Flame Retardant

Magnesium Hydroxide Flame Retardant (MDH)

MAGNESIUM HYDROXIDE · MINERAL FLAME RETARDANT

High-Purity Synthetic Mg(OH)₂ for Halogen-Free Compounds

As a magnesium hydroxide flame retardant supplier, Sychem offers synthetic Magnesium Hydroxide (MDH) — a fatty-acid-coated, ultra-fine mineral flame retardant filler engineered for halogen-free polymer compounds. With ≥98% purity, sub-2 μm median particle size, and a high decomposition onset of 340 °C, our MDH delivers reliable smoke suppression and char promotion across wire & cable, EV battery components, and engineering thermoplastics — the workhorse mineral retardant of choice for high-loading, cost-sensitive halogen-free formulations.

Headline Performance Indicators

The four numbers that compounders care about most

≥ 98%
MG(OH)₂ PURITY
340 °C
DECOMPOSITION ONSET
< 2.0 μm
D50 PARTICLE SIZE
Halogen-Free
ROHS / REACH

Why Magnesium Hydroxide

Three engineering reasons MDH remains the dominant mineral flame retardant in halogen-free polymer compounds worldwide

01 / ENDOTHERMIC ACTION

Heat Absorption + Water Release

At 340 °C, Mg(OH)₂ decomposes endothermically into MgO and H₂O — absorbing heat from the flame front while releasing water vapor that dilutes combustible gases. The high decomposition onset enables compounding with engineering thermoplastics that mineral retardants like ATH cannot survive.

02 / SMOKE SUPPRESSION

Lower Smoke, Zero Toxic Acids

The MgO residue forms a protective ceramic layer that suppresses smoke generation and traps soot — outperforming halogen / antimony systems on smoke density and toxicity. Critical for transit, marine, and indoor cable applications subject to IEC 61034 and EN 45545.

03 / FORMULATION FLEXIBILITY

High-Loading Workhorse

Fatty-acid surface coating enables loadings of 50–65 wt% with retained mechanical performance. Pairs naturally with Sychem’s HF-80 / HF-90 phosphorus systems for synergistic char + endothermic action — the standard halogen-free wire & cable formula.

FULL TECHNICAL DATA

Synthetic Mg(OH)₂ — Verified Specifications

Fatty-acid-coated synthetic magnesium hydroxide · CAS No. 1309-42-8

Composition & Primary Properties
CAS 1309-42-8
Property Value Unit / Method
Mg(OH)₂ Content≥ 98%
MgO Content≥ 69%
Surface TreatmentFatty acid coatedFor polymer compatibility
Wetting Water Temperature340°C
Loss on Ignition≥ 30.0%
Whiteness≥ 98%
pH Value10 ± 1—
Physical & Particle Properties
PROCESSING
Property Value Unit / Method
Particle Size — D50< 2.0μm · Laser diffraction (ISO 13320)
Particle Size — D90< 5.0μm · Laser diffraction (ISO 13320)
Specific Gravity2.36g/cm³
Bulk Density (Volume)0.36g/cm³ · Range 0.3 – 0.5
Compaction Density0.54g/cm³
Mohs Hardness2.50—
Moisture (at 105 °C)≤ 0.26%
Trace Impurities
PURITY VERIFIED
Impurity Maximum Content (%)
Calcium Oxide (CaO)0.02
Iron (as Fe₂O₃)0.0008
Chloride (as Cl⁻)0.48
Moisture0.3
Acid Insoluble0.03
Verification: All values from the standard production grade. Particle size analysis follows ISO 13320 laser diffraction methodology. Custom particle size cuts (D50 sub-1 μm or D50 1.5 – 3 μm) are available on request for specialty applications. COA accompanies every shipment.
APPLICATIONS

Where Synthetic MDH Is Used

High-loading mineral flame retardant for halogen-free polymer compounds

LSZH Wire & Cable
Low-smoke zero-halogen insulation and jacketing for transit, marine, building cable
EV Battery Components
Battery pack covers, busbar insulation, thermal-runaway shielding
Engineering Plastics
PA, PBT, PPS, PPO compounds where high processing temp rules out ATH
EVA & Polyolefins
Cable compounds, high-loading FR formulations, photovoltaic encapsulation
Construction Materials
Insulation panels, composite boards, fire-rated wall systems
Rubber Compounds
EPDM and silicone fire-rated elastomers, conveyor belts
Adhesives & Sealants
Fire-rated PU and silicone formulations for construction joints
Synergy with HF-80 / HF-90
Co-loaded with phosphorus systems for char + endothermic action

MDH vs ATH — When to Specify Magnesium Hydroxide

Both are mineral flame retardants — but the 340 °C decomposition onset of MDH unlocks polymer systems that ATH cannot serve

Property MDH — Mg(OH)₂ ATH — Al(OH)₃
Decomposition Onset340 °C~ 220 °C
Engineering Plastics Compatible✓ PA, PBT, PPO, PPS✗ Decomposes during compounding
Smoke SuppressionExcellent — MgO ceramic layerGood
Endothermic Heat Capacity~ 1300 kJ/kg~ 1100 kJ/kg
Acid-Resistance / pH SensitivityMildly alkaline (pH 10) — stableAmphoteric — sensitive to acidic environments
Best ApplicationHigh-temp engineering compounds, EV, LSZH cableLower-cost PE / EVA cable jacketing
Sychem recommendation: We supply MDH as our primary mineral retardant focus — the 340 °C decomposition onset and superior smoke suppression align with the markets we serve (automotive, EV, engineering plastics, premium cable). For commodity PE / EVA cable applications where cost is the dominant constraint, ATH may be the right choice — contact our team to discuss.

Dosage Guidelines & Processing

Recommended starting points — final dosage depends on substrate, target rating, and co-additives

Dosage Recommendations by Substrate
STARTING POINT
Substrate Target Rating MDH Loading Notes
EVA — LSZH CableV-0 / IEC 6033255 – 65 wt%Pair with silane for mechanical retention
PP / PEV-0 @ 1.5 mm50 – 60 wt%Or co-load with 8 – 12% HF-90 for synergy
PA6 / PA66V-0 @ 1.6 mm35 – 45 wt%High decomp temp critical for nylon processing
EPDM RubberUL94 V-0100 – 150 phrConveyor belt and cable jacket compounds
PVCSmoke suppression8 – 15 phrCo-additive for low-smoke PVC
Decomposition Onset
340 °C
Stable through engineering plastic processing
Compounding Equipment
Twin-Screw
Co-rotating with side feeder for high loadings
Coupling Agent
Silane
0.5 – 1.5% silane improves mechanical retention
P-N Synergy Ratio
3 : 1 — 5 : 1
MDH to HF-80 / HF-90 for synergistic systems

Safety, Handling & Compliance

Non-hazardous goods classification with full regulatory documentation

✓ NON-HAZARDOUS

Hazard Classification

Classified as non-hazardous goods. No explosion hazard — environmentally friendly halogen-free flame retardant. No fire, no toxic gas evolution under normal handling conditions.

DUST EXPOSURE

Handling Precautions

Dust may enter via inhalation, ingestion, or absorption through nose and mouth. Use standard dust mask, eye protection, and ventilation when handling. No special hazardous-goods storage or transport required.

✓ COMPLIANT

Regulatory Documentation

Full documentation package available: SDS, TDS, COA, REACH registration, RoHS certification, halogen-free declaration. Packaged in 25 kg bags or 1 ton FIBC bulk bags. Container-load shipping worldwide.

The Sychem Sourcing Advantage

Reliable mineral flame retardant supply from China, with the technical depth of a specialty distributor

≥ 98%
Verified Purity
Every batch arrives with COA confirming Mg(OH)₂ content, particle size, and trace impurities.
FCL
Bulk-Ready Logistics
25 kg bags or FIBC bulk bags, full container loads, consolidated with magnesium FR portfolio.
P-N + MDH
One-Stop FR Sourcing
Pair MDH with our HF-80 / HF-90 phosphorus systems in a single shipment.
24h
Technical Response
Particle size selection, silane treatment guidance, and synergy formulation support within one business day.

Sample Synthetic MDH for Your Halogen-Free Compound

Tell us your polymer, target UL rating, and processing temperature — we will recommend the right MDH grade and confirm if synergy with HF-80 or HF-90 phosphorus systems can lower your total loading.

Request Sample & TDS →

Your Magnesium Hydroxide Flame Retardant Supplier

Magnesium hydroxide flame retardant (MDH) — high-purity synthetic Mg(OH)2 from SYCHEM TECH

SYCHEM TECH is a magnesium hydroxide flame retardant supplier based in Shenyang, China, offering high-purity (≥98%) synthetic, fatty-acid-coated MDH with sub-2 μm median particle size and a 340 °C decomposition onset for halogen-free wire and cable (LSZH), EV battery components, and engineering thermoplastics. As your formulation development partner, we match the right particle size, coating, and loading to your polymer and UL94 target, and can combine MDH with phosphorus systems to lower total loading. For background, see the overview of magnesium hydroxide.

Looking for a reliable magnesium hydroxide flame retardant with technical support? Tell us your polymer, target UL rating, and processing temperature, and our team will recommend an MDH grade and arrange samples. Explore the parent flame retardants range, our phosphorus-based flame retardants, and the full functional additives portfolio.