Modification of cellulose acetate fabric with cyclodextrin to improve its dyeability

Cellulose acetate fibers are usually dyed with disperse dyes in the presence of various additives to ensure coloration leveling. The possibilities of formation of complexes between disperse dye molecules and cyclodextrin (CD) can be of beneficial use. In this respect, the modification of the fiber with CD, then subjecting it to dyeing with disperse dye was performed on the basis of host/guest system as an alternative to overcome the low solubility of disperse dyes in water. The additives of the dyeing bath can be eliminated. The attained color intensities as well as the fastness properties are enhanced upon using CD. The depth of the dye inside the fiber structure is highly enhanced, while the thermal properties such as the glass transition temperature, crystallinity temperature, and melting temperature remain nearly constant. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Modification of cotton to improve its dyeability. Part 1 — pretreating cotton with reactive polyamide-epichlorohydrin resin

Pretreatment of cotton with the polyamide-epichlorohydrin resin Hercosett 125 produces a fibre that may be dyed with selected reactive dyes under neutral pH conditions in the absence of salt and with high fixation efficiency. The physical and mechanical properties of the modified cotton, the colour fastness of the reactive dyeings and mechanistic implications are also discussed.     

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.     

New methods for improving the dyeability of cellulose fibres with reactive dyes*

Cellulose fibres may be dyed with reactive dyes in the absence of added electrolyte under neutral to slightly acidic conditions provided the fibre is modified to include cationic sites. The effect of amine substitution has been examined in detail using the activated substrate prepared by the reaction of cotton with N-methylolacrylamide. Dyes containing pendant aliphatic amino groups were also prepared and their reactivity towards the pre-activated cotton substrate assessed.     

Ultrasonic‐assisted dyeing: I. Nylon dyeability with reactive dyes

The use of ultrasonic power (38.5 KHz, 350 W) to assist the dyeability of nylon‐6 fibre with reactive dyes is reported. The effects of the different factors that may affect the dyeability of nylon‐6 fibre with Reactive Red 55 were simultaneously carried out under both ultrasonic power and conventional heating conditions. The colour strength values obtained for the dyed samples using ultrasonic power were higher than those obtained using conventional heating. Also, the effect of alkaline soaping treatment on dye fixation for the dyed fabrics with different reactive dyes, at both acidic and neutral pHs, is generally better with ultrasonic than with conventional heating. The overall results indicate that the enhancing effect is mainly attributed to the de‐aggregation of dye molecules, which leads to better dye diffusion and possible assistance for dye‐fibre covalent‐bond fixation. The results of wet fastness properties of the dyed fabrics reveal improvement using ultrasonic power dyeing relative to the conventional heating method. © 2003 Society of Chemical Industry     

New cationic agents for improving the dyeability of cellulose fibres. Part 2-pretreating cotton with polyepichlorohydrin-amine polymers for improving dyeability with reactive dyes

Pretreatment of cotton with polyepichlorohydrin-dimethylamine produces a modified cotton that can be dyed under neutral conditions with selected low-reactivity dyes using a small amount of salt or with selected high-reactivity dyes without salt. The dyeings of treated cotton exhibit improved colour yield and high wash fastness. The properties and the quality of the reactive dyeings are discussed.     

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.     

Dry transfer printing of silk and cotton with reactive dyes and mixed polysaccharide thickeners

Dry transfer technology involving adhesion and steaming was designed for the printing of untreated silk and cotton with reactive dyes. The transfer paper was prepared by coating mixed polysaccharide thickeners composed of adhesive high‐substituted hydroxypropyl cellulose (H‐HPC) and another thickener, either sodium alginate (SA), carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), guar gum (SG‐9) or carboxymethyl starch (SG‐24). Patterns on the transfer paper were obtained by means of ink‐jet. The thermal plasticity of H‐HPC was observed and 120 °C was determined as the adhesion temperature. Rheological testing of all the thickeners verified that their shear‐thinning behaviour favoured successful coating. By comparing the effects of different mixed thickeners on the prints’ quality with regard to colour depth, sharpness, colour fastness and handle, it was concluded that the colour depth depended on the adhesion extent and reactivity between the thickener and reactive dye. Using H‐HPC/SA and H‐HPC/HEC produced the highest and lowest colour depths, respectively. The sharpness was visibly influenced by the different mixed thickeners. A clear pattern was achieved when the other thickener was CMC, SG‐9 or SG‐24. Both the colour fastness and handle were desirable, irrespective of the mixed thickeners used.     

Physical properties and dyeability of NaOH-treated silk fibers

Domestic (Bombyx mori) and wild (tussah, Antheraea pernyi) silk fabrics were treated with diluted NaOH solutions by the pad/batch method. The equillbrium moisture regain of tussah silk fibers increased steadily with alkaline treatment, while that of B. mori did not change. B. mori tensile strenght and elongation at break were slightly impaired. The average molecular orientation and crystallinity of both kinds of silk remained unchanged. Differential scanning calorimetry (DSC) and thermomechanical analysis(TMA) showed that the thermal behavior of B. mori silk was almost unaffected, while that of tussah exhibited slight changes in the temperature range 250–300°C. By dynamic mechanical measurements (DMA) it was elucidated that both storage and loss moduli of B. mori silk fibers decreased following NaOH treatment. On the other hand, tussah silk exhibited a noticeable upward shift of the major loss peak. Alkali-treated tussah silk fibers, dyed with an acid dyestuff, attained a lower degree of dye-bath exhaustion. © 1995 John Wiley & Sons, Inc.     

Physical properties and dyeability of silk fibers modified with ethoxyethylmethacrylate polymer

The structural characteristics, physical properties, and dyeing behavior of Bombyx mori silk fibers containing ethoxyethylmethacrylate (ETMA) polymer are reported in relation to the add-on. The add-on value increased with the reaction time and attained a maximum after 60 min at 80°C. The surface of silk fibers with an add-on value of 40% showed the presence of several irregular granules, consisting of ETMA oligomers. The infrared spectrum of the silk fibers containing the ETMA polymer showed overlapped absorption bands due to the molecular conformation of untreated silk and ETMA polymer, giving evidence that the ETMA polymerization occurred inside the fiber matrix. The DSC results suggested that the thermal decomposition behavior of the silk fiber remained almost unchanged, except that the decomposition temperature shifted slightly to higher temperature. The tensile properties of the silk fiber remained unchanged regardless of the ETMA polymerization. The rate and extent of acid dye uptake was greatly increased by the polymerization of ETMA into the silk fibers as well as the transfer printing properties.     

Studies on the dyeability and dyeing mechanism of polyurethane/clay nanocomposite filaments with acid,basic and reactive dyes

Polyurethane/clay nanocomposite (PUCN) filaments were spun by the dry‐jet‐wet spinning method. To prepare the PUCN filaments, 0.25, 0.50 and 1% of nanoclay on the weight of polyurethane were incorporated in the polyurethane dope. The interaction between clay and polyurethane was analysed by attenuated total reflectance–Fourier Transform‐infrared (ATR‐FTIR) spectroscopy. The structure and morphology of the PUCN filaments were analysed by wide‐angle X‐ray diffraction (WAXD) and transmission electron microscopy (TEM). Both the neat polyurethane and the PUCN filaments were dyed with different acid, basic and reactive dyes. The neat polyurethane filaments exhibited poor dyeability with all three classes of dyes. By contrast, the PUCN filaments showed a significantly higher dye uptake with all of the dyes used. Furthermore, the dye uptake increased significantly as the percentage of clay in the filaments increased, as indicated by the increase in the K/S values of the dyed filaments. The dyeing mechanism with all three dyes, as well as the increased dyeability of the PUNC filaments in comparison to those of the neat polyurethane filaments, was discussed.     

Structure and dyeability of Bombyx mori silk fibers with different filament sizes

This study deals with the analysis of structure, physical properties, and dyeing behavior of silk fibers with different filament sizes. Fine and coarse silk fibers were obtained from Akebono and Ariake cocoon varieties, respectively. Both samples exhibited a fairly similar x-ray crystallinity, while the degree of molecular orientation increased with decreasing the fiber size. Tensile strength and energy of fine silk fibers were significantly higher, while elongation at break did not change in relation to the fiber size. Fine silk fibers exhibited a slightly higher thermal stability, as shown by the upward shift of both the DSC decomposition temperature and the TMA final extension step at above 300°C. The TGA and DMA (E″) patterns remained unchanged regardless of fiber size. The amino acid analysis confirmed the absence of any difference of chemical structure between fine and coarse silk fibers, the content of acidic, basic, and other characteristic amino acid residues being exactly the same. Accordingly, both samples adsorbed the same amount of hydrochloric acid. Ex-haustion dyeing tests with various direct, acid, and reactive dyes showed the occurrence of appreciable differences in the perceived color between fine and coarse silk fibers. The size of color difference was quantitatively evaluated by reflectance measurements and discussed in relation to silk fiber morphology, structure, as well as dyeing conditions. The kinetics of diffusion of two model dyes was not significantly affected by the different fiber size and structure. © 1996 John Wiley & Sons, Inc.     

Modification of cellulose with N-(2-chloroethyl)diethylamine hydrochloride: mechanism of improved dyeability with 5-chloro-2,4-difluoropyrimidinyl dyes

Monofluorotriazinyl and 5-chloro-2,4-difluoropyrimidinyl dyes were each reacted, in turn, with trimethyl- and triethyl-amine in aqueous solution. Trimethylamine was quaternised by both the fluoroheterocyclic reactive dyes. In the case of the chlorodifluoropyrimidinyl dye, NMR spectroscopy showed that displacement of the C-2 fluorine atom had occurred. Triethylamine, on the other hand, failed to react with either fluoroheterocycle, strongly suggesting that the covalent bond formation reaction of DEAE-cotton, with a 5-chloro-2,4-difluoropyrimidinyl dye under neutral conditions, does not involve initial quaternisation. A mechanism involving the deprotonation of the cellulose hydroxy groups, catalysed by the basic groups in DEAE-cotton, is proposed.     

A new approach to the dyeing of silk with sulphatoethylsulphone dyes

A new approach to the dyeing of silk with sulphatoethylsulphone dyes, based on ß-elimination before dyeing, has been investigated. Some factors affecting both (β-elimination and dyeing have been studied. The improved dyeing process shows a high degree of dyebath exhaustion and excellent fixation in the absence of salt, thus reducing the risk of environmental pollution from salt and dyes.     

Jet printing with reactive dyes

The history of ink jet printing on textile substrates is reviewed and the major projects currently under examination are examined. The development of Procion reactive dye formulations and associated application technology for the ink jet printing of cellulose fabrics is discussed in detail.     

Modification of polypropylene fibres with cationic polypropylene dispersion for improved dyeability

Polypropylene (PP) fibres are important hydrophobic fibres which are used in the production of functional textiles such as sports textiles. The absence of functional groups and low polarity make PP fibres difficult to dye, thus mass coloration during fibre extrusion is the major technique applied today. However, the disadvantage of mass coloration is the low flexibility and the demand to produce high volumes. A new method to modify the surface of PP fibres utilises the deposition and thermal fixation of cationic PP dispersion. Through padding and thermal fixation of a cationic PP dispersion, dyeable 100% PP fibres can be obtained. The effects of fixation temperature, and of the amount of dispersion used on the modified fibres were studied using Fourier Transform‐infrared spectroscopy, laser scanning microscopy, dyeing experiments with CI Acid Red 151, and by determining selected fastness properties. The results indicate the potential of this new method to produce surface‐modified 100% PP fibres, which can be dyed in conventional acid‐dyeing processes and therefore used in fibre blends, for example in combination with wool.     

Photofading of reactive dyes on silk and cotton: effect of dye—fibre interactions

Fading characteristics of selected bifunctional and monofunctional reactive dyes have been studied on silk and cotton. Dyes were applied in the reactive and hydrolysed forms in order to study the influence of covalent bonding on the photofading of reactive dyes. The active dye-fibre interaction was found to influence the light fastness of dyes. Reactive dyes forming covalent bonds exhibited better fastness especially on cotton. Only a slight difference in light fastness of fixed and unfixed dyes was observed in the case of silk. The bifunctional reactive dyes, due to the formation of crosslinks, maintain the integrity of the fibre particularly for short periods of light exposure.