Aluminum Trihydrate (ATH) is an inorganic white fine crystal, non-hygroscopic powder. Its solubility in water and organic solvents is very low. By volume, ATH is the largest non-halogen flame retardant (NHFR) used in various end applications.
The working principle is based on the thermal decomposition of aluminum hydroxide into aluminum oxide and water (vapor). This endothermic reaction starts at about 200°C and consumes energy from the ignition source. The generated water vapor cools the polymer surface and dilutes the concentration of combustible gases in the surrounding environment.
The remaining metal oxide residue has a relatively high inner surface, in which soot particles (respectively polycyclic aromatic hydrocarbons) are adsorbed so that ATH is also a smoke suppressant. The oxide layer serves as a barrier layer to protect the polymer from further decomposition.
The median particle size (D50) of ATH commercially available is 0.5 – 80 µm. In the non-halogen flame-retardant (NHFR) wire and cable (W&C), one of ATH's largest markets, fine precipitated ATH is used for sheathing and insulation.
The NHFR compound is based on a mixture of EVA (poly(ethylene-vinyl acetate)) and LLDPE (linear low-density polyethylene). In plasticized PVC, finely precipitated ATH is used as a flame retardant and smoke suppressant. Low-smoke flame-retardant (LSFR) cable.
More detailed information for Zibo Pengfeng's PF series fine aluminum hydroxide:
Download the TDS: