FR synergist and smoke suppressant for rigid PVC, polyolefins, and engineering plastics. Partial ATO replacement with superior smoke suppression profile.
FL-ZS is a zinc stannate (ZnSnO₃) flame retardant synergist and smoke suppressant for rigid and flexible PVC, polyolefins, engineering plastics, thermosets, and rubber. It functions as a partial replacement for antimony trioxide (ATO) in halogenated FR systems, with the advantage of superior smoke suppression and no IARC Group 2B classification.
| Property | FL-ZS Value |
|---|---|
| Chemical name | Zinc Stannate (ZnSnO₃) |
| CAS No. | 12036-37-2 |
| Zinc content | ~35% |
| Tin content | ~43% |
| Form | White powder |
| Particle size (D50) | ~3–5 μm |
| Density | ~3.9 g/cm³ |
| Decomposition onset | Highly thermally stable |
| Halogen content | None |
| TSCA status | Listed |
| IARC classification | None (vs Group 2B for ATO) |
| Typical ATO replacement loading | 3–6 phr (partial replacement) |
| Packaging | 25 kg bags / 500 kg supersacks |
| U.S. lead time | Confirmed at quotation |
FL-ZS operates through combined gas-phase and solid-phase mechanisms. In the gas phase, tin and zinc species inhibit radical chain reactions during combustion, synergizing with halogen released by the primary FR (TCPP, TDCPP, or brominated FR). In the solid phase, zinc and tin oxides formed during decomposition catalyze char formation at the polymer surface, providing a physical barrier that reduces heat release and smoke generation.
This dual mechanism is why FL-ZS typically delivers better smoke suppression than ATO at equivalent loadings. ATO operates gas-phase only with no solid-phase contribution.
| Substrate | FL-ZS | Notes |
|---|---|---|
| Rigid PVC | ✓ Primary recommendation | Commercially proven in profiles, sheets, conduit. Synergistic with TCPP/TDCPP. Good thermal stability. |
| Flexible PVC | ✓ Good | Use FL-ZHS for wire & cable where IEC 61034 smoke limits apply |
| Polyolefins (PP, PE) | ✓ Good | In combination with brominated FRs or halogen-containing co-additives |
| Engineering plastics (PBT, PA) | ✓ Good | Thermal stability advantage over zinc hydroxystannate in high-temp processing |
| Thermosets / epoxy | ✓ Good | FR synergist for epoxy laminates and coatings with brominated FRs |
| Rubber / elastomers | ✓ Good | PVC-based and halogenated rubber compounds |
| Halogen-free systems | ✗ Not suitable | Requires halogen to activate gas-phase mechanism. Use FL-ZB for LSZH. |
Starting evaluation: 3–5 phr FL-ZS as partial replacement for ATO in rigid PVC with TCPP or TDCPP. Maintain existing primary FR loading.
Formulation testing against target fire standard (UL 94, ASTM E84) required. Evaluation quantities available on request: contact us.
FL-ZS supplied DDP from a US-based supplier. SDS, TDS, TSCA compliance letter on request. DDP pricing: response within one business day.
Request FL-ZS Pricing & TDSZinc synergists technical guide · FL-ZS vs FL-ZHS comparison
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Related: compare FL-ZS with zinc hydroxystannate (FL-ZHS), see the full zinc synergist comparison, or read the ATO substitution guide.
Zinc stannate (FL-ZS) is a flame retardant synergist and smoke suppressant rather than a standalone flame retardant. It works alongside other flame retardants, contributing in both the gas phase and the condensed phase, and is used to reduce smoke as well as support flame retardancy. It is commonly used as an antimony trioxide alternative.
Yes, in many systems. FL-ZS is used as a partial antimony trioxide (ATO) replacement, a way to reduce ATO loading, or a synergist in brominated systems. Full ATO elimination is possible in specific systems but should be confirmed by application-specific fire testing (LOI, UL-94).
FL-ZS is used across rigid PVC, polyolefins, engineering plastics, thermosets, and rubber. Because it is thermally stable to high temperatures, it suits sustained higher-temperature processing where some other synergists are less suitable. Suitability for a specific compound should be confirmed by testing.