids and then converted to their ammonium salts. Pad liquors containing dye, cyanamide and ammonium dihydrogen phosphate were applied to cotton fabric. In the case of the bis-phosphonoethylamino- s -triazine dye, very high dye–fibre fixation values (>90%) were achieved using a pad–batch–bake procedure; for the Procion T model dye, the comparative maximum fixation was only modest. In the absence of cyanamide, no fixation could be obtained for the arylphosphonate dye but both bis-phosphonoalkylaminotriazine dyes gave significant fixation.     

Telechelic PEG-polymers end-capped with chromophores: Using as cationic reactive dyes and salt-free dyeing properties on cotton fabrics

In this article, telechelic polymers containing polyethylene glycol (PEG) moieties as space groups were combined with chromophores to synthesize cationic reactive dyes (BCD-R, BCD-Y, and BCD-B). The salt-free dyeing performance of these telechelic polymeric cationic reactive dyes on cotton fabrics was evaluated. The exhaustion and fixation of the dyes in salt-free dyeing was above 89.33 and 77.22%, respectively. The color fastness of dry rubbing for the three dyes reached grade 4–5, and their color fastness to light reached grade 5–6. Their washing fastness also reached grade 4–5, except for that of BCD-Y (grade 3–4). The results showed that the dyes possessed good leveling and build-up properties and substantivity to cellulose fiber. The zeta potential (ξ-potential) of dyed fabric was estimated, and it was found that the ξ-potential of the fabrics increased after dying with telechelic polymeric cationic reactive dyes, and the more dye that was used, the greater ξ-potential increase. The exhaustion curves of dyes were also determined, and they were much different from those of anionic reactive dyes. The adsorption kinetics and isotherms of BCD-R were investigated. It was found that the pseudo-second-order kinetic model gave the best fit of the experimental data at all three tested dyeing temperatures (25, 45, and 65°C) with R² values over 0.998. Both the Langmuir and Freundlich models could be used to describe the adsorption of BCD-R onto cellulose fibers and the Langmuir model fit the experimental data better than the Freundlich model. The thermodynamic parameters (ΔG, ΔS, ΔH, and activation energy) of the dye adsorption process were researched further. The results indicated that the adsorption of BCD-R onto cotton fibers was spontaneous and exothermic and that after adsorption onto the cotton fibers, the degree of freedom of the dye decreased.     

The dyeing of cotton with phosphonic reactive dyes in alcohols

The poor fixation achieved with phosphonated reactive dyes on cotton in practice, particularly in printing, has prompted a study of the effect of reaction conditions and the use of different diimides to achieve fixation. It has been possible to achieve as much as 95% fixation with a typical dye under suitable application conditions, where decomposition of the diimide can be minimised.     

Dyeing of nylon with reactive dyes. Part 1. The effect of changes in dye structure on the dyeing of nylon with reactive dyes

The dyeing behaviour of seven red commercial cellulosic reactive dyes, all based on the same chromophore and possessing one or more reactive group, and one to three chromophore units, were evaluated on nylon. Fixation levels appeared to be independent of the number of either reactive groups or chromophore units. Also, the degree of sulphonation, per se, appeared to have little effect on fixation, whereas the type of reactive group was important. The major determinant of dye fixation appeared to be associated with the shape of the molecule and the type, not the number, of reactive groups.     

Application of chitosan/nonionic surfactant mixture in reactive dyes for dyeing wool fabrics

The feasibility of wool fabrics pretreated with a chitosan/nonionic surfactant mixture and dyed with reactive dyes was studied. The results showed that the presence of the chitosan/surfactant improved the application to wool, which greatly enhanced the color strength when dyed at 50°C but little change was observed when dyed at 80°C. The higher the concentration of chitosan/surfactant added, the greater was the color strength of the dyed wool fabrics. The amounts found to be optimum for dyeing were 0.5% chitosan and 1.0% surfactant. The washing fastness of the dyed wool fabrics was in the range of grades 4–5, the dry rubbing fastness was in the range of grades 4–5, and the wet rubbing fastness was in the range of grades 3–4. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2859–2864, 2001     

Continuous dyeing of cationised cotton with reactive dyes

Cotton fabrics pretreated with cationic starch have been dyed with reactive dyes by a continuous dyeing method and the pretreatment conditions influencing dyeability of the treated cotton investigated. Cationised cotton has been found to give level dyeing without the presence of salt and dye fixation is improved compared with untreated cotton. The dyeings show good wash and rub fastness.     

The effects of pregrafting cotton fabrics with MAA/MAM on the dyeing kinetics of direct dyes in a finite bath

The influence of pregrafting of cotton fabrics with mixed monomer on the dyeing kinetics of direct dyes was investigated. The results of this research show that the equilibrium absorption (a_e) and activation energy (ΔE*) in the dyeing of grafted fabrics are smaller than those of ungrafted fabrics. The experimental results show that the value of the equilibrium absorption is smallest when the molar ratio of MAA/MAM (methacrylic acid/methylacryl amide) is 4/6. However, the rate constant (k′) is larger for grafted fabrics than for ungrafted fabrics. No significant difference was observed between the structural diffusion resistance constant (n) of grafted and ungrafted fabrics. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1139–1142, 1997     

Developments in direct dyes for cellulosic materials

Single crystal data and the X-ray powder pattern are reported for CI Solvent Yellow 2 (l-phenylazo-4-NN-dimethylamine). The powder pattern has been indexed from cell dimensions given by single crystal measurements. The problems of multiple indexing have been reduced by comparing the powder data with observed single crystal intensities.     

The dyeing of cellulose with reactive dyes containing phosphonic acid groups

The fixation of some Procion T phosphonated reactive dyes on cotton in the presence of dicyandiamide in different conditions of dyeing is reported, in order to clarify the role of the carbodiimide in the fixation process.Paper chromatographic studies on Procion Red T-2B show that the reaction mechanism between the phosphonic dye and cellulose in the presence of dicyandiamide is an initial condensation of the phosphonic dye with dicyandiamide to produce a phosphonic acid anhydride, followed by subsequent reaction with cellulose to give a dye covalently bonded to the cellulose. The phosphonic acid anhydride, isolated by means of column chromatography, shows the characteristic adsorption bands of the P—O—P linkage.     

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.