Halogen-free mineral flame retardants that cool the flame instead of fighting it: magnesium hydroxide (MDH) and aluminium hydroxide (ATH) absorb heat and release water vapor as they decompose — suppressing smoke at the same time. Supplied as surface-treated powders and pre-dispersed masterbatch for LSZH cable compounds, PE, EVA, PP and TPU.
Fig. MIN01 — mineral flame retardant powder & LSZH pelletsWhite mineral flame retardant powder and LSZH compound pellets.
Magnesium hydroxide flame retardant — Mg(OH)₂, "MDH" — is a halogen-free mineral that works by physics, not halogen chemistry: heated past ~330 °C it decomposes endothermically, soaking up heat and releasing water vapor that cools the flame zone, dilutes flammable gases and scrubs smoke. What remains is a magnesium oxide layer that insulates the polymer beneath. Aluminium hydroxide (ATH) works the same way at a lower temperature.
The high-temperature mineral: stable to ~330 °C, so it survives PP, PA and engineering-plastic processing where ATH cannot go. Stronger smoke suppression per kilogram.
The volume workhorse: decomposes from ~200 °C, lowest cost per kilogram of any flame retardant, ideal where processing stays below ~190 °C — PE, EVA, flexible PVC and rubber.
At 55–65% loading, untreated mineral turns a compound stiff and brittle. Stearic acid, silane and vinylsilane treatments plus coupling agents keep elongation, flexibility and line speed alive.
Fig. MIN02 — mineral flame retardant powder at incoming QCParticle size and surface treatment checked before compounding.
Fig. MIN03 — LSZH compound built on MDH/ATHLow-smoke validation on the finished cable compound.Three physical actions happen at once when the mineral decomposes — and all three matter to why LSZH specifications are built around this chemistry.
Decomposition is strongly endothermic — the mineral absorbs large amounts of heat from the flame zone, slowing the polymer below its ignition temperature.
Roughly a third of the mineral's mass leaves as water vapor, diluting flammable pyrolysis gases and oxygen at the surface — and washing smoke particles out of the plume.
The MgO / Al₂O₃ residue forms an insulating ceramic-like layer over the polymer, cutting heat flux and fuel release — a mineral char where the polymer itself makes none.
Mineral flame retardants dominate wherever low smoke and zero halogen are specification lines, and wherever high loadings are mechanically tolerable. Use this table as the first filter.
| Application | Preferred Mineral | Typical Loading | Key Targets | Notes | Related Page |
|---|---|---|---|---|---|
| LSZH cable jacket / insulation | ATH or MDH in EVA/PE host | 55–65% | IEC 60332 · 61034 smoke · 60754 acidity | Surface treatment decides flexibility and line speed | LSZH compounds |
| PE film, pipe & molded parts | ATH (economy) or MDH | 50–60% | UL94 · LOI 24–30 | Thick sections tolerate mineral loads film cannot | FR polyethylene guide |
| PP compounds | MDH only (ATH decomposes in process) | 50–60% | UL94 · GWFI | The classic case where the 330 °C stability earns its premium | FR polypropylene |
| TPU & elastomer jackets | MDH (fine, treated grades) | Limited by hardness budget | UL94 · VW-1 | Only harder grades tolerate meaningful mineral loads | FR TPU guide |
| Flexible PVC (smoke suppression) | ATH / MDH as co-additive | 20–60 phr | LOI 30+ · reduced smoke | Partners antimony and zinc borate in cable PVC | PVC flame retardant |
Same mechanism, one deciding variable: temperature. The choice is usually made by your processing window before any other property is discussed.
Your process or resin runs hotter than ATH survives — or smoke numbers are the hardest line in the spec.
Processing stays below ~190 °C and cost per rated meter is the priority — the majority of LSZH cable volume runs this way.
"MDH" on a label says almost nothing — particle size, morphology and surface treatment separate a compound that extrudes fast and bends clean from one that cracks on the spool.
We supply MDH and ATH as surface-treated powders, formulated packages and pre-dispersed masterbatch — matched to your host resin and verified in our own burn lab before shipment.
Fig. MIN04 — burn verification in our labEvery loading ladder is burn-tested before recommendation.
Fig. MIN05 — export packagingBags, big bags and palletized supply for overseas buyers.Direct answers for engineers and procurement comparing mineral flame retardants before sampling.
A halogen-free mineral flame retardant — Mg(OH)₂ — that decomposes endothermically at ~330 °C, absorbing heat and releasing water vapor that cools the flame and suppresses smoke, leaving an insulating magnesium oxide layer on the polymer.
Temperature. ATH starts decomposing around 200 °C and costs less; MDH holds to ~330 °C, so it can be compounded into PP, PA and other resins that process too hot for ATH. MDH also suppresses smoke somewhat more effectively per kilogram.
Mineral flame retardants work by mass: LSZH cable compounds typically run 55–65% loading. At that level, particle size, morphology and surface treatment decide whether mechanicals and extrusion speed survive — which is why grade selection matters more than the chemical name.
Yes — MDH and ATH are halogen-free inorganic minerals with no restricted substances, the default chemistry behind LSZH (low smoke zero halogen) compounds. RoHS/REACH documentation and third-party test reports ship with each batch.
Send your host resin, processing temperature, target standard (IEC 60332 / UL94 / LOI / smoke) and mechanical requirements. We will recommend the mineral, grade and surface treatment — and prove the loading in our burn lab before you commit a line trial.