Dyeing with Fluorescence Dyes—A Study Comparing Cotton and Lyocell Fibers in Dyeing Behavior and Achieved Fluorescence

Fluorescence is a powerful tool to realize textile products with high-visibility effects. Fluorescent materials can transfer non-visible UV light into visible light, and by doing so, the visibility under illumination with sunlight increases. For textile products, the application of fluorescence dyes on synthetic fibers is broadly used. However, fluorescence applications are rarely reported for regenerated cellulosic fibers, such as lyocell. For this, the actual study reports on a selection of five different fluorescence dyes investigated for applications in cotton and lyocell fabrics. Dyes are considered acid dyes, basic dyes and reactive dyes, and dye application is done in increasing concentrations. Prepared textile samples are investigated according to color strength and color shade (K/S values and CIE Lab coordinates). Fluorescence emission is determined by fluorescence spectroscopy. Fastness properties are measured against rubbing, washing and light. The attained coloration increases with increased applied dye concentrations. In contrast, the achieved fluorescence emission differs strongly depending on the dye, and also, for some dye/fiber combinations with low applied dye concentration, a higher fluorescence emission is achieved. For most investigated samples, superior fluorescence effects are gained for applications in lyocell compared to simultaneously treated cotton fabrics. Especially for the investigated reactive fluorescence dyes, excellent fastness properties against rubbing, washing and light are observed. Finally, fluorescence properties can be effectively transferred to regenerated cellulosic fibers by use of fluorescence reactive dyes. These data are quite valuable for people working on new regenerated cellulose fibers and open up new perspectives for these fiber types in the development of high-visibility sportswear.