Protective clothing is an important defense against sunburn, but heat-absorbing colorants can cause discomfort. Some fabric colorants reflect near-IR and UV radiation, which provides a cooling effect. Aluminum-based reflective pigments corrode in acidic or alkaline solutions, which destroys their reflectivity, and the formulation process can release hydrogen gas.
Shaohai Fu, Jiangnan University, Wuxi, China, and colleagues circumvented these problems by encapsulating the pigments in polymers. They used a sol-gel process to encapsulate the pigment particles in silica, which was then functionalized with amino groups and dye molecules. They spray-dried a hexane dispersion of these particles with methyl methacrylate, 1,6-hexanediol diacrylate styrene, glycidyl methacrylate, and 2,2-azobis-iso-butyronitrile to produce the polymer coating.
Color treatments on cotton, polyester, and silk fabrics held up after washing with various solvents and did not corrode in acid or alkaline solutions. The polymer coating protected the colored particles at the expense of color strength and near-IR reflectance, but it did not affect UV reflectance.
- Polymer-Encapsulated Colorful Al Pigments with High NIR and UV Reflectance and Their Application in Textiles,
Benjamin Tawiah, Christopher Narh, Min Li, Liping Zhang, Shaohai Fu,
Ind. Eng. Chem. Res. 2015.