Zinc Borates for Fire Retardancy, Safety, and Performance

:: Tuesday, June 1, 2021 :: Posted By Emmanuel Laval
Polymers are an essential building block for a vast number of the products we use every day. When you think of polymers, you may imagine “plastics”—which is right, in general. But think beyond plastic packaging to furniture, cable and wiring, appliances, cars, fabrics, carpet, building materials, plumbing fixtures, paint, and more. In this diverse and dynamic arena, polymer manufacturers continuously improve their processes to ensure they are providing high quality products while meeting evolving requirements for sustainability and safety.
A key element of concern across the polymer industry lies in the addition of flame retardants. Because polymers can ignite and burn easily, flame retardant additives are often required to meet safety standards. Our Firebrake® products are a unique form of zinc borate—a proven, multifunctional flame retardant—that is especially well-suited for polymer formulations.
Firemen battle a roaring fire
Leverage the multifunctional benefits of the zinc borates in Firebrake ZB and Firebrake 500 flame retardant products across a variety of polymer applications and formulations.
Watch the video >

Zinc borates for fire retardancy: Supporting sustainability and compliance

Polymer producers face a range of challenges as they strive to find a balance of sustainability, safety, and quality in their products.
Sustainability encompasses a range of requirements for polymer formulations. Demand for compostable or biodegradable bio-based polymers is growing, so producers must ensure that the flame-retardant additives will not be harmful to people or the environment when the product breaks down. In addition, those additives must not interfere with the product’s recyclability.
Producers must find additives that are safe across the entire lifecycle of the polymer compound, from production to use to recycling or incineration. Choosing a non-halogenated flame retardant is important for ensuring that when products are incinerated or degrade, they won’t form toxic chemical compounds such as dioxins and furans.
As a naturally occurring mineral compound, zinc borate—and the Firebrake ZB and Firebrake 500 products made from it—provides manufacturers with a safer and more sustainable flame retardant option for their formulations. In addition, Firebrake products—on their own or in combination with other additives—minimize interference with the quality and properties of the product.

Boosting your benefits by using Firebrake in polymers

Zinc borates function as flame retardants, smoke suppressants, afterglow suppressants, and anti-tracking agents in both halogen-containing and halogen-free polymers. In addition, zinc borates provide multiple other benefits such as enhancing corrosion resistance, promoting adhesion, and boosting UV protection and antimicrobial effects.
Firebrake products have low solubility and high thermal stability that enable them to integrate well in a wide range of polymer formulations—and withstand the intensity of polymer manufacturing processes. While Firebrake ZB and Firebrake 500 are highly effective flame retardants on their own, these products also have a synergistic effect when used in combination with metal-hydroxide flame retardants.
For example, magnesium hydroxide (MDH) and alumina trihydrate (ATH) are inorganic flame retardants that are commonly used because they are safe, effective, and low cost. However, to be effective, they need to be used at high loading in polymer formulations (up to 50-60% by weight in some systems).
At this level, there can be performance tradeoffs such as reduced physical or mechanical properties and reduced rheological performance. Adding a small amount of Firebrake to a metal-hydroxide–containing compound can result in synergistic performance benefits, improving both the compound’s fire performance and rheological properties. In this combination, Firebrake can further reduce the rate of heat release and smoke evolution and promote the formation of a strong char residue.
This synergistic effect allows manufacturers to reduce the total loading of fire-retardant additives in their formulations—thus also reducing the impact on physical and mechanical properties.

Stay on top of fire retardancy in polymers with Pinfa

To keep up with changes, regulations, and innovations in flame retardant technologies, polymer manufacturers turn to the Phosphorus, Inorganic and Nitrogen Flame Retardants Association North America (Pinfa-NA). U.S. Borax is proud to be a member of this non-profit trade organization and support its educational programs and events.
Pinfa-NA brings together manufacturers and users of fire-retardant technologies to advance best practices and use of environmentally friendly non-halogenated flame-retardant solutions. They help their members support fire safety through:
  • Innovative, reliable, and sustainable fire performance solutions
  • Sponsoring and participating in conferences and workshops on flame retardants and end uses
  • Monitoring and working with industry and regulatory organizations

For help choosing the right Firebrake product for your polymer application, contact the technical experts at U.S. Borax. We are here to help ensure your success.



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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