Disperse dyeing of polyester fibers: Kinetic and equilibrium study

The effect of temperature on the dyeing rate constant k, diffusion coefficient D, time of half‐dyeing t_1/2 was evaluated for the dyeing of polyester fibers with two disperse dyes, an azo and an anthraquinone dye. Activation energies of diffusion E were calculated. The polyester dyeing equilibrium was also studied and the partition coefficient K and standard affinity Δμ° at various temperatures were determined for the anthraquinone dye. Standard enthalpy ΔH° and standard entropy ΔS° of dyeing were also obtained. The same equilibrium parameters were not obtained for the azo dye because of its dyeing behavior. A similar kinetic and equilibrium study was made for the pure azo and anthraquinone compounds free from the dispersing agents present in the commercial dyes and the results are discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2785–2790, 2002; DOI 10.1002/app.10254     

Basofil纤维分散染料染色性能研究

选择了4只蒽醌结构和2只偶氮结构的分散染料，用于Basofil纤维的染色，用0.5molHCl和DMF在高温条件下将纤维上的染料萃取完全后、染料的最大吸收峰不变：在染色达到平衡时，测定了纤维上染料的浓度，结果显示：分子结构小、具有共平面的蒽醌染料适合上染Basofil纤维。染料的扩散系数和扩散活化能随染色温度上升而明显增加，其中C.I.Disperse Blue 56在纤维中扩散速度最快实验结果表明：染料的分子结构越小，染料上染量越大，扩散系数和扩散活化能的研究也揭示了相同的规律.     

Effect of microencapsulation on dyeing behaviors of disperse dyes without auxiliary solubilization

Microencapsulated disperse dye can be used to dye hydrophobic fabric in the absence of auxiliaries and without reduction clearing. However, little available information for dyeing practice is provided with respect to the effect of microencapsulation on the dyeing behaviors of disperse dyes. In this research, disperse dyes were microencapsulated under different conditions. The dyeing behaviors and dyeing kinetic parameters of microencapsulated disperse dye on PET fiber, e.g., dyeing curves, build up properties, equilibrium adsorption capacity C_∞, dyeing rate constant K, half dyeing time t_1/2, and diffusion coefficient D were investigated without auxiliary solubilization and compared with those of commercial disperse dyes with auxiliary solubilization. The results show that the dyeing behaviors of disperse dye are influenced greatly by microencapsulation. The diffusion of disperse dyes from microcapsule onto fibers can be adjusted by the reactivity of shell materials and mass ratios of core to shell. The disparity of diffusibility between two disperse dyes can be reduced by microencapsulation. In addition, the microencapsulation improves the utilization of disperse dyes due to no auxiliary solubilization. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

含羧甲磺酰基水溶性分散染料的研究

本文提出一类含有羧甲磺酰基（—SO_2CH_2COOH）的新的水溶性分散染料。利用应用时的高温,它转变为不溶性的分散染料。因此,在成品加工时不必进行砂磨,不需要扩散剂。它在弱酸、中性和碱性中都可使用,并适用于纯涤纶和涤/棉织物的印花和轧染。     

Variations in diffusion coefficient of disperse dyes in single PET fibres: monitored and interpreted by confocal laser scanning microscopy

A novel method is proposed for determining the diffusion coefficient (D) of disperse dyes in PET fibres. Concentration-distance profiles are recorded on optical sections of single fibres by confocal laser scanning microscopy. This allows for an accurate value of the true diffusion coefficient in the fibres as well as for a founded insight in the dye diffusion process and its interrelation with the glass transition, which is not possible by the commonly used methods. At 130 °C, the common industrial dyeing temperature, the diffusion coefficient showed to be constant for the dyes tested, with D being about five times larger for the anthraquinone dye than for the benzodifuranone dye. At 100-110 °C, near to the start of the glass transition region of the fibres, D could no longer be regarded as a constant for the anthraquinone dye but was concentration dependent. This was explained by the plasticising effect of the anthraquinone dye.     

Studies on dyeing and structural behavior of chemically treated polyester yarns

The dyeing behavior of poly(ethylene terephthalate) based flat, high twist, and spun yarns pretreated with trichloroacetic acid–methylene chloride (TCAMC) reagent was studied. Disperse dyes having two different energy levels were employed for the dyeing work. The effect of time, temperature, and dye diffusion transition temperature (T_D) on dye uptake was analyzed. A considerable increase in equilibrium dye uptake and decrease in T_D of all the treated yarns were observed. The variation in dye diffusion behavior of higher and lower molecular weight dyes and the difficulties encountered in calculating the diffusion coefficient of the dyes are discussed. The structural and morphological changes effected by the pretreatment were also investigated using XRD and SEM, respectively. The increase in lateral order of the treated yarns was noted. The possible reason for an unusual relationship between the increase in lateral order and increase in dye uptake was explained. The cross-sectional shape and swelling and the smoothening out of the fiber surface were evidence by SEM. © 1996 John Wiley & Sons, Inc.     

The carrier dyeing of synthetic fibers

The mode of action of carriers in augmenting the rate of dyeing of disperse dyes with acrylic and polyester fibers is discussed in terms of the plasticizing action of the carrier. It is shown that the effectiveness of a carrier is determined by its ability to reduce the glass transition temperature of the fiber and not by the fiber swelling. The rate of dyeing as measured by the diffusion coefficient of the dye is shown to be uniquely related to the difference between the dyeing temperature and the glass transition temperature (T – T_g). In the light of these results, some aspects of carrier action in dyeing from perchlorethylene are discussed. Treatment of polyester fibers with carrier also increases crystallinity. Changes in diffusion for a series of copolyesters have been correlated with the long spacing obtained from small angle X-ray scattering (SAXS).     

Explanatory Paper on Modern Theory

Before the standard affinity of dyeing — Δü± can be determined, it is necessary to develop a theory of the dyeing process. This theory should indicate clearly the measurements that must be made and the manner in which they must be interpreted in order to determine — Δμ±. Each existing theory of dyeing provides a theoretical model of the dyeing process with which the behaviour of the real dyeing system may be compared. Only when the theoretical model is correct in every respect is — Δμ±, calculated with the aid of the model, a true thermodynamic variable, and only then can reliance be placed upon the values that are obtained for this parameter. From the variation of — Δμ± with the absolute temperature T, it is possible to determine the standard heat of dyeing ΔH±, which then enables the standard entropy of dyeing ΔS± to be derived. The measurement and the significance of the thermodynamic variables — Δμ±, ΔH±, and ΔS± are discussed in detail, with particular reference to the mechanism of dyeing of synthetic-polymer fibres with disperse dyes.     

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.     

Evaluation of a functionalized copolymer as adsorbent on direct dyes removal process: Kinetics and equilibrium studies

Functionalized polymeric microbeads were investigated as adsorbent for the removal of three direct dyes from aqueous solutions. The effects of different experimental parameters, such as initial dye concentration, temperature, and solution pH on the adsorption process were investigated. The adsorption process can be conducted with very good result at normal working conditions: neutral pH and normal temperature. The maximum percentage removal obtained was 99.11% for the symmetrical disazo dye, 90.14% for asymmetrical disazo dye, and 98.53% for trisazo dye. The adsorption kinetics followed the pseudo‐second‐order equation for all three investigated dyes in all working conditions. The experimental data were fitted to Langmuir, Freundlich, Sips, and Redlich–Peterson isotherm models, and the best fit was obtained with Sips model. Thermodynamic parameters (ΔH°, ΔS°, and ΔG°) revealed that dye adsorption is an endothermic and spontaneous process. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Decolourization of textile dyes by the white‐rot fungi Phanerochaete chrysosporium and Pleurotus ostreatus

BACKGROUND: The ability of the fungi Pleurotus ostreatus and Phanerochaete chrysosporium to decolourize and detoxify 11 (mono‐, dis‐, poly‐ azo, and anthraquinonic type) dyes, widely used across the textile and leather industries, was tested. RESULTS: Different substrate specificities were revealed between P. ostreatus and P. chrysosporium in decolourization experiments. The latter fungus provided almost complete decolourization of the tested azo dyes up to 600 ppm and dis‐azo dyes up to 1000 ppm, and 80% decolourization of the tris‐azo dye DBU1L38 at 1000 ppm, after 6 days. P. ostreatus provided almost total decolourization of the anthraquinone type dye ABU62 (1000 ppm) after just 1 day. P. ostreatus also showed the ability to decolourize the tested dis‐azo and tris‐azo dyes, giving the best performances against the dis‐azo DBU1U1 (600 ppm) dye, which was 100% decolourized after 6 days. Laccases proved to be the main enzymatic activities acting in P. ostreatus decolourization. CONCLUSION: The potential of the fungi P. ostreatus and P. chrysosporium as efficient bio‐systems for decolourization and detoxification of several toxic industrial dyes was demonstrated. The role of laccases in the decolourization of dis‐azo dyes by P. ostreatus was demonstrated for the first time. Copyright © 2008 Society of Chemical Industry     

Synthesis and characterisation of benzothiazole‐based solid‐state fluorescent azo dyes

Novel solid‐state fluorescent azo dyes containing a 2‐[4‐(dimethylamino)phenyl]benzo[d]thiazol‐6‐amine as the electron donor group were synthesised. These dyes showed a molar extinction coefficient in the range of 20 000–30 000 l/mol/cm. These compounds were characterised by strong solid‐state fluorescence under long ultraviolet light (365 nm). Absorption and fluorescence spectra revealed that electron coupling originating from broad π‐electron delocalisation and the keto–enol form is responsible for the large Stokes shift. These dyes were readily soluble in common solvents such as dichloromethane, chloroform, dimethyl formamide , tetrahydrofuran and dimethyl sulphoxide and were characterised by means of elemental analysis, proton nuclear magnetic resonance and mass spectrometry. Thermogravimetric analysis of solid‐state fluorescent dyes show thermal stability up to 270 °C and can therefore be used for polymer application. The coloristic properties of these dyes were evaluated on polyester by the disperse dyeing method.     

Halochromism of acrylic fibres dyed with some disperse dyes

Anomalous dyeing behaviour has been found when regular acrylic fibre treated in hydrochloric acid, in which the sulphonic acid group was present entirely in the acid form, was dyed in neutral condition with azo and anthraquinone disperse dyes. In the very early stages of dyeing there was an abnormally high degree of dye exhaustion, with bathochromic (azo) or hypsochromic (anthraquinone) colour changes on the fibre. These phenomena gradually disappeared after prolonged dyeing, with normal adsorption equilibria and colours eventually being obtained. The results were explained on the basis of protonation by the sulphonic acid groups of treated fibre which occurs at the azo nitrogen or the amino nitrogens of the substituents in the 1 — or 1,4-positions of anthraquinone. The normal adsorption equilibria after prolonged dyeing was attributed to hydrolysis of the cyano side group to form carboxylic acid. This produces ammonia to liberate neutral dye from the protonated dye cation adsorbed electrostatically by the sulphonic acid anion of the treated fibre.     

Studies on mixture dyeing. IV. Equilibrium adsorption of direct dyes

Chrysophenine G (C.I. Direct Yellow 12), Benzopurpurine 4B (Red 2), Sirius Red 4B (Red 81), Sirius Supra Blue BRR (Blue 71) and Sky Blue 6B (Blue 1) were selected as typical direct dyes, and the equilibrium adsorptions on cellulose (Cellophane) from the 1:1 and 2:1 molar mixture dye baths were investigated at 90° and 70°C. The standard affinity in mixture dyeing was obtained by the equation derived from the assumption of monodispersed and diffusive adsorption. The standard affinity in mixture dyeing was nearly equal to that in single dyeing, except for the Chrysophenine G–Sky Blue 6B system. However, judging from the fiber and solution log sum plots, there was a definite difference between mixture and single dyeing. It was explained by the change of activity of dye and sodium ions on substrate followed by the marked change of the total adsorption. The adsorption behavior of direct dyes is discussed in detail from the viewpoint of concentration dependence of the activity coefficient of dye and sodium ions on the substrate.     

Studies in dyeing. I. Effect of crystal modification of disperse dyes on their dyeing behavior

Three commerical disperse dyes and a laboratory-synthesized disperse azo dye were converted to different crystal forms. These were characterized by melting point, x-ray diffractograms, and their dyeing behavior on polyester fibers. The different crystal modifications of the same dye were shown to dye polyester fibers (but not polyamide fibers) at different rates and to different fiber saturation values. An attempt has been made to explain these differences based on a thermodynamic approach. An attempt is made to apply the concept of crystal modification of disperse dyes to some of the earlier studies done on dyeing and printing of disperse dyes on polyester and secondary cellulose acetate substrates reported in the literature.     

Dyeing fine denier polypropylene fibers with phenylazo-β-naphthol-containing sulfonamide disperse dyes

A series of phenylazo-β-naphthol-containing sulfonamide disperse dyes were prepared from C.I. Acid Orange 7 by successive reactions of chlorination and amination, and their chemical structures were characterized by FTIR, ¹H NMR, and mass spectrometry. The dyes were applied to coloring of knitted fabrics from fine denier polypropylene fibers by exhaust dyeing and their optimal dyeing conditions, such as dyebath pH, dyeing temperature, dyeing time, and dye concentration were investigated in detail. Then, dye exhaustion, color strength, and color fastnesses of the dyes on the fibers were assessed and summarized. In view of dye exhaustion and color strength of the sulfonamide dyes on fine denier PP fabrics, 90°C was selected as the best dyeing temperature at dye concentration below or equal to 3.0% owf. For achieving higher color strength, 130°C was the better choice when the dye concentration was above 3.0% owf. The sulfonamide dyes, especially secondary sulfonamide dyes, exhibited superior dye exhaustion and color fastnesses to washing, sublimation, and rubbing on fine denier PP fabrics in comparison to C.I. Solvent Yellow 14 bearing the same chromophore but without sulfonamide group.     

Molecular Mechanisms of Disperse Dyeing of Polyester and Nylon Fibres

The kinetics of the dyeing of polyester fibres with disperse dyes have previously been discussed in terms of a model in which the only forces of interaction between dye and polymer are those that give rise to mutual solubility. The rate and extent of dyeing depend on the size and shape of the dye molecules and the detailed structure of the fibre. The concentration profiles of dye within single filaments of polyesters and nylons have now been determined by a new method termed ‘optical sectioning’, in which an image of a filament is scanned by a narrow slit. The dye distributions are found by comparing experimental transmission values with those calculated by a computer for a model system in which various parameters can be adjusted. For the polyester-dye systems the rate constant of transfer of dye from dyebath to fibre (k₁) was the same as the rate constant of diffusion away from the interface (k₂). Some nylon-dye systems, on the other hand, behaved as if k₂ = k₁, whereas others behaved initially as if k₁ = k₂ but later as if k₂ > k₁. Apparent diffusion coefficients were also derived from sorption measurements and were found to fall as the dye concentration in the fibre increased. Measurement of the orientation of the dye molecules by optical dichroism showed that the dye molecules entering the filaments late in the dyeing process were more highly orientated than the earlier ones. The decrease in diffusion coefficient has been interpreted in terms of the observed higher orientation, as resulting from a greater entropy of activation in the diffusion process.     

Kinetics of thermo-fixation of solvent dyes and pigments in polyester fibres

The diffusion coefficient of a dye in fibres is critical to understanding the dyeing process and coloration quality of products. In this paper, the diffusion kinetics of solvent dyes in the thermosol dyeing of polyester fibres was studied by measuring K / S of the dyed polyester fabrics based on the Kubelka–Munk equation. The diffusion coefficients of two model solvent dyes were estimated with Hill's equation using the experimentally measured K / S values and were found to be in good agreement with those calculated from the traditional extraction method. Such a measurement method was applied to several other solvent dyes and pigments that have different molecular sizes and a good correlation between the measured diffusion coefficients and sizes of these dyes and pigments was found. The results indicate that it is feasible to use K / S measurement of dyed fabrics and Hill's equation to evaluate the kinetics of the thermosol dyeing process under certain conditions.     

Study of the Influence of Gemini Cationic Surfactants on the Dyeing and Fastness Properties of Polyester Fabrics Using Naphthalimide Dyes

In this paper, the dyeing and fastness properties of three monoazo naphthalimide dyes including different imide groups (dye 1: ethyl amine, dye 2: ethyl glycinate and dye 3: glycine) on a polyester fabric were investigated in the presence of two gemini cationic surfactants (symbolized as 12‐4‐12 or 14‐4‐14) and a conventional single chain surfactant, dodecyltrimethylammonium bromide (DTAB). The color strength (K/S) of naphthalimide dyes on polyester fabric was measured through the reflectance spectrophotometric method, and the values obtained in the presence of different cationic surfactants increased in the order of dye 3 < dye 2 < dye 1. Although the K/S values indicated that the gemini cationic surfactants had almost no effect on the dyeing behavior of dye 1, but they were effective in dyeing ability of dye 2 and dye 3. The data for dye 2 demonstrated that build up of polyester fabrics in the presence of gemini surfactants are more than the conventional cationic surfactant, and also K/S values of dye 3 on polyester fabrics were in the order: DTAB > 12‐4‐12 > 14‐4‐14. It was found that the washing and rubbing fastness properties improved with increasing the concentration of surfactants. In addition, the sublimation fastness of dye 3 was more than the other dyes owing to the presence of a polar group in its chemical structure, and the light fastness of naphthalimide dyes on polyester fabrics was generally moderate.     

One-bath dyeing of wool/polyester blends with acid and disperse dyes. Part 2 — disperse dye distribution on polyester and wool

Disperse dye distribution on polyester and wool during one-bath dyeing of wool/polyester blends is discussed. The addition of carriers increases the wool's intrinsic saturation value for disperse dye, thus raising the degree of staining on the wool component at the low dye uptakes. However, staining can be minimised if the dyeing is close to or attains equilibrium conditions. Sequestering agents can accelerate the disperse dye diffusion out of the wool fibre, further reducing staining on wool and transferring more disperse dyes from wool to polyester. Citric acid can be used as a sequestering agent as well as a pH adjusting agent.