Halogen-Free Flame Retardant for Drone Battery Enclosure
Key Features
- UL 94 V-0 in PA6 at 1.6 mm and ABS at 3.2 mm — meets most drone battery enclosure regulatory requirements
- Halogen-free APP + MCA — no toxic HCl, HBr, or dioxin combustion products in thermal runaway fire scenarios
- RoHS, REACH, WEEE compliant — required for European and US market drone manufacturers
- Intumescent char layer reduces heat release rate 40–60% in cone calorimeter — slows flame spread from battery compartment
- Surface-coated APP (15–20 μm) disperses readily in twin-screw compounding without silanization
- Compatible with UV stabilizer and colorant packages for drone shell compounds
A phosphorus-nitrogen synergistic, halogen-free flame retardant (HFFR) package for engineering thermoplastics used in drone battery enclosures, ESC housings, and power distribution compartments. The system is based on ammonium polyphosphate (APP) with melamine cyanurate (MCA) synergist, providing a char-forming intumescent action that creates an insulating carbonaceous layer over the polymer surface during combustion — blocking oxygen supply and heat feedback to the underlying substrate without generating toxic halogen gases.
The formulation achieves UL 94 V-0 at 1.6 mm wall thickness in PA6 at 15–20 phr loading and UL 94 V-0 at 3.2 mm in ABS at 20–25 phr loading, with limiting oxygen index (LOI) above 28 in both systems. Critically, the halogen-free design meets RoHS, REACH, and WEEE directives — required for drone manufacturers selling into European and US markets — and avoids the toxic combustion products (HCl, HBr, dioxins) associated with brominated flame retardants in the catastrophic fire scenarios that lithium battery thermal runaway represents.
The surface-coated APP particles (median particle size 15–20 μm) disperse readily in twin-screw compounding of PA6, PA12, ABS, and PC/ABS without silanization. Heat release rate is suppressed by 40–60% at 20 phr in PA6 per cone calorimeter testing (ASTM E1354), reducing the flame spread speed from a battery compartment fire. Compatible with standard colorant and UV stabilizer packages.
Specifications
| Parameter | Value |
|---|---|
| Flame retardant type | Intumescent halogen-free (APP + MCA synergist) |
| Nitrogen content (APP) | 14–15 wt% |
| RoHS / REACH compliance | Yes — halogen-free |
| Phosphorus content (APP) | 31–32 wt% |
| Median particle size (APP) | 15–20 μm |
| UL 94 rating in ABS (20–25 phr) | V-0 at 3.2 mm |
| UL 94 rating in PA6 (15–20 phr) | V-0 at 1.6 mm |
| Limiting oxygen index (PA6, 20 phr) | >28 |
| Thermal stability (APP, TGA 5% wt loss) | >280°C |
| Heat release rate reduction (cone calorimeter) | 40–60% vs unfilled PA6 |
Applications
FAQ
PA12 is more difficult to flame retard than PA6 due to its longer carbon chain and lower natural char-forming tendency. For PA12, achieving UL 94 V-0 at 1.6 mm requires 22–28 phr of the APP/MCA intumescent package — higher than the 15–20 phr needed in PA6. At these loading levels, the tensile strength of PA12 drops by 15–25% and the HDT drops by 20–30°C from the unfilled value. If maintaining PA12 mechanical properties is critical, consider a combined approach: 15 phr APP/MCA plus 5 phr of a phosphinate-based co-FR additive to achieve V-0 at lower total FR loading and reduced property impact.
Direct Contact
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