TiO₂ Nanoparticle UV Protection Finish
topic
Rutile TiO₂ nanoparticles (5–25 nm, refractive index 2.7) are preferred over anatase for UV protection due to lower photocatalytic activity (reducing substrate degradation) and broader UV absorption. Applied to cotton, polyester, or nylon at 1.0–3.0 g/m² via pad-dry-cure (120–150°C, 2–3 min) with silica binder (TEOS 0.5–1.0%), UPF increases from 5–15 (untreated cotton) to >50–200. Photocatalytic oxidation of fiber substrate by anatase TiO₂ under UV is suppressed in rutile by 85–90% due to lower electron-hole mobility. Particle size below 50 nm ensures fabric transparency (no whitening effect above 30 nm critical scattering threshold for visible light at 400–700 nm). Wash durability exceeds 40 cycles at 40°C with organosilane binder. Cost of $0.08–0.15/m² at 2 g/m² TiO₂ loading makes it the most economical UPF50+ finishing option.
Role
Most cost-effective and durable inorganic UV protection finish for outdoor apparel, swimwear, and protective workwear, providing permanent UPF50+ rating without the photocatalytic fabric degradation associated with anatase TiO₂ formulations.