Green Preparation of Near-Infrared-Excited Upconversion (UCNP) Invisible Patterns on Clothing and Leather

Hongying Guo, Shuzhen Liu, Xiaojia Zhao, Xuan Li, Zhengguang Zhang, Ninghao Niu, Yunyang Xiao

Article
2025 / Volume 8 / Pages 1124-1139
Received 17 September 2025; Accepted 17 October 2025; Published 29 December 2025
https://doi.org/10.31881/TLR.2025.1124

Abstract
This study addresses the critical need for advanced anti-counterfeiting solutions in the textile industry by developing a sustainable functional finishing process. The methodology utilizes upconversion nanoparticles (UCNPs), which convert near-infrared (NIR) light into visible green emission, thereby providing a high-security, invisible anti-counterfeiting feature. An eco-friendly, water-based ink was formulated and successfully applied to cotton fabric using the industry-standard screen-printing technique. The process employs a low-temperature curing step (105 °C) to minimize thermal damage and preserve the inherent flexibility of the textile substrate. The finished fabric patterns remain completely invisible under ambient light but exhibit brilliant, characteristic green luminescence under 980 nm NIR excitation, which can be readily authenticated using digital imaging sensors, even under safe, low-power irradiation. Importantly for apparel applications, the patterns demonstrate outstanding durability. The finished cotton fabric retains over 85% of its initial luminescence after 10 standard washing cycles, indicating excellent washing fastness. Furthermore, superior dry and wet rubbing fastness ratings of Grade 4–5 were achieved. This work presents a scalable and environmentally friendly strategy for integrating high-security luminescent features into textiles, providing a practical solution for brand protection that aligns with the principles of sustainable textile manufacturing.

Keywords
textile anti-counterfeiting, functional finishing, upconversion nanoparticles, screen printing, washing fastness