Transmission Reduction for UV and IR Radiation with Dyed Lyocell Knitted Textiles

Sunlight is essential for humans. However, sunlight can be the source of several disadvantageous effects and illnesses, e.g., skin aging, sunburn, and skin cancer. Textiles with functional protective effects can counteract these problems. In the current research, knitted fabrics were produced from Lyocell yarns spin-doped with the inorganic UV absorber titanium dioxide TiO2. Lyocell yarns without TiO2 were used as reference materials. The produced knitted fabrics were dyed with different dyestuffs to improve the protective properties against UV light and infrared light. The protective properties are determined by optical spectroscopy in an arrangement of diffusive transmission. With the two dyestuffs Drimaren Yellow HF-CD and Solophenyl Bordeaux 3BLE, dyes were determined which complete UV protection and additionally reduce transmission in the near-IR range (700 nm to 1000 nm). TiO2 in the fibers enhanced this effect. In the UV range (280 nm to 400 nm), the transmission was almost zero with both dyes. Overall, the Lyocell samples containing TiO2 exhibit less sensitivity to abrasion and a UV protective effect after washing can be still determined. The weight loss after the abrasion test for these samples is quite low with only around 8.5 wt-% (10,000 rubbing cycles in the Martindale device). It is concluded that the right choice of dye can improve the protective effect of textiles against various types of radiation. Lyocell fiber-based textiles are suitable for the production of summer clothing due to their good moisture management. Compared to other radiation protective materials based on coating application, the presented solution is advantageous, because the textile properties of the realized products are still present. For this, a direct transfer to clothing application and use in apparel is easily possible. This study can be seen as the first proof-of-concept for the future development of light-protective clothing products.

Automated summary

Sunlight is important for humans, but it can also cause negative effects and diseases such as skin aging, sunburn, and skin cancer. In this study, knitted fabrics made from Lyocell yarns spin-doped with TiO2 were found to have protective effects. Dyeing the fabrics with different dyestuffs further improved their protection against UV and infrared light. It is concluded that the right choice of dye can enhance the protective effect of textiles against radiation, and Lyocell fiber-based textiles are suitable for summer clothing due to their good moisture management.