关键词: Lyocell织物, 活性染料, 轧染, 无盐, 原纤化

Abstract: Lyocell fibers are regenerated cellulose fibers. In addition to the advantages of hygroscopic property, good luster and comfortable wearing, Lyocell fibers also have better wet and dry strength than other regenerated cellulose fibers. However, Lyocell fibers are prone to fibrination, which limits their application in textile applications. The reactive dye is one of the most commonly used dyes for cellulose fiber dyeing, with advantages of simple application, cheap price and bright color, but in the process of immersion dyeing, to promote reactive dye dyeing, a large number of inorganic salts are often added in the dyeing solution. Therefore, there are high energy consumption, complex and variable dyeing wastewater composition, deep color, alkaline and expensive treatment costs and many other drawbacks. In this paper, the continuous salt-free rolling dyeing process of Lyocell fiber fabrics with reactive dyes was systematically studied, which not only improved the dyeing property and reduced the emission of inorganic salts, but also improved the fibrillation degree of Lyocell fibers and effectively improved the quality of Tencel fabrics.
The effects of dyeing and fixing process and formula (baking temperature, baking time, dipping times, dosage of alkali and urea) on dyeing properties (K/S value and fixing rate) of fabrics were discussed. The dyeing properties and fibrination degree of fabrics were compared with those of traditional dyeing process. The results show that the optimized rolling, baking and dyeing formula and process of the Lyocell fabric require alkali of 25 g/L, urea of 60 g/L, and a baking time of 2 min at 160℃ after twice dipping and twice padding. The three dyes of Br Red CA, Br Yellow CA and Blue CA have good dyeing effect, and the color fixing rates are 76.98%, 67.48%, 77.15%, and K/S values are 21.87, 10.87, 15.85, respectively. Compared with the traditional immersion dyeing process, the continuous salt-free rolling dyeing can obtain higher dyeing depth , and the K/S values of the three dyes are increased by 28.10%, 5.23% and 6.20%, respectively. The maximum absorption wavelength of the same dye is the same under rolling, baking and immersion dyeing, indicating that pad dyeing does not change the color light of the fabric. The L* value of the pad dyeing fabric is generally lower than that of the immersion dyeing fabric, indicating that the color of the Lyocell fabric dyed by the former will be darker under the condition of the same amount of dyes. The dry rubbing fastness of the three dyes is higher than that of the wet rubbing fastness, reaching grade 5, while the wet rubbing fastness is one or two grades lower. Both of them have good soap color fastness, generally at grade 4-5 or above. The surface fibril of Lyocell fibers after continuous salt-free rolling dyeing is less than that of immersion dyed fabrics, and the fibrillarization degree of the fabric is weaker and the surface is smoother.
Continuous salt-free rolling dyeing of Lyocell fibers can obtain good dyeing effect, reduce energy consumption and pollutant emission in the dyeing process, which will be conducive to clean dyeing of cellulose textiles, and promote the sustainable development of the whole dyeing process.

Key words: Lyocell fabric, reactive dye, pad dyeing, salt-free, fibrination