Some quantitative studies on light fading of after-treated direct dyes

Quantitative measurements of increase in lightfastness of direct dyes on cellophane on after-treatment with different metallic salts, e.g. sulphates of copper, cobalt, nickel, chromium and (ferrous) iron have been carried out. Copper sulphate has been found to be the best of all these salts. About 2% copper sulphate is found to cause considerable increase in the lightfastness. Measurements of y/x ratios of dyed and after-treated cellophane and also slopes of CF curves have shown that the higher fastness is due to higher aggregation of the dye in the fibre on after-treatment with copper sulphate. Metal complex formation with dye structures of the type o-hydroxy-o′-methoxy (or o′-hydroxy or ethoxy) azo has been found to be more useful for copper after-treatment than complex formation with dyes with a salicylic acid residue.     

UV absorber aftertreatment to improve lightfastness of natural dyes on protein fibres

The effect of a UV absorber on the lightfastness of natural dyes has been investigated. Wool and silk fabrics, dyed with natural dyes with or without mordants, were aftertreated with two UV absorbers. This treatment improved the lightfastness of the mordant-dyed fabric without affecting its colour or shade. The extent of photofading was evaluated by measuring the colour difference, Δ E , of the dyed sample before and after a 20 h period of irradiation under a xenon arc lamp. The uptake of the UV absorber on wool was much higher than that on silk.     

Carbon black as a dulling agent for nylon 6 filaments and the lightfastness of dyes on dulled filaments

Nylon 6 filaments containing 0–1.5% carbon-black pigment are dyed to different depths of shade. The colour on the substrate is evaluated on CIELAB a* b* diagrams at given concentrations of carbon black and dye. The carbon-black pigment acts essentially as a neutral dulling agent and only with a few dyes does it appear to alter the hue angle slightly. Thus, it is possible to use nylon 6 filaments containing carbon-black pigment to produce dull shades by the overdyeing process. The dyed samples thus produced are exposed to mercury-lamp light as well as daylight. The lightfastness is evaluated visually using the Blue Wool Scale. There is a remarkable improvement in the lightfastness of all dyes on nylon 6 containing carbon-black pigment. The carbon black in the filament appears to protect both the dye and the polymer from the degrading action of actinic radiation. However, the remarkable improvement in the lightfastness is essentially due to the optical effect.     

Graft copolymerization of acrylonitrile onto acetylated jute fibers

Graft copolymerization of acrylonitrile (AN) onto acetylated chemically modified jute was carried out in the temperature range 40–60°C using V⁵⁺-cyclohexanone redox initiator system. The effects of temperature, time, concentrations of metal ion (V⁵⁺), monomer (AN), cyclohexanone, some inorganic salts, and organic solvents on percent grafting have been studied. IR spectra of acetylated chemically modified jute and grafted jute have been taken, and their characteristic bands have been identified. Grafting has improved the thermal stability and also the lightfastness rating of jute fibers dyed with basic dyes.     

Dyeing of pet textile fibers and films in supercritical carbon dioxide

Polyethylene terephthalate (PET) textile fibers were dyed with a disperse dye in the presence of supercritical carbon dioxide at three temperatures of 333.2, 363.2 and 393.2 K and at pressures between 15 and 25MPa. The PET film was also dyed at 393.2 K. It was found that the dye uptake in the fiber increased 2–5 times when a small amount of acetone was added as a cosolvent. The equilibrium dye uptake increased with increasing pressure at all temperatures. At 393.2 K the pressure effect appeared to be much larger. It was explained with the shift of the glass transition temperature of the polymers at high pressures. These results may be useful in designing and developing the pollution-free supercritical dyeing technique, a potential alternative to the conventional dyeing of polyesters that produces a lot of wastewater.     

The effects of functional polysiloxane resins on the color gamut and color yield of dyed polyester

It is important to evaluate the influence of textile finishing using the polymer resins on the color of dyed fabrics. In this article, three functional polysiloxanes modified with different organic groups were used to treat dyed polyester microfiber fabrics. Effects of the polysiloxanes on the color of the dyed polyester were investigated by color yield (K/S), colorimetric data of CIELAB, and the color differences (ΔE). Chemical structures of three functional polysiloxanes were the polysiloxanes with amino groups (polymer A), with perfluorocarbon groups (polymer B), or with quaternary ammonium salts and perfluorocarbon groups (polymer C). Compared with the dyed fabrics treated with the polysiloxane with amino group, the K/S of dyed fabrics treated with the polysiloxane with perfluorocarbon obviously improved. Effects of the polysiloxanes with perfluorocarbon and cationic groups on the color shade of the dyed polyester were noticeable. The fastness had not significantly changed. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2012     

Substituent effects on the colour,dyeing and fastness properties of 4-N-β-cyanoethyl-N- β-hydroxyethylaminoazobenzenes part I—monosubstituted derivatives

Data on a series of 40 monosubstituted derivatives of 4-N-β-hydroxyethyl-N-β- cyanoethylaminoazobenzene are reported. Structure-property relationships with respect to electronic spectra of the dyes, coloration and fastness properties on cellulose secondary acetate and polyester fibres are investigated. Reasons for the anomalous properties of the 2′-nitro derivative in exhibiting low lightfastness on synthetic polymer fibres are presented. The coloration of polyester fibres is additionally assessed in terms of data derived from tristimulus values of dyed fibres, and the effect of substituents on such data is discussed.     

Synthesis and properties of novel aziridinyl azo dyes from 2-aminothiophenes—Part 2: Application of some disperse dyes to polyester fibres

A series of yellow to greenish-blue aziridinyl azo dyes and their azo precursors containing a thienyl coupling moiety has been applied to conventional polyester fibre as well as microdenier polyester by high temperature exhaust dyeing. Heat transferability of these dyes onto polyester fibre has also been examined, using conventional heat-transfer printing techniques. The relevant dyeing characteristics, heat transferability, build-up, dyeability on microfibre polyester, washfastness and lightfastness are given. These aziridinyl dyes are reactive to polyester fibres under HT dyeing conditions. Fabrics dyed with aziridinyl dyes are more resistant to solvent extraction than those dyed with conventional dyes. Residual liquors showed only a pale colour when fabric dyed with aziridinyl dyes was dissolved and then precipitated, whereas a coloured polyester precipitate was obtained.     

The influence of moisture content on the colour appearance of dyed textile materials. Part 1-dyeing methods and reflectance measurements on wool

The colour appearance of dyed textile materials changes upon wetting. This paper provides a graphical representation of reflectance changes with varying moisture content, and supplies a method of representing all reflectance changes for reactive dyes on wool on a single graph.     

Adsorption and functional properties of natural lac dye on chitosan fiber

Natural lac dye was applied to the dyeing of chitosan fiber in order to prepare healthy and hygienic textile materials, and the adsorption and functional properties of lac dye on chitosan fiber were studied. The functional properties of the dyed chitosan fiber depended greatly on the adsorption quantity of lac dye, which was related to dyeing temperature, neutral electrolyte dosage, and initial dye concentration. Lac dye displayed a very high adsorption capability on chitosan fiber, and a high utilization rate. The research on equilibrium adsorption showed that the Langmuir–Nernst isotherm was the most appropriate model to describe the behavior of lac dye, and the electrostatic interactions between lac dye and chitosan fiber contributed to Langmuir adsorption whereas the non-electrostatic interactions contributed to partition adsorption. The functionality analyses showed that the dyed chitosan fiber exhibited the good antioxidant activities determined by the DPPH radical scavenging assay and the ABTS radical decolorization assay, and the good deodorizing performance towards ammonia. This study points out that the lac dyed chitosan fiber can be utilized as functional textile materials with the requirements of antioxidant activity and deodorizing performance.     

Dyeing properties of textiles by Turkish hazelnut (Corylus colurna): leaves,coat, shell and dice

Turkey has a great number of hazelnut trees that possess nutritious components. However, only the inside part of the hazelnut is used as a nutrient, while the rest of it is waste. This study suggests that the waste parts of the Turkish hazelnut could be used as a natural dye for dyeing textile fabrics. The dyeing properties of the leaves, coat, shell and dice of the hazelnut were studied on wool, cotton and viscose fabric by using three different mordants: copper sulphate, iron sulphate and aluminium sulphate. The selected dyed fibre sample surfaces were observed using a scanning electron microscope. The colour strength (K/S), light, washing, rubbing, and perspiration fastness levels of the dyed fabrics were investigated. The experimental natural dyeing results indicate that waste hazelnut‐based products can be used as a natural dye for textile coloration.     

The Effects of Softeners on the Properties of Sulfur-Dyed Cotton Fibers

The processing of textiles to achieve a particular handle is one of the most important aspects of finishing technology. Softeners can improve some properties of textiles, depending on the chemical nature, including soft handle, smoothness, elasticity, hydrophilic, antistatic and soil release properties. They can affect the color and fastness of the dyed textile. In this research project, cotton fabrics were first scoured with nonionic detergent and then dyed with four sulfur dyes of different structures. The colors of the dyed fabrics was yellow, bluish black and bright blue. The dyed fabrics were then treated with anionic, cationic, nonionic, micro and macro silicone softeners. Nonionic, micro and macro silicone softeners decreased the lightness (L*) of all sulfur-dyed samples while anionic and cationic softeners caused only a slight alteration in lightness. The a*, b* and c* values of most dyed samples showed a little change after treatment with softeners except for the color coordinates of the yellow samples, which increased. A considerable increase in the fk values for silicone softener-treated samples was obtained. The washing fastness properties of blue samples decreased while they remained unchanged for other samples. The light fastness properties decreased for all samples after treatment with softeners.

Modification of cellulose fiber with silk sericin

Cellulose fiber surface was modified with silk sericin (or simply, sericin). Sericin fixation on cellulose was confirmed by environmental scanning electron microscopy (ESEM) and Fourier transform infrared spectrophotometry–attenuated total reflectance (FTIR‐ATR). Sericin content in finished samples was estimated by dyeing treated fabrics with an acid dye, Supranol Bordeaux B, and determining K/S and L values of the dyed fabrics. The treated fabrics were tested for free formaldehyde content, crease recovery, tensile strength, electrical resistance, water retention, and biocidal activity. From ESEM and FTIR‐ATR results, it was found that sericin coated onto cotton surfaces as a film. Increasing sericin content in the finishing solution increased the amount of coated sericin, and a greater depth of color in dyed samples and reduced free formaldehyde content in treated samples were observed. The sericin content in samples was found to have a negligible influence on tensile strength and crease recovery angle. With increasing sericin content, electrical resistivity of the samples dramatically decreased and water retention increased, indicating that sericin‐treated fabrics may be comfortable to wear because of its maintenance of moisture balance with respect to human skin. Because cotton textile coated with sericin exhibited low formaldehyde content and no biocidal activity against Klebsiella pneumoniae and Staphylococcus aureus, the fabric may reduce skin irritation and disturbance of physiological skin flora arising from textile contact. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1421–1428, 2005     

Illumination correction of dyed fabrics method using rotation forest‐based ensemble particle swarm optimization and sparse least squares support vector regression

Different illuminations adversely affect color difference evaluation of textile images in dyed fabrics. To address the problem, we propose a rotation forest (RF)‐based ensemble particle swarm optimization and sparse least squares support vector regression (RF‐PSO‐SLSSVR) for building an accurate illumination correction model. In our algorithm, grey‐edge is first used to extract the statistics characteristics of the textile image. Second, as the standard LSSVR cannot yield a sparse solution, we develop sparse LSSVR (SLSSVR) by calculating the maximal independent subset in the extracted feature space. Then, SLSSVR is embedded into RF by substituting for the regression tree which is the base learner in the original RF, and the PSO technique is employed to obtain the optimal regularization parameter γ and kernel parameter σ. The final model is obtained by fusing the predictions of the different trees through a weighted average method and RF‐PSO‐SLSSVR is constructed to learn the textile illumination estimation model. To verify the effectiveness of our algorithm, we carry out the experiments on the real dyed fabric images by comparison to several related methods and the performance is measured by the different criterions, including the chromaticity error, the angle error, and the Wilcoxon signed‐rank test. Compared with the traditional SVR and ELM algorithm, the results show that the RF‐PSO‐SLSSVR method reduces ~13.6% and 10.6% over the angle RMSE.     

Substituent effects on the colour,dyeing and fastness properties of 4-N-β-cyanoethyl-N-β-hydroxyethylaminoazobenzenes Part II—disubstituted derivatives

Dyeing and fastness properties on cellulose secondary acetate and polyester fibres of a series of 2′-substituted-4′-nitro, 4′-substituted-2′-nitro and 2′,6′-disubstituted-4-N-β-cyanoethyl-N-β-hydroxyethylaminoazobenzenes are reported. All dyes gave good coloration, with the exception of those containing the methylsulphonyl group, which had poor substantivity for polyester. Electronic spectra data of all dyes are reported; considerable steric hindrance was apparent with certain types of 2′,6′ disubstitution. Data derived from tristimulus values of dyed polyester showed the degree of 'off-tone' build up is greater with red dyes, than with orange and yellow dyes. The presence of a 2′-nitro group leads to poor lightfastness.     

Natural dyes in madder (Rubia spp.) and their extraction and analysis in historical textiles

Textiles coloration using extracts from the roots of various madder species (Rubia spp.) has been performed for centuries. To date, 68 anthraquinone colorants have been detected in Rubia spp. used to dye textiles. Many of these dyes are sensitive to hydrolysis and degradation from enzymes, extraction chemicals and processing temperatures, and are often overlooked as colorants in historical textiles. Conclusions in literature of the past 30 years concerning colorants present in planta and, particularly, in madder‐dyed artefacts are being challenged as new analysis methods are developed. The recent advent of ‘soft’ extraction techniques has demonstrated that anthraquinone glycosides and other sensitive molecules, such as carboxylated compounds, need to be preserved; this valuable chemical information embedded in the dye structure may be lost if extraction and analysis is too harsh. Some compounds thought to be present in madder and madder‐dyed artefacts are in fact degradation products resultant from the extraction process, and degradation pathways have been developed to better understand the reactivity and stability of these compounds. Detailed analysis of dyes in textile artefacts can reveal important cultural and heritage information concerning historical textiles relative to the specific dye species, the area of the world where this may have grown, how and where it was dyed, and, perhaps, where it was traded. Understanding the precise molecular structure of these dyes and their chemical reactivity is important to provide knowledge of their interactions with physical substrates, such as textile fibres, which could be used to develop superior techniques for analysis of artefacts.     

Self-assembly of the polysiloxane modified with cationic and perfluorocarbon groups on the polyester surface and its effect on the color shade of the dyed polyester

The polysiloxane modified with cationic and perfluorocarbon groups could form film on the polyester surface by macromolecular self-assembly process. The thin film on the polyester surface could affect the color shade of dyed materials. The effect of the polysiloxane film on the color shade of the dyed polyester was investigated by reflectance spectra, color yield (K/S) and the color differences (ΔE). The colorimetric data of CIELAB was discussed. The results show that the thin film of the polysiloxane modified with cationic and perfluorocarbon groups on the polyester surface had good water repellency. The effect of the polysiloxane film on the color shade of dyed polyester was noticeable. The K/S of the dyed polyester fabrics with the modified polysiloxane film obviously increased. The reflectance spectra of the dyed fabrics treated without and with the modified polysiloxane had not significant change.     

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.     

The evaluation of procedures for dyeing silk with buckthorn and walloon oak on the basis of colour changes and fastness characteristics

In this study, silk fabric samples were dyed according to various procedures with buckthorn (Rhamnus petiolaris Boiss) and walloon oak (Quercus ithaburensis Decaisne) extracts. Reversed‐phase high‐performance liquid chromatography with diode‐array detection was utilised for the identification of dyes present in the dyed silk fabrics and the plant extracts. The extraction of dyes was carried out with a hydrochloric acid/methanol/water (2:1:1; v/v/v) mixture. The colour coordinates of the silk fabrics were measured, and the rubbing, wash and light fastness properties of the dyed silk materials were determined and are discussed.     

Synthesis and application of Fluorescent Dyes on basis of 1,8-naphthalic carboximides

The naphthalimide derivatives ( 2a–g, 3a–e ) were synthesized from 1,8-naphthalic carboximides. They show green fluorescence, and are suitable for dyenig of textile materials and epoxy resins. The colour parameters of the dyed fabrics were measured. The assessment of colour was made in terms of CIE tristimulus values as well as the position of colour in CIELAB coordinates (L*, a*, b*). The correlation between colour and structure of the dyes is discussed.