Influences of diantimony trioxide on laser-marking properties of thermoplastic polyurethane

The influences of diantimony trioxide (Sb2O3) on the laser-marking properties of thermoplastic polyurethane (TPU) are studied. The TPU/Sb2O3 composites are prepared by melt blending in a HAAKE mixer. A neodymium-doped yttrium aluminum garnet (Nd:YAG) pulsed laser beam of a wavelength of 1064 nm is used to scan the surfaces of the composites to create markings. Visual and microscopic analyses of the TPU/Sb2O3 composites after laser treatment show high-contrast black markings, depending on the Sb2O3 loading, Sb2O3 particle size, and laser-beam power. The laser-marking properties of the composite surfaces are analyzed by X-ray diffraction, Raman spectroscopy, and thermogravimetric analysis. Furthermore, a mechanism for the laser-induced darkening of the TPU/Sb2O3 composites is proposed. The Sb2O3 particles absorb laser energy and convert it into thermal energy. This causes the surrounding TPU matrix to carbonize into amorphous carbon, forming black markings.