One element, four very different products. Red phosphorus is the strongest flame retardant per gram in the industry — V-0 nylon at 6–10% — but only in dark colors. Phosphate esters keep PC/ABS clear-headed. APP builds intumescent char in polyolefins. Phosphinates own the EV connector. This page maps the family; we supply all four directions.
Fig. P01 — weighing a phosphorus FR ladderPhosphorus package weighed for a halogen-free trial.
Every phosphorus flame retardant ends the same way: phosphoric acid species form in the fire and force the surface to char instead of feeding the flame. What differs is the delivery vehicle — and the vehicle decides which resin each one fits.
Nearly pure phosphorus per gram. V-0 in glass-filled PA66 at 6–10% — half of what any other system needs, with mechanicals to match. The catch: dark colors only, and it demands encapsulated grades.
Liquid or low-melting aromatic phosphates (BDP, RDP) that dissolve into PC/ABS and charring resins. 8–14% for V-0 housings — the standard halogen-free route for laptop and appliance shells.
The other two family members have dedicated pages: ammonium polyphosphate for intumescent polyolefins, DEPAL for engineering plastics and EV connectors.
Char is the product. Everything phosphorus does converges on building and keeping a carbon shield.
Heat converts the phosphorus source to phosphoric and polyphosphoric acids right at the burning surface.
The acids dehydrate the polymer toward carbon. Fuel that would have fed the flame stays on the part as insulating char.
A share of phosphorus escapes as PO• radicals that quench the combustion chain in the gas phase — bromine’s job, done halogen-free.
The family splits cleanly by resin. Find your row; the column tells you what to ask for.
| Resin / Part | Phosphorus Route | Typical Loading | Watch-out | Related Page |
|---|---|---|---|---|
| Glass-filled PA66 (dark parts) | Encapsulated red phosphorus | 6–10% | Dark colors only; dry handling | FR nylon 66 guide |
| PC/ABS housings | Phosphate esters (BDP/RDP) | 8–14% | Heat distortion drops — verify HDT | FR polycarbonate |
| PP / PE compounds | APP intumescent system | 18–30% | Coated grades for humid service | APP page |
| GF PA/PBT connectors, TPU jackets | DEPAL + N-synergist | 15–22% | Premium cost; wins on CTI and color | DEPAL page |
| Flexible PVC (fire-safe plasticizer) | Phosphate ester partial swap | Partial DOP/DOTP replacement | Cost per phr rises; LOI climbs | FR PVC guide |
Same resin, same V-0 target, both halogen-free — and a factor-of-two loading difference. Color and CTI decide who wins.
Black connector bodies, under-hood parts, industrial housings: nobody sees the color, everybody sees the cost sheet.
Light housings, HV signal orange, tight creepage: the spec stack red phosphorus cannot enter.
Nine questions, one answer. Most inquiries resolve at the first three.
All four family routes from one lab: encapsulated red phosphorus masterbatch, phosphate ester packages, APP systems and DEPAL blends — each burn-verified at your wall thickness before we quote.
Fig. P02 — burn verification in our labEvery route is burn-tested at your wall before quoting.
Fig. P03 — export packagingBags, big bags and palletized supply for overseas buyers.The four that open most phosphorus inquiries.
A halogen-free family sharing one mechanism — phosphoric acid species force the polymer to char instead of burn. Four members: red phosphorus, phosphate esters, ammonium polyphosphate and metal phosphinates. Each owns different resins.
It is dark red-violet and tints every compound it enters — dark red, brown or black parts only. That single cosmetic limit, not performance, pushed light-colored connectors to DEPAL despite double the loading.
Encapsulated grades, yes — each particle is coated to block moisture and suppress phosphine. Use masterbatch form, keep the compound dry, follow SDS ventilation. Uncoated red phosphorus powder has no place on a compounding floor, and we do not supply it that way.
They lower heat distortion temperature — the ester is also a plasticizer. Typical V-0 loadings cost 10–20 °C of HDT, so verify the part’s service temperature before committing. Where HDT is tight, we rebalance the package rather than just cutting dose.
Resin, color, UL94 class at your wall — those three answers usually pick the route. Send them with your volume and we reply with the grade, loading and burn data.