Fading of azo reactive dyes by perspiration and light

The fastness of azo reactive dyes on cellulose in a combined perspiration and light test was investigated, and compared with the results obtained in a conventional light fastness test. Whereas reactive dyes containing an H-or K-acid azo chromophore performed better in the conventional light fastness test, reactive dyes of the J-or γ-acid type exhibited a higher fastness in the combined test. The results suggest that testing under combined perspiration and light conditions involves a photoreduction mechanism, but a photo-oxidation mechanism operates when dyed fabrics fade under light only.     

Levelling properties of some reactive dyes on cellulose

The levelling properties of nine reactive dyes containing one or two sulphatoethylsulphone reactive groups or one sulphatoethylsulphone and one monochlorotriazine reactive groups have been investigated. A novel test method specifically applicable to reactive dyes has been used in order to evaluate levelling. Undyed and dyed cotton samples were simultaneously dyed in the same bath and the fractions of the additional dye fixed on each of the cotton samples were determined afterwards. A dye distribution index has been proposed that predicts reactive dye levelling according to whether the index exceeds 50% or not. The index was found to depend not only on the nature of the dyes, but also on the concentration of the dye fixed on cotton, the dyeing temperature and the salt concentration in the dye liquor. In redyeing tests the degrees of primary and secondary exhaustion and of dye fixation were measured as a function of concentration of the dye fixed on cotton. Finally a satisfactory correlation was found between the index and the classical inorganicity/organicity value of the dyes. The results also suggest that the levelling properties depend on the degree of dye aggregation.     

Fading characteristics of a disperse dye on cellulose triacetate, polyester and nylon under monochromatic light radiation

Light fastness of CI Disperse Blue 165 dye on cellulose triacetate, polyester and nylon fabric substrates exposed to monochromatic light was examined on a radiant energy basis. The action spectra indicated a strong effect on the substrate-fading characteristics: nylon exhibited poorer light fastness in the visible and ultraviolet light range than polyester and cellulose triacetate. Two specific fading peaks were found for the nylon substrate, which were different to those found for the polyester and cellulose substrates. It was shown that polyester exhibited the best light fastness properties overall. The colour changes in the fading process suggested that the fading products of the dye on nylon (where reduction occurred) were different from those on the polyester and cellulose triacetate substrates (where oxidation occurred).     

Studies of light fading of reactive dyes on cellophane

The ratios of extinction of the short wave (y) and the long wave (x) band in the visible region of the absorption spectra of three reactive dyes on cellophane film and also in aqueous solution, both in the presence and absence of urea, have been measured. Also changes in the ratio with time of exposure were determined. The ratio is found to increase with the concentration of the dye in the fibre and also in aqueous solution. Urea causes disaggregation. The state of aggregation of reactive dyes in cellophane is found to be intermediate between that obtained in a polyester–disperse dye system and nylon or cellulose acetate or cellulose–triacetate–disperse dye system.     

Diffusion with simultaneous reaction of reactive dyes in cellulose

The theoretical equations which described the concentration profile of immobilized species of reactive dyes in the substrate were derived from the diffusion equation with the chemical reaction of first-order or pseudofirst-order. The theoretical profiles in the substrate described by the equations were discussed. The larger the diffusion coefficient D of active species and the smaller the reaction rate constant k, the deeper is the penetration of the immobilized and active species of reactive dyes into the substrate. The method of estimating D and k from the diffusion profiles of both species obtained by means of the method of the cylindrical cellophane film roll was described. The diffusion coefficients of the hydrolyzed species of C.I. Reactive Orange 1 and Red 1 were nearly constant in all the pH values examined. The concentration profiles of both the species of Orange 1 at pH 8.8 were identical with the theoretical ones; while the profiles of immobilized species of Red 1 at pH 10 and of Orange 1 at pH 12 agreed with the theoretical ones and those of active species did not because of the hydrolysis. The diffusion coefficients of active species of these dyes at these pH ranges were smaller than those of the hydrolyzed species.     

The dyeing of cellulose with reactive dyes containing phosphonic acid groups

The fixation of some Procion T phosphonated reactive dyes on cotton in the presence of dicyandiamide in different conditions of dyeing is reported, in order to clarify the role of the carbodiimide in the fixation process.Paper chromatographic studies on Procion Red T-2B show that the reaction mechanism between the phosphonic dye and cellulose in the presence of dicyandiamide is an initial condensation of the phosphonic dye with dicyandiamide to produce a phosphonic acid anhydride, followed by subsequent reaction with cellulose to give a dye covalently bonded to the cellulose. The phosphonic acid anhydride, isolated by means of column chromatography, shows the characteristic adsorption bands of the P—O—P linkage.     

Recent developments in the optimised dyeing of cellulose using reactive dyes

To obtain the optimum conditions for dyeing cellulosic fibre with reactive dyes, it is necessary to find out how dyeing results depend upon the properties of the dyes and the fibres. The relationships between the rates of dyeing, dyeing equilibria, types of dye and additions of auxiliaries are important. Based on data that are already available or easy to acquire, it is possible to control the pH of the dyebath and the addition of auxiliaries to obtain optimum exhaustion and fixation for each reactive dye. The advantages to be gained are shorter dyeing times, better dyeing reproducibility and better levelness.     

Dyeing cotton with reactive dyes under neutral conditions

This paper describes a new method to dye cotton with selected reactive dyes by long-liquor – or so-called 'exhaustion'– processes under neutral conditions. Particularly promising results were obtained with reactive dyes containing free vinyl sulphone residues. Although there are dyes on the market that contain free vinyl sulphone groups, for example, the Novacron C (Huntsman) range of dyes, many of this class contain 'blocked' vinyl sulphone residues; examples include sulphatoethylsulphone or chloroethylsulphone precursor groups, and these may be preactivated to the highly reactive vinyl sulphone form simply by a mild alkali treatment. After this activation, neutral, long-liquor dyeings can be carried out at the boil in the presence of electrolyte. This new dyeing method gave very good results in terms of overall fixation efficiency values, without the need for alkali additions.     

Diffusion properties of reactive dyes into net modified cotton cellulose with triazine derivative

Cotton fabric is chemically modified with a 1,3,5‐triazine derivative containing multireactive and multicationic groups. The diffusion properties of the reactive dyes into net modified cotton cellulose are investigated. When the dyeing temperature is raised, the dye uptake increases gradually and approaches equilibrium after dyeing for 60 min. The diffusion coefficients at different temperatures and the activation energy of the dye are discussed. Compared with unmodified cellulose, the diffusion kinetics of the dye in the net modified cotton cellulose show significant changes. The activation energies of dyes in net modified cotton fibers are much lower than those of dyes in unmodified cotton. The dyeing behavior of the modified cotton is analyzed and compared with the unmodified cotton. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2166–2171, 2007     

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.     

Fading of azo dyes with sodium sulphite

The fading behaviour of a variety of naphthol azo dyes with an excess of sodium sulphite was investigated spectrophotometrically at 30°C in the pH range from 3 to 10. The fading occurred most efficiently under neutral conditions. The azo dyes employed were grouped distinctly into the following three types on basis of the observed spectroscopic characteristics: addition type (A-type), in which the dyes had relatively faster rates had isosbestic points at near 440 nm; reduction type (R-type), in which the dyes had slower fading rates and no clear isosbestic point; and no reaction type (N-type), in which the dyes showed no fading under the experimental conditions. The results suggested that the fading of the azo dyes with sodium sulphite occurred through a Michael addition of a sulphite ion to a conjugate active enone moiety in the hydrazone tautomer (A-type), or to a conjugate iminone moiety in the same tautomer (R-type).     

Diffusion with simultaneous reaction of reactive dyes in cellulose. II. Effect of hydrolysis

Theoretical equations that describe the concentration profiles of immobilized and active species for reactive dyes were derived from the diffusion equation accompanied by the reaction with cellulose and water in the substrate. The diffusion coefficient D and the rate constant of the reaction with cellulose, k_cell, and that with water in cellulose, k_w, were estimated by using the theoretical equations and the cylindrical film roll method. The theory predicted that the apparent diffusion coefficients decreased with the hydrolysis of active species in cellulose. Results from diffusion experiments with C.I. Reactive Yellow 4 and Orange 1 show that the ratio P of k_w to k_cell for Orange 1 increased with increase in pH to about pH 13 and that the P for Yellow 4 was smaller than unity. Using an alternative experiment to diffusion, P of Orange 1 was measured to be 1.0–1.5, and that of Yellow 4 was smaller than unity at pH 11.6 at 30°C. It was therefore concluded that the D of active species was constant to a highly alkaline region and that the decrease in the apparent diffusion coefficient of Orange 1 was mainly due to the hydrolysis of active species in cellulose.     

The stability of monochlorotriazinyl reactive dyes on cellulose films in aqueous alkaline solutions containing peroxide bleaching agents

The stability of seven reactive (one difluoromonochloropyrimidinyl and six monochlorotriazinyl) dyes on cellulose immersed in sodium peroxoborate (PB) solution (UK–TO solution) containing tetraacetylethylenediamine (TAED) was examined using cellulosic films at 60 °C. The extent of dye loss that occurred from the dyed cellulosic films which were immersed in the UK–TO solution without detergent correlated closely to the ratings obtained using the BS 1006 UK–TO wash test. The dye loss that occurred from the dyed cellophane films was attributed to three contributions, namely, alkaline hydrolysis of dye–fibre bonds, oxidative fading of the dye chromophore by peroxides and cellulose degradation accelerated by PB and TAED. The alkaline hydrolysis of the dye–fibre bond and the extent of cellulose degradation in the UK–TO solution were the main contributions to the dye loss; dye oxidation was a minor factor in the dye loss mechanism. The physical bonding of the dye molecules reinforced the covalent dye–fibre bond stability towards the UK–TO solution.     

Synthesis of reactive dyes based on the bis-(N-carboxymethylamino)monoquaternary-triazine-bis-ethylsulphone reactive group. Part 1: Application to cotton cellulose

Reactive dyes containing the bis-( N -carboxymethylamino)monoquaternary-triazine-bis-ethylsulphone [bis-( N -CMA)-MQT-bis-ES] group and related derivatives have been synthesised. When boiled under mildly acidic conditions, such dyes are able to form two small vinylsulphone dye molecules through a process of 1,2-trans elimination. The bis-( N -CMA)-MQT-bis-ES dye was applied using different dyeing procedures (novel dyeing methods 1 and 2). The dyeing and soaping-off results of bis-( N -CMA)-MQT-bis-ES dye were compared with a model sulphatoethylsulphone dye applied using the conventional alkaline fixation method used for applying this type of reactive dye to cotton. The bis-( N -CMA)-MQT-bis-ES dye showed higher exhaustion and fixation values applied using novel dyeing method 2 compared with the sulphatoethylsulphone dye applied using the alkaline fixation method. The soaping-off efficiency for the large bis-( N -CMA)-MQT-bis-ES dye applied using novel dyeing method 2 was the same as that obtained for the sulphatoethylsulphone dye applied using the alkaline fixation method.     

Colour removal of three reactive dyes by UV light exposure after electrochemical treatment

This study applies UV light irradiation after a low current density electrochemical treatment to degrade reactive dyes to remove wastewater colour. The combination of these two techniques improves the quality of the treated effluent with respect to only an electrochemical treatment. Synthetic dyeing effluents containing a reactive dye (C.I. Reactive Orange 4, C.I. Reactive Black 5 or Procion Navy H-EXL) and Na₂SO₄ were studied. Ti/Pt oxides electrodes and UV irradiation lamp (6 W, 254 nm maximum emission) were used. Kinetic constants of the UV irradiation step were calculated. The influence of chloride ion at 3 and 6 mA/cm² was evaluated. Results showed that, with a very small Cl^? concentration (in the order of the net water content) the combined techniques provided full decolourization. The possible presence of 25 organic halogenated compounds was studied by gas chromatography–mass spectrophotometry (GCMS). Only four of them were detected after the electrochemical treatment at low intensity, mainly chloroform. Its concentration was found to be highly dependent of the Cl^? concentration, being much lower when reducing the amount of chloride ion. In all cases, the chloroform concentration was dramatically reduced by further UV irradiation which destroyed it up to a 75%.     

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.     

Behavior of cellulose grafted with poly(methyl methacrylate) and polyacrylonitrile toward some direct and reactive dyes

Viscose rayon fibers modified with polyacrylonitrile (PAN) and poly(methyl methacrylate) (PMMA) were dyed with some direct and reactive dyes. Exhaustion rate of the dye onto fibers was governed by the amount and nature of the polymer grafted. In general, the dye affinity for cellulose and dye exhaustion onto fibers decreased as the graft yield increased. Dye affinity for the PAN–cellulose graft copolymers was greater than that found with PMMA–cellulose graft copolymers. Except in a few cases, the tendency of cellulose graft copolymers of ca. 13% graft to accept direct dyes was more than that of the untreated cellulose, whereas the affinity of reactive dyes for cellulose graft copolymers of up to ca. 43% polymer was more than that of untreated cellulose. The dye fixation, based on the weight of cellulose component, increased as the graft yield increased. The dyeability of cellulose oxidized with ceric ammonium nitrate was also examined. Oxidation of cellulose prior to dyeing reduced the affinity of the dye for cellulose.     

Studies in chemically modified celluloses. VII. Periodate oxidation of cellulose dyed with reactive dyes

Periodate oxidation of cellulose and cellulose dyed with reactive dyes at 32°C in the presence and absence of various concentrations of alkali metal chlorides and sulfates has been studied. The extent of oxidative degradation undergone by cellulose and assessed in terms of copper number and cuprammonium fluidity of the oxidized dyeing, the oxygen consumption during the oxidation, and the rate constant were shown to be markedly increased by the presence of the salts in the oxidizing solution. Borohydride and chlorous acid treatment were used to further modify the periodate oxycelluloses, and the effect of these treatments on the properties was studied.     

国内外活性染料的进展

两个三聚氯氰取代基分别在染料母体两端,藏青色染料结构如下[42]: