Antimony Trioxide (ATO)

Antimony trioxide, often abbreviated ATO, is the inorganic antimony(III) oxide used as a synergist in selected halogen-containing flame-retardant packages. It supports the action of the complete additive system rather than providing a universal flame rating on its own. It differs from antimony pentoxide and should be identified by CAS 1309-64-4.

The supply grade controls Sb2O3 at ≥99.5%, average particle size at ≤1.6 µm and whiteness at ≥93%. Arsenic, lead, iron, copper and selenium limits support incoming inspection and formulation consistency. Compare the stated oxide basis of impurity limits when reviewing another supplier specification.

For PVC, polyolefin, styrenic and rubber compounds, assess powder dispersion with the halogenated flame retardant, resin, fillers and stabilizers. Optimize loading through trials that measure the required fire test, colour, processing behaviour and physical properties of the finished compound.

Industrial glass, ceramic and enamel applications require separate qualification against the relevant composition and colour requirements. Fine powder handling needs enclosed feeding or local extraction and workplace exposure assessment. Non-dangerous-goods transport status does not remove the carcinogenic hazard or the need for protective controls.

See related plastics and rubber chemicals in our catalog.