Flame Retardants: SEMITECH Halogen-Free Portfolio — ATH, MDH, Surface-Treated Mineral Fillers, and Zinc Borate Synergists
SEMITECH supplies 7 halogen-free flame retardant grades — mineral fillers (ATH, MDH), surface-treated premium grades, and char-forming synergists (ZB, Sb₂O₃) — for HFFR cable jackets, intumescent coatings, mineral-filled engineering plastics, and EU CPR-compliant building cables.
Contents
| 7 | 180–340°C | 25 kg |
|---|---|---|
| Halogen-free grades | Decomposition window | Standard MOQ |
Why Halogen-Free Flame Retardants Now
REACH SVHC restrictions, EU CPR B2ca/Cca requirements, and end-customer halogen-free specs are driving a structural pivot from brominated to mineral-filler systems. Surface-treated grades are critical: untreated ATH at 60% loading gives LOI 32+ but tensile drops to ~6 MPa — silane- or zirconate-coated ATH recovers tensile to 10–12 MPa and elongation to 180–250%, qualifying for IEC 60332 cable burn tests.
Tier 1: Mineral Fillers — ATH and MDH Foundations
ATH — Aluminum Trihydrate, Al(OH)₃ (CAS 21645-51-2)
Decomposes endothermically at 180–200°C, releases 35% water vapor, leaves an alumina thermal barrier. Loaded at 50–65% in HFFR cable. SEMITECH supplies three cuts: ATH-1 (D50 1 µm, premium HFFR EVA), ATH-3 (D50 3 µm, workhorse), ATH-10 (D50 10 µm, high-loading non-critical). Thermal cap at 200°C excludes use in nylon, PBT, and engineering polymers.
MDH — Magnesium Dihydroxide, Mg(OH)₂ (CAS 1309-42-8)
Decomposition at 320–340°C — 120–140°C higher than ATH. The only viable mineral FR for nylon 6/66, PBT, and PPS compounding. SEMITECH supplies MDH-1 (D50 1 µm) and MDH-3 (D50 3 µm). Pricing runs 1.8–2.2× ATH — justified only when ATH thermal stability fails.
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Tier 2: Surface-Treated Premium — Silane and Zirconate-Coated Fillers
ATH-Silane — Vinyl- or Amino-Functional Silane Coated ATH
Silane at 0.5–1.0% on filler — recovers 30–50% tensile and 50–80% elongation versus untreated ATH at 60% loading. Vinyl-silane requires peroxide cure; amino-silane works in thermoplastic extrusion without cure step.
ATH-Zirconate — Premium Surface Treatment for HFFR Cable
Neoalkoxy-zirconate at 0.3–0.5% on filler reduces extrusion mixing torque 25–35%, enabling 15–20% higher throughput at 60–65% loading. Premium pricing 3–5× untreated ATH; payback is rapid when extrusion productivity is the constraint.
MDH-Silane — Engineering Plastic FR Compound Workhorse
KH-550 amino-silane on MDH for nylon 66 / PBT / PPS V-0 compounds at 50–55% loading. The cost-rational alternative to Nabaltec Apyral grades with 30% landed-cost savings.
Tier 3: Synergists — Zinc Borate and Antimony Trioxide
Zinc Borate (ZB-2335) — 4ZnO·6B₂O₃·7H₂O (CAS 138265-88-0)
Multifunctional synergist: char promotion (glassy borate layer at 290–450°C), smoke suppression (40–60% reduction in HFFR EVA), and anti-tracking (CTI +30–50 points). Loaded at 5–15% in HFFR cable, 3–8% in intumescent paint. Typical design: 55% ATH + 5% ZB in EVA.
Antimony Trioxide — Sb₂O₃ (CAS 1309-64-4)
Classical halogen synergist for legacy brominated FR systems. REACH SVHC since 2022. Supplied for inventory continuity — not promoted as a growth grade. Recommend migration to ATH/MDH + ZB over 24–36 months.
Regulatory Landscape: EU CPR, REACH, UL94, IEC 60754
EU CPR B2ca-s1,d1,a1 minimum for high-rise/hospital/tunnel cables mandates halogen-free, low-smoke formulations. REACH removed HBCD (2011), decaBDE (2017). RoHS caps brominated FRs at <0.1% in EEE. IEC 60754-1 requires acid gas <0.5%; IEC 60754-2 requires pH >4.3. SEMITECH provides full regulatory documentation per shipment — REACH, CPR, RoHS, and SVHC flagging.
SEMITECH Flame Retardant Grade Reference
| Tier | Grade | Chemistry / CAS | Decomp T | Typical Loading | Primary Application | Pack Size |
|---|---|---|---|---|---|---|
| 1 | ATH-1 / 3 / 10 | Al(OH)₃ / 21645-51-2 | 180–200°C | 50–65% | HFFR cable, EVA, PE | 25 kg / 1 t bag |
| 1 | MDH-1 / 3 | Mg(OH)₂ / 1309-42-8 | 320–340°C | 45–55% | Nylon, PBT, engineering plastics | 25 kg / 1 t bag |
| 2 | ATH-Silane (vinyl) | ATH + KH-171 / A-172 | 180–200°C | 55–65% | Peroxide-cure HFFR EVA cable | 25 kg / 1 t bag |
| 2 | ATH-Silane (amino) | ATH + KH-550 / A-1100 | 180–200°C | 55–65% | Thermoplastic HFFR PE / EVA | 25 kg / 1 t bag |
| 2 | ATH-Zirconate | ATH + Kenrich NZ-44/97 eq. | 180–200°C | 60–65% | High-throughput HFFR cable extrusion | 25 kg / 1 t bag |
| 2 | MDH-Silane | MDH + KH-550 | 320–340°C | 50–55% | Nylon 66 / PBT V-0 compounds | 25 kg bag |
| 3 | Zinc Borate (ZB-2335) | 4ZnO·6B₂O₃·7H₂O / 138265-88-0 | 290–450°C | 5–15% synergist | Char former, smoke suppressant | 25 kg bag |
| 3 | Sb₂O₃ | Antimony trioxide / 1309-64-4 | 650°C (mp) | 3–5 phr | Halogen synergist (legacy) | 25 kg drum |
CoA per shipment, 25 kg standard MOQ, 2–4 week ex-China lead time.
FAQ
+ATH or MDH — when should I specify each?
ATH (180–200°C) covers PE/EVA/EPDM cable, epoxy potting, UPE casting — all below 180°C processing. MDH (320–340°C) is mandatory for nylon 6/66, PBT, PPS. Cost is 1.8–2.2× MDH/ATH per kilogram; choose by downstream specification.
+Why does surface treatment matter so much for HFFR cable?
At 60% ATH loading, untreated filler gives tensile ~6 MPa and elongation ~80% — below cable specs. Surface treatment raises tensile to 10–12 MPa and elongation to 180–250% at the same loading. The 0.5–1.0% silane cost is small versus the formulation freedom.
+Is brominated FR still allowed in EU buildings?
Most are legacy-restricted under REACH/RoHS. EU CPR B2ca/Cca requires halogen-free directly. Buyers in EU construction should plan halogen-free migration.
+How much does surface treatment add to compound cost?
Silane (0.5% on filler): ~USD 18–24/tonne of compound. Zirconate (0.4% on filler): ~USD 60–84/tonne. Both are recovered via 8–15% premium on treated compounds.
+What MOQ, packaging and lead times apply?
25 kg sample qualification, 1 tonne production scale. Surface-treated grades in nitrogen-blanketed bags. Lead time 2–3 weeks to Asia, 4–5 weeks to Europe/NA.
+How do I qualify SEMITECH grades against Albemarle, Nabaltec, or J.M. Huber?
All grades target drop-in equivalence (ATH-1 vs Martinal OL-104, MDH-Silane vs Magnifin H10A). Send your spec for a 5–10 kg sample; typical qualification is 6–8 weeks.