Resource-Efficient Production of a Smart Textile UV Sensor Using Photochromic Dyes: Characterization and Optimization

Niche products like smart textiles and other technical high-end products require resource-efficient processes and small batches contrary to conventional textile processes that require larger batches and are water-, chemical- and energy-intensive. This study focuses on digital inkjet printing and UV light curing as a flexible and resource-efficient and therewith economic production process of a smart textile UV sensor. The UV sensor is based on a UV-curable inkjet ink and a commercial photochromic dye. The inkjet ink is cured via free radical polymerization initiated by a UV–LED lamp. This system contains two photoactive compounds for which UV light both cures and activates the prints. An important challenge is therefore polymer crosslinking of the resin and UV-sensing performance of the photochromic dye. In this paper, we present performance as a function of belt speed and lamp intensity during curing. Via wash tests, we investigate the durability of the photochromic prints. The UV-sensing textile is characterized by colour measurements, differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA).