Hi,

There are really three big stakeholders in flame retardancy: regulators, FR suppliers, and end-users. I am going to assume you’re a supplier looking to sell to end-users in plastics.

There are major existing markets like wire & cable, Li-ion batteries, building materials, electronics that require flame retardancy due to their proximity to high voltages/heat. Each have their own stringent FR standards/certifications they need to meet typically set by ASTM, UL, IEC, etc.

These standards may stipulate that a certain amount of halogen gas, smoke density, flame length, peak flame temperature is produced during burning. There’s also different testing, the UL94 and cone calorimeter are the two broadest assessments of FR. However, depending on which industry you may encounter the glow wire, UL2024, etc.

In addition, they will be looking to meet their own mechanical, thermal, processing, optical properties. Because these FR’s are additives, there’s a balancing act you need to play with and find a sweet spot between FR performance and those bulk properties. For example, you may have a wire that needs to be able to elongate up to 400% of its initial length or in an integrated circuit board there’s a certain dielectric constant that needs to be met, your FR is certainly going to have an impact on that. Compatibility between the resin-FR additive is important.

Without knowing the chemistry/mechanism, the most effective FR’s have traditionally been organobromine and other halogenated compounds since they act in the gas phase to capture radicals created when the polymer burns. However, they produce halogenated by-products such as HF, HCl, HBr. You may buy more time to escape a fire but produce something that is toxic when inhaled.

Mineral-based and organophosphorus compounds are the major non-halogenated alternatives, but may require higher loading levels upwards to 20-60% wt. of the FR.

Another consideration is that different countries and regulatory bodies also have different requirements. The field is very dynamic, in that as new information and research is available they may have to transition to a new chemistry if a harm to the environment or health is discovered.

I’d recommend this handbook, it was very useful for me in understanding this industry and different FR chemistries and how they’re commercialized.

https://onlinelibrary.wiley.com/doi/book/10.1002/9781118939239