Phosphorus-Containing Flame Retardants of the Future for Polymer Materials

Flame retardants (FRs) are materials or substances that prevent or slow the spread of fire. They are essential additives in plastic materials. Flame retardants can therefore make a decisive contribution to the safety of people, animals, buildings, furniture, electrical and electronic appliances, textiles, as well as public and private means of transport. Since July 2008, the European Union has banned a large proportion of halogenated flame retardants currently on the market for environmental reasons. Phosphorus-based flame retardants (PBRs) are a promising alternative. They can act in different ways: either in the gas phase, by capturing the flame radicals responsible for flame propagation; or in the condensed phase, by promoting a barrier effect through the formation of a charcoal layer. These modes of action were presented in the first section [AF 6047] , as well as commercial phosphorus-based flame retardants.

The literature is rich in new phosphorus-based flame retardants, but a few approaches seem more relevant to the phosphorus-based flame retardants of the future. Current research into new phosphorus-based flame-retardant systems is broadly in line with a sustainable development dynamic, and involves two distinct approaches. The first is to improve the effectiveness of current phosphorus-based flame retardants through synergy effects, so as to reduce the amount of phosphorus-based flame retardants required. The second is to mitigate the negative impacts of flame retardancy (plasticization, migration, etc.) by using oligomeric or reactive phosphorus flame retardants. This latter approach is also being developed on biobased raw materials, so as to reduce the carbon footprint of the phosphorus flame retardant.