Coloration Technology最新文献

A series of 3-(2-aryl-hydrazone)-quinolin-2,4-diones were synthesised by the reaction of aryldiazonium chlorides with 6-butyl-4-hydroxyquinolin-2(1H)-one dissolved in water containing equimolar amount of sodium hydroxide. All the reactions were carried out at 0–5°C and the corresponding hydrazones were obtained in satisfactory yields and purified easily by recrystallisation from hot dimethylformamide. According to proton nuclear magnetic resonance (¹H NMR) and ultraviolet-visible (UV-visible) results, there are two kinds of intramolecular hydrogen bonds in these synthesised aryl-hydrazones which enables the compounds to be rotated about the hydrazone C=N bond and through that leads to a reversible isomerisation between their E and Z configurations. The isomers populations and the rotation phenomenon can be controlled by changing the polarity of the solvents. The E/Z ratio of each synthesised compound was studied in deuterated dimethyl sulfoxide (DMSO-d₆) and, if soluble in deuterated chloroform (CDCl₃) and compared. The results reveal that a decrease in solvent polarity (upon changing the solvent from DMSO-d₆ to CDCl₃) shifts the isomeric balance to Z-geometrical form and substantially increase the E/Z ratio. A density functional theory (DFT) analysis regarding highest occupied molecular orbital (HOMO), HOMO −1, lowest unoccupied molecular orbital (LUMO), and LUMO +1 has been conducted and discussed. The results obtained from DFT calculations at B3LYP/6-31G(d) level of theory, demonstrated that the hydrazone tautomeric forms are more stable with the lowest total energy and showed a good agreement with the experimental findings in both gas and solution states. As it is expectable, DFT calculation in CDCl₃ and DMSO-d₆ indicate that the dipole moments of the Z configurations are significantly higher than those of the E structures.

The search for a more ecological alternative to dyeing processes, which is the most polluting textile process, has become one of the most studied topics today. In this respect, enzymatic colouring with the use of laccases offer important opportunities, but studies on enzymatic colouring are still very limited. However, in order for enzymatic dyeing to find industrial-scale use, the colour variety must be wide. Within the scope of this study, it is an important output that this study has brought to the literature, that the variety of colours that have been obtained in the literature in enzymatic dyeing has been increased so far by working with a wide variety of precursors and their mixtures, including those that have not been tested on wool before. At the same time, the reaction mechanism of the enzymatic dye synthesis and the chemical structures of the dyes were elucidated by Fourier-transform infrared spectroscopy. Beyond that, as it is known, when a new dyeing process is developed, its technical, economic and ecological advantages and disadvantages compared to the currently accepted conventional dyeing should be revealed. In this study, the colours obtained by enzymatic dyeing were matched with 1:2 metal complex dyes and then two fabrics dyed with the same colour, one enzymatic and the other with conventional method, were compared in terms of technical (colour, fastness), economic (water, energy and chemical consumption) and ecological (biological oxygen demand of wastewater, chemical oxygen demand, etc.) aspects.

Detecting colour differences in warp-knitting fabric is essential to ensure its quality. Machine vision algorithms are commonly used for automatic colour difference detection. However, the current algorithm directly extracts RGB (red, green, blue) colour stimulus values from the image without considering the image's colour attributes, leading to a significant error in colour difference detection. To solve this issue, a colour appearance model is introduced into the field of colour difference detection for warp-knitted fabric. Initially, a colour appearance model based on CAM16 is established, and the critical parameters are calculated to obtain the colour appearance attribute of the fabric. The colour difference calculation formula is then constructed in the uniform colour space of CAM16-UCS. A template selection algorithm based on principal component analysis was designed to select warp-knitted cloth images with standard colours. Subsequently, a cloth colour difference detection algorithm was developed using the cloth colour profile model. The performance of the colour difference formula based on the colour profile model was evaluated using the PF/3 method. To compare the CIELab, CMC(2:1), and CIEDE2000 colour difference formulas, standardised residual sum of squares was used. The results indicated that the colour difference formula based on the colour-appearance model is about 5.32% different from the visual colour difference perceived by the human eye. However, it can perform as well as the CMC(2:1) colour difference formula, which is widely used in the textile industry.

The synthesis of a range of new linear substituted heptamethine dyes has been designed and described. The photophysical properties of all the dyes were investigated, with many exhibiting improved fluorescent quantum yields when compared with indocyanine green. Finally, growth inhibition studies were performed in the fission yeast Saccharomyces pombe, which suggests potential antifungals activity in the μM range.

Fabric defect detection is a crucial aspect of fabric production. At present, deep learning detection methods mostly rely on supervised learning. To tackle this issue, this study proposes an unsupervised fabric defect detection approach based-on normalising flow. The method only needs to train the mapping of the feature probability distribution of defect-free samples to a Gaussian distribution. In the inference process, the location of defects can be determined by testing the distance between the probability distribution of image features and the estimated distribution. To adapt to the complex background and various minor defects of the fabric, a feature pyramid structure is adopted. Moreover, considering the gradient vanishing and network degradation caused by deep layers during training, a residual structure is incorporated into the model. Experimental results demonstrate that the feature pyramid flow model outperforms other methods in defect detection across multiple datasets, with an average score rate of 98.7% and 100% for pixel-level area under the curve (AUC) receiver operating characteristic and image-level AUC, respectively, compared to an average score rate of 91.1% and 85.4% for other methods.

Colour in a Chinese painting not only conveys cultural, historical, and philosophical concepts but also carries specific symbolic meanings and emotions, possessing a high level of artistic value. However, the sensitivity of Chinese paintings to light results in exhibition environments being characterised by low illuminance and low colour temperature. Therefore, accurately assessing colour preferences in Chinese paintings under such conditions is an issue that needs to be addressed. This study conducted simulated experiments in real museum exhibition halls, with 36 participants providing subjective evaluations of Chinese paintings, to explore the effects of various lighting parameters on colour preferences. Through statistical analysis and multiple linear regression, the relationship between lighting parameters and colour preferences in a Chinese painting was determined, and an evaluation model was established. This research outcome provides important mathematical tools for selecting appropriate lighting and developing dedicated lighting for Chinese paintings, ensuring the artistic inheritance of Chinese painting colours.

There is a lot of repetitive work involved in exploring the dyeing performance of natural dyes. To improve the experimental efficiency, save material, reduce time costs and shorten the research cycle, this study collects and analyses the literature data of 350 natural dye experiments to construct the Natural Dyes Dataset, and achieves rapid prediction of the optimal reaction conditions and dyeing effects of natural dyes using a lightweight integrated learning model. The size of the trained XGBoost model is only 562 KB; only the name of the dye and its approximate chemical composition need to be input to predict the results of the reaction environment pH, colour fastness to washing (CFW) and colour fastness to rubbing (CFR) of the natural dye on silk fabrics with the highest K/S in a very short time of 52 ms. The prediction accuracies for pH, CFW and CFR in the validation set are as high as 94.12%, 93.75% and 100%, respectively, and 77.78%, 91.67% and 83.33% for the real test set, with both validity and transferability. The integrated learning approach provides valuable guidance for exploring the dyeing performance of natural dyes with very small deployment costs and a very short inference time, expanding the possibilities of cross-application of the disciplines of machine learning and textile dyeing.

The non-cellulosic impurities like oil, wax, and pectins present in the cotton fibre adversely impact wetting. Consequently, these impurities must be removed during the pretreatment process to prevent unevenness of subsequent coloration. Generally, an alkaline treatment with petroleum-based synthetic surfactants is done, which is called scouring. This study attempts to develop an environmentally safe alternative using alkali from wood ash extract (WAE) and surfactant from soapnut extract (SE). The factors of WAE (10%–30%), SE (5–15 g/L), temperature (75–95°C), and time (20–60 min) were optimised using response surface methodology. A concentration of 20% WAE and 10 g/L SE at 90°C for 30 min was found to be adequate to remove impurities. The statistically optimised method showed good hydrophilicity, indicated by an average wetting time of 15 s, and 2.7% weight loss. The scoured fabric was subsequently dyed with natural dye extracted from marigold flowers and reactive dye. The scoured cotton was evaluated by weight loss, wettability, tensile strength, whiteness index, and colour value (K/S) and showed comparable results to conventional scouring.

Colour fastness of polyurethane fibre dyed with conventional disperse dyes is always poor owing to the insufficient affinity between fibres and dyes. Thus, three novel azo dyes containing an α-phenyl diazo ester moiety were designed in this study. The dyes were synthesised through two-step post-modification of a hydroxylated azo benzene chromophore. All three dyes were characterised using proton and carbon nuclear magnetic resonance, high-resolution mass spectrometry and infrared spectrometry. The ultraviolet-visible absorption and thermal properties of the dyes were also studied. Fixation properties of these dyes on polyurethane fibre were examined using samples dyed using a non-aqueous dyeing method. Practicality of these dyes, that is colour depth, fixation value, colour fastness and dye migration degree, was further verified on fibre dyed via an aqueous dyeing method. Finally, the mechanical properties of the dyed polyurethane fibre were explored.

The kinetics of the redox reaction of methylene green (MG) and the novel photo-redox agent titanium trichloride (TiCl₃) in water were investigated by real-time spectrophotometric analysis of the change in absorbance of the reaction mixture at 655 nm. The novelty of this redox reaction is that the TiCl₃ is an inorganic compound in contrast to the previously studied organic redox couples. The redox reaction was analysed in depth and the effects of the concentration of the TiCl₃, MG, pH, dielectric constant, ionic strength, metal ions, and temperature on the reaction kinetics were observed. The rate of reaction had a direct relationship with the pH, dielectric constant, and ionic strength of the reaction medium, while an increase in temperature decreased the rate of reaction. The activation energy (E_a) was calculated by the Arrhenius relation, and the other thermodynamic parameters, such as enthalpy change of activation (∆H*), free energy change of activation (∆G*), and entropy change of activation (∆S*) were also evaluated to support the findings of the kinetic measurements. The presence of any reaction intermediate other than the species in the reaction mechanism was ruled out by the spectroscopic analysis of the reaction mixture and Michaelis–Menten plot while the absence of any free radicals was confirmed by the negative polyacrylamide test. A reaction mechanism for the redox reaction of MG⁺ and TiCl₃ was proposed based on the different excited states of the MG⁺ involved in the reaction and the results of the product analysis. The decolourisation of MG by the TiCl₃ is overall a second-order reaction and is significantly affected by the pH of the reaction medium. The overall rate law for the redox reaction of MG and TiCl₃ is as follows.