Improvement of the Rubbing Fastness of Cotton Fiber in Indigo/Silicon Non-Aqueous Dyeing Systems

Study on the simultaneous release of microfiber and indigo dye in denim fabric home washing

In recent years, with the increasing global focus on environmental protection, the issue of microfiber release from denim during the washing process has gained attention. In this study, a programmable washing device simulating household drum washing was designed and developed, microfibers and indigo dyes released from denim washing were quantitatively detected, and we have also developed a novel method for estimating the release of microfibers during washing. The effects of washing time, washing temperature, and washing load on microfiber and indigo dye release from denim were explored. The results showed that the effect of washing load on microfiber and indigo dye release was greater than washing temperature and washing time. The research findings indicate that with an increase in washing time (35-95 min) and washing load (100-250 g), the shedding of microfibers and indigo dye significantly increases, reaching peak release levels of 343.6 μg/g fabric and 0.027 mg/L, respectively. However, there is a decreasing trend in the release of microfibers and indigo dye when the washing temperature exceeds 50 °C. Furthermore, our data suggests that an increase in washing load leads to a significant change in the number of microfibers (from 978 items/g fabric to 1997 items/g fabric) and their mass (from 156.87 μg/g fabric to 343.56 μg/g fabric). The influence of washing time, washing temperature, and washing load on microfiber length shows relatively small fluctuations within the range of 600-900 µm. This study provides new ideas and methods for estimating the release of microfiber and indigo dye in denim washing around the world.

Digital Grading the Color Fastness to Rubbing of Fabrics Based on Spectral Reconstruction and BP Neural Network

To digital grade the staining color fastness of fabrics after rubbing, an automatic grading method based on spectral reconstruction technology and BP neural network was proposed. Firstly, the modeling samples are prepared by rubbing the fabrics according to the ISO standard of 105-X12. Then, to comply with visual rating standards for color fastness, the modeling samples are professionally graded to obtain the visual rating result. After that, a digital camera is used to capture digital images of the modeling samples inside a closed and uniform lighting box, and the color data values of the modeling samples are obtained through spectral reconstruction technology. Finally, the color fastness prediction model for rubbing was constructed using the modeling samples data and BP neural network. The color fastness level of the testing samples was predicted using the prediction model, and the prediction results were compared with the existing color difference conversion method and gray scale difference method based on the five-fold cross-validation strategy. Experiments show that the prediction model of fabric color fastness can be better constructed using the BP neural network. The overall performance of the method is better than the color difference conversion method and the gray scale difference method. It can be seen that the digital rating method of fabric staining color fastness to rubbing based on spectral reconstruction and BP neural network has high consistency with the visual evaluation, which will help for the automatic color fastness grading.

Sustainable dyeing of ramie fiber with ternary reactive dye mixtures in liquid ammonia

Liquid ammonia (LA) dyeing is a zero-effluent and sustainable dyeing technology investigated for textiles. In the present work, three bi-functional reactive dyes, Reactive Red 195 (R195), Reactive Yellow 145 (Y145), and Reactive Blue 194 (B194), were used to dye ramie fiber in liquid ammonia, and the dye exhaustion (%) and fixation (%) were compared with ramie fibers dyed with the same dyes in an aqueous dyeing method. Dyeing with a single reactive dye, a binary dye mixture, and a ternary dye mixture in liquid ammonia showed that all the dyes are highly compatible as they showed similar uptake. The total dye exhaustion percentage of dyeing with the ternary dye mixture was 22.6%. After dyeing, a cationic fixing agent (CFA)/decamethylcyclopentasiloxane (D5) micro-emulsion was applied and the dye fixation rate was 96.7% accompanied by high colorfastness to washing (Grade 4-5) and produced uniform shades. Finally, a color triangle of dyed ramie fibers was prepared to exhibit many colorful shades. This work demonstrates the viability of dyeing of textile fibers in liquid ammonia.