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.     

Studies in dyeing. II. Effect of crystal modification of disperse dyes on polyester dyeing at 130°C

Four commercial disperse dyes were purified and their different crystal forms were prepared by crystallizing from different solvents or precipitating from their solutions in glacial acetic acid by dilution with water. These forms were found to have different melting points. They were dyed on polyester fibers at 130°C to fiber saturation values by changing the dyebath every 15 min. The effect of pretreatment of the dyes in an aqueous environment at different temperatures (60°, 100°, and 130°C) for 15–60 min in the presence and absence of a dispersing agent on the dye uptake values was also studied. Such treatments are shown to reduce the dye uptake. The implication of these treatments in practical dyeing are pointed out.     

One‐pass process for the continuous dyeing of polyester/unmercerised cotton blends with disperse/reactive dyes. Part 2: Process modifications to improve the colour yield of selected reactive dyes on the cotton component of the blend†

One of the limitations of DyStar’s TTN one‐pass continuous dyeing process for dyeing polyester/unmercerised cotton blends with disperse and reactive dyes is its inability to achieve heavy depths economically and part 1 of this study indicated that the limitation could be attributed to the reactive dye [ 1 ]. In this study, the constituents of the pad liquor were varied to determine if the visual colour yield of selected reactive dyes could be improved. In so doing, it was possible to speculate whether the low colour yield from some of the reactive dyes used in the TTN process was as a result of inefficient ‘delivery’ of the dye to the reactive sites on the cotton.     

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.     

Novel hydrolysable azo disperse dyes based on N‐ester‐1,8‐naphthalimide: dyeing of polyester–cotton blends

The dyeing of polyester–cotton blends with new alkali‐hydrolysable azo disperse dyes based on N‐ester‐1,8‐naphthalimide was investigated. Polyester–cotton blend fabrics were dyed using both one‐ and two‐bath methods. Dyes 3 and 4 offered lower colour yield on polyester using the one‐bath method. For the rest of the dyes, employing either the one‐ or two‐bath method resulted in a similar colour yield on polyester fabric. The results for fastness properties and colour yield of the dyeings showed that the dyes were suitable for dyeing polyester–cotton blends using the one‐bath method. The kinetic study of hydrolysis of the dyes in alkali media obeyed the pseudo first‐order reaction rate.     

One‐bath union dyeing of a modified wool/acrylic blend with acid and reactive dyes

Pretreated wool/acrylic fibre was obtained by a facile amidoximation process. Fibre characterisation (nitrogen content, tensile strength, shrinkage, infrared spectra and X‐ray diffraction) proved the success of the pretreatment. Union dyeing of wool/acrylic fabrics with acid and reactive dyes, namely CI Acid Red 40, CI Acid Blue 25, CI Reactive Red 194 and CI Reactive Blue 25, was obtained using a one‐bath dyeing process. Different factors that may affect the dyeability of the blend fibre, such as dyebath pH, liquor ratio, temperature, time and dye concentration, were evaluated with respect to the dye exhaustion, fixation, colour strength, levelling and fastness properties. Excellent to good fastness was obtained for all samples, irrespective of the dye used. The result of the investigation offers a new viable method for union dyeing of wool/acrylic fibres in a one‐dyebath process.     

Possibilities of polymer‐aided dyeing of cotton fabric with reactive dyes at neutral pH

Water‐soluble polymers have versatile application, viz., water‐soluble polyacrylates have been widely used in the reactive dyeing of cellulosic fibers and the related soaping as an important component of the leveling and washing agent. In this article, one such water‐soluble polymer, polyacrylic acid has been synthesized, characterized, and applied in conjunction with various types of reactive dyes, namely triazinyl, vinyl sulfone, high exhaustion, and bifunctional reactive dyes, along with crosslinking agents, namely glycerol 1,3‐dichlorohydrin and hexamethylene tetramine‐hydroquinone, respectively. One of the crosslinking agents (the former one) has been synthesized in the laboratory. Crosslinking agent is necessary to adhere the dye molecule onto the cellulose macromolecule. Different process sequences have been formulated and explored for dyeing purpose. All such dyeings were carried out at neutral pH. The dyed samples were assessed through color strength in terms of K/S values and their fastness properties were assessed by standard methods. All such dyeings were compared with conventional dyed samples. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

One-bath dyeing of polyester/cotton with disperse and bis-3-carboxypyridinium-s-triazine reactive dyes. Part 1: Factors limiting production of heavy shades

Over the last 20 years, selected disperse dyes and bis-3-carboxypyridinium- s -triazine reactive dyes have been widely promoted for the exhaust dyeing of polyester/cotton blends in a one-bath-one-stage ('all-in') process under neutral conditions. However, despite the time and energy savings afforded by this elegant dyeing process, there is a belief in the dyeing industry that economical production is limited to pale and medium depths of shade. In this paper, the two dye classes (disperse dyes on polyester and bis-3-carboxypyridinium- s -triazine reactive dyes on cotton) have been investigated to understand why heavy depths of shade cannot readily be obtained economically using this process.     

Synthesis and application of KM‐type reactive dyes containing 2‐ethoxy‐4‐chloro‐s‐triazine

A new kind of hetero‐bifunctional reactive dye containing 2‐ethoxy‐4‐chloro‐s‐triazine, with better activity matching with β‐hydroxyethyl sulphone sulphate at a low fixation temperature, was successfully synthesised and characterised. An ethoxy group was designed to be introduced into triazine to increase the substantivity and the reactivity of the dyes. Thereby, the fixation of mono‐s‐chlorotriazine/hydroxyethyl sulphone sulphate (KM‐type) bifunctional reactive dyes on cotton was improved, and dyeing under mild conditions with high fixation was realised. Nineteen dyes with orange, red and blue colours were synthesised and characterised by UV‐Vis and infrared spectroscopy and mass spectrometry. Synthesised dyes were dyed at 60, 75 and 90°C, respectively. Exhaustion and reactivity for all of the ethoxy‐containing KM‐type dyes was over 90% at the optimal temperature, and fixation was over 87%, which was higher than the ethoxy‐free comparative dyes. The optimal fixation temperature of ethoxy‐containing dyes was initially reduced to 75°C, and then to 60°C. Compared with comparative dyes, the wash fastness and light fastness were basically unchanged, and the wet rub fastness of the H‐acid series was reduced by one grade.     

Deep‐coloured polyester/cotton blends with low concentrations of polymethylol dyes by a one‐pass continuous dyeing process

An obvious limitation of the one‐pass continuous dyeing process for polyester/cotton blends is its inability to achieve deep colour depth, which is caused by the low dye fixation yields of commercial reactive dyes. In this study, the performances of polyester/cotton blends dyed with high‐fixation polymethylol dyes and disperse dyes were compared with those of polyester/cotton blends dyed with a mixture of reactive dyes and disperse dyes. Polymethylol dyes were observed to be suitable for dyeing polyester/cotton blends when used in low concentrations; the required concentrations of polymethylol dyes were only 23–58% of the concentrations of commercial reactive dyes required to reach a given colour level on polyester/cotton blends. The wash and crocking fastness of polyester/cotton blends dyed with polymethylol dyes were similar to those of polyester/cotton blends dyed with reactive dyes.     

Quaternary reactive dyes containing a thioether‐ethylsulphone group. Part 2; Application methods for the dyeing of nylon†

A member of the new series of cationic reactive dyes containing a thioether‐ethylsulphone grouping referred to in Part 1 of this series has been applied to nylon at pH 3–10. The dye is water soluble and shows excellent substantivity for nylon 6.6 when dyed at the boil at pH 8–10. Under alkaline conditions, gradual β‐elimination back to the vinylsulphone dye occurs and covalent bond formation quickly takes place with the fibre; the higher the pH the more rapidly this occurs. Dyeings carried out at pH 10 showed very good brightness and levelling, together with good wash fastness. The light fastness of dyeings at moderate depth was 4–5 on the Blue Wool scale.     

Seam penetration in the dyeing of garments using reactive dyes. Part 2: Evaluation of the effect of processing conditions on the efficacy of seam penetration in the dyeing of cotton with reactive dyes†

In a previous report, the development of an instrumental method for the quantitative assessment of seam penetration by reactive dyes was described. This paper now reports the use of this instrumental protocol to evaluate the effect of processing variables, especially temperature, pH and dye concentration, on the efficacy of seam penetration in the dyeing of cotton with reactive dyes. A simple approximate relationship has been established between the migration index of a reactive dye to its ability to penetrate seams efficiently.     

Influence of different preparation and dyeing processes on the physical strength of the Ingeo† fibre component in an Ingeo fibre/cotton blend. Part 1; Scouring followed by dyeing with disperse and reactive dyes‡

A study has been conducted to examine the effect of different preparation and dyeing processes on the physical strength of the Ingeo fibre component of an Ingeo fibre/cotton blend. An alkaline scouring process (for the cotton), followed by a two‐bath, two‐stage dyeing process in which the Ingeo fibre underwent a simulated dyeing with disperse dyes, followed by the cotton being dyed with reactive dyes, caused minimal deterioration to the strength of the Ingeo fibre. However, it is considered that problems might arise if the Ingeo fibre was subjected to prolonged dyeing times, particularly at neutral or alkaline pH, e.g. if an excessive number of shading additions needed to be carried out.     

Influence of different preparation and dyeing processes on the physical strength of the Ingeo† fibre component in an Ingeo fibre/cotton blend. Part 2; Bleaching followed by dyeing with disperse and reactive dyes‡

A study has been conducted to examine the effect of a vigorous alkaline scour–bleaching preparation, followed by high temperature dyeing, reduction clearing and a reactive dyeing process on the physical strength of the Ingeo fibre component of an Ingeo fibre/cotton blend. The results indicate that the physical strength will be retained at a technically‐ and commercially‐acceptable level provided that prolonged high temperature processing times are not employed.