Research Inventory of the Synergistic Flame Retardant Effect of Zinc Borate

What ingredients have a synergistic flame retardant effect with zinc borate?

In actual flame retardant technology, a single flame retardant is rarely used, but several flame retardants or flame retardant synergists are used in combination to achieve a synergistic flame retardant effect and reduce the amount of flame retardant. Herein, Alfa Chemistry focuses on the synergistic flame retardant effect of zinc borate and other ingredients and summarizes some research cases.

Zinc borate has a synergistic flame retardant effect with a variety of other ingredients, including antimony trioxide, aluminum hydroxide, ammonium polyphosphate, and melamine cyanurate. These combinations enhance the overall flame retardancy of the materials they are added to, providing improved fire resistance properties.

Synergistic flame retardancy of zinc borate and intumescent flame retardants

A new hybrid intumescent flame retardant (IFR) is prepared from silane coupling agent modified aluminum diethylphosphinate (ADP), neopentyl glycol (NPG) and melamine (MEL), and then combined with ZB compound forms a synergistic flame retardant system, which is used to improve the flame retardancy of linear low-density polyethylene (LLDPE). The results show that the maximum limiting oxygen index of LLDPE/IFRs/ZB composite material is 28.7%, and the combustion grade is V-0. [1]

Synergistic flame retardancy of zinc borate and intumescent flame retardants

Synergistic flame retardancy of zinc borate and antimony trioxide

In epoxy-based intumescent fire retardant coatings, the introduction of ZB and antimony trioxide (Sb2O3) can effectively suppress smoke and heat during the entire combustion process. On the one hand, ZB and Sb2O3 can improve the stability and density of the shielding layer, thereby inhibiting smoke generation and heat release. On the other hand, ZB and Sb2O3 absorb a large amount of heat during the melting process. [2]

Synergistic flame retardancy of zinc borate and red phosphorus

Microcapsules (Mic-MBP) based on melamine borate-coated red phosphorus (RP) were developed, and their synergistic flame retardant effect with ZB on polyethylene (PE) was studied. Research results show that the PE composite material with 20% Mic-MBP and 10% ZB has the best flame retardant performance, and its carbon residue has thermal stability. In this flame retardant system, Mic-MBP/ZB shows condensed and gas phase flame retardant effects. [3]

TEM micrograph of PS added with MgAl LDH/APP.

Synergistic flame retardancy of zinc borate and ammonium polyphosphate

The flame retardant formula of ammonium polyphosphate (APP)/ZB mixture was prepared by resin infusion method and used in natural fiber epoxy-based system. Studies have shown that the addition of 10% and 5% of APP and ZB particles, respectively, was found to produce synergistic effects and self-extinguishing flames with 0 s flame time, 0 s dripping time, and a burning length of less than 3 mm. [4]


  1. Xu, Ya, et al. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2022, 640, 128400.
  2. Zhang, Feng, et al. Journal of Thermal Analysis and Calorimetry, 2016, 123, 1319-1327.
  3. Liu, Junbang, et al. Journal of Vinyl and Additive Technology, 2022, 28(3), 591-603.
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