Research on the Dyeing Properties of Chinese Fir Using Ultrasonic-Assisted Mulberry Pigment Dyeing

Abstract

Wood dyeing plays a crucial role in improving the aesthetic appeal of wood. To enhance the value of Chinese fir, this study used environmentally friendly mulberry pigment and ultrasonic technology to dye Chinese fir. A single-factor test was conducted to investigate the impact of ultrasonic power, dyeing temperature, dyeing time, and dye concentration on dye uptake and color difference. The results revealed that ultrasonic treatment significantly increased the dye uptake and color difference compared with conventional water bath dyeing methods. Based on the single-factor test, two indexes for the color fastness of washing and sun were added, and an orthogonal test was carried out. The range analysis results demonstrated that ultrasonic power had the greatest influence on dye uptake, while dye concentration showed the strongest impact on the color difference and color fastness in washing and sunlight. The dyeing process was optimized using the fuzzy comprehensive evaluation method, with the optimum parameters determined as follows: ultrasonic power of 340 W, dyeing temperature of 90 °C, dyeing time of 5 h, and dye concentration of 10%. Scanning electron microscopy revealed that ultrasound increased wood permeability and created cracks, providing attachment sites for dye molecules. Infrared analysis indicated that ultrasonic action enhanced the degradation of wood components, transforming them into smaller molecular substances and increasing the accessibility of dyes to wood. X-ray diffraction analysis demonstrated that ultrasonic action reduced wood crystallinity, facilitating the entry of dye molecules into Chinese fir fibers. In this study, we proposed for the first time to dye fir wood with mulberry pigment and use ultrasonic-assisted dyeing to investigate the effect of dyeing factors on the dyeing rate, color difference, and color fastness, which provides a valuable reference for natural pigment dyeing of Chinese fir.