What is Zinc Borate CAS 12767-90-7?

Zinc borate is a white inorganic flame-retardant powder supplied in the ZB-2335 grade, commonly described by the formula 2ZnO·3B2O3·3.5H2O. The product combines zinc oxide and boron oxide functionality with controlled particle size for compounding into plastics, rubber, and coatings.

How does zinc borate work as a flame retardant and smoke suppressant?

On heating, the hydrated zinc borate releases water, absorbs heat, and forms a glassy boron-rich layer that protects the substrate and stabilizes char. This mechanism reduces flame spread, slows oxygen transfer, and lowers smoke generation in many polymer systems.

Why is ZB-2335 suitable for high-temperature polymer processing?

ZB-2335 has a dehydration temperature above about 290 degrees C, so it remains stable during many demanding extrusion and compounding operations. Its high whiteness and D50 particle size of about 2.0-5.0 micrometers also help maintain good dispersion in PVC, polyolefins, engineering plastics, and rubber.

Can Zinc Borate CAS 12767-90-7 replace antimony trioxide completely?

It is usually used as a partial replacement or synergistic flame retardant with antimony trioxide and halogenated systems, not as a guaranteed one-for-one substitute. The optimal replacement ratio depends on the resin, flame-retardant package, processing conditions, and required UL or fire-performance result.

What types of products commonly use zinc borate?

It is used in PVC, polyethylene, polypropylene, synthetic rubber, wire and cable compounds, conveyor belts, and intumescent coatings. In intumescent coatings, it can act as a fluxing agent that helps stabilize the protective char layer during fire exposure.

Zinc Borate (ZB-2335) CAS 12767-90-7

Zinc Borate, specifically the 3.5 hydrate grade known as ZB-2335, CAS 12767-90-7, is a white inorganic flame retardant and smoke suppressant supplied for polymer compounding and intumescent coatings. Confirm the required grade and specification, then request a quotation with COA/TDS/SDS for bulk supply.

CAS: 12767-90-7
Synonyms: Boric acid zinc salt, Zinc Borate 2335, Anhydrous Zinc Borate, Flame Retardant ZB, Zinc Borate Hydrate.
Einecs: 235-804-2
Molecular Formula: 2ZnO·3B₂O₃·3.5H₂O
Grade: Industrial Grade / Flame Retardant Grade
Package: 25kg/bag, 500kg/bulk bag, or 1000kg/palletized bag

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Product Description

Zinc Borate (ZB-2335) CAS 12767-90-7 is a white inorganic flame-retardant powder, also known as boric acid zinc salt, with the formula 2ZnO·3B₂O₃·3.5H₂O and EINECS 235-804-2.

Synonyms: Boric acid zinc salt; Zinc Borate 2335; Anhydrous Zinc Borate; Flame Retardant ZB; Zinc Borate Hydrate.

CAS: 12767-90-7.

Molecular formula: 2ZnO·3B₂O₃·3.5H₂O.

It appears as a white inorganic powder with high whiteness and controlled particle size.

The D50 particle size is typically about 2.0-5.0 micrometers, supporting good dispersion in polymers.

On heating, the hydrated zinc borate releases water, absorbs heat, and forms a glassy boron-rich layer that stabilizes char.

This mechanism reduces flame spread, slows oxygen transfer, and lowers smoke generation in many polymer systems.

ZB-2335 has a dehydration temperature above about 290 °C, so it remains stable during demanding extrusion and compounding.

The typical zinc oxide (ZnO) content is about 37.0-40.0%, and boron trioxide (B₂O₃) about 45.0-48.0%.

It is usually used as a partial replacement or synergistic flame retardant with antimony trioxide and halogenated systems.

It is used in PVC, polyethylene, polypropylene, synthetic rubber, wire and cable compounds, conveyor belts and intumescent coatings.

Store in a dry, cool, well-ventilated area; it is non-hygroscopic, but avoid high humidity to prevent compaction.

Keep bags tightly sealed when not in use.

Confirm appearance, ZnO content, B₂O₃ content, whiteness, moisture, loss on ignition, particle size and grade as required.

Use suitable eye and skin protection during handling, and wash skin contact with soap and water.

Confirm packaging with the requested quantity and destination requirements.

The page is an RFQ entry point and does not state stock, price, MOQ or fixed lead time.

For an RFQ, state the intended application, required grade, quantity, packaging, destination and document needs.

FAQ - Technical & Supply Chain

Q:
What is Zinc Borate CAS 12767-90-7?

A: Zinc borate is a white inorganic flame-retardant powder supplied in the ZB-2335 grade, commonly described by the formula 2ZnO·3B2O3·3.5H2O. The product combines zinc oxide and boron oxide functionality with controlled particle size for compounding into plastics, rubber, and coatings.
Q:
How does zinc borate work as a flame retardant and smoke suppressant?

A: On heating, the hydrated zinc borate releases water, absorbs heat, and forms a glassy boron-rich layer that protects the substrate and stabilizes char. This mechanism reduces flame spread, slows oxygen transfer, and lowers smoke generation in many polymer systems.
Q:
Why is ZB-2335 suitable for high-temperature polymer processing?

A: ZB-2335 has a dehydration temperature above about 290 degrees C, so it remains stable during many demanding extrusion and compounding operations. Its high whiteness and D50 particle size of about 2.0-5.0 micrometers also help maintain good dispersion in PVC, polyolefins, engineering plastics, and rubber.
Q:
Can Zinc Borate CAS 12767-90-7 replace antimony trioxide completely?

A: It is usually used as a partial replacement or synergistic flame retardant with antimony trioxide and halogenated systems, not as a guaranteed one-for-one substitute. The optimal replacement ratio depends on the resin, flame-retardant package, processing conditions, and required UL or fire-performance result.
Q:
What types of products commonly use zinc borate?

A: It is used in PVC, polyethylene, polypropylene, synthetic rubber, wire and cable compounds, conveyor belts, and intumescent coatings. In intumescent coatings, it can act as a fluxing agent that helps stabilize the protective char layer during fire exposure.

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