The chemistry that took engineering plastics halogen-free: aluminum diethylphosphinate (also written aluminium diethylphosphinate, “DEPAL” or ADP) delivers UL94 V-0 on glass-filled PA66, PBT and TPU at 15–20% loading — with the high CTI, light colors and glow-wire performance that EV and E&E connectors demand. Supplied as powder and complete nitrogen-synergized packages.
Fig. DP01 — phosphinate powder at incoming QCFine white DEPAL powder checked before compounding.
Aluminum diethylphosphinate is the aluminum salt of diethylphosphinic acid — a metal phosphinate packing ~23–24% phosphorus into a thermally rugged white powder. Its claim to fame: it survives the 280–300 °C melt of PA66 and PBT, which is exactly where most halogen-free chemistries give up. That thermal window made halogen-free engineering plastics practical.
Decomposition onset above ~300 °C lets DEPAL compound into PA66, PBT and PPA without gassing or plate-out — the resins where connector work actually lives.
DEPAL rarely rides alone: melamine polyphosphate (MPP) in PA66/PBT and melamine cyanurate (MC) in TPU sharpen the rating and cut the total loading.
High-voltage connectors demand V-0 at thin walls, GWIT 775 °C, CTI for tight creepage and signal-orange color — DEPAL systems tick all four where bromine cannot.
A rare double act — phosphinates fight in both the gas phase and the condensed phase at once.
In the flame, phosphinate fragments release PO• species that scavenge the H• and OH• radicals driving combustion — the same interruption bromine performs, without the halogen.
Phosphoric acid species formed at the surface catalyze charring and crosslinking, building a barrier that starves the flame of fuel — boosted by the nitrogen synergist.
The aluminum fraction remains as aluminum phosphate in the char — a thermally stable mineral skeleton that reinforces the protective layer on glass-filled parts.
Wherever “halogen-free” meets “engineering plastic” — connectors, contactors, breakers, e-mobility hardware and the elastomer jackets feeding them.
| Application | System | Typical Loading | Key Targets | Related Page |
|---|---|---|---|---|
| PA66 / PA6 connectors (GF) | DEPAL + MPP | 15–20% | V-0 @ 0.8 mm · GWIT 775 °C · CTI | FR nylon 66 guide |
| PBT terminal blocks & HV connectors | DEPAL + N-synergist | 15–25 phr | CTI 400–600 V · HV orange color | FR PBT guide |
| TPU cable jackets (EV charging) | DEPAL + melamine cyanurate | 18–22% | UL94 V-0 · VW-1 · flexibility retained | FR TPU guide |
| Epoxy & thermoset E&E parts | DEPAL as co-FR | System-dependent | Halogen-free laminates and encapsulants | — |
The engineering-plastics fork in the road: both routes reach V-0 — the spec lines around the flame rating decide which one your part needs.
The spec stack goes beyond UL94 — electrical, color or halogen lines rule.
Cost per rated part is the binding constraint and halogen is accepted.
The phosphinate is the anchor; the synergist choice, ratio and stabilization around it decide whether the compound passes your exact spec stack at the lowest total loading.
We supply DEPAL as powder and as complete phosphinate packages — nitrogen synergist and stabilization balanced for your resin, burn-verified in-house at your wall thickness. Our halogen-free FR-PA66, FR-PA6 and FR-PBT standing grades run on this chemistry.
Fig. DP02 — burn verification in our labEvery phosphinate ratio is burn-tested at your wall thickness.
Fig. DP03 — export packagingBags, big bags and palletized supply for overseas buyers.Direct answers for formulators and procurement evaluating aluminum diethylphosphinate before sampling.
The aluminum salt of diethylphosphinic acid — a metal phosphinate with ~23–24% phosphorus, halogen-free and antimony-free. It is the workhorse chemistry behind halogen-free V-0 grades of glass-filled PA66, PBT and TPU.
Because the spec stack goes past UL94: phosphinate compounds hold CTI in the 400–600 V class for tight creepage, reach V-0 at 0.8 mm with GWIT 775 °C, and color cleanly in HV signal orange — four boxes brominated systems cannot tick together.
Melamine polyphosphate (MPP) in PA66 and PBT; melamine cyanurate (MC) in TPU and softer systems. The nitrogen partner sharpens char formation and cuts the total loading — our packages arrive pre-balanced so you dose one product, not three.
Per kilogram, yes — it is the premium route. Per qualified part it often closes the gap: lower density than mineral routes, no antimony exposure, and it unlocks specs (CTI, halogen-free, colors) that bromine simply cannot bid on. We quote both routes where both qualify.
Send your resin and glass content, the full spec line (UL94 class at wall, GWIT, CTI), and color requirements. We will design the phosphinate package — and prove it in our burn lab before you commit a line trial.