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    Dyes and Pigments

    Synthesis, stability and printing properties of a novel 2‐sulphophenoxy‐4‐chloro‐s‐triazine reactive dye for ink‐jet printing of wool

    Abstract

    We report here the synthesis and characterisation of a new medium‐reactivity reactive dye containing 2‐sulphophenoxy‐4‐chloro‐s‐triazine, having enhanced the activity of the chlorine atom for further substitution by the functional groups carried by wool fibre. In addition, a dichloro‐s‐triazine dye was also synthesised for the purpose of comparison. The progress of synthesis reactions and purity of the dyes were determined using capillary electrophoresis and thin layer chromatography. The molecular structure and the chemical compositions of the synthesised dyes were confirmed using Fourier Transform–infrared spectral data and elemental analyses. The inks containing the synthesised dyes were formulated and ink‐jet‐printed onto wool fabrics and then the printed fabrics were steamed at 102°C. Compared with the dichloro‐s‐triazine dye, superior performance in terms of ink stability, K/S and dye fixation was observed for the new 2‐sulphophenoxy‐4‐chloro‐s‐triazine dye. In addition, the light fastness of the fabric printed with the inks containing the new dye was 0.5‐grade greater than that of the fabric printed with the inks containing the dichloro‐s‐triazine dye, and no changes in shade and staining were observed following wash fastness tests of the fabrics printed with the inks containing the new dye.

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    Source:: Coloration Technology

          

    Realisation of polyester fabrics with low transmission for ultraviolet light

    Abstract

    Due to the hazardous impact of ultraviolet (UV) light, textiles with UV‐protective properties are in great demand. This paper is related to the equipment of polyester textiles, with three different organic and water‐insoluble UV absorbers containing a cinnamate basic structure. To apply the UV absorbers from water‐based recipes, they are combined with polyethylene glycol PEG200 and different dispersing agents. The application onto two different polyester textiles is performed with a conventional high temperature process driven at 130°C with a process duration of more than 1 hour. Alternatively, an innovative microwave‐assisted process of a shorter duration of only 15 minutes is performed at 130°C. This microwave process is performed under solvothermal conditions using a CEM discover microwave machine. The sample evaluation is performed by UV‐visible spectroscopy in an arrangement of diffusive transmission with a special view of the spectral region from 300 to 500 nm. Finally, polyester fabrics with enhanced UV‐protective properties are realised. It is possible to decrease the diffusive transmission for the complete range of UV light to values of smaller than 5%. By contrast, the influence on the interaction with visible light is low, so the coloration properties of the treated polyester fabrics are less affected. The developed process can be used to realise polyester fabrics for various UV‐protective applications by a simple approach. The developed microwave process allows a decrease in process duration to more than 75% compared with the analogously presented high temperature process.

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    Source:: Coloration Technology

          

    Reactive dyeing of silk using commercial acid dyes based on a three‐component Mannich‐type reaction

    Abstract

    Acid dyes are employed for commercially dyeing silk, which results in ionic bonds between the silk fibroin and the dye. This generally leads to low wet fastness properties for dyed silk fabrics. In this work, three commercial acid dyes with aromatic primary amine structures were selected to dye silk using a Mannich‐type reaction, resulting in improved wet fastness of dyed silk by forming covalent bonds between silk fibroin and dye. The Mannich‐type reactive dyeing was applied to silk fabrics at both 30 and 90°C in trials. Dyeing at 90°C can shorten the dyeing time compared with dyeing at 30°C, even although dye exhaustion and relative fixation at 90°C were a little lower. The dyeing process was optimised when the dyeing temperature was 90°C, dyebath pH 4, dye‐to‐formaldehyde ratio 1:30 and holding dyeing time 60 minutes. The results showed that the dye exhaustion on silk fabrics for the three aromatic primary amine‐containing acid dyes exceeded 94% and their relative fixation was over 80%. Their washing and rubbing fastness reached grade 4 or higher. Hence, the colour fastness properties of dyed silk fabrics using the Mannich‐type reactive dyeing method is superior to the conventional acid dyeing method using the same aromatic primary amine‐containing acid dyes. The Mannich‐type reactive dyeing for silk fabrics at 90°C can be developed into a novel and rapid reactive dyeing method, promising an effective dyeing process with excellent colour fastness.

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    Source:: Coloration Technology

          

    Reduced angle sensitivity of structural coloration on an industrial aluminium platform

    Abstract

    Existing structural coloration methods using thin films, commonly implemented in high‐purity aluminium, produce colours which are highly dependent on the viewing angle because of the inherent angular dependence of thin film interference. Adapting the thin film coloration mechanism to anodisation of industrial‐quality aluminium alloys, which scatter light more efficiently than their high‐purity counterparts, reduces angle dependence in the colour produced. This reduction of angle dependence, as well as the wide use of anodised aluminium in consumer products, suggests that structural colour based on anodised aluminium could potentially be scaled up for commercial scale production.

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    Source:: Coloration Technology

          

    Synthesis and dyeing properties of polyvinylamine dyes for cotton

    Abstract

    Novel polyvinylamine dyes were designed and synthesised from poly(N‐vinylformamide‐co‐vinylamine) and reactive dyes, then used to dye cotton fibres by the dip‐pad‐steam process, with the dyeing methods being examined in detail. Each polyvinylamine dye was fixed to cotton without a crosslinking agent through covalent bonds formed between the reactive group of the dye and the cotton fibres. A fixation of 99% was achieved, with grades of 4 and 4‐5 wash and dry‐rub fastness, respectively.

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    Source:: Coloration Technology

          

    Optimisation of process parameters of Alpaca wool printing with Juglans regia natural dye

    Abstract

    The aim of this research study was to optimise the process parameters of Alpaca wool hand‐knitted samples screen‐printing with Juglans regia natural dye and to set the optimal conditions regarding colour yield, colour fastness and colouristic properties of printed samples. An extensive preliminary examination of the Alpaca woollen yarn and hand‐knitted samples characteristics, the characteristics of suitable thickeners and the optimisation of the printing paste composition, was performed. A starch‐based thickener, British Gum, with a dry matter content of 4% was selected due to its rheological properties responding to properties of the Alpaca yarn and knitwear. It was determined that the fluidity increases while the viscosity and the elasticity decrease in acidic pH, so a pH of 4 was set for the thickener preparation. The thickener of lower viscosity and higher fluidity assures easier pressing of printing paste through the screen, giving uniform colour yield on the substrate, contributing to easier absorption of dyes into the fibre. A 45‐minute fixing process at 105°C by steaming delivered the best results of printing quality. Iron sulphate was used as the mordanting agent. The colour fastness to washing, dry and wet rubbing, and to light, was tested for samples with and without mordanting. The highest light and washing fastness were obtained with the iron sulphate mordanting agent printed in acid (pH 4) with paste containing 4% dry matter‐based thickener. The rubbing fastness was satisfactory for samples with iron sulphate printed with paste containing 4% dry matter thickener, fixed for 45 minutes, regardless of the pH.

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    Source:: Coloration Technology

          

    Oxygen plasma pretreatment improves dyeing and antimicrobial properties of wool fabric dyed with natural extract from pomegranate peel

    Abstract

    This paper presents the application of conventional potassium aluminium sulphate wool mordanting and a biochemical method with silver nitrate (as antimicrobial agent and mordant), alone and in combination with oxygen plasma, as part of comprehensive research into pretreatment processes for wool dyeing with natural extract from pomegranate peel (Punica granatum L.). Pretreatment with oxygen plasma significantly improved the hydrophilicity and tensile strength of all tested samples and showed that oxygen plasma can improve K/S, washing fastness, and even replace certain mordants in wool dyeing with natural pomegranate dye. All dyed samples exhibited good antibacterial activity against Staphylococcus aureus, which can be contributed to the phenol content in pomegranate dye. Only after 28 days of intensive ageing in natural weathering conditions did K/S and antibacterial activity against Klebsiella pneumoniae slightly decrease in dyed samples pretreated with oxygen plasma.

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    Source:: Coloration Technology

          

    Colour matching for smart and sustainable spinning of coloured textiles

    Abstract

    The colours and patterns of coloured textiles are usually obtained via dyeing or printing processes. However, these processes consume large amounts of electricity and cause water pollution, which affects the ecological environment. The hand feel of dyed fabrics is superior to that of printed fabrics. Three‐channel rotor spinning is a highly flexible, adaptable and sustainable method for producing coloured textiles by blending precoloured fibres during the spinning process. Additionally, the process requires approximately half the water required for fabric dyeing or printing. Herein, the colour characteristics, as well as the advantages, of the coloured textiles produced by the new method are demonstrated. Three types of Stearns‐Noechel models are modified to describe the relationship between the blending ratios and resulting textile colours. The colour‐matching accuracy is high. As demonstrated by the results, the three‐channel rotor spinning method can effectively promote coloured textile engineering.

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    Source:: Coloration Technology

          

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