Firebrake ZB: A Modern Choice for Fire Retardancy in Polymers

:: Monday, March 2, 2020 :: Posted By Emmanuel Laval
Polymers and plastics are part of nearly every area of modern life, from the furniture we use to the packaging of goods we buy to the electronics in our pockets. And, polymers are essential not only in how we live but also where we live. Our homes and public buildings include a dizzying array of polymer and composite materials that are used for both interior and exterior construction. From wiring and plumbing fixtures to wall panels, siding, roofing, and decking, polymers provide versatile and durable construction materials.
As with all types of building materials in modern construction, flame retardancy is a primary concern for builders in selecting the polymer-based materials they use. Some polymers, such as polypropylene or polyethylene, are highly flammable when they are unprotected, allowing flame to spread quickly. Others, such as polyvinyl chloride (PVC), are less flammable but release dense, toxic smoke in a fire. And, when polymers melt and drip, they can increase the spread of the fire.
20 Mule Team® Borax Firebrake® ZB is a flame retardant and smoke suppressant that can help improve the safety properties of polymer and composite materials—and increase the time that people inside a building have to escape if a fire happens.

Flame resistance and a healthy environment: Compounding builders’ critical concerns

As urban populations around the world continue to grow, builders face numerous challenges that go beyond simply keeping up with the demand for housing and other structures. They also must contend with increased regulations aimed at improving the safety of those structures while keeping health and environmental concerns firmly top of mind.
Although fire protection and safety has long been at the top of every builders’ regulatory list, finding flame-resistant polymer products can be a continuing challenge as some halogen-based fire-retardants (containing ingredients such as bromine and chlorine) have come under scrutiny. Today’s builders look to non-halogen-based fire retardants such as Firebrake ZB, nitrogen, and phosphorous compounds.

Slowing the burn: How Firebrake ZB improves the flame retardant properties of polymers

The dangers of fire are multiplied when polymers are involved. Polymers burn when they are heated to a decomposition temperature that breaks downs their polymer structure. This breakdown produces volatile gases, which also burn and radiate heat back onto the polymer—literally adding fuel to the fire and intensifying the burning process.
Firebrake ZB is a boron-based multi-functional flame retardant, smoke suppressant, and afterglow suppressant. Adding a flame retardant such as Firebrake ZB to the polymer during its manufacture changes the polymer composition and interferes with the combustion process, reducing the likelihood of fire.
If a flame does ignite, Firebrake ZB forms a protective vitreous layer. This strong layer reduces the degradation rate of the polymer, helping to prevent volatile gases from igniting and reducing dripping and flame spread.

Economy and effectiveness: Firebrake ZB is a smart choice for polymer manufacturers

Many polymer manufacturers seek to increase the positive properties of flame retardancy by using a combination of fire retardants to create synergistic benefits. Firebrake ZB is a halogen-free flame retardant, which makes it a safer alternative to halogen-containing products.
It can also be used in combination with other flame retardants, including non-halogenated flame retardants such as metal hydroxides, nitrogen/phosphorus compounds, and silicon-based flame retardants. The synergistic effects of these combination applications improve the flame-retardancy properties of the specific products they are used in, including PVC, polyamide (nylon), polyolefin, epoxy, acrylics, silicones, and various elastomers.
Firebrake ZB is made with boric acid and zinc oxide. Boric oxide is extracted and purified at the source, our mine in Boron, California. The refined boric oxide is then combined with pure zinc oxide at our Wilmington, California plant. The resulting product is pure, provides a highly consistent material for manufacturing formulations, and is easily available through our reliable and extensive distribution network.
A cost-effective alternative to more costly flame retardants such as antimony oxides, Firebrake ZB can be used in most polymers (halogen-containing or halogen-free) in various applications. Manufacturers rely on the quality and consistency of Firebrake ZB to provide multiple benefits:
  • A very fine particle size (either 1.8µm or 2.3µm), which is critical for good dispersion and surface finish
  • Stability at very high temperatures (Firebrake ZB is stable up to 290°C and Firebrake 500 can be used up to 500°C), which is essential for high temperature processing of polymers such as nylon
  • Consistent round particle shape for improved powder flow
  • Consistent bulk density and particle size distribution
  • Tight production specifications

Pioneering and perfecting flame retardants

U.S. Borax pioneered the use of zinc borate as a fire retardant. Our leading industry experts offer technical advice, troubleshooting, and formulation support to help our customers answer questions about:
  • Applications and uses of our products
  • Which polymer to use for an application
  • Polymer processing temperatures
  • Working with halogenated or halogen-free fire retardancy systems
  • Meeting fire safety standards
  • Smoke restrictions
In addition, we provide support and guidance for regional and global regulatory issues.
Want to talk to us in person? Visit U.S. Borax at the AMI Fire Retardants in Plastics conference, March 31-April 1.



U.S. Borax, part of Rio Tinto, is a global leader in the supply and science of borates—naturally-occurring minerals containing boron and other elements. We are 1,000 people serving 650 customers with more than 1,800 delivery locations globally. We supply around 30% of the world’s need for refined borates from our world-class mine in Boron, California, about 100 miles northeast of Los Angeles.  Learn more about Rio Tinto.

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