Aluminium Trihydrate (ATH)
A flame retardant filler used in automotive cables, wire harnesses, and interior polymers, releasing water vapour when heated to suppress combustion and reduce smoke.
Overview
Aluminium trihydrate (ATH), also known as aluminium hydroxide (Al(OH)₃), is the most widely used flame retardant in the world and plays an important role in automotive fire safety. ATH functions as a reactive flame retardant filler: when exposed to heat above approximately 180–200°C, it undergoes endothermic decomposition, releasing chemically bound water (approximately 34.6% by weight). This water vapour dilutes flammable gases, cools the burning substrate, and leaves a protective alumina (Al₂O₃) char layer. Critically, ATH is halogen-free, producing no toxic halogenated gases during combustion — a significant advantage in automotive applications where occupant safety and low-smoke requirements are paramount. In automotive applications, ATH is used as a filler and flame retardant in wire and cable insulation, underbonnet wiring, EV battery enclosure materials, interior polymer components, carpet backing, and adhesive sealants. As EV battery fire safety becomes increasingly critical, ATH-loaded polymer enclosures and thermal barrier coatings are gaining importance.
Automotive Applications
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Properties
Category
Type
Metal Hydroxide
Available Colors
Available Forms
Key Properties
- Halogen-free flame retardant
- Endothermic decomposition absorbs heat
- Releases water vapour to suppress flames
- Low smoke and toxic gas emission
- Acts as both filler and flame retardant
- Good electrical insulation properties
- Compatible with polyolefins and rubber compounds
- Cost-effective vs. other flame retardants
Technical Specifications
Density
2.42 g/cm³
Temperature Resistance
Decomposes at 180–200°C (releasing H₂O)
Sustainability
Sustainability Rating
ATH is considered one of the most environmentally benign flame retardants available. It is halogen-free, produces no persistent organic pollutants, and generates only water vapour and alumina during decomposition. ATH is produced as a by-product of the Bayer alumina process, making it closely linked to the broader aluminium production chain. Its use is strongly preferred over halogenated flame retardants (e.g. brominated compounds) which are subject to increasing regulatory restriction under REACH and RoHS.