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.     

Coloration of Apocynum venetum/cotton blends with an acid dye through combined pretreatment using cationic nanoparticles

Cationic copolymer nanoparticles were used to modify Apocynum venetum/cotton blended fabrics. The modified blends were then dyed using CI Acid Red 14. In order to enhance the colour performance, the effects of combined pretreatment using nanoparticles and sodium hydroxide (NaOH) or carboxymethylcellulose (CMC) or plasma were investigated. The results show that combined pretreatment with NaOH and nanoparticles improved the dyeing effect. The optimum concentrations of NaOH and nanoparticles were 100 and 2 g l⁻¹ respectively. In addition, using CMC to pretreat the fabrics could also improve the acid dyeing performance. However, the combination of plasma pretreatment and cationic nanoparticle modification produced the best colour performance for acid-dyed A. venetum/cotton blends. The dye exhaustion rate is highest (up to 95%) with plasma pretreatment. Scanning electron microscopy revealed that combined treatment with plasma and nanoparticles resulted in a far greater number of nanoparticles being deposited on the fibre surface. X-ray photoelectron spectroscopy indicated that the pretreatments with different procedures significantly changed the chemical components of the fibre surfaces. The aromatic rings of acid dye molecules covered the fibre surfaces after plasma and nanoparticle pretreatment and acid dyeing.     

Kinetic study on the sunlight-induced degradation of acid azo dyes on silk

The effects of solar irradiation on the two azo dyes CI Acid Red 1 and CI Acid Orange 8 were investigated both on dyed silk and in aqueous solution at pH 2–4.5. When absorbed on silk, the dyes were more photoreactive, both undergoing photodegradation, though at different rates, and displaying a protective action towards the fibre substrate, as evidenced by viscosimetric analysis. In aqueous solution CI Acid Orange 8 underwent photodegradation, with a quantum yield around 10⁻³ mol einstein⁻¹, while the predominant reaction occurring from CI Acid Red 1 was photocyclization, especially at low pH.     

Determining the effect of enzymatic pretreatment on the low temperature dyeability of polyamide fabrics

In this study, by pretreating polyamide 6/elastane knitted fabrics with serine-type protease enzyme, the aim was to reduce dyeing temperatures. It is known that the elasticity of elastane fibres is damaged in dyeing at high temperatures. On the other hand, to enable efficient dyeing, it is necessary to use boiling temperatures in synthetic fibres such as polyamide, or even mild high temperature conditions, to support more uniform dyeing. Protease enzymes are enzymes that hydrolyse amide bonds, and consequently, new amine and carboxyl groups are released in fibre macromolecules, resulting in an increase in the functional group content to which anionic dyes can bind. In this study, to compensate for the loss of colour yield caused by lowering the dyeing temperature, an increase in the functional groups was provided by enzymatic pretreatment. For this purpose, the fabrics were pretreated with a commercial serine-type protease enzyme then dyed with 1:2 metal complex dyes at different temperatures. The effects of enzymatic pretreatment on colour, fastness, fibre surface characteristics and fabric strength were investigated.     

Swelling of cotton as a tool to enhance the response of cellulase enzymes

Enzymes are now widely used in various textile processes, such as pretreatment and finishing. In the present investigation, undyed as well as vat‐dyed cotton fabrics were pretreated with intracrystalline swelling agents, such as sodium hydroxide and ethylene diamine, and an intercrystalline swelling agent, morpholine. Acid hydrolysis was also carried out on cotton. All the samples were further treated with acid and neutral cellulase enzymes. The effect of pretreatment and enzyme action on the vat dyeing was then studied. In all cases, it was found that intra‐ as well as intercrystalline swelling resulted in enhancing the response of the enzymes.     

Dyeing of nylon 66 with a disperse-reactive dye using supercritical carbon dioxide as the transport medium

Nylon 66 fabric was dyed with a disperse-reactive yellow dyestuff which was synthesised in our laboratory, using a supercritical carbon dioxide dyeing process. The structure of the disperse-reactive yellow dyestuff and its covalent bond with nylon 66 fibres were confirmed by FTIR, NMR, EA and MS analysis. The nylon fabric was also dyed with CI Disperse Yellow 3 and the dyeing results compared. Colour yield values were measured for both dyed fabrics, with those of the disperse-reactive dye showing much better values than CI Disperse Yellow 3. Wash fastness of the fabric dyed with the disperse-reactive yellow dye was tested by the ISO 2 method and showed excellent results. Light fastness was tested by the ISO 105 B05 method and the results were satisfactory. The results obtained indicate fabric immersed in supercritical carbon dioxide does not undergo any fibre damage.     

Assessment of uniformity of fibre coloration in Tencel woven fabrics dyed using reactive dyes

Weave structure and fabric density has an influence on dye penetration. The uniformity of dyeing, expressed as the uniformity of fibre coloration, of Tencel woven fabrics comprised of different weave structures, was assessed. The fabrics were dyed by exhaust and continuous dyeing methods using selected reactive dyes. Cross‐sectional images were captured and then given a rating 1–5 with respect to the depth of the fibre filaments of the yarn of the woven fabric. The images were assessed both subjectively and objectively. The uniformity of fibre coloration was expressed in terms of the standard deviation, mean value and histogram analysis such as dispersion and bandwidth. Objective assessment of uniformity of fibre coloration is a more accurate and quicker method than visual assessment and can be used to assess the uniformity of fibre coloration of woven and knitted fabrics dyed by any class of dyes. Improvement of the uniformity of fibre coloration of Tencel fabrics of various weave structures by causticisation of the fabrics and by modification to the padding process was investigated.     

Chemical modification of cotton to improve fibre dyeability

A new fibre-reactive quaternary compound containing an acrylamide residue was synthesised and used as a cotton modification reagent. The agent was applied to cotton fabrics using a pad-bake process. It was found that the treated fibre could be dyed with reactive dyes without the addition of salt or alkali. The reactive dyes were almost completely exhausted and showed a high degree of covalent bonding with the pretreated cellulose. The effect of varying the pretreatment conditions was investigated and the optimum conditions for pretreating and dyeing were established.     

Effect of reactive dyes upon the uptake and antibacterial action of poly(hexamethylene biguanide) on cotton. Part 1: Effect of bis(monochlorotriazinyl) dyes

Poly(hexamethylene biguanide) (PHMB) is of interest as a bactericide for fabrics. It has affinity for cotton by reaction with the cellulosic carboxylate groups. In this study, the capacity of undyed cotton to absorb PHMB has been determined and compared with cotton dyed with anionic bis(monochlorotriazinyl) reactive dyes. When cotton is dyed with these dyes the absorption of PHMB increases, the dye providing sulphonic acid sites with which the PHMB can react. The reacted PHMB and the percentage fixation of reactive dye were determined and from this the concentration of sulphonic acid on the dyed fibre. In the case of cotton dyed with Procion Yellow H-E4R, the dye increased the absorption of PHMB to approximately 1.45 mequiv. of biguanide per sulphonic acid group. For Procion Red H-E3B and Navy H-ER the figures were 1.18 and 1.00, respectively.     

Microwave‐assisted dyeing of poly(butylene terephthalate) fabrics with disperse dyes

In this study, conventional heating and microwave dielectric heating in the exhaust dyeing of poly(butylene terephtalate) fabrics with disperse dyes were studied in order to determine whether microwave heating could be used to increase the dyeability of poly(butylene terephtalate) fibre in shorter processing times and enable dyeings of adequate wet fastness to be obtained. Accordingly, the samples of 100% poly(butylene terephtalate) single jersey knitted fabric were dyed with CI Disperse Yellow 160 and CI Disperse Yellow 42, CI Disperse Red 177 and CI Disperse Red 91, CI Disperse Blue 79:1 and CI Disperse Blue 54 at 98 °C with or without microwave dielectric heating. The colouristic properties, colour fastnesses and the tensile properties of the dyed fabrics were investigated and compared with each other. Microwave dielectric heating is regarded as a tool for ‘green chemistry’ and provides many advantages over conventional heating without any deterioration in the properties of the dyed materials. Microwave heat dyeing enhances the exhaustion and the fixation of dye, and good colour fastnesses and repeatability in dyeings are achieved in short heating times of the dyebath.     

Acid dyeable and printable acrylic fabrics treated with cationic aqueous polyurethane

An acid dyeable acrylic fabric has been obtained by the pretreatment with cationic aqueous polyurethane, containing different amounts of quaternary nitrogen. Cationic polyurethane has the ability to interact with the carboxylic groups in the acrylic fabrics, as well as providing basic sites suitable for acid dyeing. The prepared polyurethane has been identified with FTIR, and the effect of the pretreatment conditions on the dyeability and printability of the fabrics has been investigated. The color strength values and the fastness properties of the dyed and printed samples, reveal the ionic interaction between the sulphonic groups in the acid dye molecules and the quaternary nitrogen on the fabrics. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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.     

Studies on the Amidoximation of Polyacrylonitrile Films: Influence of Synthesis Conditions

Chemical transformation of acrylic membranes with hydroxylamine hydrochloride (HA) was carried out to introduce amidoxime groups. It was found that the reaction conditions, such as reaction time, HA concentration and temperature influence the amidoxime content, significantly. A sharp enhancement in the amidoximation at 80°C was observed. The FTIR studies showed a significant loss of nitrile groups during amidoximation process. Optimum conditions for the amidoximation process were investigated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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.     

A novel strategy to improve the dyeing properties in laccase-mediated coloration of wool fabric

Enzymatic coloration of fabrics has received worldwide attention in recent years. In order to improve the dyeing properties of enzymatically coloured fabrics, a novel strategy using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), a biological coupling agent, to pretreat wool fabric was employed in this paper. Enzymatic coloration of wool fabrics with syringic acid was carried out in the presence of laccase from Trametes versicolor. The effect of different periods on laccase-catalysed polymerisation of syringic acid was examined by UV-vis spectroscopy. Enzymatic coloration results of dyed wool fabrics were evaluated by means of K/S value and colour difference (∆E*). Process parameters, including the dosages of syringic acid and incubation time, that influenced the colour depth were studied. Meanwhile, the colour fastness and levelness of dyed wool fabrics were tested. The results showed that the UV-vis absorbance of reaction solution increased as oxidation time elapsed, and a new peak appeared at 360 nm. After pretreatment, the K/S values and colour difference values of wool fabrics dyed with poly(syringic acid) improved appreciably compared with the control samples without any pretreatment. Moreover, pretreated wool fabrics showed better dyeing fastness and levelness than control samples.     

Pretreating poly(p‐phenylene benzobisoxazole) fibre with polyphosphoric acid and dyeing with disperse dyes

In recent years, many advanced composite materials based on poly(p‐phenylene‐2,6‐benzobisoxazole) fibres have become prominent in applications requiring high‐strength and flame‐retardance such as body armour, industrial reinforcement materials and military camouflage. However, the application of these fibres used as protective clothing is limited due to difficulties in dyeing and printing. In the present work, a process for pretreating poly(p‐phenylene benzobisoxazole) fibre with polyphosphoric acid was applied, and the pretreated fibre was then dyed with disperse dyes via dip dyeing. Effects of pretreatment temperature and time on structure and properties were investigated. Surface morphology, crystallinity, chemical structure and degree of orientation of fibres were characterised. The results indicated that the supramolecular structure of the fibre was relaxed or swelled by polyphosphoric acid in the pretreatment process, so that the dyeability of poly(p‐phenylene benzobisoxazole) fibre was improved, with satisfactory dye exhaustion, K/S values and dyeing fastness. Also, with the appropriate pretreatment process, the swelling effect of polyphosphoric acid on the structure of poly(p‐phenylene benzobisoxazole) fibre was limited, so as to control the decrease in tensile strength and limiting oxygen index of the dyed fibre.     

Acid dyeing isotherms of cotton fabrics pretreated with mixtures of reactive cationic agents

Reactive cationic agents, phenylmonochlorotriazinyl and epoxypropyl, are used for cotton pretreatment using a pad–dry–curing technique. The dyeability of cationised cotton fabrics using CI Acid Red 1, determined spectrophotometrically for the residual dyebath, has been dependent on the cationic agent concentration and the appropriate mixture used. Comparative sorption isotherms, rate of dyeing at different temperatures, standard affinity, entropy and heat of dyeing for three different pretreated fabrics have been calculated and discussed. The equilibrium data obtained were fitted by the Langmuir isotherm model, allowing the corresponding sorption parameters to be determined.     

Investigation into the sequential application of cationic/anionic fixing agents to improve the oxidative washing resistance of CI Leuco Sulphur Black 1‐dyed cotton fabric

Sulphur‐dyed cellulosic textiles are susceptible to washing powders containing activated peracid formulations resulting in obvious fading during repeated laundering. This study presents a novel one‐bath/two‐stage exhaust finishing process to improve the oxidative wash fastness of CI Leuco Sulphur Black 1‐dyed cotton fabric. The effect of the combined Tinofix ECO and Bayprotect Cl after‐treatment was to impart better colour fastness to oxidative International Organisation for Standardisation (ISO) 105 CO9 washing of the dyed cotton compared with those dyed fabrics after‐treated with Tinofix ECO alone. In addition, while the dyed fabrics rub and light fastness performances were unchanged by the after‐treatments, some improvement in the tensile strength of the combined Tinofix ECO and Bayprotect Cl after‐treated fabrics was observed.     

锦纶织物原位矿化染色新技术

应用Erionyl系列弱酸性染料,分别采用传统工艺和原位矿化工艺对锦纶织物进行染色加工。对比了采用不同染色工艺的耗水量、排放残液的化学需氧量(CODC)r、染品色牢度及各项物理性能指标,结果表明:与传统工艺相比,采用原位矿化工艺对锦纶织物进行染色加工,染色节水率高达80%;排放染色废水中CODCr显著降低;不同工艺的染色织物颜色深度和各项色牢度基本一致;采用原位矿化工艺染色的织物断裂强力及断裂伸长率略优于传统工艺。     

Supercritical fluid dyeing of cotton modified with 2,4,6-trichloro-1,3,5-triazine

Supercritical carbon dioxide dyeing of cotton modified with the fibre reactive group 2,4,6-trichloro-1,3,5-triazine has been examined and the results are discussed. The modification of cotton was carried out in acetone, as well as by a new method using water as the solvent. For level dyeing results a degree of fixation of the fibre reactive group on cotton of 3% owf was required without changing the hydrophilicity of the fibre. The results show that dyeing of modified cotton is possible with dyes containing hydroxy or amino groups which react via a substitution reaction with the chlorine atoms of 4,6-dichloro-1,3,5-triazine-2-yl on the fibre surface. The K/S values at 383 nm of modified cotton dyed with CI Disperse Yellow 23 were found to be between 1.44 and 4.79 depending on the dyeing conditions used. The washing, rubbing and light fastness data that were obtained were between 3 and 5.