Compatibility of a disperse dye mixture in supercritical carbon dioxide dyeing

The compatibility of three disperse dyes, CI Disperse Orange 30, CI Disperse Red 167 and CI Disperse Blue 79, which are commonly used as a trichromatic combination for conventional dyeing, was studied in supercritical carbon dioxide dyeing. Both the dyeing rate and the build‐up of the selected dyes were measured. Experimental results showed that they were quite compatible. The dyeings of a binary combination (CI Disperse Orange 30 and CI Disperse Blue 79, mass ratio 1:1) and a ternary combination (CI Disperse Orange 30, CI Disperse Red 167 and CI Disperse Blue 79, mass ratio 1:1:1) at different dye concentrations showed an on‐tone uptake and presented the same metric hue angles. This proved that the selected dyes could form a useful trichromatic combination in supercritical carbon dioxide dyeing. Furthermore, the uptake and exhaustion of the single dyes in supercritical carbon dioxide dyeing were similar to those in aqueous dyeing, implying that the dyeing media play only a minor role in the dyeing of polyester fibres with disperse dyes.     

分散红73和分散蓝183及其混合物在超临界二氧化碳中溶解度的测定与关联(英文)

The solubility of disperse dyes and their mixture in supercritical carbon dioxide is an important property in study and development of supercritical fluid dyeing technology. In this study, solubilities of C.I. Disperse Red 73, C.I. Disperse Blue 183 and their mixture in supercritical CO2 are measured at temperatures from 343.2 to 383.2 K and pressures from 12 to 28 MPa with a static recirculation method. Under the experimental conditions for the binary (C.I. Disperse Red 73 + CO2 or C.I. Disperse Blue 183 + CO2) and ternary (C.I. Disperse Red 73 + C.I. Disperse Blue 183 + CO2) systems, the solubilities increase with pressure. The solubility of C.I. Disperse Blue 183 decreases with the increase of temperature when the pressure is lower than 16 MPa, and the trend is opposite when the pressure is higher than 16 MPa. However, there is no crossover pressure for C.I. Disperse Red 73. The solubilities are also affected by molecular polarity of dyes. The co-solvent effect exhibited in the dissolving process of mixed dyes promotes their disso-lution in supercritical CO2. The experimental data of solubilities of C.I. Disperse Red 73, C.I. Disperse Blue 183, and their mixture are correlated with the Chrastil model and Mendez-Santiago/Teja model. The former is more accurate.     

Redispersibility of disperse dyes containing polymeric dispersants

Dispersing agents are used during the manufacture of disperse dyes to ensure standard dyeing properties. Polymeric dispersing agents have advantages over classical dispersants in that they are are colourless and easily degraded and do not have to be present in such large quantities. Redispersibility is a potential problem and we have therefore investigated the redispersibility of CI Disperse Red 60 (pure colorant) achieved with classical and polymeric dispersants. We have developed a calculation procedure that will provide some basis characteristics of the studied system and make it possible to choose the composition of mixture of components used for preparation of disperse dye at which the relative coefficient of redispersibility (K_r) is optimised. We found that the K_rof dye prepared with classical dispersants was 10–40 while that of dye prepared with polymeric dispersant was 0.05–7.0.     

Correlation of solubility data of azo disperse dyes with the dye uptake of poly(ethylene terephthalate) fibres in supercritical carbon dioxide

Solubility data of disperse azo dyes in supercritical carbon dioxide are presented for dyeings of poly(ethylene terephthalate) fibres with CI Disperse Red 167:1, carried out at 200–300 bar and 80–120 °C, with varying amounts of adulterants. The same dyeings were also carried out in water for comparison. Scanning electron micrographs were taken of the dyes which show a growth of dye crystals during treatment in supercritical carbon dioxide. The paper reports that at 120 °C, melting of the pure dye CI Disperse Red 167:1 is observed. The presence of adulterants in the dye formulations help prevent agglomeration by acting as spacers between the dye molecules. Dyeings of PETP carried out under conditions of the highest solubility of the dye in supercritical carbon dioxide do not necessarily result in a very high dye uptake. This was shown by pressure- and temperature-dependent dyeing experiments of PETP in supercritical carbon dioxide.     

Synthesis of temporarily solubilised azo disperse dyes containing a β‐sulphatoethylsulphonyl group and dispersant‐free dyeing of polyethylene terephthalate fabric

Disperse dyes containing a β‐sulphatoethylsulphonyl group have temporary solubility and can be applied for dispersant‐free dyeing of hydrophobic fibre. Six novel temporarily solubilised azo disperse dyes having a β‐sulphatoethylsulphonyl group in their structures were synthesised, and their dyeing properties on polyester were investigated. As a dye intermediate, a diazo component having dibromo groups was prepared, and 4‐diethylamino‐4′‐(2‐sulphatoethylsulphonyl‐4,6‐dibromo)azobenzene dyes were prepared by a diazo‐coupling reaction. Then, the dyes containing dicyano groups were prepared by cyanation of corresponding dyes with dibromo groups. The absorption maxima of the dyes were affected by the substituents in the diazo and coupling component rings and varied from 434 to 616 nm in dimethylformamide. Polyethylene terephthalate woven fabric could be dyed with the synthesised temporarily solubilised dyes without using any dispersants. Dyebath pH affected the K/S value at maximum absorption as well as percentage exhaustion on polyethylene terephthalate fabric, and the optimum pH was 5. The dyes gave brownish orange, red, purple, and greenish blue hues on polyethylene terephthalate fabrics, and colour build‐up was good. Wash fastness was good to excellent, rubbing fastness was moderate to excellent, and light fastness was poor to moderate.     

A new dye‐modified poly(ethylene oxide)–poly(propylene oxide) polymer used as a dispersant for CI Disperse Red 60

A new dye‐modified poly(ethylene oxide)–poly(propylene oxide) polymer, in which the dye molecule (CI Disperse Red 60) is bonded onto polyether monoamine via a triazine ring, was synthesised for the preparation of dye aqueous dispersions and was characterised by Fourier Transform‐infrared spectroscopy, ¹H nuclear magnetic resonance spectroscopy and elemental analysis. This polymer exhibits unique dispersing performance for CI Disperse Red 60. The mechanism behind the improved performance is briefly discussed with the help of adsorption isotherms. The results indicated that the hydrophobic dye group of this polymer can strongly adsorb onto the dye particle surface through π–π interaction while its long hydrophilic poly(ethylene oxide) chains allow the formation of a thick layer around the dye particles. It was speculated that the adsorbed polymer molecule on the dye surface would form a brush‐like monolayer conformation. The dyeing performance of the prepared dye dispersions on polyester fabrics was also investigated. It was found that this polymer can effectively increase the apparent solubility of disperse dye. The dyed fabrics showed very good to excellent fastness to washing and rubbing, while the dyeing effluent was colourless.     

Improved mechanism of polyester dyeing with disperse dyes in finite dyebath

A new sorption mechanism of polyester dyeing with disperse dyes in water is proposed. It is considered dye aggregates could not be sorbed unless they turn into single molecules. However, this theory could not explain numerous sorption phenomena: sorption continues when equilibrium dye concentration exceeds its solubility; dyeing at long liquor ratio, using microencapsulated or crystal‐modified dyes do not change concentration of single dye molecules or dye solubility, but increase sorption rate and quantity in a fixed time. We demonstrate that both single and aggregated dye molecules could be sorbed using CI Disperse Blue 56. Because of the large size and low diffusion rate, dye aggregates could temporarily block sorption channel and prevent entry of other dyes. Therefore, only using extra more dyes could get a dark colour. Series of approaches could be proposed to reduce or eliminate the sorption problems caused by aggregates using the new sorption mechanism.     

Use of γ-cyclodextrin/epichlorohydrin polymer in merging fabric formation and coloration processes

A candidate polymeric size was synthesised by the polymerisation of γ -cyclodextrin with epichlorohydrin under alkaline conditions. The motivation for the synthesis was to produce a polymer that could not only function as a warp size for fabric formation, but also serve as a host for dye molecules that could subsequently be released after the weaving process, ultimately promoting the merging of fabric formation and coloration processes. The γ -cyclodextrin/epichlorohydrin polymer has been found to promote the dissolution of textile dyes, such as CI Disperse Blue 3, CI Disperse Yellow 82 and CI Disperse Red 91 to yield pad baths capable of evenly coating polyester fabric. Upon padding and subsequent drying, the dye– γ -cyclodextrin/epichlorohydrin polymer pad baths have been used for dyeing the fabric upon thermofixation. Furthermore, cross-sections of fibre dyed in the same manner indicate dye penetration into the fibre.     

The dyeing of nylon with a microencapsulated disperse dye

Melamine resin microcapsules containing CI Disperse Blue 56 were prepared by in situ polymerisation. The microcapsules were characterised by their thermal properties and morphology, such as particle size and particle size distribution. The dyeing behaviour of the microcapsules on nylon 6.6 was evaluated. The microencapsulated dye exhibited good build-up, levelness and fastness properties. It has been demonstrated that microencapsulated disperse dye can be used to replace commercial disperse dyes in dyeing polyamide fabric without dyeing additives, and the resulting effluent can be easily recycled after filtration.     

Blue core–shell nanospheres prepared by dyeing poly(styrene‐co‐methacrylic acid) dispersions

Blue poly(styrene‐co‐methacrylic acid) nanospheres were prepared by dyeing polymer dispersions with CI Disperse Blue 56. The coloured nanospheres had a clear shell with a thickness of 32.5 nm. The average diameter of the nanospheres increased from 288 to 353 nm, and the glass transition temperature was raised from 109.6 to 117.9 °C after coloration. Ultraviolet‐visible absorption spectra, transmission electron microscopy, and differential scanning calorimetry show that the amino and/or hydroxyl groups of the disperse dyes formed hydrogen bonds with the carboxyl groups on the surfaces of the nanospheres during the coloration process, resulting in increased particle sizes and shell layers. The dye content increased almost linearly with increasing dye concentrations or dyeing temperatures within a certain range. By increasing the pH of the dyeing bath from 4 to 5, the dye content increased sharply from 0.68 to 1.49% because of the ionisation of the carboxyl groups of the macromolecules.     

Effect of microwave pretreatment on the dyeing behaviour of polyester fabric

Polyester fabric (filament by filament) was pretreated in a microwave oven in the presence of solvents and subsequently dyed with commercial disperse dyes [Dispersol Red C‐B (CI Disperse Red 91) and Dispersol Blue B‐G (CI Disperse Blue 26)] at different temperatures and for different durations of time. It was observed that the solvent interaction with the polyester could be enhanced by using microwave heating. Solvent molecules interact rapidly, not only with the surface of the fibre but also with the interior parts. Scanning electron microscope results showed that structural modifications take place, which produce surface roughness and voids. This enhances the dye uptake by threefold in comparison to conventional methods.     

Comparison of different ultrasound support methods during colour and chemical oxygen demand removal of disperse and reactive dyebath solutions by ozonation

In this study, the effects of ozonation, ozonation with ultrasonic bath and ozonation with ultrasonic homogeniser processes on colour and chemical oxygen demand removal properties of disperse (CI Disperse Red 60, CI Disperse Blue 337) and reactive (CI Reactive Blue 171 and CI Reactive Blue 19) dyebath solutions with and without dyeing auxiliaries were investigated. Chemical oxygen demand (in mg/l) and colour (in Hazen) measurements of the studied dyebath solutions were determined. The ozonation process caused simultaneous chemical oxygen demand removal during decolorisation. However, the improvement in chemical oxygen demand reduction was less than of that on decolorisation. The application of the combination of ozonation with ultrasonic homogeniser is the most efficient process and creates a great time advantage over the other process types studied (ozonation alone and ozonation with ultrasonic bath) to reach the same colour and levels of chemical oxygen demand removal.     

VIS absorption spectrophotometry of disperse dyes

In the investigations of the dyeing processes, the low solubility of disperse dyes in water represents a practical problem for the determination of dye concentration in dyebaths and waste waters. Therefore the use of an organic solvent which, dissolves disperse dyes, is recommended in visible spectrophotometry of disperse dyes. Three organic solvents (ethanol, N,N-dimethylformamide, acetone) and two disperse dyes, the disazo dye C.I. Disperse Orange 29 and the anthraquinone dye C.I. Disperse Blue 56, were used for spectroscopic analysis in this present work. The absorbance of aqueous dye dispersions and various organic solvent dye solutions was measured to evaluate the effect of the solvent on the shape and intensity of the absorption spectra and on the wavelength shift of maximum absorption. The validity of Beer–Lambert’s law in each system was ascertained. A suggestion is made how VIS absorption spectrophotometry can be used to determine the dye concentration in disperse dyebaths. The addition of organic solvent to the dyebath leads to dye dissolution, and the Beer-Lambert’s law is then fulfilled. The optimum ratio between the dyebath dispersion and the organic solvents for the dyes investigated is also determined.     

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.     

Dyeing of polyester using micro-encapsulated disperse dyes in the absence of auxiliaries

Polyurea microcapsules were prepared in this study, using disperse dye as the core material and diphenylmethane-4,4'-diisocyanate as the wall-former. Microencapsulated disperse dyes have been characterised in terms of their thermal properties, average particle size and size distribution, morphological structure and composition. Polyester fabric was dyed with microencapsulated CI Disperse Blue 56 using a high temperature dyeing process without dispersing agents, penetrating agents, levelling agents or other auxiliaries. The quality of the polyester fabric dyed in this manner – without reduction clearing – was at least as good as that dyed traditionally after washing and reduction clearing. After separating off the polyurea microcapsules, the dyebath was virtually colourless and was shown to be suitable for reuse.     

Relationship between the solubility of disperse dyes and the equilibrium dye adsorption in supercritical fluid dyeing

In order to understand the dyeing behaviour of synthetic fibres in supercritical carbon dioxide, the solubility of some disperse dyes in supercritical fluid, as well as the rate of dyeing and the equilibrium adsorption of these dyes, have been studied. Dye solubility was measured by a dynamic analytic method at a range of pressure (7.5–25 MPa) and temperature (50–145 °C). The apparent rate of dyeing was measured and the dyeing isotherm was obtained by plotting the equilibrium dye adsorption against the equilibrium dyebath concentration. Linear isotherms were obtained when poly(ethylene terephthalate) samples were dyed with the disperse dyes. The mechanism of dyeing using supercritical carbon dioxide was discussed by considering the solubility, the dyeing rate and the dyeing isotherm.     

Enhancing the wash fastness of disperse dyes on wool with oxidants

Disperse dyes are not currently applied to wool commercially, in large part because of inadequate wash fastness, but they do have potential, especially for wool‐polyester blends. In this study, for the first time hydrogen peroxide was investigated to increase the wash fastness of disperse dyes on wool. In the absence of oxidants, 10 disperse dyes from seven classes imparted colours with a range of depths (K/S 2‐26) with wash fastness (grey scale ratings for colour change) grades of 3 to 4‐5. Hydrogen peroxide had only small effects on colours and gave only small enhancements to wash fastness, which were limited to anthraquinone, nitrodiphenylamine, disazo and coumarin dyes. The bleach activators Prestogen W and citric acid enhanced the bleaching effect of hydrogen peroxide but did not assist with raising wash fastness. Hydrogen peroxide in post‐dyeing scouring made the dyeings brighter but did not significantly enhance wash fastness. Ammonium persulphate, which was included for benchmarking with earlier studies, yellowed the wool and decomposed some dyes. This study extends the range of dye classes whose wash fastness on wool can be improved by ammonium persulphate to now include diazo, coumarin and methine, and confirms that oxidants/free radical initiators have potential for enabling the disperse dyeing of wool.     

Afterclearing of disperse dyed polyester with gaseous ozone

The efficiency of ozone treatment for the clearing of disperse dyed polyethylene terephthalate fibres has been examined. The ozone treatment for the clearing of the dyed samples was performed by blowing the ozone gas from the ozone generator on to the wet fabric samples. The results indicated that 3‐ and 5‐min ozonation times were appropriate to achieve comparable wash fastness results with conventional reduction clearing without significant colour differences (ΔE* value) for the samples dyed with CI Disperse Yellow 23 and CI Disperse Blue 79, respectively; however, the ozonation time had to be increased to 15 min for CI Disperse Red 82. Tensile strength tests and scanning electron microscopy analysis indicated that the ozone treatment did not cause any severe damage to the fabrics. Ozone treatment for the afterclearing of disperse dyed polyester fabric can lead to energy and time savings and environmental load reduction when compared with conventional reduction clearing. This study tested a new method of ozone application for clearing of disperse dyed polyester by blowing ozone directly on to the fabric samples. This new method of application has the advantage of being readily adoptable for continuous treatment lines and lower water consumption.     

Effects of the side chain density of polycarboxylate dispersants on dye dispersion properties

Comb‐like polycarboxylates were synthesised by copolymerisation of methacrylic acid and nonylphenol polyethylene glycol methacrylate ester, and can be used as dye dispersants. In order to achieve good dispersive ability, three polycarboxylates were synthesised, each having a different side chain density. The side chain density of polymers was controlled by different ratios of monomers in the copolymerisation process. Acidic polymers were neutralised using sodium hydroxide. These polymers exhibit good dispersing performance, such that carboxylate groups are adsorbed onto the dye particle surface and the side chains enable the formation of a thick layer, thus providing the steric hindrance effect. Improvement of dye dissolution in the presence of polycarboxylates was studied. Polymers with a lower side chain density demonstrated a higher dye dissolution in water, which could be as a result of more effective adsorption of dispersant on the dye surface (CI Disperse Blue 79). The dyeing performance of the prepared dye dispersions on polyester was investigated. Spectrophotometric analysis of dyed fabrics using synthesised polycarboxylates demonstrates that there should be an optimum side chain density of polymer in order to control both dye solubility and dispersive ability. The result of turbidimetry and particle size analysis have proven this phenomenon. A comb‐like polycarboxylate with optimum side chain density was a better dye dispersant compared with a commercial sodium naphthalene sulphonate compound, as a result of its better heat stability.     

人造麂皮在超临界二氧化碳中的染色研究

通过改变超临界系统的条件,研究C.I.分散蓝79以超临界CO2为介质对人造麂皮的上粢性能.结果表明,温度和压力都时上染性能有明显影响;C.I.分散蓝79在110℃,22 MPa,染色人造麂皮45分钟,能达到理想效果.染色牢度优于常规水浴染色效果.