Coloration Technology最新文献

Print nonuniformity is the variation of optical density (reflection) on the print and can occur in several different types that can be classified into two basic groups: random and systematic variations. This article examines two types from each group of variations that are most commonly found in digital printing systems: blotches and streaks, where amplitude and size were varied. Three most commonly used methods for measuring the print nonuniformity were used: Grey Level Co-occurrence Matrix (GLCM), ISO 13660 and Integration (also Improved Integration) method. The results obtained by measuring were compared with a visual assessment to find the link between objective and subjective analysis and to define and determine which method/parameter is the best for the measurement of which type of print (non)uniformity. The obtained results indicate the possibility of selecting the measurement parameter, but that the choice of the parameter depends on the type of nonuniformity. It is concluded that in the case of the GLCM method, the entropy and energy parameters are strongly related to the visual assessment for all three sets of samples. These parameters can be used regardless of the type of nonuniformity. The ISO G parameter can be used to measure both graininess and mottling, while the ISO M parameter is only suitable for measuring mottling. Integration method could be used to measure systematic error. On the basis of conclusions of the research, it is possible to propose the development of an industrially applicable solution for measuring print nonuniformity of digitally printed samples.

The solubility of 1-amino-2-hydroxy-4-methoxy-anthraquinone (CI Disperse Red 4) and 1-amino-2-hydroxy-anthraquinone (CI Disperse Red 15) in supercritical carbon dioxide was measured using a dynamic method over a temperature range from 343.15 to 373.15 K and a pressure range from 14 to 22 MPa. The experimental data are analysed by using the back propagation neural network constructed by MATLAB. In the back propagation neural network, the input layer consisted of two inputs, which are temperature and pressure, the output layer consisted of the solubility of dyes, and the hidden layer function was composed of a non-linear function. The results of the analysis showed that a good fitting level of 0.99 was obtained, which means that the back propagation neural network can accurately estimate the solubility data in supercritical carbon dioxide.

Detecting defects of yarn-dyed fabrics automatically in industrial scenarios can improve economic efficiency, but the scarcity of defect samples makes the task more challenging in the customised and small-batch production scenario. At present, most reconstruction-based methods have high requirements on the effect of reconstructing the defect area into the normal area, and the reconstruction performance often determines the final defect detection result. To solve this problem, this article proposes an unsupervised learning framework of dual attention embedded reconstruction distillation. We try to use this novel distillation scheme to provide some contribution to the defect detection field. Firstly, different from the encoder-encoder structure of traditional distillation, the teacher-student network in this article adopts the encoder-decoder structure. The purpose of the student network is to restore the normal feature representation of the pre-trained teacher network. Secondly, this article proposes a dual attention residual module, which can effectively remove redundant information and defective feature information from the teacher network through the double feature weight allocation mechanism. This helps the student network to recover the normal feature information output by the teacher network. Finally, the multi-level training deployment at the feature level in this article aims to make the model obtain accurate defect detection results. The proposed method has been extensively tested on the published fabric dataset YDFID-1, ZJU-Leaper dataset and the anomaly detection dataset MVTec. The results show that this method not only has good performance in fabric defect detection and location but also has universal applicability.

Ultrafine polyamide/polyurethane synthetic leather (UP/PSL), with a highly natural leather-like appearance and touch, is widely used in many leather commodities. Generally, acid dyes, which are mostly used for dyeing UP/PSL, exhibit poor colour fastness. While, reactive dyes are well-known for their good colour fastness. However, reactive dyes are not used to dye UP/PSL because they are water-soluble and cannot stain the polyurethane (PU) in UP/PSL. In this study, five low water-soluble reactive dyes with good affinity for both polyamide (PA) and PU were synthesised and characterised using ultraviolet-visible and infrared spectroscopy, and mass spectrometry. All low-water-soluble reactive dyes were monoazo dyes with only one sulfonic group and two different functional groups. The reactive dyes were used to dye UP/PSL at 98°C and fixed at 90°C with 7-azatridecane-1,13-diamine as a crosslinking agent. For comparison, Eriofast Red-2B (ER-2B) was used to dye UP/PSL using a special dyeing procedure. ER-2B showed severe issues related to low utilisation and uneven dyeing, whereas the five low water-soluble reactive dyes exhibited better performance than ER-2B. Both the exhaustion and fixation of dyes 1 and 4 exceeded 90.0% when the dosage was less than 3.0% owf (on weight of fabric). In addition, they exhibited good levelling. The washing fastness of the five reactive dyes was excellent and higher than grade 4. The dry rubbing fastness was higher than grade 3-4. Therefore, UP/PSL can be satisfactorily dyed using the reactive dyes with a solubility of less than 1.0 g/L and meet the requirements of daily life applications.

Currently, the use of natural indigo dye has been treated as an alternative to overcome the environmental pollution caused by synthetic indigo. Irrespective of the indigo dye source, it must be reduced to its soluble form by using reducing agents in a suitable alkaline environment. Herein, bio-sugars such as glucose or fructose were used for this purpose. The results revealed that when fructose was used instead of glucose, colour strength (K/S) values increased. In this work, cotton was cationised with water-soluble chitosan. Water-soluble chitosan in a wide pH range extends the use of chitosan in textiles, which otherwise is limited due to its poor water solubility at pH above 6.0. Colour fastness washing test was conducted to evaluate the efficacy of cotton cationisation. The performance of cationised samples was around 30% higher in comparison to non-cationised samples. Moreover, in this article we have focused on integrating materials and design. We propose a garment, using natural indigo-dyed cotton and a zero-waste modelling approach, as a sustainable fashion product.

In the present study, polycaprolactone/polyethylene glycol (PCL/PEG) electrospun nanofibres with different anthocyanin (1%, 2%, 3%, and 5%) were fabricated for the instant measurement of pH, especially for applications—such as food freshness detection—where quick response is required. The solution, surface, chemical, thermal, wettability, mechanical, and release properties of the samples were evaluated by viscosity measurements, scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), contact angle measurements, and tensile tests, respectively. The colorimetric analyses were also investigated against the solutions at different pH values and bacterial solutions. Finally, the on-site performance of the sensor was evaluated. Anthocyanin addition initially lowered the solution viscosity, resulting in thinner fibres with a diameter of 288 nm. The diameters were increased up to 395 nm with the increasing anthocyanin. Anthocyanin addition enhanced the wettability and the mechanical properties, and the contact angles decreased to 43°. The highest modulus was observed for 1% anthocyanin, with a value of 6.162. The release experiments revealed that the anthocyanin-loaded samples released a large amount of anthocyanin (between ~12% and 38%) in the first 15 s. The colorimetric analyses showed that PCL/PEG nanofibre mats with 2% and 3% anthocyanin concentrations were the most capable pH-sensitive sensors for detecting pH changes from 2 to 8. As a result, it can be concluded that 3% anthocyanin is the threshold value for the production of the anthocyanin-loaded nanofibre mats, and these structures are promising for the instant detection of pH proved by the on-site application.

Meta-aramid fibre exhibits poor dyeing performance when treated using conventional dyeing methods. In this study, coloration of meta-aramid fabrics was performed at room temperature utilising diazonium salts from weakly basic aromatic amines and was achieved via in situ construction of azo chromophores on the meta-phenylenediamine moiety. To promote diazonium-salt penetration into the meta-aramid fibre, the pretreatment of meta-aramid fabrics with dimethyl sulfoxide at 55°C for 30 min and the utilisation of methanol were involved during the coloration process. As a result, the fabrics could be coloured with deep, levelled and firm shades of brown series. The azo chromophore is derived from the skeleton of the polyamide chain. Therefore, the coloured fabrics exhibit good resistance to organic solvents as well as good to excellent colour fastness to soaping, rubbing and sublimation. A study of the coloration mechanism revealed that the terminal and middle meta-phenylenediamine moieties serve as the main coupling reaction sites. When treated with a diazonium salt, the highly reactive terminal meta-phenylenediamine moiety reacted first and generated chromophores with an absorption peak in the long-wavelength region. However, such chromophores only contributed a limited colour depth owing to the limited number of the terminals. If excess diazonium salts were used, the main hue can be attributed to the azo chromophores based on the massive middle meta-phenylenediamine moieties, although these moieties are less reactive than the terminal meta-phenylenediamine moieties.

In this study, the ecological dyeing process of wool fabrics was investigated. Wool fabric samples were treated with atmospheric pressure plasma-jet and corona discharge plasma to modify the surface to make the process sustainable and greener. The samples were dyed with the aqueous extract procured from the powdered roots of Rubia tinctorum L. (madder) using the ultrasonic-assisted method. Scanning electron microscopy and Fourier Transform–infrared analysis were performed to investigate the effect of plasma treatment on the physical and chemical properties of wool fibres. The effects of plasma treatment type, plasma treatment parameters and the duration of dyeing on colorimetric and fastness properties were investigated. The etching of the wool fibre surface and roughness after plasma treatment were proven with scanning electron microscopy images. The Fourier Transform–infrared spectra showed that no significant differences in the functional groups of wool fibre occurred after plasma treatment. The experimental results proved that plasma treatment parameters and dyeing time had an effect on the colorimetric and fastness properties of the samples. Furthermore, an artificial neural network model was proposed for estimating the dyeing properties of wool fabrics, namely, L, a, b, K/S, colour change, rubbing fastness (dry) and rubbing fastness (wet). The experimental results show that the proposed model achieves regression values greater than 0.97 for all dyeing properties. The proposed model is successful and can be efficiently used for estimating the dyeing characteristics of wool fabrics.

The current study reports the results of non-aqueous dyeing on polyamide fabrics based on a reverse micellar system composed of a stable emulsion of soybean oil, a co-surfactant, a nonionic surfactant and acid dyes. The system does not make use of water or electrolytes and significantly reduces the dyebath volume. The influence of the hydrophilic lipophilic balance of the surfactants was evaluated, and it was found that the more hydrophilic the surfactant, the better the interaction of the reverse micellar emulsion with the substrate and, consequently, the greater the resulting colour strength. The co-surfactant plays an important role in the system, as its proportion to the surfactant/oil mixture is directly related to better exhaustion of the dyebath. The results were compared with those from a conventional water-based dyeing system. Colour matching was performed using the CIELab colour difference formula (ΔE) measured by a reflectance spectrophotometer.

Polylactic acid (PLA) fibre, as a renewable and biodegradable synthetic polymer, is attracting increasing attention in the field of textiles. However, there are still some problems associated with PLA fibre dyeing, with a traditional water bath using disperse dyes restricting its industrialisation. Waterless dyeing, as a green and environmentally friendly dyeing method for PLA fibre, is expected to replace the traditional water bath dyeing method. However, the disperse dyes suitable for PLA fibre are different from those that are suitable for traditional poly(ethylene terephthalate) fibre. In the current study, the waterless dyeability of PLA fibre using disperse dyes with different chemical structures, and decamethylcyclopentasiloxane (D5) as the media, was investigated. First, the optimal dyeing process conditions of dye concentration, dyeing temperature, dyeing time and liquor ratio for PLA waterless dyeing were determined. The results indicated that the most suitable dyeing process conditions were: a dye concentration of 5%, dyeing temperature and time of 120°C and 40 minutes, respectively, and a liquor ratio of 1:10. Next, PLA was dyed with 10 disperse dyes with different structures using the determined optimum dyeing process conditions to compare their dyeing properties. The results showed that there were obvious differences in the K/S values for PLA dyed with dyes of different structures. The K/S values for PLA dyed with monoazo structure dyes were significantly higher than those for anthraquinones and heterocyclic structure dyes. Disperse dyes with a monoazo structure are suitable for PLA waterless dyeing. This study provides a research basis to develop suitable dyes for waterless dyeing PLA using D5 as the media.