Zinc Borate is a multifunctional, halogen-free flame retardant, smoke suppressant, and anti-arcing agent. It is the most common commercial grade of zinc borate, known for its synergistic effects with a wide range of polymers and other flame retardants.

Flame Retardant Mechanism Zinc Borate’s (ZB-2335) mechanism is complex and multifunctional:

1. Endothermic Decomposition: Starting at ~290°C, it undergoes a strong endothermic (heat-absorbing) decomposition, releasing 3.5 moles of water (approx. 13% of its weight). This action cools the polymer (heat sink) and dilutes the flammable gas concentration.

2. Glassy Layer Formation: The remaining anhydrous acts as a flux, melting at high temperatures to form a glassy, insulating barrier. This layer stabilizes and strengthens the char, blocking heat and oxygen.

3. Synergy & Smoke Suppression: In halogen systems (e.g., PVC), the acts as a potent acid scavenger (trapping /) and promotes cross-linking, which dramatically reduces smoke generation.

4. Afterglow Suppression: The borate component is a highly effective afterglow suppressant.

Key Application Areas

• Flexible & Rigid PVC: Widely used in wire & cable insulation/jacketing, profiles, and flooring as a smoke suppressant and synergist to reduce or replace Antimony Trioxide.

• Polyolefins (PE/PP) & TPEs: Used in halogen-free systems in synergy with ATH and MDH to improve char strength and fire performance.

• Polyamides (PA): Acts as a synergist in both halogenated and halogen-free PA systems.

• Coatings: Used in intumescent coatings to strengthen the insulating char foam.