Applications & Benefits
Firebrake® ZB is a multifunctional boron-based fire retardant with applications in a variety of plastic and rubber compounds. Since Firebrake® ZB releases its water of hydration at temperatures exceeding 290 °C (554 °F), it can be used in systems requiring high processing temperatures. Firebrake® ZB has a refractive index similar to that of most polymer systems, which results in the retention of considerable translucency and allows the use of low pigment loading. It can be fed into extruders, calenders, or injection molding equipment in much the same way as other solid polymer additives.
Firebrake® ZB is used as a flame retardant, smoke and afterglow suppressant, and anti-arcing agent in polymer systems such as polyvinyl chloride, nylon, epoxy, polyethylene, polypropylene, polyesters, thermoplastic elastomers and rubbers.
Depending on the base polymer used and fire standards to be met, Firebrake® ZB can be used to replace partially (or even completely) other fire retardant additives such as antimony oxide. In some systems, Firebrake® ZB displays synergism with antimony oxide. In halogen-containing systems, the usage level of Firebrake® ZB is in the range of 3-25 parts per hundred parts of resin (phr). In halogen-free systems, the recommended level is in the range of 10-250 phr, normally used in conjunction with alumina trihydrate, magnesium hydroxide, or a silicone polymer. Examples of starting point formulations are available upon request.
Firebrake® ZB-Fine is recommended for applications where maximum fire test performance is needed, and physical properties such as film forming and adhesion are critical. In contrast to Firebrake® ZB-Fine, the XF grade has no particles greater than 12 microns, as determined by laser diffraction technique.
Chemical and Physical Properties
Boric Oxide, B2O3 48.05%
Zinc Oxide, ZnO 37.45%
Water of Crystallization, H2O 14.50%
Anhydrous Equivalent 85.50%
Characteristics (typical values)
Refractive Index 1.58
Median Particle Size:
ZB 7 microns (Sedigraph)
9 microns (Laser diffraction)
ZB-Fine 3 microns (Sedigraph)
3 microns (Laser diffraction)
Solubility Less than 0.28% in water at room temp.
Stability Thermally stable up to 290 °C. Can be hydrolyzed by strong acids and bases.
Specific Gravity 2.77
Firebrake® ZB-Fine: A Zinc borate recommended for applications where maximum fire test performance is needed, and physical properties such as film forming and adhesion are critical.
Senior Development SpecialistFred Ascherl
Fred has worked for Rio Tinto Borates for over 37 years. He currently holds a position as a Senior Development Specialist.