Coloration Technology最新文献

Herein, we initially used sodium hydroxide to pretreat cotton fabric to obtain different wettability. Then the non-aqueous dyeing system was applied to the eco-friendly dyeing and washing process of cotton fibre. Meanwhile, Fourier-transform infrared (FTIR) spectrometry and zeta potential analysis were performed to analyse the difference of cotton fibres before and after pretreatment. Furthermore, the effect of pretreatment on the adsorption behaviour was investigated by molecular dynamic (MD) simulations. Compared with control cotton, an approximate increase of 23.0% in the colour strength (K/S) value was achieved. Findings from FTIR and zeta potential showed that the number of available hydroxyl groups of cotton involved in the dyeing increased after pretreatment. MD simulations demonstrated reactive dye molecules showed a faster adsorption behaviour on the fibre surface with good wettability. It was attributed to the increased interaction energy between dye molecules and cotton fibres. Therefore, improving the cotton fabric's wettability is an effective way to improve the utilisation rate of reactive dyes in a non-aqueous medium dyeing system.

Most modern colourants are acquired from petroleum-based sources or mining, which often causes environmental degradation. Consequently, alternative colouring solutions are sought, such as using biocolourants, which are organic colourants from bio-based sources. Although biocolourant research is prevalent in the textile dyeing field, biocoloration of thermoplastics remains relatively unexplored. Thus, our study presents lightfastness and mechanical properties of polylactic acid (PLA) biocoloured with biochar, kraft lignin, indigo from Isatis tinctoria, madder extract from Rubia tinctorum, and weld extract from Reseda luteola. Indigo, madder extract, and weld extract are common bio-based textile dyes, whereas biochar and lignin are more known as easily accessible filler additives than as colourants. Stemming from promising results with bio-based indigo in our previous studies, this study broadens the scope with new colourants and analysis methods. In this study, mixtures of biocolourant powder and PLA granules were heated to a viscous state, blended inside an injection screw, and injection moulded into plastic specimens. The PLA-biocolourant specimens were inspected with scanning electron microscopy (SEM) and subjected to ASTM D638 tensile test. Furthermore, the specimens were exposed to ISO 105-B02 lightfastness test under xenon arc light. Before and after xenon light exposure, the specimens were analysed with visual inspection, reflectance spectrophotometry, hyperspectral imaging, and Fourier-transform infrared (FTIR) spectroscopy. The results showed that most of the biocolourants produced an even colour with adequate lightfastness. Moreover, lignin, biochar, and madder extract substantially improved photodegradation resistance and tensile properties of PLA. Thus, further development of biocolourants, especially lignin, as functional PLA additives is recommended.

A less water dyeing system using non-aqueous medium as dyeing medium shows promising application potential due to its environmentally friendly and efficient dyeing processes, achieving high dyeing and fixation percentage of 100% and 90%, respectively. While previous studies have focused on the dyeing procedures and mechanisms of cotton dyeing in non-aqueous medium, there has been limited research on colour matching between reactive dyes. This study investigates the matching performance of the representative dyes C.I. Reactive Red 195 and C.I. Reactive Blue 19 in a novel non-aqueous dyeing system, and compares their effectiveness to that of traditional aqueous dyeing systems. The building up power of reactive dyes in different dyeing bath was studied, as well as the influence of compounding ratio and fixing temperature on dyeing performance. The results reveal that reactive dyes exhibit better building up properties in non-aqueous medium compared to traditional water bath. The colour change and matching of the reactive dyes was different between non-aqueous medium and water bath, showing noticeable variations in fixation percentage. Notably, when the ratio between Reactive Red 195 and Reactive Blue 19 was 1:1, the absorption wavelength of the blend dye in the non-aqueous medium remained stable with increasing fixation temperature, while a redshift occurred in the water bath. Overall, the colour matching performance of reactive dyes in the less water dyeing system using a non-aqueous medium is impressive, suggesting significant potential for further development in sustainable dyeing technology.

Previously published kinetic-derived data reported for the temperature-dependent diffusional behaviour of two direct dyes and a reactive dye within both cellophane and cotton substrates, in the presence of both a constant amount and varying amounts of added inorganic electrolyte, and over a diverse range of dyeing temperatures, were re-evaluated using the Williams–Landel–Ferry equation. The experimentally observed diffusivity of the various anionic dyes within both types of cellulosic material and the structural relaxation times of the respective, water-plasticised, cellulose I and cellulose II macromolecules, were shown to be intrinsically related, thermally regulated phenomena. The plasticisation model of dye diffusion seems to offer a plausible explanation of the temperature-dependent diffusional behaviour of direct dyes and reactive dyes within cellulosic fibre/polymers in the presence of added inorganic electrolyte.

Traditional reactive dyeing has the technical problems of high water consumption and high pollution. In this article, the effect of polyethylene glycol 400 (PEG-400) on the dyeing properties of cotton fabrics with high concentration reactive dyes in non-aqueous medium was studied. Initially, the effects of PEG-400 on colour strength (K/S) and colour fastness of dyed fabric with reactive dye are systematically discussed. In addition, the effect of PEG-400 on the hydrolysis properties of reactive dyes was analysed by high-performance liquid chromatography (HPLC). At the same time, the molecular interaction force between the dye and PEG-400 was analysed by ultraviolet-visible (UV-visible) spectroscopy. The results showed that when PEG-400 concentration was 3.0 g/L, K/S value of dyed fabric (5.0%, on weight of fabric, owf) was increased by 33.5%, and is much higher than dyed fabrics without PEG-400. HPLC and UV-visible analysis showed that the addition of PEG-400 effectively reduced the hydrolysis rate of dye II containing two vinyl sulfone reactive groups, which was converted from C.I. Reactive Black 5 containing contains diethylsulfone sulphate group. Its hydrolysis rate was reduced by 20.9%. PEG-400 also decreased the aggregation degree of high concentration reactive dye, and increased the solubility of reactive dye. This method has certain universality. Therefore, using PEG-400 as an additive is an effective way to improve the dye uptake of reactive dyes in non-aqueous medium dyeing system and realise cleaner production.

The coloration performance and colour fastness properties, crucial for industrial textile printing, depend on the spreading and fixation behaviour of ink-jet droplets on porous fabrics. Current nano-pigment-based ink-jet applications provide unstable results for these properties, especially for synthetic and blended fabrics. This study focuses on cellulose-based blended fabrics as substrates to modify the wetting properties of fabrics through cationic and water-repellent treatments, to improve the coloration performance and colour fastness systematically. The study conducted analytical experiments to analyse the surface element composition, ion potential and surface morphology of the fabrics. Differences in printing colour and pattern performance were attributed to the behaviour of ink droplet spreading on the fabric surface and inside the fabric, including wetting time, colourant distribution, and ring shape. The results indicate that ink droplet spreading on fabrics significantly influences printing pattern sharpness, including edge clarity and colour intensity, which can be improved through surface modification, including cationic and water repellent treatment. The use of blended fabrics treated with 1% cationic modifier and 0.05% fluorine-containing water repellent resulted in effective suppression of droplet formation and significant enhancement of colour performance and fastness. Furthermore, as the ink droplet volume decreased from 5 to 1 μL, the coffee ring effect on the fabric treated with the water repellent agent gradually diminished, leading to improved printing sharpness during the printing process.

Enzymatic dyeing is an environmentally friendly and energy-efficient dyeing method conducted at low temperatures, making it an important option for sustainable dyeing processing technology. This study investigated the enzymatic dyeing of cotton and silk fabrics using six phenolic monomers (catechol, hydroquinone, 2-aminophenol, 4-aminophenol, 1,4-phenylenediamine and 2,5-diaminobenzenesulphonic acid) via oxidative polymerisation catalysed by horseradish peroxidase (HRP). The research explored the colouring mechanism, functional attributes and dyeability of the fabrics. The polymerisation mechanism of the polymer was elucidated through liquid chromatography–tandem mass spectrometry, while the functional and morphological characteristics of the dyed fabric were examined via Fourier transform–infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy imaging. The dyed fabric underwent dyeability assessments, including colour depth analysis and various fastness tests. Under mild reaction conditions, nearly all the phenolic monomers successfully dyed both the silk and cotton fabrics using HRP. The dyed fabrics demonstrated enhanced thermal stability and dyeability. However, the cotton fabrics exhibited worse dyeability and fastness than the silk fabrics, with noticeable stains on their surfaces when dyed with certain phenols. These findings underscore the suitability of enzymatic oxidative dyeing for protein fibres over vegetable fibres, as well as the importance of tailoring enzymatic dyeing processes for vegetable fibres.

The aim of this study was to investigate the extraction of anthocyanins from the fruits of Caucasian blueberry (Vaccinium arctostaphylos L.) and examine the colour stability of anthocyanins encapsulated through spray drying in model systems. The trials were conducted to determine the optimal conditions for anthocyanin extraction using an ultrasonic water bath at temperatures of 25, 50 and 75°C. The ideal anthocyanin extraction occurred at 25°C using 100% acetone in an ultrasonic bath for 15 min at 35 kHz. Anthocyanin concentrations were evaluated using the pH differential method. The extracted anthocyanins were encapsulated through spray drying with maltodextrin as the encapsulating material. The encapsulation efficiency was 80.4 ± 0.20%, and the anthocyanin retention rate was 83.0 ± 0.76%. The coloured capsules were added to model systems with pH values of 4.50, 5.00, 5.50 and 6.00. The colour values (L* 50.16 ± 0.05, a* 4.08 ± 0.04, b* −9.35 ± 0.01, H° 293.57 ± 0.15, C* 10.20 ± 0.03) were measured during varying storage conditions. The results showed, that colour loss began on the fifth day and this was accelerated with higher temperatures and pH values. It was found that encapsulation significantly preserved the stability of the blue colour and the loss of the blue colour followed first-order reaction kinetics. The study showed that the blue colour of microcapsules was best preserved at pH 5.00 at 25°C. In this case, the measured total colour change (∆E) was 5.86, the activation energy (E_a) was 37.64 kJ/mol, and the half-life (t_1/2) was determined to be 19.08 days.

The use of natural pigments in the food industry has increased due to their health benefits. Carotenoids are natural pigments that carry the disadvantage of sensitivity to temperature, light and the presence of enzymes and oxygen. Microencapsulation technology is widely used to protect these compounds against degradation, preserving their physicochemical characteristics. The research objective was to obtain the kinetics of carotenoid degradation of a microencapsulated extract of orange-fleshed sweet potato (Ipomoea batatas L.) and to establish its physicochemical properties. The sweet potato extract was obtained using ultrasound and then microencapsulated by spray drying using maltodextrin as the wall material. The microencapsulate obtained was subjected to degradation kinetics at 30, 40 and 50°C. Carotenoid quantification analysis, colour, rehydration properties, antioxidant capacity, Fourier-transform infrared (FTIR) and RAMAN spectroscopy and microstructural characterisation were performed on the microencapsulated carotenoids. From the kinetic analysis, the activation energy of the sweet potato extract was 16.31 kJ/mol while that of the microencapsulated sweet potato extract was 10.27 kJ/mol. Thus, it can be concluded that the microencapsulation process improved the stability of carotenoids subjected to thermal conditions. FTIR and RAMAN spectra confirmed the microencapsulation of the carotenoids. The microencapsulated powder showed a hygroscopicity of 0.22 g/100 g, wettability of 49 s and high solubility. The results obtained in the kinetics are a useful tool to predict losses during the process of heating the carotenoids from sweet potato, thus allowing improvement and selection of the products to which this powder can be applied, in either thermal or cold processes.