Zinc Borate (Firebrake ZB) Flame Retardant

Name: Zinc Borate (Firebrake ZB) Flame Retardant
Brand: Chemzip
Price: 1 USD
Availability: InStock

CAS Number: 138265-88-0

Zinc borate (2ZnO·3B2O3·3.5H2O, Firebrake ZB) is a multifunctional inorganic flame retardant, smoke suppressant, and afterglow suppressant used in halogenated and halogen-free polymer systems. It functions through endothermic dehydration, boron oxide glass-forming char promotion, and zinc ion Lewis acid catalysis. Zinc borate is widely used as a partial replacement for antimony trioxide in halogen systems, and as a synergist with ATH or MDH in halogen-free cable compounds, providing additional smoke suppression benefits.

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Technical Specifications

appearance	White powder
ZnO content (%)	37–39
B2O3 content (%)	47–49
dehydration onset (°C)	290–300
particle size D50 (µm)	5–8
water of crystallization (%)	13–14

Applications

Partial Sb2O3 replacement (up to 50%) in PVC and halogenated polymer FR systems
Halogen-free cable and wire compounds as ATH/MDH synergist for improved smoke suppression
Intumescent fire-retardant coatings as afterglow suppressant and char stabilizer
Cellulosic and wood composite products requiring combined FR and mold resistance
Rubber conveyor belts and seals requiring FR with smoke suppression certification

Key Features

Triple functionality: flame retardancy, smoke suppression, and afterglow inhibition in a single mineral additive
Partial Sb2O3 replacement (up to 50%) reduces cost while maintaining halogen FR system performance
High dehydration onset (290–300 °C) stable during PVC and engineering plastic processing
Synergy with ATH/MDH in halogen-free systems provides additional LOI improvement and smoke reduction