CAS No. 138265-88-0
EC No. 235-804-2
Synonyms Boric acid, Zinc salt, Hexaboron dizinc undecaoxide 3.5 hydrate

Zinc Borate

Zinc borate is a halogen-free, inorganic boron based multifunctional flame retardant. It is non-toxic, has excellent dispersibility in a number of different polymer systems and shows high thermal stability.

It is used in paints, adhesives, plastics, cellulose fibres , rubbers and textiles. As a flame retardant, it loses its water of hydration at temperatures above 290°C, cooling the front of the flames and subtracting energy to the fire and it can replace levels of antimony trioxide as a synergist in both halogen-based and halogen-free systems.

In halogen-containing systems, zinc borate can be used together with antimony trioxide and alumina trihydrate where it shows a strong synergistic effect. Here it catalyses the formation of char and creates a protective layer of glass It also acts as a synergist in conjunction with other halogenated compounds, so that lower loadings of halogenated flame retardant additives are required.

In halogen-free systems, zinc borate can be used together with alumina trihydrate, magnesium hydroxide, red phosphorus, or ammonium polyphosphate. .

Additionally Zinc borate is used in polyvinyl chloride, polyolefins, polyamides, epoxy resins, polyesters, thermoplastic elastomers, rubbers, etc. It is also used in some intumescent systems.


  • Non-toxic flame retardants          
  • Inorganic Additives
  • Fire retardants
  • Intumescent coatings
  • Preservatives in coatings
  • Agricultural micronutrients

Shelf Life

Under proper storage conditions, the shelf life is 36 months.

Health & Safety

Detailed information on the product described can be found in our relevant Health and Safety Information (Material Safety Data Sheet).