One-bath dyeing of wool/acrylic blends with reactive cationic dyes based on monofluorotriazine

A series of reactive cationic dyes containing the monofluorotriazine structure has been synthesised and their dyeing behaviour on wool, acrylic and a 50:50 wool/acrylic blend studied using a one-bath method. The results indicate that reactive cationic dyes having this structure give a high level of exhaustion and fixation on these fibres. Fastness properties on the wool/acrylic blend were also in general very good.     

The effect of reactive dyes on damage in wool dyeing

This paper demonstrates that reactive dyes exert a significant fibre–protective effect when dyeing wool fabric; this effect may be measured, in a reproducible manner, using the wet–burst strength test. The effect of dyebath pH, dye concentration, dyebath temperature and dyeing time on wool can thus be evaluated. The magnitude of the above protective effect has been compared with that achieved using commercially available fibre–protective agents. It is concluded that reactive dyes are significantly more effective than the latter agents when employed in medium to full depths. It is proposed that the unusual protective effect afforded by reactive dyes is related to the following factors. Reactive dyes readily react with sulphur nucleophiles, thus inhibiting thiol–disulphide interchange reactions and thereby significantly interfering with the level of set produced in a boiling dyebath. Reactive dyes react preferentially with non–keratinous proteins in the intercellular cement and the endocuticle thus reducing their tendency to hydrolyse and to partially dissolve in the hot aqueous dyebath.     

Absorption of betaines by wool and its effect on dyeing

This paper reports a study of betaine absorption by wool, the main parameters affecting it and its influence on dyeing with acid dyes. An attempt to establish the types of interaction between fibre, betaine and dye is discussed. The influence of pretreatment with various betaines on the dye distribution (whether the dye is superficially deposited or has diffused into the fibre) throughout the whole dyeing process is also studied.     

Metal ion effect on dyeing of wool fabric with catechu

Wool fabric was dyed with catechu by two different process sequences using various metal sulphates as mordant. The dyeing behaviour has been assessed by measuring K/S values and different fastness properties. The effect of different metal ions have been studied with respect to their influence on colour and fastness properties. The mechanism of mordant interaction with the fibre has been briefly considered.     

Plasma modification on wool fibre: effect on the dyeing properties

The dyeing properties of wool fibre treated with low-temperature plasma (LTP) were investigated kinetically and thermodynamically. Three non-polymerising gases, namely oxygen, nitrogen and a 25% hydrogen/75% nitrogen gas mixture, were used for the LTP treatment. It was found that the dyeing rate, dye uptake, standard affinity, heat of dyeing, entropy of dyeing and activation energy of diffusion were improved after the treatment.     

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.     

Non-isothermal dyeing of wool

Kinetic models of the dyeing process are reviewed and diffusion of dye into the fibre is identified as the rate-determining step in most dyeing processes. A simpler approach to defining a linear exhaustion profile of acid dyes on wool fibres is proposed that takes into account non-isothermal kinetic models and analyses their possibilities of use. In this endeavour a novel dyeing rate constant is defined that appears to be characteristic of a particular dye class.     

The reaction of sodium cyanate with wool and nylon and its effect on subsequent dyeing

This paper describes the reaction of the simplest isocyanate, isocyanic acid, conveniently generated in situ from sodium cyanate, with nucleophilic carboxylate and amino residues in polyamide fibres. Changing the pH conditions greatly affects the outcome of these reactions: under acidic conditions the carboxylate residues are selectively carbamoylated, whereas under neutral conditions both residues are carbamoylated. Such modifications greatly change the dyeing behaviour of the treated substrates. The carboxylate carbamoylation reaction leads to the formation of amides rather than the carbamoylcarboxylate, which is a reactive intermediate.     

The effects of residual surfactants on the dyeing of wool

Wool fabric was extracted with various organic solvents at their boiling points and then dyed with Coomassie Blue BL200. Non–dyed areas of fabric were observed after extraction with ethanol, acetone/ water (70:30) and chloroform/methanol (70:30) mixtures, but not after extraction with perchloroethylene. Silica column chromatography separated the extracts from various solvent pretreatments into five major peaks, based on mass obtained. Some of these peaks were shown to contain cholesterol, non–ionic surfactant and phospholipid. Up to 14 components were detected by two–dimensional thin layer chromatography of the extracts. Thin layer chromatography revealed that some of the more polar components were not extracted by perchloroethylene. Separation of the extracts by column chromatography enabled a study of dye uptake to be carried out after recontamination of pretreated fabric with the major fractions. Materials in two of these fractions were found to eliminate the uneven dyeing observed with Coomassie Blue BL200. Column chromatography and spot tests showed that they behaved similarly to the non–ionic surfactant Antarox CO 630. These experiments also showed that refluxing perchloroethylene extracted only about half as much non–ionic surfactant as did refluxing chloroform/methanol (70:30) mixture. The residual surfactant may originate from the scouring process and/or from processing oils such as Mulrex.     

Neutral dyeing of wool and wool/polyester blend fabrics using sulphatoethylsulphone reactive‐disperse dyes

Two models of temporarily anionic sulphatoethylsulphone reactive disperse dyes were applied to wool, polyester and wool/polyester blend fabrics at different dyeing pH. Maximum exhaustion values and colour yield were observed at pH 7. The results showed that reactive disperse dyes containing bis‐sulphatoethylsulphone reactive groups were more convenient for neutral dyeing of wool and wool/polyester blend fabrics if compared with a dye containing a mono‐sulphatoethylsulphone group. Excellent to very good wet fastness properties on all dyed fabrics were achieved.     

Quantitative analysis of wool/cotton blends: An infrared method

An infrared method is described for the analysis of wool/cotton blends. The method employs the absorption peak of wool at 1520 cm^?1 and that of cotton at 1160 cm^?1 simultaneously to get a reliable accuracy greater than ±3% in the determination of blend composition in the analysis of actual blends.     

The effect of various anti-setting systems in wool dyeing. Part 1: Hydrogen peroxide based systems

Extensive setting of wool fabrics occurs during piece dyeing at the boil and gives rise to adverse changes in dimensional stability such as variable hygral expansion, loss in tensile strength and the appearance of unsightly marks such as 'crow's-feet' on the fabric surface. Anti-setting agents such as stabilised hydrogen peroxide systems have thus been marketed to control this problem. Much has been published regarding the anti-setting and hygral expansion properties achievable but little information regarding the chemical effect of boiling wool with acidic solutions of hydrogen peroxide is available. Fourier transform infrared reflectance spectroscopy has thus been extensively used to quantify the chemical changes occurring on boiling wool in such aqueous solutions of hydrogen peroxide.     

The effect of various anti-setting systems in wool dyeing. Part 4; Sodium tetrathionate based systems

The tetrathionate anion has the potential to oxidise thiols specifically to disulphides; this property has been investigated in this paper from the point of view of using tetrathionate as an anti-setting agent in wool dyebaths. It was found that at pH 3 the addition of tetrathionate actually made the degree of permanent set greater than in its absence; however at pH 5 and pH 7 significant anti-setting benefits were achieved. The reason for the apparently contradictory result at pH 3 was found to be the substantivity and subsequent reactivity of thiosulphate anion for wool – this anion is a product of the reduction of tetrathionate by wool cysteinyl thiol residues.     

The effect of various anti-setting systems in wool dyeing. Part 3; Sodium thiocyanate based systems

Wool fabrics undergo setting during dyeing. The degree of set can be controlled by careful selection of dyebath conditions and also by the addition to the dyebath of chemicals termed anti-setting agents. The anti-setting effect of sodium thiocyanate has been evaluated according to its concentration in the dyebath and the dyebath pH. The fabric crease-angle method was adopted to estimate the degree of anti-setting. In the case of wool fabric boiled in the presence of sodium thiocyanate, good anti-setting effects resulted from the pH 3 and pH 5 treatment baths. Chemical changes in the wool were detected using FTIR analysis.     

The effect of various anti-setting systems in wool dyeing. Part 2: Sodium maleate based systems

Wool is subject to permanent setting reactions during dyeing at the boil. Sodium maleate additions to the dyebath exert an anti-setting effect, and in the case of wool piece-goods dyeing, the magnitude of anti-setting was evaluated using the crease angle method. To achieve anti-setting, the key reactions are the nucleophilic addition of the activated double bond in sodium maleate with wool thiolate anion groups and with free hydrosulphide anions generated by cysteine thiol decomposition. Optimum antisetting effects were achieved when wool fabric was treated with sodium maleate at pH 3. Fourier transform infrared reflectance spectroscopy was used to monitor chemical changes to the wool fibre. Compared to untreated wool, two new frequencies at 1354 and 865 cm⁻¹ were apparent; the highest intensity values for these bands were obtained for wool treated at pH 3, which indicates that wool, being positively charged in this acidic solution, adsorbed more sodium maleate, thus enhancing the chances for nucleophilic addition reactions.     

Selecting reactive dyes for all-in dyeing of polyester/ cotton blends

As a preliminary study to an investigation of the feasibility of dyeing polyester/cotton blend by an all-in process using a pH-shift method, we have investigated the suitability of three types of conventional reactive dyes by considering the effects of pH and temperature on their hydrolysis and fixation behaviour. Monochlorotriazine, vinyl sulphone and bifunctional high exhaustion dyes were assessed but only the bifunctional reactive dye gave acceptable colour yield under the conditions likely to be employed during such a dyeing process.     

洗毛及染色综合废水处理技术

介绍了利用物化法对洗毛废水预处理后再与染色废水合并处理的实际情况和工程治理效果,解决了该污水处理中的几个关键问题。结果表明：洗毛废水经预处理后,CODcr、SS去除率可分别达90%、95%以上,综合废水经水解酸化一好氧及物化处理后,CODcr可下降为180mg／L,色度可降为4。     

One–bath dyeing of polyester/wool blend with disperse dyes

The present work aims to investigate and develop a one–bath dyeing process for most common blend fibres to replace the conventional two–step process usually applied to dye each fibre constituent separately. The main objectives of the proposed process is the conservation of energy, raw materials, dyes, auxiliaries and labour.