- ▸ Used as a flame retardant and smoke suppressant in PVC, polyolefins, nylon, and epoxy compounds, where it forms a protective borosilicate char layer and releases water of hydration to cool the polymer.
- ▸ Acts as a synergist alongside antimony trioxide and aluminum trihydrate, allowing formulators to partially replace antimony in halogenated systems while improving afterglow suppression.
- ▸ Incorporated into intumescent and fire-retardant coatings and paints to reduce flame spread and char-form on wood and structural substrates.
- ▸ Added to flame-retardant elastomers, rubber, and wire-and-cable insulation as an anti-tracking and arc-suppression agent.
- ▸ Applied to wood-composite, textile, and cellulosic treatments for combined flame retardancy and anti-fungal / preservative function.
A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.
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Zinc borate is a multifunctional flame retardant, smoke suppressant and afterglow suppressant — a halogen-free borate used both as a synergist (and partial antimony replacement) and as a flame retardant in its own right. Identity: CAS 1332-07-6.
What it is
Zinc borate (CAS 1332-07-6; the common commercial grade is the hydrated 2ZnO·3B2O3·3.5H2O, “Firebrake ZB” type) is a white powder. It is multifunctional — flame retardant, smoke suppressant, afterglow suppressant and anti-arcing/anti-tracking agent — and works in both halogenated and halogen-free systems.
How it performs in fire
It promotes char and forms a protective glassy borate layer, releases water of hydration endothermically, and suppresses smoke and afterglow. In halogenated systems it acts as a synergist and partial replacement for antimony trioxide; in halogen-free systems it boosts mineral and intumescent packages.
Applications
Zinc borate is used in PVC, polyolefins, elastomers, thermosets, coatings and wood-plastic composites, as a synergist with antimony trioxide or with mineral hydroxides (ATH/MDH). See the flame retardants guide.
Forms, grades and handling
Zinc borate is supplied as a fine white powder (hydrated grades) in bags and bulk. Properties are typical reference values; the Certificate of Analysis (CoA) for the lot you buy governs. Handle per the current Safety Data Sheet (SDS), and confirm regulatory status and restrictions for your market and end use. Each lot ships with CoA, TDS and SDS.
Bulk supply and RFQ
RawSource sources Zinc Borate direct from producers in bulk, with CoA, TDS and SDS per lot. Tell us your polymer or system, the fire test you must pass, your maximum loading, and any particle-size or grade requirement, and we will quote the right grade. See the full range and selection logic in the flame retardants guide.
Typical Properties
Typical reference values, not a specification; the Certificate of Analysis (CoA) for the lot governs.
| Property | Typical Value |
|---|---|
| Chemical / class | Flame retardant / smoke suppressant (borate) |
| Flame-retardant type | Multifunctional borate |
| Role in fire performance | Char + glassy layer; smoke & afterglow suppression |
| CAS Number | 1332-07-6 |
| Molecular Formula | B2O6Zn3 |
| Molecular Weight | 313.8 g/mol |
| Handling | Refer to the current SDS |
Regulatory & registration requirements
- TSCA (US):
- REACH (EU):
- EC number: 215-566-6
Source: EPA TSCA Inventory (July 2025 release) · ECHA CHEM — retrieved 2026-07-12
Frequently Asked Questions
What is zinc borate used for?
Zinc borate (CAS 1332-07-6) is a multifunctional halogen-free flame retardant, smoke suppressant and afterglow suppressant used in PVC, polyolefins, elastomers, coatings and wood-plastic composites, both as a synergist (and partial antimony-trioxide replacement) and as a flame retardant in its own right.
Can zinc borate replace antimony trioxide?
Yes, partially — zinc borate is widely used to reduce antimony trioxide loading while adding smoke and afterglow suppression and char/glass-layer formation; the optimum ratio depends on the polymer and the fire test.
How is bulk zinc borate supplied and quoted?
RawSource supplies zinc borate in bulk with CoA, TDS and SDS per lot. Pricing is quote-based on grade, particle size and volume; submit an RFQ with your polymer/system and the fire test you must pass.
What is the REACH and TSCA regulatory status of Zinc Borate?
Zinc Borate (CAS 1332-07-6) is subject to U.S. TSCA Inventory requirements; supplying it into the EU requires valid REACH registration ((EC) No 1907/2006). RawSource cannot verify a third-party supplier's registrations — buyers should require documented TSCA and REACH compliance for their jurisdiction and volume (EC 215-566-6).