Dyeing properties of natural Gardenia on the lyocell fabric pretreated with tannic acid

With the enhancement of awareness of environmental protection, the green natural dyes gradually come into people’s view again. This subject studied the dyeing performance of natural dye Gardenia on tannic acid modified lyocell fabric. The effect of tannic acid concentration, pH of dyeing solution, dyeing time and dyeing temperature on k/s value and colorimetric data (L*, a*, b*, c*) of the dyed lyocell fabric was investigated. The results showed the color strength and yellowness value increased with the increase in dyeing time (within 60 min), dyeing temperature and tannic acid concentration and the decrease in pH value of dye bath. The dyeing process was optimized by response surface analysis. The experimental results showed that the linear effects of dyeing pH, dyeing temperature and tannic acid concentration on the K/S values of the dyed lyocell fabrics were extremely significant. The results of X-ray diffraction, electron microscopy scanning, fourier transform infrared spectroscopy and water contact angle measurements showed that the morphological structure of the tannic acid-treated dyed lyocell fabrics did not change. The results of practical validation and optimization showed that the optimal process of tannic acid pre-mordanting natural dyes Gardenia dyed lyocell fabric was: dyeing time 60 min, dyeing pH = 3.5, dyeing temperature 90 °C, and the measured K/S value of the dyed specimen under this condition was 7.45. Its color fastness to washing and rubbing was above 3. The successful combination of bio-mordant tannic acid and natural dye Gardenia yellow on lyocell fabric provided a green dyeing method for lyocell fiber.