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Polymer flame retardant for any temperature

The U.S. Borax Firebrake® family of products can be used in a multitude of formulations for fire retardancy in polymers, plastics, and rubber compounds.

Firebrake ZB is a unique zinc borate that combines the best of zinc and boron oxides with water release. Because Firebrake ZB releases its water of hydration at temperatures exceeding 290 °C (554 °F), it can be used in systems that require high processing temperatures. Firebrake ZB has a refractive index similar to that of most polymer systems, so it retains considerable translucency and enables the use of low pigment loading.

Firebrake 500 is an anhydrous zinc borate for multi-functional fire-retardant applications in a variety of polymers. Because it contains no water of hydration, it is stable up to 600 °C (1112 °F) and can be used in polymer systems that require very high processing temperatures.

Firebrake applications

What can Firebrake products do for you?

Both Firebrake products can be fed to extruders, calenders, or injection molding equipment, much like other solid polymer additives.

Firebrake ZB provides fire retardant protection for polymers

Firebrake ZB is used as a flame retardant, char promoter, afterglow and smoke suppressant, and anti-arc agent in polymer systems, including:

  • Polyvinyl chloride

  • Nylon

  • Epoxy

  • Polyethylene

  • Polypropylene

  • Polyesters

  • Elastomers

Depending on the base polymer that you use and the fire protection standards you must meet, you can use Firebrake ZB to partially or completely replace other fire-retardant additives such as antimony oxide. (In some systems, Firebrake ZB displays synergism with antimony oxide.)

For situations that demand maximum fire-test performance as well as film forming and adhesion, Firebrake ZB is available in a fine formulation.

Firebrake products are used in a variety of fire retardant applications.

Firebrake 500 protects polymers in very-high-temperature processes

Firebrake 500 is an anhydrous form of Firebrake ZB that is specially designed for applications in which no water evolution is permitted. You can use Firebrake 500 as a flame retardant, char promoter, and smoke suppressant in a variety of polymers, including:

  • High temperature polyamides (PPA) and polyamide 6.6

  • Polyetherketones

  • Polysulfones

  • Fluoropolymers

  • Polyesters

Firebrake 500 has a significant beneficial effect on the rate of heat release, a quality that is of special interest in aircraft applications. It can also function as a corrosion inhibitor in polymer processing.

Firebrake

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U.S. Borax products are used in a variety of fire retardant applications, including polymer-based applications, cellulose protection, lumber, and plywood.

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Polymers and coatings

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Firebrake ZB technical details

Chemical and physical properties

› Refractive Index: 1.58

› Median particle size (laser diffraction): Firebrake ZB Fine: ≤ 2.5 microns

› Molecular weight: 434.67

› Specific gravity: 2.77

› Appearance: White, crystal-like powder

› Solubility: Less than 0.28% in water at room temperature

› Stability: Thermally stable up to 290 °C (554 °F); can be hydrolyzed by strong acids and bases

Chemical composition (theoretical)

› Boric oxide, B2O3: 48.05%

› Zinc oxide, ZnO: 37.44%

› Water of crystallization, H2O: 14.51%

› Anhydrous equivalent: 85.49%

› Containers: 22.7 kg (50 lbs) and 25 kg (55 lbs) multi-wall paper bags with a polyethylene moisture-resistant film barrier; and IBCs

Firebrake ZB product details

Specification sheets
Additional downloads
Related resources
Additional assistance

Have questions about how Firebrake ZB is working in your formulations? Contact our fire retardancy and polymer technical expert for help.

Firebrake 500 technical details

Chemical and physical properties

› Refractive Index: 1.58

› Median particle size: ≤12 microns (laser diffraction)

› Weight loss (TGA): 1.5% maximum to 400 °C

› Stability: Thermally stable to >600 °C; can gradually absorb surface moisture

› Molecular weight: 371.62

› Specific gravity: 2.6

› Appearance: White, crystal-like powder

› Stability: The product is chemically stable and shows little tendency to cake.

Chemical composition (theoretical)

› Boric oxide, B2O3: 56.20%

› Zinc oxide, ZnO: 43.80%

› Containers: 25 kg (55 lbs) plastic bags and IBCs

› Store Firebrake 500 in a sealed container because of its tendency to gradually pick up surface moisture in high-humidity environments. This surface moisture is easily removed by heating at about 200 °C.

Firebrake 500 product details

Specification sheets
Additional downloads
Additional assistance

Have questions about how Firebrake 500 is working in your formulations? Contact our fire retardancy and polymer technical expert for help.

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